Quality of cross-infection control in dental laboratories. A critical systematic review

Quality of cross-infection control in dental laboratories. A critical systematic review Abstract Purpose To identify reported practices for cross-infection control in dental laboratories and to quantify the importance of the flaws encountered. Data sources Systematic search (cross-infection AND dental laboratory) at EMBASE, PubMed, SciELO and Scopus databases. Study selection Papers reporting on cross-sectional studies providing original data about cross-infection knowledge, practices and attitudes of dental technicians. Papers reporting on a single laboratory or institution were excluded. Data extraction Data extraction was undertaken independently by three reviewers using a purpose made form. The outcome of this study was analyzed in five aspects, namely process organization, disinfection, working environment, use of individual protective equipment and vaccination policy. Results of data synthesis The systematic search output was 1651 references and 11 papers were finally selected. Flaws were more frequently identified in terms of vaccination policy, biological safety of the working environment and use of individual protective equipment (100%). Slightly better results were found in terms of organization of the cross-infection control process (89.47%) and disinfection practices (85.71%). The application of the formula for disclosing the relative importance of the flaws identified in the literature prioritizes the need for interventions aimed at improving the organization of the cross-infection control procedures, followed by training in item disinfection. The control of the working environment together with the use of individual protective equipments rank closely in importance, followed by the existence of a vaccination policy Conclusions Sub-standard cross-contamination practices seem to be a common finding in dental laboratories, which may well compromise the quality of certain dental treatments. cross-infection, dental laboratories, dentistry, systematic review, patient safety Introduction One of the six domains describing quality in healthcare is patient safety (avoiding damage to patients from care intended to help them) [1]. Prevention of care-related contagion is a key issue, as it is reported the most common adverse effect on care delivery [2]. A number of potentially infectious biological agents from the dental team, the patient and the environment meet at the dental setting and contagions (including patient-to-patient transmissions) have been documented [3, 4]. In order to prevent these events, professional boards and government agencies have issued protocols and recommendations [5–7], which are reinforced by periodical inspections of dental offices in many countries. However, certain dental treatments require bespoke appliances which are not made within the clinical premises and have to be sent to a dental laboratory. Although most cross-infection control protocols include a section on this topic [5] and specific guidelines for preventing disease transmission within the dental laboratory exist [8], the issue does not seem to have been solved as these recommendations are not always fulfilled [9]. This is particularly relevant when infections of technicians working with contaminated prosthesis have been reported [10]. Moreover, ~25% of dental impressions received at commercial laboratories are visibly contaminated with blood [11] and >60% of the prostheses delivered from laboratories to dental clinics are contaminated with pathogens originated in the oral cavity of patients [12]. Despite the obvious need for cross-infection control at every stage of dental treatment, no information on the actual effects on patients of the flaws in disinfection observed at the laboratory could be retrieved. However, the number of dental prosthetic items installed in Spain in 2012 (5 37 4700) may help to understand the potential size of the problem [13]. The presence of non-oral bacteria with potential for causing serious diseases if passed to patients has also been identified in dental laboratory machinery [14]. Therefore, a potential for patient-to-patient and technician-to-patient cross-contamination via the prosthodontics laboratory certainly exists [15]. Furthermore, some authors consider that the real risk of cross-transmission in dentistry is probably higher than that of other clinical settings, once unrecognized or under-reported cases are accounted for [16]. Cross-infection control practices in dental laboratories vary worldwide, and existing reports on this issue offer a wide range of results but, despite the mixture of approaches used to assess this topic, the presence of sub-standard practices seems to be a common finding [17, 18]. Thus, the aim of this critical systematic review was to identify the reported practices for cross-infection control in dental laboratories and to quantify the importance of the flaws encountered in order to disclose targets for potential educational interventions. Methods and materials In order to achieve these objectives, a critical systematic review approach was chosen. This review follows the PRISMA guidelines (Preferred Reporting Items for Systematic reviews and meta-Analyses) [19] and its protocol was registered in PROSPERO (International Prospective Register of Systematic Reviews) with the code PROSPERO 2017:CRD42017058512. Papers were included if reporting on cross-sectional studies providing original data about cross-infection knowledge, practices and attitudes of dental technicians. Papers reporting on a single laboratory or institution were excluded. The EMBASE, PubMed, SciELO and Scopus databases were searched to identify relevant papers published from 1 January 1991 to 1 February 2017, together with a hand-search at the Galician network of university libraries. The search strategy was ‘cross-infection AND dental laboratory’ and was undertaken on 1 February 2017. No language limits were set. Two reviewers (Inés Vázquez-Rodríguez and Pablo Varela-Centelles) independently searched the databases and reviewed both titles and abstracts. The results were discussed and merged into a single list; a third reviewer (Urbano Santana-Mora) was called in case of disagreement. The resulting list included both relevant articles and those whose abstract did not provide clear or complete information. These papers were retrieved for full-text assessment. In the case of conference proceedings, the corresponding author was contacted in order to obtain the original report. This final set of publications was assessed by all three reviewers and differences about eligibility were solved by consensus. A flowchart of the study is depicted in Fig. 1. Figure 1 View largeDownload slide Flowchart of the study. Figure 1 View largeDownload slide Flowchart of the study. The numerical synthesis of the results was undertaken following a methodology previously developed by our group [20]. The quality of the selected reports was evaluated following the recommendations made by Bennet et al. [21] using a 38-item checklist. Each item was verified and its presence or absence was recorded in a custom-made form. A third option (partially/unclearly present) was also considered. Those articles showing >50% of the items were classified as ‘low-risk bias’, where those scoring >50% were considered at high risk for bias. Any other circumstance was categorized as ‘moderate risk’. Data extraction was undertaken independently by three reviewers (Inés Vázquez-Rodríguez, Ana Estany-Gestal and Pablo Varela-Centelles) using a purpose made form (Table 1). Table 1 Quality score of the selected studies   Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y    Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y  Table 1 Quality score of the selected studies   Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y    Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y  Cross-infection was defined as ‘any infection which a patient contracts in a healthcare institution’ [22]; cross-contamination was defined as ‘transfer of a contaminant from a source, specimen, etc., to a different or uncontaminated one’ [23]. Dental laboratory was defined as ‘facilities for the performance of services related to dental treatment but not done in the patient’s mouth’ [24], equipped for the fabrication of dental models and appliances (e.g. dentures, orthodontic devices, crowns and bridges, etc.). For the sake of this study, a flaw in aspects of care that lead to cross-infection was defined as ‘the absence of answer, incorrect answer, or erroneous identification or definition given by 10% or more of the sample investigated in each study’. The outcome of this study (knowledge, attitudes and practices about cross-infection control) was assessed in five aspects, namely process organization, disinfection, working environment, use of individual protective equipment and vaccination policy. The prevalence of flaws in each aspect for each paper is presented as a percentage of questions if a deficit was identified related to the total number of questions made to investigate it. To determine the relative importance (RI) of the flaws in each aspect, an expression was formulated using the number of papers investigating each aspect of the problem (research priority), their methodological quality (Q) (Table 2: headings methods, sample selection and research tool), the depth in which each aspect is studied (number of questions made) and the percentage of flaws identified (F): RIa = ∑Qn·Gn. Table 2 Summary of the papers included in the systematic review Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  Table 2 Summary of the papers included in the systematic review Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  This approach considers the importance of each aspect in the problem (the more important, the more studies would have investigated it), the quality of each independent report and the importance of the flaws identified in each aspect in each article. Results The systematic database search output was 1 651 references, which were merged with the three reports identified through the hand-search. After assessing their titles, 218 references were considered relevant. Once duplicates were removed, 188 single references were identified and their abstracts checked. As a result, 169 papers were discarded because they were not relevant to the aims of this investigation. Therefore, the full texts of the remaining 19 references [9, 15, 17, 18, 25–39] were retrieved. After assessing the full text of these 19 reports, 8 papers were discarded because they did not meet the inclusion/exclusion criteria set in the protocol of this systematic review: four of them described cross-infections protocols and another four dealt with respiratory disorders amongst dental technicians. Thus, 11 papers [9, 17, 18, 25–29, 37–39] were finally selected for analysis (Fig. 1). Assuming an average of eight technicians per laboratory [28], this systematic review summarizes the performance of 6057 dental technicians. Sample sizes ranged from 3200 [28] to 11 interviewees [25] from four continents: Europe [9, 25–27, 29, 38, 39], Asia [18], Africa [17] and America [28, 37] (Table 2). Most of the reports included in this review showed a high risk for bias [9, 17, 26–29, 37, 39] and only three were found to be at low risk [18, 25, 38] (Table 2). Flaws in cross-infection control procedures were identified in each individual study (raw data) and grouped into five key aspects (dimensions). The grouping process is summarized in Table 3 to preserve the richness of the original data and to clarify the procedure [40]. Table 3 Summary of the grouping process and presence of flaws in each study Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  Table 3 Summary of the grouping process and presence of flaws in each study Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  The information included in one report (conference proceedings) was incomplete [29] and the authors were contacted in order to obtain further details on their research but no response was obtained. When all dimensions were considered (Table 4), flaws were more frequently identified in terms of vaccination policy, biological safety of the working environment and use of individual protective equipment (100%). Slightly better results were found in terms of organization of the cross-infection control process (89.47%) and disinfection practices (85.71%). Table 4 Quantitative synthesis of the results (raw data) Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  Table 4 Quantitative synthesis of the results (raw data) Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  The methodological quality of the papers included in this systematic review (presence of the items in Table 2 under the headings ‘methods’, ‘sample selection’ and ‘research tool’) was expressed as a percentage divided by 10 and ranged from 0.53 [39] to 5.79 [25]. The application of the formula for disclosing the RI of the flaws identified in the literature prioritizes the need for interventions aimed at improving the organization of the cross-infection control procedures, followed by training in item disinfection. The control of the working environment together with the use of individual protective equipments rank closely in importance, followed by the existence of a vaccination policy (Fig. 2). The size of each point in the figure is related to the RI of each flaw in the cross-infection control process in the dental laboratory considered as a whole. Figure 2 View largeDownload slide Relative importance of the dimensions studied. Figure 2 View largeDownload slide Relative importance of the dimensions studied. Discussion When analyzing quality in dental care, patients’ top priority is adherence to the rules of antisepsis and sterilization [41]. Although the scope of this systematic review is focused on a particular part of dental care, the information obtained from each single report (Tables 2 and 3) may indicate that the dental laboratory could be the weakest link in the chain of cross-infection control. Contaminated items from the lab may not reach the patient, as they could be disinfected on arrival at the clinic (which is not assessed in this review), but the high percentages (~60%) of contaminated items not disinfected when leaving the dental office [12, 42] and the poor communication between laboratories and clinics [9, 17, 18, 25, 28, 38], make cross-contamination control practices for preventing cross-infection in the dental laboratory a matter of concern from the perspectives of both quality of care and occupational hazard [8, 14]. It may be argued that all papers reporting on cross-infection control practices in dental laboratories should be considered in this critical systematic review. Although no paper was finally excluded for reporting on a single laboratory or institution, we set this exclusion criterion because perhaps these papers would be more likely to describe examples of ‘best practices’, as investigations with a poor outcome would have less chances to be disclosed out of the concerned institution (publication bias). In addition, reports using an epidemiologic approach would