Success of palatal implants or mini-screws placed median or paramedian for the reinforcement of anchorage during orthodontic treatment: a systematic review

Success of palatal implants or mini-screws placed median or paramedian for the reinforcement of... Summary Objectives To assess the failure rates of palatal implants and palatal mini-screws, independently and comparatively, used for supplementing anchorage during orthodontic treatment. Protocol and registration The protocol was not registered prior to the study. This study was not registered in any publicly assessable database. Materials and methods Screening for inclusion eligibility, quality assessment of studies, and data extraction was performed independently by two authors. The electronic databases MEDLINE, EMBASE, and CENTRAL, as well as unpublished literature, were searched with no restrictions on publication date or language using detailed strategies. The main outcome assessed was palatal implant or mini-screw failure. Randomized controlled trials were evaluated according to the Cochrane risk of bias tool. Prospective and retrospective studies were graded employing the adjusted predetermined criteria of Bondemark. Results Twenty-seven studies satisfied the inclusion criteria. Four were RCTs of low risk of bias, 12 were prospective (2 low, 7 unclear, 3 high risk of bias) and 11 were retrospective studies (6 unclear, 5 high risk of bias). Only one retrospective study assessed both palatal implants and mini-screws. Seventeen studies, including the four RCTs, assessed solely palatal implants and nine studies palatal mini-screws. The median failure risk of palatal implants was 6.0 per cent (range: 0.0–26.1%) and of mini-screws 6.1 per cent (range: 0.0–33.3%). The median follow-up period was 17.9 months for palatal implants and 6 months for mini-screws. Limitations Significant clinical and methodological heterogeneity among studies and highly variable outcomes. Conclusions Both palatal implants and mini-screws have quite low failure rates that are also comparable, though the median follow-up period of palatal implants was quite larger. Therefore, in regular orthodontic cases, the choice between anchoring devices may rely on other factors, such as costs, patient comfort, personal preferences, familiarity with the device, and insertion procedures. Introduction Temporary anchorage devices (TADs) are the gold standard in reinforcement of orthodontic anchorage, as they are simple to insert and manage and have low failures (1–3). TADs can be divided into two main categories: the osseointegrated mini-implants and the mini-screws. Mini-screws are significantly smaller in diameter, they are designed for immediate loading and rely primarily on mechanical stability. On the contrary, palatal implants are larger in diameter, they are placed in the palate, and they usually require a healing period of several weeks for osseointegration, as well as a surgical procedure for insertion and removal (4–7). Recent studies have indicated that palatal implants can also be immediately loaded (during the first week after insertion) with similar success rates to the conventionally loaded (4, 8). The anterior palate is the ideal area for placement of orthodontic TADs due to the thin soft tissue and the appropriate quality and quantity of cortical bone (9). Besides, in the posterior palate there are several limiting anatomical structures, such as the increased soft tissue thickness composed mainly of adipose tissue and minor salivary glands, and the pathways of the greater palatine arteries, veins, and nerves (9). In adults, the median palatal suture zone is usually the site of choice for placement of palatal implants. In adolescents, however, the paramedian region is preferred to avoid possible growth disturbances of the maxilla in the transverse dimension (10). Regarding mini-screws, they are usually placed paramedian, both in adolescents and adults (11, 12), whereas median insertion is also possible (13). TADs placed in the palate can be used either indirectly, for instance as a part of a transpalatal arch for stabilizing molars while closing spaces after premolar extractions or by applying forces directly from the TADs to the teeth. A systematic review published in 2012 on bone anchor systems for orthodontic applications showed high success rates of TADs, with some variability, however, between the different anchorage systems: 91–100 per cent for mini-plates, 74–93 per cent for palatal implants, and 61–100 per cent for mini-screws, placed at various sites. The loading period varied from 3 up to 24 months for mini-plates, from 2 to 33 months for palatal implants and from 2 to 22 months for mini-screws (3). Despite the already available systematic evaluations of relevant studies (most recent update: December 2011), the topic of bone anchored devices is of great clinical interest with new appliances coming to the market and various scientific studies published every year. Therefore, an updated systematic review was deemed necessary. The aim of this review was to provide a comprehensive update of the literature on the failure rates of palatal implants and palatal mini-screws, independently and comparatively, used for supplementing anchorage during orthodontic treatment. As several terminologies for the different types of TADs exist in the literature, a clarification is necessary: in the present systematic review, the term ‘palatal implants’ will refer to mini-implants with diameter from 3.3 to 4.5 mm placed in the palate. The terms miniscrews, mini screws, mini-pins, and pins will be included in the term ‘mini-screws’ and will include all mini-screws with diameter from 1.1 to 2 mm, also placed in the palate. Materials and methods Protocol and registration The protocol was not registered prior to the study. This study was not registered in any publicly assessable database. Selection criteria applied for the review Study design: Any study design was considered eligible for inclusion in this review, including randomized clinical trials (RCTs), non-randomized, or quasi-randomized controlled trials, prospective, and retrospective studies. Types of participants: Orthodontic patients of any age who received palatal implants or palatal mini-screws for orthodontic anchorage reinforcement. Type of intervention: Median and paramedian palatal implants or mini-screws of any diameter or length. Primary outcome: Failure/success. Secondary outcome: any adverse events. Follow-up: All observation periods were accepted. Exclusion criteria: Animal and in vitro studies. Case reports or studies reporting less than five palatal implants or mini-screws. Mini-screws placed palatally, albeit with interradicular location. Search strategy for identification of studies Detailed search strategies were developed and appropriately revised for each database, considering the differences in controlled vocabulary and syntax rules. The following electronic databases were searched: MEDLINE (via Ovid and Pubmed, Appendix 1, from 1946 to May 2nd, 2017), EMBASE (via Ovid), the Cochrane Oral Health Group’s Trials Register, and CENTRAL. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database. The search attempted to identify all relevant studies irrespective of language. The reference lists of all eligible studies were hand-searched for additional studies. Selection of studies Study selection was performed independently and in duplicate by the first two authors of the review, who were not blinded to the identity of the authors of the studies, their institutions, or the results of their research. Study selection procedures comprised of title-reading, abstract-reading, and full-text-reading stages. After exclusion of non-eligible studies, the full reports considered by either author eligible for inclusion were obtained and assessed independently. Disagreements were resolved by discussion and consultation with the last author. A record of all decisions on study identification was kept. Data extraction and management Data extraction was performed independently and in duplicate by the first two authors. The following information was extracted from all eligible studies, if available: Methods: Author/title/year of study, design of study Participants: Number/age/gender of patients recruited Interventions: Type of palatal implant or mini-screw, manufacturer, diameter, length, placement location in the palate, direct or indirect use for anchorage reinforcement, healing period/ timing of loading, observation period (follow-up of patients) Outcome: type of outcome(s) and method of outcome assessment Measures of treatment effect For dichotomous data, number of TADs with events and total number of TADs in experimental and control groups were considered. Unit of analysis