Glass-ionomer open exposure (GOPEX) versus closed exposure of palatally impacted canines: a retrospective study of treatment outcome and orthodontists’ preferences

Glass-ionomer open exposure (GOPEX) versus closed exposure of palatally impacted canines: a... Summary Objectives To investigate which surgical technique orthodontists prefer for exposing palatally impacted canines (PICs), and to compare closed exposure and glass-ionomer open exposure (GOPEX) with regard to pre- and post-surgical orthodontic variables. Materials and methods A questionnaire with 19 questions and three cases visualising superficial, deep, or medial PICs was sent to 48 orthodontists working in a Swedish county. Sixty case records for patients with unilateral PICs from two centres were analysed; 30 patients having GOPEX (Centre A), and 30 undergoing closed exposure (Centre B). Pre- and post-surgical orthodontic variables were collected from the dental records. Results The response rate was 81 per cent. There was an equal distribution of preference between open and closed exposure. Glass-ionomer cement (GIC) was predominately used as surgical packing in open exposure. No active traction was initiated until the canine erupted spontaneously. In the closed exposure cases, traction started shortly after exposure. The clinicians mentioned similar advantages of choosing one technique over the other and the main basis for the decision was the clinician’s preference and not the location of the canine. There were no differences regarding post-exposure complications between the techniques. The overall treatment time was the same but there were fewer appointments and significantly shorter active treatment time with traction of the PIC in the GOPEX group. Limitations Despite the homogeneity of the baseline patient characteristics, pre- and post-surgical orthodontic variables were analysed retrospectively, therefore, it is difficult to assess what impact these confounding factors may have had on the treatment time. Conclusions The choice of exposure technique depends on the clinician’s preferences. The active treatment time is shorter and the number of appointments fewer with open exposure when GIC is used as surgical packing. Introduction Accurate and early diagnosis of palatally impacted canines (PIC) is important, as this condition will lead to permanent impaction (1–3) and on rare occasion’s resorption of adjacent teeth (4, 5). Early interceptive treatment, such as extraction of the deciduous canine, is therefore desirable. Naoumova et al. (6) have shown that early extraction is an effective measure but that it is dependent on the severity of the displacement and the age of the patient. Despite the successful outcome after interceptive extraction, not all canines erupt (7) and other interventions are required. There are various treatment options for the management of PICs, with surgical exposure and a subsequently fixed appliance being a frequently chosen treatment (8). Two different surgical procedures are routinely used to uncover PICs: open and closed surgical exposure. The open exposure technique consists of surgical removal of the tissue covering the tooth, leaving it exposed to the oral cavity. Surgical dressing or packing is often placed over the exposed area for approximately 10 days. The tooth is then left to erupt naturally, or a bonded attachment may be put in place and orthodontic force applied to pull the tooth into its correct position (9). In the closed exposure technique, the palatal mucosa is raised through a flap operation and an attachment, often a gold chain or similar, is bonded to the exposed tooth. The palatal mucosa is then repositioned and sutured, with the chain exiting through the mucosa. Shortly after surgery, orthodontic traction is applied to bring the tooth into its correct position (9). There is no evidence or consensus among clinicians on which surgical technique is the best method. Those advocating the closed technique mention benefits such as patient comfort and post-treatment periodontal status, whereas clinicians favouring the open technique state that the risk of a need for repeated surgical interventions is smaller than with closed exposure. A survey carried out in the UK (10) revealed that 50 per cent of the 325 orthodontists who responded favoured the open exposure technique, and another survey, Spencer et al. (11), showed that there are considerable variations among clinicians in the design of the mucosal flap procedure and the use of surgical dressing and packing. Two systematic reviews have recently been published (9, 12), concluding that there is a lack of evidence on whether the open or the closed exposure technique is the treatment of choice in terms of treatment outcomes. However, it is important to highlight that previous comparative studies (13–16) mainly have focused on exposures where orthodontic traction is applied shortly after, regardless if it is an open or a closed technique. No studies have so far focused on comparing closed exposure to a Glass-ionomer OPen EXposure (GOPEX) where the canine with its glass-ionomer coverage is left for several months to self-erupt