better reflect the situation on a particular area than a paper reporting on a single laboratory. Reports on this topic are scarce and mostly based on relatively small convenience samples in a variety of geographical areas. These investigations use a range of survey-type approaches with different questionnaires assessing particular aspects of the problem (Table 3). These variations in methods and outcomes result in such a scattered and fragmented information that it is very difficult to obtain a general perspective on the situation. In fact, and to the best of our knowledge, this is the first attempt to summarize available data through a systematic review approach. The quality assessment of the reports included in the review has disclosed papers at low risk of bias: two from Europe [25, 38] and one from Asia [18]. The differences in the way survey instruments were applied (most groups used a self-applied questionnaire [9, 17, 18, 25, 27, 36, 38, 39], whereas other reports chose face-to-face [29, 37] or telephone [28] interviews), together with those related to sampling methods or sample size may have influenced response rates, reliability and representativeness of the information obtained. However, the results reported by the individual investigations point at the same direction, so these hypothetical biases may not have critically affected the resulting image of the problem of cross-contamination control in dental laboratories obtained from this review. A major difficulty in synthesizing the information from the selected publications was the broad range of questions employed by the different research groups. Our approach to this challenge was to gather related questions under five key aspects (dimensions) of cross-infection control, and to assume that both the type and the number of questions made by each research group for each dimension reflects the importance of each aspect in a particular geographical area. However, more questions about a dimension do not necessarily imply a more precise picture of the situation. Our results show a generalized lack of compliance with existing recommendations with 100% flaws in most dimensions. Although some dimensions (‘disinfection practices’ and ‘process organization’) behaved slightly better, their scores ranked well above 80% of errors (85.71% and 89.47% respectively). The threshold established in our definition of flaw (10% of error/non-response) may explain these poor results, as a less demanding standard would have shown a less disheartening picture. Even so, our view was that a percentage of errors beyond 10% for healthcare professionals, in basic routine practice, within their field of expertise, requires intervention for improving performance. The high risk for bias observed for some reports may have also influenced our raw results, but the introduction of weighting factors, like methodological quality and the depth in which each dimension is studied, may contribute to overcome these shortcomings. Our results (Fig. 2) prioritize the need for improving the organization of the process of cross-contamination control (communication with the clinic and existence of written protocols in the laboratory), which agrees with the conclusion of several research groups assessing their local realities [9, 25, 27, 28]. A common finding in the literature is the need for an improvement in disinfection practices, which our weighted results rank in second position. In this sense, it seems reasonable that once the relevant information (protocol) has been provided, the probabilities for a better disinfection increase. Unfortunately, this is not as straightforward as knowledge is necessary but not sufficient for changing a behavior [43]. Additional components may be needed to ensure an improvement in cross-infection control practices, such as the implementation of effective external monitoring for these practices [29]. The third and fourth priorities for intervention identified by our results are related to occupational hazards (biological safety of the working environment and use of individual protective equipment). This lack of compliance has been put down to a misperception of the level of risk [17] and negligence towards self-protection [26]. These findings are also interesting as government agencies in many countries issue mandatory regulations on occupational hazards which do not seem to be effective in this particular environment. The last area for intervention among the five dimensions of cross-infection control considered in this systematic review is the existence of vaccination policies for dental technicians. Although vaccination can not be compulsory in most countries, hepatitis B virus (HBV) immunization is strongly recommended for dental care workers and dental technicians are not an exception [8, 44]. The percentage of vaccinated technicians against HBV in the analyzed reports ranges from 59.6% [37] to 10% [18]. Some explanations for the overwhelming dismissal of cross-infection control guidelines may be related to the absence of continuous professional development courses on this topic, either voluntary [17, 25, 28] or compulsory [18], to a lack of monitoring of these practices [29], or even to technicians’ negligence and lack of interest [26]. The avoidance of an ‘additional’ financial burden [26] has also been described. An issue often mentioned in the literature which may have a part in these attitudes is the possibility for the disinfecting chemical agents to affect precision of dental impressions [28, 45], although adequate training on disinfectant selection and use may solve this inconvenience. Anyhow, cross-contamination probability between the clinical setting and the dental technician seems to be greater than contamination risks between dentist and patients or from one patient to another [46]. In fact, and despite the lack of contact with patients, dental technicians have been reported to experience significantly higher exposure to hepatitis B virus than a comparable population (2.7% vs. 0.76%) [47]. Our study permitted the synthesis of incomplete and scattered information to produce a portrait of the situation of cross-infection control practices in dental laboratories. Existing isolated studies undertaken in very different settings may hide the size of a problem which is more extended and deeper than what may have been expected. Besides identifying gaps of knowledge, the methodology used in this critical systematic review (data extraction and grouping, and determination of the RI) also permitted a prioritization of the educational needs to be satisfied. In general terms, specific educational interventions should be implemented in aspects like communication with the dental clinics and designing updated protocols to solve the observed flaws in these processes. 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Incidence of hepatitis B exposure among USAF dental laboratory technicians. Am J Dent  1990; 3: 236– 8. Google Scholar PubMed  © The Author(s) 2018. Published by Oxford University Press in association with the International Society for Quality in Health Care. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal for Quality in Health Care Oxford University Press

Quality of cross-infection control in dental laboratories. A critical systematic review

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press in association with the International Society for Quality in Health Care. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
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1353-4505
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1464-3677
D.O.I.