issues In all cases, the unit of analysis was the palatal implant or mini-screw placed. Dealing with missing data We tried to contact study authors via email to request information where missing. In case of no response or no access of the missing data, only the available data were reported and analyzed. Assessment of heterogeneity We assessed clinical heterogeneity by examining the characteristics of the studies, the similarity between the types of participants, the interventions and the outcomes as specified in the inclusion criteria. Assessment of reporting bias Reporting biases arise when the reporting of research findings is affected by the nature or direction of the findings. We attempted to minimize potential reporting biases including publication bias, multiple (duplicate reports) publication bias, and language bias in this review, by conducting an accurate and at the same time a sensitive search of multiple sources with no restriction on language. We also searched for ongoing trials. Data synthesis We planned to conduct meta-analyses if there were at least two studies of similar comparisons reporting the same outcomes at similar follow-up periods. Risk ratios were to be combined for dichotomous data using the random-effects model. Quality assessment Risk of bias assessment was performed by two review authors (L.K., M.A.), independently and in duplicate. Disagreements were resolved through discussion with the last two authors. The methodological quality of RCTs was assessed using the Cochrane risk of bias tool (14). Risk of bias was assessed and judged for seven separate domains and each study received a judgment of low risk, high risk, or unclear risk of bias (indicating either lack of sufficient information to make a judgment or uncertainty over the risk of bias) for each domain. Studies were finally grouped into the following categories: Low risk of bias (plausible bias unlikely to seriously alter the results) if all key domains of the study were at low risk of bias. Unclear risk of bias (plausible bias that raises some doubt about the results) if one or more key domains of the study were unclear. High risk of bias (plausible bias that seriously weakens confidence in the results) if one or more key domains were at high risk of bias. Prospective and retrospective studies were graded as low, unclear, or high risk of bias according to the following criteria, adapted from the Bondemark scoring system (15): - Low risk of bias (all criteria should be met): Randomized clinical study or a prospective study with a well-defined control group. Defined diagnosis and endpoints. Diagnostic reliability tests and reproducibility tests described. Blinded outcome assessment. - Unclear risk of bias (all criteria should be met): Cohort study or retrospective cases series with defined control or reference group. Defined diagnosis and endpoints. Diagnostic reliability tests and reproducibility tests described - High risk of bias (one or more of the following conditions): Large attrition. Unclear diagnosis and endpoints. Poorly defined patient material. Results Description of studies In total, 766 studies were identified from the electronic search as relevant. All abstracts were retrieved and the specific inclusion criteria were applied. After exclusion of duplicates and detailed assessment of the abstract and the full text reports, 27 studies were considered eligible for inclusion in this review. Out of the 27 studies, 4 were RCTs, 12 were prospective, and 11 were retrospective studies (Table 1). The process of study inclusion in this review is presented in Figure 1. Table 1. Characteristics of included studies ordered by study design, within anchorage type. Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility NA: not Available. View Large Table 1. Characteristics of included studies ordered by study design, within anchorage type. Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility NA: not Available. View Large Figure 1. View largeDownload slide Studies flow diagram. Figure 1. View largeDownload slide Studies flow diagram. Quality assessment RCTs The summary of methodological quality of the four included RCTs (4, 16–18) is shown in Figure 2. All studies demonstrated adequate randomization and allocation concealment. Blinding of the clinicians, patients, and assessors was not possible due to the nature of the interventions, but we still considered the possibility of bias as low since palatal implant/mini-screw failure (mobility, loss, etc.) is a hard outcome. Losses to follow-up were appropriately described and there was no evidence of selective outcome reporting and other biases. All four studies were rated at low risk of bias. Figure 2. View largeDownload slide Risk of bias summary for RCTs. Figure 2. View largeDownload slide Risk of bias summary for RCTs. Prospective studies Twelve prospective studies were identified, but only two were judged as low risk of bias (22, 23). None of the rest of the studies met all the necessary criteria outlined by the Cochrane Handbook. Three studies were judged as high risk of bias (6, 31, 32) due to lack of adjusting for confounders, which also had inadequate inclusion criteria. The rest seven prospective studies were rated as unclear risk of bias (5, 19–21, 29, 30, 33). Blinding of the assessors was difficult due to the nature of the interventions. However, as described earlier, it was not considered important because implant failure is a hard outcome (Table 2). Table 2. Quality assessment for included prospective and retrospective studies. Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear View Large Table 2. Quality assessment for included prospective and retrospective studies. Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear View Large Retrospective studies Eleven retrospective studies were identified. Five of them (9, 10, 13, 26, 28) were judged as high risk of bias due to lack of appropriate adjustment for confounder and/or inadequate inclusion criteria. The rest six retrospective studies (8, 11, 24, 25, 27, 34) were graded as unclear risk of bias mainly due to inadequate adjustment for confounders (Table 2). Quantitative synthesis of the included studies Only one retrospective study evaluated and reported both on palatal implants and mini-screws, among other TAD designs (28). All other included studies assessed, exclusively, either palatal implants or mini-screws. The multiplicity of screw designs and implant locations, however, in this study (28) did not allow for direct comparisons between the two groups. Furthermore, the significant clinical heterogeneity among studies did not allow for meta-analysis. Qualitative synthesis of the included studies Due to the reasons described above, the qualitative synthesis of the results was limited to failure rates for either palatal implants or mini-screws, separately. The number of palatal implants or mini-screws per study ranged from 9 to 384 (Table 3). Great differences were observed also in follow-up periods among studies. Züger et al. (27), in a retrospective study, demonstrated the greatest follow-up period, which was 35.6 months, whereas Jackson et al. (18), in an RCT, study reported only 2 months of follow-up. Table 3. Outcomes and interventions of included studies ordered by study design, within anchorage type. Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 View Large Table 3. Outcomes and interventions of included studies ordered by study design, within anchorage type. Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 View Large Palatal implants In total, the risk of failure for palatal implants was assessed in 18 studies and ranged from 0.0 per cent (5, 19, 26) to 26.1 per cent (16), with a median risk of 6.0 per cent. The median follow-up period was 17.9 (range: 2.0–35.6) months. Thirty-nine palatal implants failed prior and 12 after loading. Among the four relevant RCTs the risk of failure for palatal implants ranged from 2.5 per cent (4) to 26.1 per cent (median: 8.8%) (16). Jung et al. (4) claimed 2.5 per cent risk of failure for palatal implants with follow-up period of 6 months. Palatal implants were used directly or indirectly. Sandler et al. (16) reported a 26.1 per cent risk of failure during an observation period of almost 26 months. Feldmann et al. (17) reported a risk of failure of 3.3 per cent for 30 palatal implants. The mean follow-up period was 17 months. Finally, Jackson et al. (18) showed a 14.3 per cent risk of failure over a 2-month observation period. All except from one palatal implant failed prior to loading. Among prospective studies (n = 7) the risk of failure for palatal implants ranged from 0 per cent (5, 19) to 14.3 per cent (6) (median: 7.7%). The follow-up period ranged from 3 to 23 (median: 11.3) months. Six palatal implants failed prior to loading and other six after loading. Among retrospective studies (n = 7) the risk of failure for palatal implants ranged from 0.0 per cent (26) to 21.4 per cent (24) (median: 5.0%). The follow-up period ranged from 22.0 to 35.6 (median: 28.0) months. Twenty-three palatal implants failed prior to loading and other five after loading. Mini-screws In total, the risk of failure for mini-screws was assessed in 10 studies and ranged from 0.0 per cent (29, 30, 32) to 33.3 per cent (31), with a median risk of 6.1 per cent. The median follow-up period was 6 (range: 4–26) months. From the studies that reported relevant information, two mini-screws failed prior and 28 after loading. No RCT assessed failure or success of mini-screws. The risk of failure for mini-screws in the prospective studies (n = 5) ranged from 0 per cent (29, 30) to 33.3 per cent (31) and in the retrospective studies (n = 5) from 2.1 per cent (11) to 16.7 per cent (28). Discussion The aim of the present systematic review was to assess the failure risk of mini-screws and palatal implants inserted in the palate, independently, and if possible, comparatively. A comparative evaluation was not possible as all but one (28) of the identified studies did not compare the anchoring devices directly. The methodological and clinical heterogeneity among studies, including considerable variations in participants (sample size, age, sex) as well as in interventions (follow-up, direct/indirect use, study design), precluded a meta-analysis. Furthermore, potential clustering effects due to the use of multiple TADs per patient, which result in unit of analysis errors, were not adequately reported by the authors of the included studies. As the focus of this review is on the failure risk of orthodontic palatal implants and mini-screws reported in the literature, an explicit definition of failure is appropriate. The most common measure was a palatal implant or mini-screw that showed mobility and thus did not remain stable, fulfilling the clinical requirements during the observation period. In general, palatal implants were successful in providing the necessary anchorage during orthodontic treatment, with a low median risk of failure (6%) among studies of all designs, although considerable variation was evident (range: 0–26%). The main limitation of palatal implants is that they usually require two surgical procedures. The first is for palatal implant placement and is similar to that of dental implants and the second, more invasive, is sometimes needed for palatal implant removal. Insertion and removal of palatal implants is a technique-sensitive procedure, which requires a specialized periodontist or oral surgeon; thus increasing treatment costs. Furthermore, palatal implants can only be used as non-compliance treatment means for maxillary tooth movements, whereas mini-screws can be also placed in the mandible. The conventional healing period of approximately 12 weeks can also be considered a disadvantage in comparison to immediate loading of mini-screws. Nevertheless, certain recent studies have demonstrated that immediate loading of palatal implants resulted in comparable success with that of conventionally loaded implants (4, 8, 18). Mini-screws have been favoured in the last decade because they can be inserted and removed easily by the orthodontist, under local or no anesthesia (3). Furthermore, they can also be placed at various locations within the dentoalveolar bone facilitating different treatment needs. The main advantage of mini-screws is the ease of use, although an important consideration is to avoid harming of vital anatomical structures during insertion (12, 35). The median failure risk among studies of all designs was 6.1 per cent, which is quite similar to that of palatal implants. Considerable variation was observed also in this case (range: 0–33%). However, it should be noted that although the median follow-up period for mini-screws was adequate for the needs of regular orthodontic cases (6 months), it was quite smaller than the 18-month median follow-up of palatal implants. Furthermore, the number of mini-screws per patient was not fully reported across studies. In addition, only few of the studies defined which failures concerned single used mini-screws or multiple mini-screws combined in one patient, precluding assessment of unit of analysis errors. The findings of our study, in terms of success rate of palatal implant or mini-screws, are in agreement with earlier systematic reviews in the literature. In the systematic review of Schätzle et al., the success rate for mini-screws, placed at different locations, was 85 per cent, with a follow-up observation period ranging from 4 to 36 months, whereas the success rate for palatal implants was 90 per cent, with a follow-up between 3 and 22 months (2). Another systematic review reported 94 per cent success rate for palatal implants. Failures were categorized to three following types: surgery-related 61 per cent, orthodontic-related 19 per cent, and patient-related failures 19 per cent (1). As far as the risk factors of failure are concerned, no significant effect was identified in various studies for the factors of patient’s sex or age. Interestingly, almost all studies included disproportional sex groups, with significantly more female patients. Oral hygiene has proved to be an important predictor of mini-screw or palatal implant success (36). There is evidence that insufficient oral hygiene leads to inflammation of the peri-implant tissues, which can affect the stability of the palatal implants. However, such a conclusion cannot be drawn from the present review since lack of information is present on this respect. In several studies, failure of palatal implants or mini-screws has been attributed to the parafunctional activity of the tongue, though no direct proof was provided. Host parameters that are considered to improve primary and secondary stability of mini implants include increased bone thickness and depth as well as high bone density (12, 35). Thin soft tissue is also considered advantageous because it is less vulnerable to inflammation. The median and paramedian regions of the anterior palate possess all those characteristics, as well as the reduced risk damaging tooth roots, and thus, are rightly considered ideal for the placement of TADs. Paramedian regions seem to be preferable for the placement of mini-screws since they demand shorter force arms and they show the greatest palatal cortical bone thickness between the canine and the first premolar. Furthermore, such placement avoids unnecessary trauma to the midpalatal region, which is rich in connective tissue and consequently, potential instability of the implants, especially in young individuals (12). TADs have a wide spectrum of clinical applications within orthodontics (37, 38). Palatal implants and mini-screws have been used both directly and indirectly. On the whole, 663 palatal implants had been used indirectly and only 126 directly, whereas, only 78 mini-screws had been used indirectly versus 653 directly. However, since many studies did not clarify if the failed palatal implants or mini-screws were used directly or indirectly, we could not assess in more detail the association between direct/indirect use and success or failure. Finally, it should be kept in mind that some of the TAD designs analysed in the cited studies may have changed over time and may not be commercially available exactly at the same design as at the time the study was published. Conclusions This review provides updated information on the failure risk of palatal implants and mini-screws used for orthodontic anchorage. Both palatal implants and mini-screws have quite low failure rates that are comparable, and thus their value as orthodontic anchorage means is not questionable. Based on the available evidence, no clinically meaningful difference in failure risk seems to exist between palatal implants and mini-screws, though the median follow-up period of palatal implants was quite larger. Therefore, in regular orthodontic cases, the choice between anchoring devices may rely on other factors, such as costs, patient comfort, personal preferences, familiarity with the device and insertion procedures. Conflict of Interest None to declare. References 1. Rodriguez , J.C. , Suarez , F. , Chan , H.L. , Padial-Molina , M. and Wang , H.L . ( 2014 ) Implants for orthodontic anchorage: success rates and reasons of failures . Implant Dentistry , 23 , 155 – 161 . 