before applying the orthodontic traction (17,18). The GOPEX technique may hence shorten the active orthodontic treatment time and also decrease the post-surgical complications compared to a closed exposure. Therefore, the aims of the current study were to: 1. Evaluate which surgical technique orthodontists prefer for treating PIC and the reasons behind their choice; 2. Retrospectively compare pre- and post-surgical orthodontic variables between closed exposure and glass-ionomer open exposure (GOPEX). Materials and methods Questionnaire A questionnaire was sent to all orthodontists with at least 1 year of specialist experience working in the county of Västra Götaland, Sweden. The questionnaire was answered anonymously. Two reminders were sent with a 1-month interval to those who had not responded. No further attempt was made to contact the non-responders. The questionnaire consisted of 19 questions divided into two categories: open questions and questions with response categories followed by three cases: one case with unilateral and two cases with bilateral impacted maxillary canines (Supplementary Appendix). The impaction of the canines in the three cases was judged as superficial (canine overlapping the lateral incisor and located at the cemento-enamel junction of the lateral incisor), deep (canine overlapping the lateral incisor and located at 1/3 of the apical part of the root of the lateral incisor), or medial (canine overlapping the central incisors and located at the middle of the root of the central incisor) (Figure 1). In all three cases, the participants were asked which surgical technique they would prefer and why. The remaining questions concerned gender, age, number of years of work as a specialist, the location and type of clinic, the number of orthodontists at the clinic, the number of PICs treated per year, access to CBCT/CT machines and which radiographs they thought were needed for the treatment planning of PICs. The participants were also asked which surgical exposure technique(s) they normally prefer, who decides and performs the surgical procedure and what the advantages of the chosen technique are. If the participants preferred open exposure, they were asked to specify the surgical dressing that was used, the time it was applied and whether spontaneous canine eruption was awaited. Those who preferred closed exposure were asked to specify the material that was used for bonding the canine. Participants using both surgical techniques were asked to explain when they would choose one technique over the other. Figure 1. View largeDownload slide The three cases in the questionnaire. Case 1: superficially located unilateral impacted maxillary canine on the left side. Case 2: medially located bilateral impacted maxillary canines. Case 3: deeply located bilateral impacted maxillary canines. More detailed information about the cases is given in the Supplementary Appendix. Figure 1. View largeDownload slide The three cases in the questionnaire. Case 1: superficially located unilateral impacted maxillary canine on the left side. Case 2: medially located bilateral impacted maxillary canines. Case 3: deeply located bilateral impacted maxillary canines. More detailed information about the cases is given in the Supplementary Appendix. Dental records survey Patient records and radiographs from two orthodontic clinics in the county of Västra Götaland, Sweden, were retrospectively reviewed. The specialist clinic in Gothenburg (centre A), which mainly performs GOPEX, and the specialist clinic in Skövde (centre B) that mainly performs closed surgical exposure. The dental records of 30 patients with unilateral palatally impacted maxillary canines were selected between January 2012 and July 2013 from Centre A, and 30 patient records were selected between October 2008 and September 2013 from Centre B. Out of this total of 60 patients, 30 were treated with GOPEX (Figure 2) and 30 with the closed technique. Figure 2. View largeDownload slide A clinical case with bilateral palatally retained canines. Left picture: open exposure with glass-ionomer cement covering the exposed canines. Middle picture: the canines have spontaneously erupted and the glass-ionomer cement has been removed and an eyelet is bonded directly on the buccal surface and orthodontic traction is applied. Right picture: canines correctly positioned in the dental arch. Figure 2. View largeDownload slide A clinical case with bilateral palatally retained canines. Left picture: open exposure with glass-ionomer cement covering the exposed canines. Middle picture: the canines have spontaneously erupted and the glass-ionomer cement has been removed and an eyelet is bonded directly on the buccal surface and orthodontic traction is applied. Right picture: canines correctly positioned in the dental arch. The inclusion criteria were patients with a unilateral palatally impacted maxillary canine, and younger than 20 years. Patients with craniofacial syndromes, including cleft-lip-and palate, odontomas, supernumerous teeth, or other pathological conditions in the maxillary anterior region were not considered eligible for the study. The following