10.1093/intqhc/mzy058
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Abstract

Abstract Purpose To identify reported practices for cross-infection control in dental laboratories and to quantify the importance of the flaws encountered. Data sources Systematic search (cross-infection AND dental laboratory) at EMBASE, PubMed, SciELO and Scopus databases. Study selection Papers reporting on cross-sectional studies providing original data about cross-infection knowledge, practices and attitudes of dental technicians. Papers reporting on a single laboratory or institution were excluded. Data extraction Data extraction was undertaken independently by three reviewers using a purpose made form. The outcome of this study was analyzed in five aspects, namely process organization, disinfection, working environment, use of individual protective equipment and vaccination policy. Results of data synthesis The systematic search output was 1651 references and 11 papers were finally selected. Flaws were more frequently identified in terms of vaccination policy, biological safety of the working environment and use of individual protective equipment (100%). Slightly better results were found in terms of organization of the cross-infection control process (89.47%) and disinfection practices (85.71%). The application of the formula for disclosing the relative importance of the flaws identified in the literature prioritizes the need for interventions aimed at improving the organization of the cross-infection control procedures, followed by training in item disinfection. The control of the working environment together with the use of individual protective equipments rank closely in importance, followed by the existence of a vaccination policy Conclusions Sub-standard cross-contamination practices seem to be a common finding in dental laboratories, which may well compromise the quality of certain dental treatments. cross-infection, dental laboratories, dentistry, systematic review, patient safety Introduction One of the six domains describing quality in healthcare is patient safety (avoiding damage to patients from care intended to help them) [1]. Prevention of care-related contagion is a key issue, as it is reported the most common adverse effect on care delivery [2]. A number of potentially infectious biological agents from the dental team, the patient and the environment meet at the dental setting and contagions (including patient-to-patient transmissions) have been documented [3, 4]. In order to prevent these events, professional boards and government agencies have issued protocols and recommendations [5–7], which are reinforced by periodical inspections of dental offices in many countries. However, certain dental treatments require bespoke appliances which are not made within the clinical premises and have to be sent to a dental laboratory. Although most cross-infection control protocols include a section on this topic [5] and specific guidelines for preventing disease transmission within the dental laboratory exist [8], the issue does not seem to have been solved as these recommendations are not always fulfilled [9]. This is particularly relevant when infections of technicians working with contaminated prosthesis have been reported [10]. Moreover, ~25% of dental impressions received at commercial laboratories are visibly contaminated with blood [11] and >60% of the prostheses delivered from laboratories to dental clinics are contaminated with pathogens originated in the oral cavity of patients [12]. Despite the obvious need for cross-infection control at every stage of dental treatment, no information on the actual effects on patients of the flaws in disinfection observed at the laboratory could be retrieved. However, the number of dental prosthetic items installed in Spain in 2012 (5 37 4700) may help to understand the potential size of the problem [13]. The presence of non-oral bacteria with potential for causing serious diseases if passed to patients has also been identified in dental laboratory machinery [14]. Therefore, a potential for patient-to-patient and technician-to-patient cross-contamination via the prosthodontics laboratory certainly exists [15]. Furthermore, some authors consider that the real risk of cross-transmission in dentistry is probably higher than that of other clinical settings, once unrecognized or under-reported cases are accounted for [16]. Cross-infection control practices in dental laboratories vary worldwide, and existing reports on this issue offer a wide range of results but, despite the mixture of approaches used to assess this topic, the presence of sub-standard practices seems to be a common finding [17, 18]. Thus, the aim of this critical systematic review was to identify the reported practices for cross-infection control in dental laboratories and to quantify the importance of the flaws encountered in order to disclose targets for potential educational interventions. Methods and materials In order to achieve these objectives, a critical systematic review approach was chosen. This review follows the PRISMA guidelines (Preferred Reporting Items for Systematic reviews and meta-Analyses) [19] and its protocol was registered in PROSPERO (International Prospective Register of Systematic Reviews) with the code PROSPERO 2017:CRD42017058512. Papers were included if reporting on cross-sectional studies providing original data about cross-infection knowledge, practices and attitudes of dental technicians. Papers reporting on a single laboratory or institution were excluded. The EMBASE, PubMed, SciELO and Scopus databases were searched to identify relevant papers published from 1 January 1991 to 1 February 2017, together with a hand-search at the Galician network of university libraries. The search strategy was ‘cross-infection AND dental laboratory’ and was undertaken on 1 February 2017. No language limits were set. Two reviewers (Inés Vázquez-Rodríguez and Pablo Varela-Centelles) independently searched the databases and reviewed both titles and abstracts. The results were discussed and merged into a single list; a third reviewer (Urbano Santana-Mora) was called in case of disagreement. The resulting list included both relevant articles and those whose abstract did not provide clear or complete information. These papers were retrieved for full-text assessment. In the case of conference proceedings, the corresponding author was contacted in order to obtain the original report. This final set of publications was assessed by all three reviewers and differences about eligibility were solved by consensus. A flowchart of the study is depicted in Fig. 1. Figure 1 View largeDownload slide Flowchart of the study. Figure 1 View largeDownload slide Flowchart of the study. The numerical synthesis of the results was undertaken following a methodology previously developed by our group [20]. The quality of the selected reports was evaluated following the recommendations made by Bennet et al. [21] using a 38-item checklist. Each item was verified and its presence or absence was recorded in a custom-made form. A third option (partially/unclearly present) was also considered. Those articles showing >50% of the items were classified as ‘low-risk bias’, where those scoring >50% were considered at high risk for bias. Any other circumstance was categorized as ‘moderate risk’. Data extraction was undertaken independently by three reviewers (Inés Vázquez-Rodríguez, Ana Estany-Gestal and Pablo Varela-Centelles) using a purpose made form (Table 1). Table 1 Quality score of the selected studies   Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y    Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y  Table 1 Quality score of the selected studies   Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y    Jagger [9]  Kugel [28]  Campanha [37]  Akeredolu [17]  Hatzikyriakos [27]  Al-Dwairi [18]  Almortadi [38]  Bârlean [39]  Sandulescu [29]  Diaconu [26]  Marinheiro Marques [25]  Background   Justification of research method  N  N  N  N  N  N  N  N  N  N  N   Background literature review  N  Y  N  Y  NC  Y  Y  NC  N  Y  Y   Explicit research question  N  Y  N  Y  N  N  Y  N  N  Y  N   Clear study objectives  NC  NC  Y  Y  Y  Y  Y  NC  Y  Y  Y  Methods   Description of methods used for data analysis  Y  N  Y  Y  Y  Y  Y  N  N  Y  Y   Method of questionnaire administration  Y  Y  Y  NC  Y  Y  Y  NC  Y  NC  Y   Location of data collection  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Dates of data collection  Y  Y  N  N  N  Y  Y  N  N  Y  N   Number and types of contact  Y  Y  NC  NC  NC  Y  Y  NC  Y  NC  Y   Methods sufficiently described for  replication  N  N  N  NC  N  NC  Y  N  N  N  Y   Evidence of reliability  N  N  N  N  N  N  N  N  N  N  N   Evidence of validity  N  N  N  N  N  N  N  N  N  N  Y   Methods for verifying data entry  N  N  N  N  N  N  N  N  N  N  N   Use of codebook  N  N  N  N  N  N  N  N  N  N  N  Sample selection   Sample size calculation  Y  N  N  Y  Y  Y  N  N  N  NC  Y   Representativeness  N  NC  N  N  N  NC  NC  NC  N  NC  Y   Method of sample selection  Y  Y  N  Y  Y  N  Y  N  N  N  Y   Description of population and sample frame  N  Y  N  N  N  N  N  N  N  N  Y  Research tool   Description of the research tool  NC  Y  Y  Y  NC  Y  Y  NC  NC  Y  Y   Description-development of research  tool  N  N  N  N  N  Y  NC  N  N  N  N   Instrument pretesting  N  N  N  N  Y  Y  Y  N  N  Y  N   Instrument reliability and validity  N  N  N  Y  N  N  N  N  N  N  NC   Scoring methods  N  N  N  N  N  Y  N  N  N  N  N  Results   Results of research presented  Y  Y  Y  Y  Y  Y  Y  Y  NC  Y  Y   Result address objectives  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Clear description- result based on part sample  NC  N  Y  N  N  Y  N  Y  N  Y  Y   Generalizability  N  NC  N  N  N  NC  N  NC  N  NC  NC  Response rates   Response rates stated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   How response rate was calculated  Y  NC  NC  Y  Y  Y  Y  N  N  Y  Y   Discussion of non-response bias  N  NC  NC  Y  Y  Y  Y  N  N  N  Y   All respondents accounted for  N  NC  Y  Y  Y  Y  Y  NC  N  Y  Y  Interpretation and discussion   Interpret and discuss findings  Y  Y  Y  Y  Y  Y  Y  Y  N  Y  Y   Conclusions and recommendations  NC  Y  Y  Y  Y  Y  Y  Y  Y  Y  Y   Limitations  NC  N  Y  N  N  N  NC  N  N  N  Y  Ethic and disclosure   Consent  Y  Y  NC  Y  NC  Y  Y  NC  NC  NC  NC   Sponsorship  N  N  N  N  N  N  NC  N  Y  N  N   Research ethic approval  N  N  N  N  N  N  Y  N  N  N  N   Evidence of ethical treatment of human subjects  N  N  N  N  N  NC  Y  N  N  N  Y  Cross-infection was defined as ‘any infection which a patient contracts in a healthcare institution’ [22]; cross-contamination was defined as ‘transfer of a contaminant from a source, specimen, etc., to a different or uncontaminated one’ [23]. Dental laboratory was defined as ‘facilities for the performance of services related to dental treatment but not done in the patient’s mouth’ [24], equipped for the fabrication of dental models and appliances (e.g. dentures, orthodontic devices, crowns and bridges, etc.). For the sake of this study, a flaw in aspects of care that lead to cross-infection was defined as ‘the absence of answer, incorrect answer, or erroneous identification or definition given by 10% or more of the sample investigated in each study’. The outcome of this study (knowledge, attitudes and practices about cross-infection control) was assessed in five aspects, namely process organization, disinfection, working environment, use of individual protective equipment and vaccination policy. The prevalence of flaws in each aspect for each paper is presented as a percentage of questions if a deficit was identified related to the total number of questions made to investigate it. To determine the relative importance (RI) of the flaws in each aspect, an expression was formulated using the number of papers investigating each aspect of the problem (research priority), their methodological quality (Q) (Table 2: headings methods, sample selection and research tool), the depth in which each aspect is studied (number of questions made) and the percentage of flaws identified (F): RIa = ∑Qn·Gn. Table 2 Summary of the papers included in the systematic review Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  Table 2 Summary of the papers included in the systematic review Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  Study  Sampling  Intervention  Objectives  Outcome  Relevant outcome  Risk of bias  Jagger UK [9]  Non-random (175 dental labs in the UK)  Mailed questionnaire  To collect data on the cross-infection control procedures adopted by dental laboratories  Technicians at a very slight increased risk of hepatitis B and other infections. The latter in varying degrees  - Response rate: 22%. Labs with cross-infection control policy: 49%. Of those laboratories with no existing policy 64% intended to implement one in the future - Labs believing work disinfected at the clinic: 4%. Labs disinfecting work on arrival: 29% 0.35% did not disinfect the work on arrival. - 44% of technicians wear gloves at work. 26% Never wear gloves - 7% Instruments used for polishing disinfected - 31% Use no disinfectant in the pumice - 74% Protective spectacles when trimming polishing dental work - Labs hiring HBV vaccinated staff: 21% and 46% have a vaccination policy  High  Kugel [28] USA  Random sampling in three areas (400 dental labs in the USA)  Telephone interview  To assess clinic–lab communication about impression disinfection. To assess technicians' cross-infection practices  - Significant lack of dentist–technician communication- Technicians attribute problems in impressions to disinfection  - Labs knowing the work they receive has been previously disinfected: 44% - Labs disinfecting all impressions no matter the treatment at the clinic: 94% - 54% Use disinfecting solutions not recommended by standard protocols - 45% of labs demand specific training on cross-infection control - Procedures disinfect impression: 34% immersion  High  Campanha [37] Brazil  Non-random (131 dental technicians in Sao Paulo state)  Face-to-face interview  To assess dental technicians' knowledge about cross-infection between the clinic and the laboratory. To evaluate the procedures performed to avoid cross-contamination  Although most technicians are aware of cross-infection risk, most labs do not adopt infection control policies for working on prosthetic appliances. A change of attitude by dentists and technicians is required to establish an effective protocol  - 51% have attended a specific technical prosthetic course - 72.1% of technicians knew appliances reaching the lab are contaminated - 86.2% prosthetic appliances should be disinfected - 13% of technicians believed disinfection is a useless procedures - 90% of technicians never disinfect incoming or outgoing dental works - 77.7% of technicians never use gloves and 26.2% never worn a mask - 12.3% have always used protective eyewear. 35.4% never worn eyewear - 94% do not sterilize pumice or wheels. 