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Tosun , T. , Keles , A. and Erverdi , N . ( 2002 ) Method for the placement of palatal implants . The International Journal of Oral & Maxillofacial Implants , 17 , 95 – 100 . Google Scholar PubMed 20. Crismani , A.G. , Bernhart , T. , Schwarz , K. , Celar , A.G. , Bantleon , H.P. and Watzek , G . ( 2006 ) Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis . Clinical Oral Implants Research , 17 , 445 – 450 . Google Scholar CrossRef Search ADS PubMed 21. Männchen , R. and Schätzle , M . ( 2008 ) Success rate of palatal orthodontic implants: a prospective longitudinal study . Clinical Oral Implants Research , 19 , 665 – 669 . Google Scholar PubMed 22. Wehrbein , H. and Göllner , P . ( 2009 ) Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study . American Journal of Orthodontics and Dentofacial Orthopedics , 136 , 695 – 699 . Google Scholar CrossRef Search ADS PubMed 23. Jung , B.A. , Kunkel , M. , Göllner , P. , Liechti , T. and Wehrbein , H . ( 2009 ) Success rate of second-generation palatal implants . The Angle Orthodontist , 79 , 85 – 90 . Google Scholar CrossRef Search ADS PubMed 24. Arcuri , C. , Muzzi , F. , Santini , F. , Barlattani , A. and Giancotti , A . ( 2007 ) Five years of experience using palatal mini-implants for orthodontic anchorage . Journal of Oral and Maxillofacial Surgery , 65 , 2492 – 2497 . Google Scholar CrossRef Search ADS PubMed 25. Jung , B.A. , Kunkel , M. , Göllner , P. , Liechti , T. , Wagner , W. and Wehrbein , H . ( 2012 ) Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients . Clinical Oral Implants Research , 23 , 746 – 750 . Google Scholar CrossRef Search ADS PubMed 26. Krieger , E. , Yildizhan , Z. and Wehrbein , H . ( 2015 ) One palatal implant for skeletal anchorage–frequency and range of indications . Head & Face Medicine , 11 , 15 . Google Scholar CrossRef Search ADS PubMed 27. Züger , J. , Pandis , N. , Wallkamm , B. , Grossen , J. and Katsaros , C . ( 2014 ) Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study . European Journal of Orthodontics , 36 , 22 – 25 . Google Scholar CrossRef Search ADS PubMed 28. Takaki , T. , Tamura , N. , Yamamoto , M. , Takano , N. , Shibahara , T. , Yasumura , T. , Nishii , Y. and Sueishi , K . ( 2010 ) Clinical study of temporary anchorage devices for orthodontic treatment–stability of micro/mini-screws and mini-plates: experience with 455 cases . The Bulletin of Tokyo Dental College , 51 , 151 – 163 . Google Scholar CrossRef Search ADS PubMed 29. Gelgör , I.E. , Büyükyilmaz , T. , Karaman , A.I. , Dolanmaz , D. and Kalayci , A . ( 2004 ) Intraosseous screw-supported upper molar distalization . The Angle Orthodontist , 74 , 838 – 850 . Google Scholar PubMed 30. Gelgör I. , Karaman A. and Büyükyilmaz , T . ( 2007 ) Comparison of 2 distalization systems supported by intraosseous screws . American Journal of Orthodontics and Dentofacial Orthopedics , 131 , 161.e1 – 161.e8 . Google Scholar CrossRef Search ADS 31. Luzi , C. , Verna , C. and Melsen , B . ( 2007 ) A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage . Progress in Orthodontics , 8 , 192 – 201 . Google Scholar PubMed 32. Tzu-yung W. , Shou-Hsin K. , Cheng-Hsien W . ( 2009 ) Factors associated with the stability of mini-implants for Orthodontic Anchorage: a study of 414 samples in Taiwan . American Association of Oral and Maxillofacial Surgeons , 67 , 1595 – 1599 . 33. Kobayashi , M. and Fushima , K . ( 2014 ) Orthodontic skeletal anchorage using a palatal external plate . Journal of Orthodontics , 41 , 53 – 62 ; quiz 63. Google Scholar CrossRef Search ADS PubMed 34. Ziebura , T. , Flieger , S. and Wiechmann , D . ( 2012 ) Mini-implants in the palatal slope–a retrospective analysis of implant survival and tissue reaction . Head & Face Medicine , 8 , 32 . Google Scholar CrossRef Search ADS PubMed 35. Alsamak , S. , Psomiadis , S. and Gkantidis , N . ( 2013 ) Positional guidelines for orthodontic mini-implant placement in the anterior alveolar region: a systematic review . The International Journal of Oral and Maxillofacial Implants , 28 , 470 – 479 . Google Scholar CrossRef Search ADS PubMed 36. Papageorgiou , S. , Zogakis , I. and Papadopoulos , M . ( 2012 ) Risk of failures and associated risk factors of orthodontic miniscrew implants: a meta-analysis . American Journal of Orthodontics and Dentofacial Orthopedics , 142 , 577 – 595 . Google Scholar CrossRef Search ADS PubMed 37. Papadopoulos , M.A. , Papageorgiou , S.N. and Zogakis , I.P . ( 2011 ) Clinical effectiveness of orthodontic miniscrew implants: a meta-analysis . Journal of Dental Research , 90 , 969 – 976 . Google Scholar CrossRef Search ADS PubMed 38. Jambi , S. , Walsh , T. , Sanlder , J. , Benson , P.E , Skeggs , R.M. and O’Brien , K.D . ( 2014 ) Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods . Cochrane Database of Systematic Reviews , 8 , CD005098 . © The Author(s) 2018. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The European Journal of Orthodontics Oxford University Press

Success of palatal implants or mini-screws placed median or paramedian for the reinforcement of anchorage during orthodontic treatment: a systematic review

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© The Author(s) 2018. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com
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0141-5387
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Abstract

Summary Objectives To assess the failure rates of palatal implants and palatal mini-screws, independently and comparatively, used for supplementing anchorage during orthodontic treatment. Protocol and registration The protocol was not registered prior to the study. This study was not registered in any publicly assessable database. Materials and methods Screening for inclusion eligibility, quality assessment of studies, and data extraction was performed independently by two authors. The electronic databases MEDLINE, EMBASE, and CENTRAL, as well as unpublished literature, were searched with no restrictions on publication date or language using detailed strategies. The main outcome assessed was palatal implant or mini-screw failure. Randomized controlled trials were evaluated according to the Cochrane risk of bias tool. Prospective and retrospective studies were graded employing the adjusted predetermined criteria of Bondemark. Results Twenty-seven studies satisfied the inclusion criteria. Four were RCTs of low risk of bias, 12 were prospective (2 low, 7 unclear, 3 high risk of bias) and 11 were retrospective studies (6 unclear, 5 high risk of bias). Only one retrospective study assessed both palatal implants and mini-screws. Seventeen studies, including the four RCTs, assessed solely palatal implants and nine studies palatal mini-screws. The median failure risk of palatal implants was 6.0 per cent (range: 0.0–26.1%) and of mini-screws 6.1 per cent (range: 0.0–33.3%). The median follow-up period was 17.9 months for palatal implants and 6 months for mini-screws. Limitations Significant clinical and methodological heterogeneity among studies and highly variable outcomes. Conclusions Both palatal implants and mini-screws have quite low failure rates that are also comparable, though the median follow-up period of palatal implants was quite larger. Therefore, in regular orthodontic cases, the choice between anchoring devices may rely on other factors, such as costs, patient comfort, personal preferences, familiarity with the device, and insertion procedures. Introduction Temporary anchorage devices (TADs) are the gold standard in reinforcement of orthodontic anchorage, as they are simple to insert and manage and have low failures (1–3). TADs can be divided into two main categories: the osseointegrated mini-implants and the mini-screws. Mini-screws are significantly smaller in diameter, they are designed for immediate loading and rely primarily on mechanical stability. On the contrary, palatal implants are larger in diameter, they are placed in the palate, and they usually require a healing period of several weeks for osseointegration, as well as a surgical procedure for insertion and removal (4–7). Recent studies have indicated that palatal implants can also be immediately loaded (during the first week after insertion) with similar success rates to the conventionally loaded (4, 8). The anterior palate is the ideal area for placement of orthodontic TADs due to the thin soft tissue and the appropriate quality and quantity of cortical bone (9). Besides, in the posterior palate there are several limiting anatomical structures, such as the increased soft tissue thickness composed mainly of adipose tissue and minor salivary glands, and the pathways of the greater palatine arteries, veins, and nerves (9). In adults, the median palatal suture zone is usually the site of choice for placement of palatal implants. In adolescents, however, the paramedian region is preferred to avoid possible growth disturbances of the