pre-orthodontic treatment variables were registered: − Patient characteristics: gender, age on exposure, side of impaction, malocclusion, dental deviations, or eruption disturbance other than palatally impacted maxillary canines, and the need for orthodontic extraction of teeth other than the maxillary canines; − Radiographic images used for treatment planning and surgical exposure; − Exposure technique and sedation administered before or during the surgical exposure. The following orthodontic treatment variables were collected: − Treatment time (treatment start and treatment completion in terms of bonding and debonding of orthodontic appliances); − Number of visits, divided into: o Active: appointments including bonding, cementing, active traction of the canine, adjustments of the appliance, debonding; o Passive: appointments without orthodontic treatment; i.e. consultation, clinical and radiographic examination, removal of sutures or glass-ionomer packing (GIC); o Emergency appointments. − Number of missed and/or cancelled appointments; − Complications during treatment; − Time to spontaneous canine eruption; − Type of orthodontic appliance. Statistics The statistical analyses were performed using SPSS software. The Chi-square test was used to determine differences between categorical variables, while Student’s t-test was used for continuous unpaired variables with approximately normal distributions to test the significance of mean differences. The level of significance was set at P < 0.05. Results Questionnaire The survey was sent to 48 orthodontists and 39 of them responded, resulting in a response rate of 81 per cent. The majority of the orthodontists had worked more than 10 years (62%), and all except one had undergone postgraduate training in Sweden. All clinics had more than at least three orthodontists. Thirty-three of the respondents treated more than 10 impacted canines per year (Table 1). Paedodontic specialists or oral and maxillofacial surgeons usually performed the surgical procedures, while the type of exposure, open or closed, was generally chosen by the orthodontist. Eighty-five per cent of the respondents had access to CT/CBCT machines, but these were mostly used ‘sometimes’, while intraoral radiographs and panoramic radiographs were taken ‘always’ in almost 90 per cent (Table 1) of the cases. Table 1. Questions about impacted canines with response options and percentages. Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  CT/CBCT, computed tomography/cone beam computed tomography; PAN, panoramic radiograph. View Large Table 1. Questions about impacted canines with response options and percentages. Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  CT/CBCT, computed tomography/cone beam computed tomography; PAN, panoramic radiograph. View Large Forty-eight per cent of the orthodontists used both open and closed procedures in the treatment regimens. An equal distribution of the respondents preferred only one of the methods. Twenty-eight per cent chose the open and 23 per cent the closed method. No orthodontist used any other method than open or closed exposure. Those who worked with more than one surgical technique preferred open exposure in cases where the tooth was judged as superficial on the radiograph, while closed exposure was chosen in deep/medial cases. The advantages of open and closed exposure, respectively, as described by the respondents, are shown in Table 2. Table 2. Advantages of open and closed exposure, as expressed by the respondents. Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  View Large Table 2. Advantages of open and closed exposure, as expressed by the respondents. Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  View Large The surgical dressing or packing used in the open exposure cases to prevent gingival healing or overgrowth was glass-ionomer cement (GIC) in 72 per cent , followed by Coe-pakTM in 3 per cent of the cases. In 25 per cent of the questionnaires, the orthodontist did not indicate which packing was used. In the majority of cases, the dressing was left on until the tooth had erupted. In open surgical cases, 23 per cent of the orthodontists did not wait for the canine to erupt before they started pulling the tooth with an appliance, 28 per cent waited until the tooth could be bonded, and 15 per cent waited approximately 3–6 months (Figure 3). A gold chain was bonded in 95 per cent of the closed surgical exposure cases. In 5 per cent of the cases, this question was not answered. Figure 3. View largeDownload slide Distribution of waiting time for spontaneous canine eruption until active pulling is initiated. Figure 3. View largeDownload slide Distribution of waiting time for spontaneous canine eruption until active pulling is initiated. Case 1: superficially located impacted canine Sixty-four per cent would have chosen open exposure and 31 per cent closed exposure. The rest of the orthodontists did not state a preference. The reasons for choosing open exposure were superficially positioned canine, familiarity with the open exposure procedure, and shorter orthodontic treatment. The orthodontists who chose closed