92.3% do not add disinfectant to pumice - 59.6% received HBV vaccination. - 13.7% disinfect impressions  High  Akeredolu [17] Nigeria  Non-random (86 dental technicians in Nigeria)  Distributed questionnaire (no further details)  To determine knowledge and determinants of current infection control practices among Nigerian dental technologists  The knowledge and practice of cross-infection control by dental technologists in Nigeria are poor and below acceptable standards  - Contagion risk at work: High HBV = 33.7%; HIV = 32.6%; No idea HCV = 41.8%; Herpes simplex = 39.5%; Tuberculosis = 35.6% - 53.5% do not sterilize hand instruments - 86% do not receive information about work disinfection at the clinic - 20.9% disinfect impressions received from the clinic. 17.4% disinfect work before sending it to the clinic. (74.4% of them by rinsing in water) - 14% disinfect work surfaces at close of the day. - 5.8% change pumice after each use - Use of protective equipment: 7% always wear gloves; 26.7% wear face mask and 32.6% wear goggles when polishing. 74.45 wear protective garments at work - 24.4% had received HBV vaccination - 61.6% wash hands before and after gloving  High  Hatzikyriakos [27] Greece  Non-random (96 dental labs in Thessaloniki)  Mailed questionnaire  To identify current trends, techniques and materials used for the fabrication of fixed prostheses. To identify problems in dentist–technician communication  Improved communication is needed in terms of time for work delivery, shade selection, infection control and problem recognition. More caution is required by both dentist and technicians during certain procedures.  - 73% disinfect incoming items - 22.5% follow a disinfection protocol agreed with the dentist  High  Al-Dwairi [18] Jordan  Non-random (200 dental technicians in Jordan)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan  Lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan  - 12% wear gloves and 83% never wear gloves when receiving clinical items. Only 3% wear them at work - 35% wear protective glasses and 40% wear face masks - 10% vaccinated against HBV - 3% regularly disinfect received items and 20% disinfect outgoing work - 17% receive information about disinfection of clinical items from the clinic - 2.5% of technicians comply with cross-infection regulations - 86% did not change the pumice slurry or water of the curing bath regularly - 20% disinfect laboratory work before sending it back to the clinic - 80% pose financial burden  Low  Almortadi [38] UK  Simple random sampling (62 dental technicians in the UK)  Mailed questionnaire  To ascertain impression decontamination and disinfection practices by dentists and technicians. To study the prevalence of contaminated voids within disinfected impressions  Compliance with good practice is less than ideal and education in impression disinfection for both dentists and dental technicians is required to address this  - 19% of technicians do not rinse impressions with water on arrival - 50% of technicians disinfect incoming impressions - 50% were informed if impression from a patient with a known bloodborne virus - 95% of technicians had received blood-contaminated impressions - 62% had encountered blood-contaminated voids when trimming impressions - 44.1% received information on the disinfection status of incoming impressions - 64.7% were confident that the dentists had disinfected the impressions  - Low  Bârlean [39] Romania  Non-random (61 dental technicians in Iasi)  Distributed questionnaire (no further details)  To assess the compliance of dental technicians in Iasi town dental laboratories with the methods used for preventing infection transmission in their practices  Educational programs aimed at increasing dental technicians´awarness of infection control by adopting the most effective prevention measures are essential for reducing the incidence of technicians, dentists and patients exposure  - 90.2% claim the need of prosthetic items disinfection upon arrival at laboratory - 86.9% finds disinfection measures useful in the laboratory - 49.1% use protection equipment; full equipment 18%, safety glasses 45.9%, mask 37.7%, gloves 19.6% - 59.1% of laboratories are provided with air ventilation - 85.2% disinfect surfaces - 62.1% disinfect impressions; 26.1% final prosthesis; 25% interocclusal registrations - 36% disinfect handpiece and rotary instruments  High  Sandulescu [29] Romania  Not stated (30 dental technicians in Bucharest)  Face-to-face interview  To investigate the role of dental laboratory as a hub for cross-contamination between patients from different dental offices  Dental laboratories in Bucharest have standard operational procedures in place, but individual practices of technicians varied to some degree  - All interviewees were aware of the possibility of getting infected from dental impressions - Most technicians counted on the dentist to disinfect clinical items at the dental clinic - Technicians were aware that protective glasses should be worn at work but admitted not wearing them all the time  High  Diaconu [26] Romania  Non-random (108 technicians in Iasi)  Mailed questionnaire  To examine knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Iasi. To analyze the effect of economic crisis in cross-infection control  - Economic crisis has caused a decreased vigilance of cross-infection control. - Certain decontamination methods are considered unnecessary. - There is a certain degree of negligence towards one’s own protection  - 95.4% of technicians are aware of the risk of contamination from lab surfaces and instruments - 95.4% aware of the high risk of cross-infection from clinical items - 63% think all devices coming from the clinic must be disinfected by the technicians - 5.6% change polishing pastes and brushes every day - 47.2% impressions like the first source of contamination - 38% decontaminate surfaces and air every day - 55.6% routinely wear protective equipment (gloves, glasses) at work - 31.5% consider an additional financial effort using the cross-infection preventing methods  High  Marinheiro Marques [25] Portugal  Non-random (11 technicians in Viseu)  Self-applied questionnaire  - To assess attitudes, knowledge and training of dentists and technicians about disinfection of impression materials - To study the degree of cooperation and communication between both groups, and the cross-infection procedures employed  Additional educational measures regarding infection control practices and improved communication between dentists and technicians. Regarding communication and confidence, the results are lower than expected and even contradictory to international literature  - Disinfection technique employed: water rinse (40%); spray (60%); immersion in disinfecting solution (40%). - Most frequently used disinfecting agent: alcohol-based products - 65.6% of dentist do not inform on the disinfection of clinical items. 