maxilla in the transverse dimension (10). Regarding mini-screws, they are usually placed paramedian, both in adolescents and adults (11, 12), whereas median insertion is also possible (13). TADs placed in the palate can be used either indirectly, for instance as a part of a transpalatal arch for stabilizing molars while closing spaces after premolar extractions or by applying forces directly from the TADs to the teeth. A systematic review published in 2012 on bone anchor systems for orthodontic applications showed high success rates of TADs, with some variability, however, between the different anchorage systems: 91–100 per cent for mini-plates, 74–93 per cent for palatal implants, and 61–100 per cent for mini-screws, placed at various sites. The loading period varied from 3 up to 24 months for mini-plates, from 2 to 33 months for palatal implants and from 2 to 22 months for mini-screws (3). Despite the already available systematic evaluations of relevant studies (most recent update: December 2011), the topic of bone anchored devices is of great clinical interest with new appliances coming to the market and various scientific studies published every year. Therefore, an updated systematic review was deemed necessary. The aim of this review was to provide a comprehensive update of the literature on the failure rates of palatal implants and palatal mini-screws, independently and comparatively, used for supplementing anchorage during orthodontic treatment. As several terminologies for the different types of TADs exist in the literature, a clarification is necessary: in the present systematic review, the term ‘palatal implants’ will refer to mini-implants with diameter from 3.3 to 4.5 mm placed in the palate. The terms miniscrews, mini screws, mini-pins, and pins will be included in the term ‘mini-screws’ and will include all mini-screws with diameter from 1.1 to 2 mm, also placed in the palate. Materials and methods Protocol and registration The protocol was not registered prior to the study. This study was not registered in any publicly assessable database. Selection criteria applied for the review Study design: Any study design was considered eligible for inclusion in this review, including randomized clinical trials (RCTs), non-randomized, or quasi-randomized controlled trials, prospective, and retrospective studies. Types of participants: Orthodontic patients of any age who received palatal implants or palatal mini-screws for orthodontic anchorage reinforcement. Type of intervention: Median and paramedian palatal implants or mini-screws of any diameter or length. Primary outcome: Failure/success. Secondary outcome: any adverse events. Follow-up: All observation periods were accepted. Exclusion criteria: Animal and in vitro studies. Case reports or studies reporting less than five palatal implants or mini-screws. Mini-screws placed palatally, albeit with interradicular location. Search strategy for identification of studies Detailed search strategies were developed and appropriately revised for each database, considering the differences in controlled vocabulary and syntax rules. The following electronic databases were searched: MEDLINE (via Ovid and Pubmed, Appendix 1, from 1946 to May 2nd, 2017), EMBASE (via Ovid), the Cochrane Oral Health Group’s Trials Register, and CENTRAL. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database. The search attempted to identify all relevant studies irrespective of language. The reference lists of all eligible studies were hand-searched for additional studies. Selection of studies Study selection was performed independently and in duplicate by the first two authors of the review, who were not blinded to the identity of the authors of the studies, their institutions, or the results of their research. Study selection procedures comprised of title-reading, abstract-reading, and full-text-reading stages. After exclusion of non-eligible studies, the full reports considered by either author eligible for inclusion were obtained and assessed independently. Disagreements were resolved by discussion and consultation with the last author. A record of all decisions on study identification was kept. Data extraction and management Data extraction was performed independently and in duplicate by the first two authors. The following information was extracted from all eligible studies, if available: Methods: Author/title/year of study, design of study Participants: Number/age/gender of patients recruited Interventions: Type of palatal implant or mini-screw, manufacturer, diameter, length, placement location in the palate, direct or indirect use for anchorage reinforcement, healing period/ timing of loading, observation period (follow-up of patients) Outcome: type of outcome(s) and method of outcome assessment Measures of treatment effect For dichotomous data, number of TADs with events and total number of TADs in experimental and control groups were considered. Unit of analysis issues In all cases, the unit of analysis was the palatal implant or mini-screw placed. Dealing with missing data We tried to contact study authors via email to request information where missing. In case of no response or no access of the missing data, only the available data were reported and analyzed. Assessment of heterogeneity We assessed clinical heterogeneity by examining the characteristics of the studies, the similarity between the types of participants, the interventions and the outcomes as specified in the inclusion criteria. Assessment of reporting bias Reporting biases arise when the reporting of research findings is affected by the nature or direction of the findings. We attempted to minimize potential reporting biases including publication bias, multiple (duplicate reports) publication bias, and language bias in this review, by conducting an accurate and at the same time a sensitive search of multiple sources with no restriction on language. We also searched for ongoing trials. Data synthesis We planned to conduct meta-analyses if there were at least two studies of similar comparisons reporting the same outcomes at similar follow-up periods. Risk ratios were to be combined for dichotomous data using the random-effects model. Quality assessment Risk of bias assessment was performed by two review authors (L.K., M.A.), independently and in duplicate. Disagreements were resolved through discussion with the last two authors. The methodological quality of RCTs was assessed using the Cochrane risk of bias tool (14). Risk of bias was assessed and judged for seven separate domains and each study received a judgment of low risk, high risk, or unclear risk of bias (indicating either lack of sufficient information to make a judgment or uncertainty over the risk of bias) for each domain. Studies were finally grouped into the following categories: Low risk of bias (plausible bias unlikely to seriously alter the results) if all key domains of the study were at low risk of bias. Unclear risk of bias (plausible bias that raises some doubt about the results) if one or more key domains of the study were unclear. High risk of bias (plausible bias that seriously weakens confidence in the results) if one or more key domains were at high risk of bias. Prospective and retrospective studies were graded as low, unclear, or high risk of bias according to the following criteria, adapted from the Bondemark scoring system (15): - Low risk of bias (all criteria should be met): Randomized clinical study or a prospective study with a well-defined control group. Defined diagnosis and endpoints. Diagnostic reliability tests and reproducibility tests described. Blinded outcome assessment. - Unclear risk of bias (all criteria should be met): Cohort study or retrospective cases series with defined control or reference group. Defined diagnosis and endpoints. Diagnostic reliability tests and reproducibility tests described - High risk of bias (one or more of the following conditions): Large attrition. Unclear diagnosis and endpoints. Poorly defined patient material. Results Description of studies In total, 766 studies were identified from the electronic search as relevant. All abstracts were retrieved and the specific inclusion criteria were applied. After exclusion of duplicates and detailed assessment of the abstract and the full text reports, 27 studies were considered eligible for inclusion in this review. Out of the 27 studies, 4 were RCTs, 12 were prospective, and 11 were retrospective studies (Table 1). The process of study inclusion in this review is presented in Figure 1. Table 1. Characteristics of included studies ordered by study design, within anchorage type. Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility NA: not Available. View Large Table 1. Characteristics of included studies ordered by study design, within anchorage type. Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility Authors Study design Study title Participants (N, gender, mean age) Interventions/comparators (length × diameter) Outcome/observation period (mean) Method of outcome assessment Sandler et al. (16) RCT Palatal implants are a good alternative to headgear: a randomized trial N = 23 (7M, 16F) 15.7 (range: 12–39) years 23 palatal implants (Orthosystem, Straumann) 6.0 × 3.3 mm or 6.0 × 4.0 mm location: median use: direct or indirect loading: 3 months after placement comparator: headgear (n = 25) Success rate 25.8 ± 0.6 months (including healing) NA (failure of osseointegration) Feldmann and Bondemark (17) RCT Anchorage capacity of osseointegrated and conventional anchorage systems: A randomized controlled trial N = 30 (15M, 15F) 14.3 ± 1.73 years 30 palatal implants (Orthosystem, Straumann) 3.3 × 4.0 mm location: paramedian use: indirect loading: 3 months after placement comparators: onplants (n = 30), headgear (n =30), transpalatal bar (n = 30) Success rate 16.6–18.4 months (including healing) Mobility Jung et al. (4) RCT Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT N = 41 (6M, 35F) range: 12–65 years 41 palatal implants (Orthosystem, Straumann) 4.1 × 4.1 mm location: median or paramedian use: direct or indirect loading: 3 months (n = 21) or 1 week (18) after placement Success rate 6 months (during loading) Mobility Jackson et al. (18) RCT A comparison of stability between delayed vs immediately loaded orthodontic palatal implants N = 21 (8M,13F) range: 13–48 years 21 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: direct or indirect loading: immediately loaded vs. not loaded Success rate 2 months Mobility Wehrbein et al. (5) Prospective Palatal implants anchorage reinforcement of posterior teeth: A prospective study N = 9 (gender NA) range: 15–35 years 9 palatal implants (Orthosystem, Straumann) 4.0 × 3.3 mm or 6.0 × 3.3 mm location: median use: indirect loading: 3 months after placement Success rate 11 ± 0.7 months (during loading) Mobility Bernhart et al. (6) Prospective Short epithetic implants for orthodontic anchorage in the paramedian region of the palate N = 21 (6M, 15F) 25.8 ± 9.9 (range: 12.7–48.1) years 21 palatal implants (Brånemark, Nobel Biocare, Sweden) 3.0x3.75 mm or 4.0x3.75 mm location: paramedian use: direct or indirect loading: 4 months after placement Success rate 11.6 ± 4.9 months (during loading) Mobility Tosun et al. (19) Prospective Method for the placement of palatal implants N = 23 (8M, 15F) 22.5 (range: 19.5–25.0) years 21 palatal implants (Frialit-2 Implant System, Synchro Screw implants, Friadent, Mannheim, Germany) 8.0 × 4.5 mm location: paramedian use: indirect loading: 3 months after placement Success rate NA (whole orthodontic treatment) Mobility or loss Crismani et al. (20) Prospective Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis N = 20 (7M, 13F) 26.4 (range 15.3–47.9) years 20 palatal implants (Orthosystem, Straumann, Institut Straumann, Switzerland) 4.0 × 3.3 mm location: median use: direct loading: 1 week after placement Success rate 3 months (including healing) Mobility or loss Männchen et al. (21) Prospective Success rate of palatal orthodontic implants: a prospective longitudinal study N = 70 (14M, 56F) 22.6 ± 10.8 years 70 palatal implants (Orthosystem, Straumann) 6.0 or 4.0x3.3 or 4.0 mm location: median or paramedian use: direct or indirect loading: 2–4 months after placement Success rate 19 months (during loading) Mobility Wehrbein and Göllner (22) Prospective Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study N = 22 (8M, 14F) range: 21–62 years 22 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 or 4.0 mm location: median use: direct or indirect loading: 3 months after placement Success rate 18.2 months (during loading) Mobility Jung et al. (23) Prospective Success rate of second-generation palatal implants N = 30 (13M, 17F) 19.7 (range: 12–41) years 30 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: median use: direct or indirect loading: 3 months after placement Success rate 6 months (during loading) Mobility or loss Asscherickx et al. (10) Retrospective Clinical observations and success rates of palatal implants N = 33 (14M, 19F) range: 10.3–53.2 years 34 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 4.0 or 3.3 mm location: median (adults) or paramedian (growing) use: direct or indirect loading: 3 months after placement Success rate 22 ± 7 months (NA) Mobility or loss or anchorage capability Arcuri et al. (24) Retrospective Five year of experience using palatal mini-implants for orthodontic anchorage N = 14 (2M,12F) > 20 years 16 palatal implants (Orthosystem, Straumann) 4.0 or 6.0 × 3.3 mm location: median use: direct or indirect loading: 3 months after placement Success rate 23 months (during loading) NA (failure of osseointegration) Göllner et al. (8) Retrospective Immediate vs conventional loading of palatal implants in humans N = 76 (30M, 46F) 18 (range: 12–54) 76 palatal implants (Orthosystem, Straumann) 6.0 or 4.0 × 3.3 mm location: median use: indirect loading: 1 week or 3 months after placement Success rate NA Mobility Jung et al. (25) Retrospective Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients N = 239 (81M, 158F) 20.6 (range: 10–65) years 239 palatal implants (Straumann, Basel, Switzerland) 6.0 or 4.0 × 3.3 mm; 4.0 × 4.0 mm; 4.1 × 4.2 mm location: median use: direct or indirect loading: 3 months after placement Success rate 33 months Mobility Krieger et al. (26) Retrospective One palatal implant for skeletal anchorage-frequency and range of indications N = 56 (M22, F34) 19.5 (range: 11–52) years 56 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: NA use: direct or indirect loading: 3 months after placement Success rate NA Mobility Zuger et al. (27) Retrospective Success rate of paramedian palatal implants in adolescent and adult orthodontic patients: a retrospective cohort study N = 143 (53M, 90F) median: 15.7 (range: 10.2–50.9) years 145 palatal implants (Orthosystem, Straumann) 4.2 × 4.1 mm location: paramedian use: direct or indirect loading: 3 months after placement Success rate 35.6 (range: 0.1–91.3) months Mobility Takaki et al. (28) Retrospective Clinical study of temporary anchorage devices for orthodontic treatment NA 148 palatal implants (PIAS, Tokyo dental college, Japan), 12 mini-srews (Dualtop autoscrew, Jeil Medical Corp, Korea; OSAS, DEWINED Co., Germany; K1 System, Dentsply-Sankin, Japan) varying diameter and length location: median or paramedian use: direct or indirect loading: 1 month after placement Success rate NA Mobility or loss Gelgör et al. (29) Prospective Intraosseous screw-supported upper molar distalization N = 25 (7M,18F) range: 11.3–16.5 years 25 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0x1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 4.6 (range: 3.0–6.2) months (during loading; until completion of distalization) Mobility Gelgör et al. (30) Prospective Comparison of two distalization systems supported by intraosseous screws N = 40 (21M, 19F) range: 11.6–15.4 years 40 intraosseous screws (IMF Stryker, Leibinger, Germany) 14.0 × 1.8 mm location: paramedian use: indirect loading: 2 weeks after placement Success rate 3–6.6 months (during loading; until completion of distalization) Mobility Luzi et al. (31) Prospective A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage N = 9 34.3 (gender NA) (range: 13–64) years Nine mini-screws (Aarhus Mini-Implants®, Medicon, Germany) 9.6 or 11.6x1.5 or 2.0 mm location: NA use: direct or indirect loading: 2–4 weeks after placement Success rate minimum 4 months (NA) Mobility or loss Wu et al. (32) Prospective Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Tawain N = 11 (gender NA) 26.5 ± 8.9 years 11 mini-srews (four types) location: NA use: NA loading: 1–2 weeks after placement Success rate 6 months (during loading) Mobility or loss Kobayashi and Fushima (33) Prospective Orthodontic skeletal anchorage using a palatal external plate N = 137 (33M, 104F) range: 10–54 years 358 mini-screws (Anchor- Lock, Synthes Co., Solothurn, Switzerland) connected to a titanium plate 8.0 or under to 12.0 or over × 2.0 mm location: paramedian loading: 2 weeks after placement Success rate 26 months (during loading) Uncontrollable inflammation or mobility Kim et al. (9) Retrospective Midpalatal miniscrews for orthodontic anchorage. Factors affecting clinical success N = 128 (27M, 101F) 23.4 ± 8.0 (range: 8.1–56.2) years 197 mini-screws (KLS-Martin, Jacksonville, Fla or Orthoplant, Biomaterials Korea, Seoul, Korea) 5.0 × 1.5 or 2.0 mm location: median or paramedien use: direct or indirect loading: immediately after