exposure also mentioned familiarity with the surgical technique, to possibility to start to distalize earlier the canine post-surgery, thus minimizing the resorption risk of the adjacent teeth, and better periodontal status after the orthodontic treatment. Case 2: medially located impacted canines Forty-six per cent would have chosen open exposure for 13 and 54 per cent a closed procedure. Almost the same distribution was seen for 23 (open, 59%; closed, 41%). The reasons for choosing open exposure for both canines were the same: easier and shorter orthodontic treatment, familiarity with open exposure, superficially located canine, and less pain during the orthodontic treatment. Five respondents would like a modified version of open exposure with glass-ionomer dressing and a gold chain, in order to start distalizing the canine earlier. Those choosing closed exposure mentioned benefits such as less pain during surgery, possibility to start distalizing the canine earlier to minimize the risk of resorption of the adjacent teeth, better periodontal status after the orthodontic treatment and familiarity with the technique. Case 3: deeply located impacted canines Almost the same distribution was reported for both canines: 13 (open, 44%; closed, 46 %; no reply, 10%) and 23 (open, 44%; closed, 41%; no reply, 15%). The same reasons were given for choosing open exposure for both 13 and 23: easier and shorter orthodontic treatment and familiarity with the technique. The same reasons were also given for choosing closed exposure for both 13 and 23: deeply located canine, need for distalization post-surgery due to the risk of resorption of adjacent teeth, familiarity with the closed technique and difficulty of performing open exposure of deeply located canines. Dental records The baseline demographic and clinical data for the 60 patients recruited from the two centres are listed in Table 3. There were no differences between the centres at baseline for age, gender distribution, and side of canine impaction or severity of canine impaction, dental deviations/other eruption disturbances, need for orthodontic extraction of other teeth than the impacted canine, and malocclusion Classes II or III. However, there were significantly more CL I cases in Centre B than in Centre A (P < 0.05). Table 3. Baseline data of the patients from Centres A and B.   Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS    Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS  NS, not significant. *Statistical significance P < 0.05. View Large Table 3. Baseline data of the patients from Centres A and B.   Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS    Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS  NS, not significant. *Statistical significance P < 0.05. View Large Radiographic images taken for treatment and surgical exposure planning included two-dimensional imaging (intraoral radiography, lateral cephalogram, and panoramic radiographs) and/or three-dimensional imaging (CBCT) in both centres (Figure 4). Significantly more 2D images were taken in Centre B (P < 0.01), while in Centre A, significantly more 2D in combination with 3D were taken (P < 0.01). Neither centre used only 3D images. Figure 4. View largeDownload slide Two (2D) and three-dimensional radiographs (3D) required for treatment planning and surgical exposure of maxillary impacted canines in Centres A and B. Figure 4. View largeDownload slide Two (2D) and three-dimensional radiographs (3D) required for treatment planning and surgical exposure of maxillary impacted canines in Centres A and B. Prior to the surgical exposure, different types of medication were administered in the two centres; either an analgesic agent alone (n = 15, Centre A, 0; Centre B, 15), sedative agent alone (n = 10, Centre A, 4; Centre B, 6) or in combination with an analgesic agent (n = 23, Centre A, 21; Centre B, 2). The types of sedative agents included general anaesthetics, nitrous oxide, and oral premedication. Twelve patients (Centre A, n = 5; Centre B, n = 7) were not given any medication prior to the surgical exposure. Significantly more patients were only given analgesics in Centre B than in Centre A (P < 0.001). However, significantly more analgesics in combination with oral premedication (P < 0.001) or analgesics in combination with both nitrous oxide and oral premedication (P < 0.05) were prescribed in Centre A than in Centre B. Nine complications were noted after the surgical exposure (Centre A, n = 3; Centre B, n = 6). In Centre A, the complication was loss of the surgical dressing between 20 and 40 days post-surgery. None of the cases needed re-operation. The complications in Centre B included loss of the suture or gold chain 3–6 days post-surgery. All the gold chains had to be rebonded; i.e. re-operations were carried out. The patients in the two centres were treated with different orthodontic appliances, such as a fixed appliance in the maxilla only or in combination with the mandible and/or with an anchorage device as extraoral traction, a goshgarian, a transpalatal bar, a lingual arch, and a transpalatal bar connected to a temporary anchorage device. Statistically