62.5% inform on high-risk patient - 80% of technicians do not receive information from the clinic on disinfection of clinical items - 80% of technicians is not confident with disinfection procedures undertaken at the dental clinic  Low  This approach considers the importance of each aspect in the problem (the more important, the more studies would have investigated it), the quality of each independent report and the importance of the flaws identified in each aspect in each article. Results The systematic database search output was 1 651 references, which were merged with the three reports identified through the hand-search. After assessing their titles, 218 references were considered relevant. Once duplicates were removed, 188 single references were identified and their abstracts checked. As a result, 169 papers were discarded because they were not relevant to the aims of this investigation. Therefore, the full texts of the remaining 19 references [9, 15, 17, 18, 25–39] were retrieved. After assessing the full text of these 19 reports, 8 papers were discarded because they did not meet the inclusion/exclusion criteria set in the protocol of this systematic review: four of them described cross-infections protocols and another four dealt with respiratory disorders amongst dental technicians. Thus, 11 papers [9, 17, 18, 25–29, 37–39] were finally selected for analysis (Fig. 1). Assuming an average of eight technicians per laboratory [28], this systematic review summarizes the performance of 6057 dental technicians. Sample sizes ranged from 3200 [28] to 11 interviewees [25] from four continents: Europe [9, 25–27, 29, 38, 39], Asia [18], Africa [17] and America [28, 37] (Table 2). Most of the reports included in this review showed a high risk for bias [9, 17, 26–29, 37, 39] and only three were found to be at low risk [18, 25, 38] (Table 2). Flaws in cross-infection control procedures were identified in each individual study (raw data) and grouped into five key aspects (dimensions). The grouping process is summarized in Table 3 to preserve the richness of the original data and to clarify the procedure [40]. Table 3 Summary of the grouping process and presence of flaws in each study Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  Table 3 Summary of the grouping process and presence of flaws in each study Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  Study  Dimension  Item  Flaws  Jagger et al. [9]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Working environment  Disinfection of polishing elements  Yes  Individual protective equipment  Gloves  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Kugel et al. [28]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  No  Campanha et al. [37]  Process organization  Existence of a cross-infection policy  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV vaccination  Yes  Akeredolu et al. [17]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Disinfection of working surfaces  Yes  Sterilization of laboratory hand instruments  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Protective garments/specific working clothes  Yes  Vaccination policy  HBV immunization  Yes  Hatzikyriakos et al. [27]  Process organization  Existence of a cross-infection policy  Yes  Disinfection  Disinfection of incoming items  Yes  Al-Dwairi et al. [18]  Process organization  Communication with the dental clinic  Yes  Procedures compliant with existing standards  Yes  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Working environment  Disinfection of polishing instruments  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Vaccination policy  HBV immunization  Yes  Almortadi and Chatwick [38]  Process organization  Communication with the dental clinic  Yes  Disinfection  Disinfection of incoming items  Yes  Bârlean et al. [39]  Disinfection  Disinfection of incoming items  Yes  Disinfection of outgoing items  Yes  Surfaces disinfection  Yes  Disinfection of instruments  Yes  Working environment  Air decontamination  Yes  Individual protective equipment  Gloves  Yes  Face masks/face shields  Yes  Goggles  Yes  Sandulescu et al. [29]  Process organization  Existence of a cross-infection policy  No  Diaconu et al. [26]  Disinfection  Disinfection of working surfaces  Yes  Working environment  Air decontamination    Disinfection of polishing instruments  Yes    Individual protective equipment  Gloves  Yes    Goggles  Yes  Marinheiro Marques et al. [25]  Process organization  Communication with the dental clinic  Yes  Existence of a cross-infection policy  No  Disinfection  Disinfection of incoming items  No  The information included in one report (conference proceedings) was incomplete [29] and the authors were contacted in order to obtain further details on their research but no response was obtained. When all dimensions were considered (Table 4), flaws were more frequently identified in terms of vaccination policy, biological safety of the working environment and use of individual protective equipment (100%). Slightly better results were found in terms of organization of the cross-infection control process (89.47%) and disinfection practices (85.71%). Table 4 Quantitative synthesis of the results (raw data) Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  Table 4 Quantitative synthesis of the results (raw data) Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  Dimension  Studies investigating each dimension  Depth of the study (number of questions)  Flaws (%)  Process organization  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredolu et al. [17]; Hatzikyriakos [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Sandulescu et al. [29]; Marinheiro Marques et al. [25]  19  17 (89.47%)  Disinfection  Jagger et al. [9]; Kugel et al. [28]; Campanha et al. [37]; Akeredulu et al. 2006; Hatzikyriakos et al. [27]; Al-Dwairi [18]; Almortadi and Chadwick, [38]; Bârlean et al. [39]; Diaconu et al. [26]; Marinheiro Marques et al. [25]  22  20 (90.90%)  Working environment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  12  12 (100%)  Use of individual protective equipment  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]; Bârlean et al. [39]; Diaconu et al. [26]  21  21 (100%)  Vaccination policy  Jagger et al. [9]; Campanha et al. [37]; Akeredolu et al. [17]; Al-Dwairi [18]  6  6 (100%)  The methodological quality of the papers included in this systematic review (presence of the items in Table 2 under the headings ‘methods’, ‘sample selection’ and ‘research tool’) was expressed as a percentage divided by 10 and ranged from 0.53 [39] to 5.79 [25]. The application of the formula for disclosing the RI of the flaws identified in the literature prioritizes the need for interventions aimed at improving the organization of the cross-infection control procedures, followed by training in item disinfection. The control of the working environment together with the use of individual protective equipments rank closely in importance, followed by the existence of a vaccination policy (Fig. 2). The size of each point in the figure is related to the RI of each flaw in the cross-infection control process in the dental laboratory considered as a whole. Figure 2 View largeDownload slide Relative importance of the dimensions studied. Figure 2 View largeDownload slide Relative importance of the dimensions studied. Discussion When analyzing quality in dental care, patients’ top priority is adherence to the rules of antisepsis and sterilization [41]. Although the scope of this systematic review is focused on a particular part of dental care, the information obtained from each single report (Tables 2 and 3) may indicate that the dental laboratory could be the weakest link in the chain of cross-infection control. Contaminated items from the lab may not reach the patient, as they could be disinfected on arrival at the clinic (which is not assessed in this review), but the high percentages (~60%) of contaminated items not disinfected when leaving the dental office [12, 42] and the poor communication between laboratories and clinics [9, 17, 18, 25, 28, 38], make cross-contamination control practices for preventing cross-infection in the dental laboratory a matter of concern from the perspectives of both quality of care and occupational hazard [8, 14]. It may be argued that all papers reporting on cross-infection control practices in dental laboratories should be considered in this critical systematic review. Although no paper was finally excluded for reporting on a single laboratory or institution, we set this exclusion criterion