placement Success rate 18 months Mobility Ziebura et al. (34) Retrospective Mini-implants in the palatal slope-a retrospective analysis of implant survival and tissue reaction N = 41 (19M, 22F) 15.1 ± 4.9 (range: 10–37) years 66 mini-screws (The Jet Screw, Promedia Medizintechnik GmbH, Siegen, Germany) 8.0 × 2.0 mm location: paramedian use: direct or indirect loading: immediately after placement Success rate 6 months Mobility Nienkemper et al. (13) Retrospective Multipurpose use of orthodontic mini- implants to achieve different treatment goals N = 43 (16M, 27F) 14.4 ± 6.6 years 80 mini-srews (Benefit; PSM Medical Solutions, Tuttlingen, Germany) 9.0 or 11.0 × 2.0 mm location: median or paramedian use: direct loading: NA Success rate 14.4 ± 3.5 or 10.0 ± 4.2 months Mobility Karagkiolidou et al. (11) Retrospective Survival of palatal miniscrews used for orthodontic appliance anchorage: A retrospective cohort study N = 196 (75M, 121F) median: 11.7 (interquartile range: 3.7) years 384 mini-screws (Ortho Easy; Pforzheim, Forestadent, Germany) 8.0 × 1.6 mm location: paramedian use: direct or indirect loading: 1 week after placement Success rate mean: 5.5 (range: 0.4–23.8) months Mobility NA: not Available. View Large Figure 1. View largeDownload slide Studies flow diagram. Figure 1. View largeDownload slide Studies flow diagram. Quality assessment RCTs The summary of methodological quality of the four included RCTs (4, 16–18) is shown in Figure 2. All studies demonstrated adequate randomization and allocation concealment. Blinding of the clinicians, patients, and assessors was not possible due to the nature of the interventions, but we still considered the possibility of bias as low since palatal implant/mini-screw failure (mobility, loss, etc.) is a hard outcome. Losses to follow-up were appropriately described and there was no evidence of selective outcome reporting and other biases. All four studies were rated at low risk of bias. Figure 2. View largeDownload slide Risk of bias summary for RCTs. Figure 2. View largeDownload slide Risk of bias summary for RCTs. Prospective studies Twelve prospective studies were identified, but only two were judged as low risk of bias (22, 23). None of the rest of the studies met all the necessary criteria outlined by the Cochrane Handbook. Three studies were judged as high risk of bias (6, 31, 32) due to lack of adjusting for confounders, which also had inadequate inclusion criteria. The rest seven prospective studies were rated as unclear risk of bias (5, 19–21, 29, 30, 33). Blinding of the assessors was difficult due to the nature of the interventions. However, as described earlier, it was not considered important because implant failure is a hard outcome (Table 2). Table 2. Quality assessment for included prospective and retrospective studies. Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear View Large Table 2. Quality assessment for included prospective and retrospective studies. Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear Authors Study design Study design and defined control group Adequately defined patient material Defined diagnosis and end points Diagnostic reliability and reproducibility tests Blinded outcome assessment Overall risk Wehrbein et al. (5) Prospective − + + + + Unclear Bernhart et al. (6) Prospective − − − + + High Tosun et al. (19) Prospective − + + + + Unclear Crismani et al. (20) Prospective + − + + + Unclear Männchen et al. (21) Prospective + + − + + Unclear Wehrbein and Göllner (22) Prospective + + + + + Low Jung et al. (23) Prospective + + + + + Low Gelgör et al. (29) Prospective + − + + + Unclear Gelgör et al. (30) Prospective + − + + + Unclear Luzi et al. (31) Prospective − − + + + High Wu et al. (32) Prospective − − − + + High Kobayashi and Fushima (33) Prospective + − + + + Unclear Asscherickx et al. (10) Retrospective − − + + + High Arcuri et al. (24) Retrospective − + + + + Unclear Göllner et al. (8) Retrospective − + + + + Unclear Jung et al. (25) Retrospective − + + + + Unclear Krieger et al. (26) Retrospective − − − + + High Zuger et al. (27) Retrospective − + + + + Unclear Takaki et al. (28) Retrospective − − + + + High Kim et al. (9) Retrospective − − + + + High Ziebura et al. (34) Retrospective − + + + + Unclear Nienkemper et al. (13) Retrospective − − + + + High Karagkiolidou et al. (11) Retrospective − + + + + Unclear View Large Retrospective studies Eleven retrospective studies were identified. Five of them (9, 10, 13, 26, 28) were judged as high risk of bias due to lack of appropriate adjustment for confounder and/or inadequate inclusion criteria. The rest six retrospective studies (8, 11, 24, 25, 27, 34) were graded as unclear risk of bias mainly due to inadequate adjustment for confounders (Table 2). Quantitative synthesis of the included studies Only one retrospective study evaluated and reported both on palatal implants and mini-screws, among other TAD designs (28). All other included studies assessed, exclusively, either palatal implants or mini-screws. The multiplicity of screw designs and implant locations, however, in this study (28) did not allow for direct comparisons between the two groups. Furthermore, the significant clinical heterogeneity among studies did not allow for meta-analysis. Qualitative synthesis of the included studies Due to the reasons described above, the qualitative synthesis of the results was limited to failure rates for either palatal implants or mini-screws, separately. The number of palatal implants or mini-screws per study ranged from 9 to 384 (Table 3). Great differences were observed also in follow-up periods among studies. Züger et al. (27), in a retrospective study, demonstrated the greatest follow-up period, which was 35.6 months, whereas Jackson et al. (18), in an RCT, study reported only 2 months of follow-up. Table 3. Outcomes and interventions of included studies ordered by study design, within anchorage type. Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 View Large Table 3. Outcomes and interventions of included studies ordered by study design, within anchorage type. Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 Study Anchorage type Number of implants/ screws Number of patients Direct use Indirect use Events of failure Risk of failure (%) Sandler et al. (16) RCT Palatal implants 23 23 0 23 6 (prior to loading) 26.1 Feldmann and Bondemark (17) RCT Palatal implants 30 30 0 30 1 (prior to loading) 3.3 Jung et al. (4) RCT Palatal implants 40 40 11 28 1 (prior to loading) 2.5 Jackson et al. (18) RCT Palatal implants 21 21 10 (11 not loaded) 0 3 (1 after loading) 14.3 Wehrbein et al. (5) Prospective Palatal implants 9 9 0 9 0 0.0 Bernhart et al. (6) Prospective Palatal implants 21 21 6 15 3 (after to loading) 14.3 Tosun et al. (19) Prospective Palatal implants 23 23 0 23 0 0.0 Crismani et al. (20) Prospective Palatal implants 20 20 20 0 2 (after to loading) 10.0 Männchen et al. (21) Prospective Palatal implants 70 70 25 42 3 (1 after loading) 4.3 Wehrbein and Göllner (22) Prospective Palatal implants 22 22 NA NA 2 (prior to loading) 9.1 Jung et al. 2009 (23) Prospective Palatal implants 30 30 4 24 2 (prior to loading) 6.7 Asscherickx et al. (10) Retrospective Palatal implants 34 33 13 18 3 (prior to loading) 8.8 Arcuri et al. (24) Retrospective Palatal implants 14 14 4 10 3 (prior to loading) 21.4 Göllner et al. 2009 (8) Retrospective Palatal implants 76 76 0 76 4 (1 prior to loading) 5.3 Jung et al. 2012 (25) Retrospective Palatal implants 239 239 29 201 11 (9 prior loading) 4.6 Krieger et al. 2015 (26) Retrospective Palatal implants 56 56 NA NA 0 (only loading period evaluated) 0.0 Zuger et al. 2014 (27) Retrospective Palatal implants 145 143 4 134 7 (prior to loading) 4.8 Takaki et al. 2010 (28) Retrospective Palatal implants and mini-screws 148 palatal implants/ 12 mini-screws NA NA NA 16/2 10.8/16.7 Gelgör et al. 2004 (29) Prospective Mini-screws 25 25 0 25 0 0.0 Gelgör et al. 2007 (30) Prospective Mini-screws 40 40 0 40 0 0.0 Luzi et al. 2007 (31) Prospective Mini-screws 9 9 NA NA 3 33.3 Wu et al. 2009 (32) Prospective Mini-screws 11 NA NA NA 0 0.0 Kobayashi and Fushima (33) Prospective Mini-screws 358 137 NA NA 11 patients (prior to loading) NA Kim et al. (9) Retrospective Mini-screws 197 128 197 0 18 (after loading; placed in 15 patients) 9.1 Ziebura et al. (34) Retrospective Mini-screws 66 41 NA NA 4 (2 prior to loading) 6.1 Nienkemper et al. (13) Retrospective Mini-screws 80 43 80 5 6.2 Karagkiolidou et al. (11) Retrospective Mini-screws 384 196 376 8 8 (after loading) 2.1 View Large Palatal implants In total, the risk of failure for palatal implants was assessed in 18 studies and ranged from 0.0 per cent (5, 19, 26) to 26.1 per cent (16), with a median risk of 6.0 per cent. The median follow-up