significantly more patients in Centre A were treated with fixed appliances in both jaws (P < 0.01), whereas statistically significantly more patients in Centre B had a fixed appliance in the maxilla in combination with an anchorage device (P < 0.001) (Figure 5). Figure 5. View largeDownload slide Distribution of patients according to the different type of orthodontic appliance used during the orthodontic treatment in Centres A and B. Figure 5. View largeDownload slide Distribution of patients according to the different type of orthodontic appliance used during the orthodontic treatment in Centres A and B. The number of appointments was significantly higher in Centre B, where the closed surgical procedure was applied (Figure 5). This was due to a larger number of active appointments when the appliances were activated. There were no differences in the number of passive appointments between the two centres, but the number of missed and cancelled appointments was significantly higher in Centre A than in Centre B (Figure 6). Figure 6. View largeDownload slide Distribution of the number of passive [appointments where no orthodontic treatment was performed; i.e. consultation, clinical and radiographic examination, removing sutures, or glass-ionomer cement (GIC)], active (appointments including bonding, cementing, active traction of the canine, adjustments of the appliance, debonding), emergency, missed and cancelled appointments, as well as the total number of absent appointments (missed and cancelled appointments) in Centres A and B. Figure 6. View largeDownload slide Distribution of the number of passive [appointments where no orthodontic treatment was performed; i.e. consultation, clinical and radiographic examination, removing sutures, or glass-ionomer cement (GIC)], active (appointments including bonding, cementing, active traction of the canine, adjustments of the appliance, debonding), emergency, missed and cancelled appointments, as well as the total number of absent appointments (missed and cancelled appointments) in Centres A and B. The overall treatment time did not differ between the open and closed procedure (Centre A; 28.0 ± 9.7 months; Centre B, 27.1 ± 8.4 months). However, when the treatment time was analysed in greater detail, some significant differences were seen. Traction of the impacted canine started earlier in the closed cases (P < 0.001), and active treatment time from the start of canine traction until debonding was shorter in the open cases (P < 0.05). The waiting time for spontaneous eruption after surgery was longer in the open cases (P < 0.001), and active treatment also started later after surgery in the open cases (P < 0.001) (Figure 7). Figure 7. View largeDownload slide Orthodontic treatment time measured in days and divided into different stages: canine traction debonding; i.e. start of canine traction to completion of the whole treatment; exposure bonding; i.e. time from exposure to start of active treatment (appointments including bonding, cementing); exposure debonding; i.e. the time from exposure to completion of the whole treatment. The duration of canine eruption; i.e. waiting time for spontaneous eruption after surgery, was also measured in days. Figure 7. View largeDownload slide Orthodontic treatment time measured in days and divided into different stages: canine traction debonding; i.e. start of canine traction to completion of the whole treatment; exposure bonding; i.e. time from exposure to start of active treatment (appointments including bonding, cementing); exposure debonding; i.e. the time from exposure to completion of the whole treatment. The duration of canine eruption; i.e. waiting time for spontaneous eruption after surgery, was also measured in days. Discussion This study aimed to compare whether open (GOPEX) or closed exposure is the most favourable treatment in PIC, in terms of treatment outcomes and in the view of the orthodontists. The open exposure method (GOPEX) where GIC is used instead of conventional dressing or packing has been used in Gothenburg since the 1980s. Glass-ionomer cement is used as bone cement in ear, nose and throat surgery and also as a retrograde filling material after apicoectomy (20). The material is considered as a biocompatible material which does not cause any tissue inflammation or reaction. The thoughts behind the method is that the glass-ionomer cement coverage, penetrates the gingival surface and thus lets the biological dental emergence system believe that the tooth has emerged and thus will continue to erupt in a normal way. The glass-ionomer coverage can sometimes be reduced by drilling if it becomes too protruded and irritates the tongue. The choice of the respondents yielded an equal distribution of the open (28%) and closed (23%) surgical method, and almost half of the respondents used both methods (49%). These results differ from a survey carried out in the UK, revealing that 50 per cent favoured open exposure (11). The main finding in the present study was that personal preferences, such as, ‘I’m used to work with this technique,’ was a decisive factor for choosing the method of exposure. To