because perhaps these papers would be more likely to describe examples of ‘best practices’, as investigations with a poor outcome would have less chances to be disclosed out of the concerned institution (publication bias). In addition, reports using an epidemiologic approach would better reflect the situation on a particular area than a paper reporting on a single laboratory. Reports on this topic are scarce and mostly based on relatively small convenience samples in a variety of geographical areas. These investigations use a range of survey-type approaches with different questionnaires assessing particular aspects of the problem (Table 3). These variations in methods and outcomes result in such a scattered and fragmented information that it is very difficult to obtain a general perspective on the situation. In fact, and to the best of our knowledge, this is the first attempt to summarize available data through a systematic review approach. The quality assessment of the reports included in the review has disclosed papers at low risk of bias: two from Europe [25, 38] and one from Asia [18]. The differences in the way survey instruments were applied (most groups used a self-applied questionnaire [9, 17, 18, 25, 27, 36, 38, 39], whereas other reports chose face-to-face [29, 37] or telephone [28] interviews), together with those related to sampling methods or sample size may have influenced response rates, reliability and representativeness of the information obtained. However, the results reported by the individual investigations point at the same direction, so these hypothetical biases may not have critically affected the resulting image of the problem of cross-contamination control in dental laboratories obtained from this review. A major difficulty in synthesizing the information from the selected publications was the broad range of questions employed by the different research groups. Our approach to this challenge was to gather related questions under five key aspects (dimensions) of cross-infection control, and to assume that both the type and the number of questions made by each research group for each dimension reflects the importance of each aspect in a particular geographical area. However, more questions about a dimension do not necessarily imply a more precise picture of the situation. Our results show a generalized lack of compliance with existing recommendations with 100% flaws in most dimensions. Although some dimensions (‘disinfection practices’ and ‘process organization’) behaved slightly better, their scores ranked well above 80% of errors (85.71% and 89.47% respectively). The threshold established in our definition of flaw (10% of error/non-response) may explain these poor results, as a less demanding standard would have shown a less disheartening picture. Even so, our view was that a percentage of errors beyond 10% for healthcare professionals, in basic routine practice, within their field of expertise, requires intervention for improving performance. The high risk for bias observed for some reports may have also influenced our raw results, but the introduction of weighting factors, like methodological quality and the depth in which each dimension is studied, may contribute to overcome these shortcomings. Our results (Fig. 2) prioritize the need for improving the organization of the process of cross-contamination control (communication with the clinic and existence of written protocols in the laboratory), which agrees with the conclusion of several research groups assessing their local realities [9, 25, 27, 28]. A common finding in the literature is the need for an improvement in disinfection practices, which our weighted results rank in second position. In this sense, it seems reasonable that once the relevant information (protocol) has been provided, the probabilities for a better disinfection increase. Unfortunately, this is not as straightforward as knowledge is necessary but not sufficient for changing a behavior [43]. Additional components may be needed to ensure an improvement in cross-infection control practices, such as the implementation of effective external monitoring for these practices [29]. The third and fourth priorities for intervention identified by our results are related to occupational hazards (biological safety of the working environment and use of individual protective equipment). This lack of compliance has been put down to a misperception of the level of risk [17] and negligence towards self-protection [26]. These findings are also interesting as government agencies in many countries issue mandatory regulations on occupational hazards which do not seem to be effective in this particular environment. The last area for intervention among the five dimensions of cross-infection control considered in this systematic review is the existence of vaccination policies for dental technicians. Although vaccination can not be compulsory in most countries, hepatitis B virus (HBV) immunization is strongly recommended for dental care workers and dental technicians are not an exception [8, 44]. The percentage of vaccinated technicians against HBV in the analyzed reports ranges from 59.6% [37] to 10% [18]. Some explanations for the overwhelming dismissal of cross-infection control guidelines may be related to the absence of continuous professional development courses on this topic, either voluntary [17, 25, 28] or compulsory [18], to a lack of monitoring of these practices [29], or even to technicians’ negligence and lack of interest [26]. The avoidance of an ‘additional’ financial burden [26] has also been described. An issue often mentioned in the literature which may have a part in these attitudes is the possibility for the disinfecting chemical agents to affect precision of dental impressions [28, 45], although adequate training on disinfectant selection and use may solve this inconvenience. Anyhow, cross-contamination probability between the clinical setting and the dental technician seems to be greater than contamination risks between dentist and patients or from one patient to another [46]. In fact, and despite the lack of contact with patients, dental technicians have been reported to experience significantly higher exposure to hepatitis B virus than a comparable population (2.7% vs. 0.76%) [47]. Our study permitted the synthesis of incomplete and scattered information to produce a portrait of the situation of cross-infection control practices in dental laboratories. Existing isolated studies undertaken in very different settings may hide the size of a problem which is more extended and deeper than what may have been expected. Besides identifying gaps of knowledge, the methodology used in this critical systematic review (data extraction and grouping, and determination of the RI) also permitted a prioritization of the educational needs to be satisfied. In general terms, specific educational interventions should be implemented in aspects like communication with the dental clinics and designing updated protocols to solve the observed flaws in these processes. 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Incidence of hepatitis B exposure among USAF dental laboratory technicians. Am J Dent  1990; 3: 236– 8. Google Scholar PubMed  © The Author(s) 2018. Published by Oxford University Press in association with the International Society for Quality in Health Care. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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International Journal for Quality in Health CareOxford University Press

Published: Apr 4, 2018

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