period was 17.9 (range: 2.0–35.6) months. Thirty-nine palatal implants failed prior and 12 after loading. Among the four relevant RCTs the risk of failure for palatal implants ranged from 2.5 per cent (4) to 26.1 per cent (median: 8.8%) (16). Jung et al. (4) claimed 2.5 per cent risk of failure for palatal implants with follow-up period of 6 months. Palatal implants were used directly or indirectly. Sandler et al. (16) reported a 26.1 per cent risk of failure during an observation period of almost 26 months. Feldmann et al. (17) reported a risk of failure of 3.3 per cent for 30 palatal implants. The mean follow-up period was 17 months. Finally, Jackson et al. (18) showed a 14.3 per cent risk of failure over a 2-month observation period. All except from one palatal implant failed prior to loading. Among prospective studies (n = 7) the risk of failure for palatal implants ranged from 0 per cent (5, 19) to 14.3 per cent (6) (median: 7.7%). The follow-up period ranged from 3 to 23 (median: 11.3) months. Six palatal implants failed prior to loading and other six after loading. Among retrospective studies (n = 7) the risk of failure for palatal implants ranged from 0.0 per cent (26) to 21.4 per cent (24) (median: 5.0%). The follow-up period ranged from 22.0 to 35.6 (median: 28.0) months. Twenty-three palatal implants failed prior to loading and other five after loading. Mini-screws In total, the risk of failure for mini-screws was assessed in 10 studies and ranged from 0.0 per cent (29, 30, 32) to 33.3 per cent (31), with a median risk of 6.1 per cent. The median follow-up period was 6 (range: 4–26) months. From the studies that reported relevant information, two mini-screws failed prior and 28 after loading. No RCT assessed failure or success of mini-screws. The risk of failure for mini-screws in the prospective studies (n = 5) ranged from 0 per cent (29, 30) to 33.3 per cent (31) and in the retrospective studies (n = 5) from 2.1 per cent (11) to 16.7 per cent (28). Discussion The aim of the present systematic review was to assess the failure risk of mini-screws and palatal implants inserted in the palate, independently, and if possible, comparatively. A comparative evaluation was not possible as all but one (28) of the identified studies did not compare the anchoring devices directly. The methodological and clinical heterogeneity among studies, including considerable variations in participants (sample size, age, sex) as well as in interventions (follow-up, direct/indirect use, study design), precluded a meta-analysis. Furthermore, potential clustering effects due to the use of multiple TADs per patient, which result in unit of analysis errors, were not adequately reported by the authors of the included studies. As the focus of this review is on the failure risk of orthodontic palatal implants and mini-screws reported in the literature, an explicit definition of failure is appropriate. The most common measure was a palatal implant or mini-screw that showed mobility and thus did not remain stable, fulfilling the clinical requirements during the observation period. In general, palatal implants were successful in providing the necessary anchorage during orthodontic treatment, with a low median risk of failure (6%) among studies of all designs, although considerable variation was evident (range: 0–26%). The main limitation of palatal implants is that they usually require two surgical procedures. The first is for palatal implant placement and is similar to that of dental implants and the second, more invasive, is sometimes needed for palatal implant removal. Insertion and removal of palatal implants is a technique-sensitive procedure, which requires a specialized periodontist or oral surgeon; thus increasing treatment costs. Furthermore, palatal implants can only be used as non-compliance treatment means for maxillary tooth movements, whereas mini-screws can be also placed in the mandible. The conventional healing period of approximately 12 weeks can also be considered a disadvantage in comparison to immediate loading of mini-screws. Nevertheless, certain recent studies have demonstrated that immediate loading of palatal implants resulted in comparable success with that of conventionally loaded implants (4, 8, 18). Mini-screws have been favoured in the last decade because they can be inserted and removed easily by the orthodontist, under local or no anesthesia (3). Furthermore, they can also be placed at various locations within the dentoalveolar bone facilitating different treatment needs. The main advantage of mini-screws is the ease of use, although an important consideration is to avoid harming of vital anatomical structures during insertion (12, 35). The median failure risk among studies of all designs was 6.1 per cent, which is quite similar to that of palatal implants. Considerable variation was observed also in this case (range: 0–33%). However, it should be noted that although the median follow-up period for mini-screws was adequate for the needs of regular orthodontic cases (6 months), it was quite smaller than the 18-month median follow-up of palatal implants. Furthermore, the number of mini-screws per patient was not fully reported across studies. In addition, only few of the studies defined which failures concerned single used mini-screws or multiple mini-screws combined in one patient, precluding assessment of unit of analysis errors. The findings of our study, in terms of success rate of palatal implant or mini-screws, are in agreement with earlier systematic reviews in the literature. In the systematic review of Schätzle et al., the success rate for mini-screws, placed at different locations, was 85 per cent, with a follow-up observation period ranging from 4 to 36 months, whereas the success rate for palatal implants was 90 per cent, with a follow-up between 3 and 22 months (2). Another systematic review reported 94 per cent success rate for palatal implants. Failures were categorized to three following types: surgery-related 61 per cent, orthodontic-related 19 per cent, and patient-related failures 19 per cent (1). As far as the risk factors of failure are concerned, no significant effect was identified in various studies for the factors of patient’s sex or age. Interestingly, almost all studies included disproportional sex groups, with significantly more female patients. Oral hygiene has proved to be an important predictor of mini-screw or palatal implant success (36). There is evidence that insufficient oral hygiene leads to inflammation of the peri-implant tissues, which can affect the stability of the palatal implants. However, such a conclusion cannot be drawn from the present review since lack of information is present on this respect. In several studies, failure of palatal implants or mini-screws has been attributed to the parafunctional activity of the tongue, though no direct proof was provided. Host parameters that are considered to improve primary and secondary stability of mini implants include increased bone thickness and depth as well as high bone density (12, 35). Thin soft tissue is also considered advantageous because it is less vulnerable to inflammation. The median and paramedian regions of the anterior palate possess all those characteristics, as well as the reduced risk damaging tooth roots, and thus, are rightly considered ideal for the placement of TADs. Paramedian regions seem to be preferable for the placement of mini-screws since they demand shorter force arms and they show the greatest palatal cortical bone thickness between the canine and the first premolar. Furthermore, such placement avoids unnecessary trauma to the midpalatal region, which is rich in connective tissue and consequently, potential instability of the implants, especially in young individuals (12). TADs have a wide spectrum of clinical applications within orthodontics (37, 38). Palatal implants and mini-screws have been used both directly and indirectly. On the whole, 663 palatal implants had been used indirectly and only 126 directly, whereas, only 78 mini-screws had been used indirectly versus 653 directly. However, since many studies did not clarify if the failed palatal implants or mini-screws were used directly or indirectly, we could not assess in more detail the association between direct/indirect use and success or failure. Finally, it should be kept in mind that some of the TAD designs analysed in the cited studies may have changed over time and may not be commercially available exactly at the same design as at the time the study was published. 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The European Journal of OrthodonticsOxford University Press

Published: Mar 28, 2018

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