assess if the severeness of the canine position based on its location horizontally and vertically, may affect the orthodontist choice of exposure technique, three clinical cases were added in the survey. However, the majority of the orthodontist preferred the surgical technique they usually work with in all cases irrespectively of the canine position. Several randomised controlled trial (RCT) studies (13–16) have shown that there are no differences in post-operative pain, periodontal health, or aesthetic impact between open and closed exposure of palatally impacted maxillary canines. Despite this, those who worked with both techniques preferred open exposure for superficially positioned canines, as it was easier to monitor the direction of traction and it was presumed to be less painful for the patients. It was also believed to lead to easier and shorter orthodontic treatment. For deeply located canines, the need to distalize the canines post-surgery due to the risk of resorption of adjacent teeth, easier control of the direction of traction, better anticipated periodontal status after the orthodontic treatment, and less pain during surgery, were reasons for choosing the closed exposure technique. Since, as far as we know, there are no studies in the literature that have investigated the operator’s reasons for choosing the appropriate surgical exposure technique, it is not possible to compare our findings with previous studies. CBCT has been recommended in severe PIC and for those with a high risk of incisor root resorption (21), as it provides the clinician with a comprehensive radiographic image in three planes. In the present study, however, the dental records showed that neither centre used 3D images as a standard procedure for treatment planning; instead, 2D images were the first-hand choice, sometimes in combination with 3D imaging. Significantly more 3D images were used in Centre A, which could be explained by Centre A being a University Clinic, while Centre B is a regular orthodontic clinic. In addition, the questionnaire, which was sent to both Centres, showed that 2D images were ‘always’ taken in almost 90 per cent of the cases for diagnosis and treatment planning, while CT/CBCT, to which 85 per cent had access, was used only ‘sometimes’ (Table 1). According to the literature, surgical exposure is generally performed by oral and maxillofacial surgeons under local or general anaesthesia (14–16). According to the questionnaire, paedodontic specialists or oral and maxillofacial surgeons usually performed the surgical exposure, but the technique was generally chosen by the orthodontist. Many different types of surgical dressing, such as Whitehead’s varnish, Coe-pakTM and SeptoplastTM, are used as packings in open exposure of teeth. These dressings are usually sutured and removed after 1–2 weeks (14–16). When conventional surgical packing is removed, there is always a risk that the opening to the tooth heals, especially if the tooth is deeply positioned in the alveolar process. Glass-ionomer cement, on the other hand, is known to bond to enamel or dentin without etching and post-operative discomfort, and complications are uncommon (17,18), even if the packing is left for several months during which the tooth can continue to self-erupt. A study by Nordenvall (17) showed that only three out of 35 (8.5%) GIC were lost during the first post-operative month, which is regarded as the most critical period. In another study by Nordenvall (18), no GIC was lost during the critical initial healing period, and only 2 of 30 were lost during the 3–9-month follow-up period. About 72 per cent of the orthodontists in the present study responded that they use GIC in open exposure cases, i.e. GOPEX, until the tooth has erupted spontaneously. The dental records from Centre A confirmed use of GIC as the wound dressing in all open exposure cases. Loss of a GIC dressing occurred in three cases (10%), two during the critical initial healing period, and one 38 days post-surgery. None of the cases needed repeated surgery. These results conform with the data published by Nordenvall (17). The overall failure rate reported in the study by Parkin et al. (15) was 6–9.6 per cent, where Whitehead varnish or Coe-pack surgical dressing was sutured in place but only applied for 1–2 weeks. According to the dental records, a golden chain was bonded to the canine in the closed exposure technique, which was also stated in the questionnaires. Complications included loss of sutures or chains 3–6 days post-surgery. Out of the six cases with complications, three were due to loss of the gold chain (10%). All chains except one (the canine was visible and an eyelet was bonded instead) had to be rebonded; i.e. required repeated surgery. Failure rates of 11.4–30.7 per cent for closed exposures have been reported (22,23); however, these results were published many years ago, and bonding techniques and materials have developed considerably since then. A more recent study had a failure rate of 2.9 per cent in a closed exposure group (14), which is less than in our study. The higher failure rate found in the dental records may be explained by the clinical experience of the clinicians performing the surgical technique. In this study, the clinicians carried out the closed exposure under local anaesthesia, while in the study by Parkin et al. (15), the surgery was performed under general anaesthesia. A wide range of average treatment times has been reported in previous studies, extending from 17 to 28 months, depending on the age of the patients, whether the cases concern unilateral, bilateral PIC or buccally impacted canines, but also on the location of the canine mesiodistally and in relation to the occlusal plane (1, 24–26). The total treatment time in this study was within the same time range as in the studies mentioned above. In addition, the total treatment time was the same, regardless of the surgical technique (Centre A, 28.0 ± 9.7 months; Centre B, 27.1 ± 8.4 months). However, the active treatment time was shorter and the number of active appointments fewer in the GOPEX cases. Furthermore, the canine traction time until completion of the orthodontic treatment was more than four months shorter when GOPEX was employed. This is due to the different treatment approach in the open exposure cases where natural eruption of the canine is awaited before the active part of the orthodontic treatment is initiated. The homogeneity of the baseline patient characteristics, with respect to age, sex, the need for orthodontic extraction and the location of the canine in relation to the occlusal plane and the mesiodistal location as seen on radiographs, is a strength of this study. The only difference seen between the two centres was significantly more CL I cases in Centre B. For this reason, and the fact that pre- and post-surgical orthodontic variables were analysed retrospectively, it is difficult to assess what impact these confounding factors may have had on the treatment time. Therefore, further studies with a prospective design are required to report on treatment outcomes accurately when performing open versus closed exposure. An RCT study comparing GOPEX with closed exposure of PIC is currently the subject of a prospective trial at our clinic. Conclusion The choice of surgical exposure technique depends on the clinician’s preference. The duration of active treatment and the active traction time for PICs is significantly shorter and the number of appointments significantly fewer with glass-ionomer open exposure (GOPEX). Supplementary material Supplementary material is available at European Journal of Orthodontics online. Funding Public dental service, Region Västra Götaland. Conflict of interest None to declare. Acknowledgment The authors wish to thank all the orthodontists for responding to the survey. References 1. Stewart, J.A., Heo, G., Glover, K.E., Williamson, P.C., Lam, E.W. and Major, P.W. ( 2001) Factors that relate to treatment duration for patients with palatally impacted maxillary canines. American Journal of Orthodontics and Dentofacial Orthopedics , 119, 216– 225. Google Scholar CrossRef Search ADS PubMed  2. Grover, P.S. and Lorton, L. ( 1985) The incidence of unerupted permanent teeth and related clinical cases. Oral surgery, Oral Medicine, and Oral Pathology , 59, 420– 425. Google Scholar CrossRef Search ADS PubMed  3. Thilander, B. and Jakobsson, S.O. ( 1968) Local factors in impaction of maxillary canines. Acta Odontologica Scandinavica , 26, 145– 168. Google Scholar CrossRef Search ADS PubMed  4. Ericson, S. and Kurol, J. ( 1988) Resorption of maxillary lateral incisors caused by ectopic eruption of the canines. A clinical and radiographic analysis of predisposing factors. American Journal of Orthodontics and Dentofacial Orthopedics , 94, 503– 513. Google Scholar CrossRef Search ADS PubMed  5. Ericson, S. and Kurol, P.J. ( 2000) Resorption of incisors after ectopic eruption of maxillary canines: a CT study. The Angle Orthodontist , 70, 415– 423. Google Scholar PubMed  6. Naoumova, J., Kurol, J. and Kjellberg, H. ( 2015) Extraction of the deciduous canine as an interceptive treatment in children with palatal displaced canines - part I: shall we extract the deciduous canine or not? European Journal of Orthodontics , 37, 209– 218. Google Scholar CrossRef Search ADS PubMed  7. Naoumova, J., Kürol, J. and Kjellberg, H. ( 2015) Extraction of the deciduous canine as an interceptive treatment in children with palatally displaced canines - part II: possible predictors of success and cut-off points for a spontaneous eruption. European Journal of Orthodontics , 37, 219– 229. Google Scholar CrossRef Search ADS PubMed  8. Manne, R., Gandikota, C., Juvvadi, S.R., Rama, H.R. and Anche, S. ( 2012) Impacted canines: etiology, diagnosis, and orthodontic management. Journal of Pharmacy & Bioallied Sciences , 4, S234– S238. Google Scholar CrossRef Search ADS PubMed  9. Parkin, N., Benson, P.E., Thind, B., Shah, A., Khalil, I. and Ghafoor, S. ( 2017) Open versus closed surgical exposure of canine teeth that are displaced in the roof of the mouth. The Cochrane Database of Systematic Reviews , 8, CD006966. Google Scholar PubMed  10. Boyd, R.L. ( 1984) Clinical assessment of injuries in orthodontic movement of impacted teeth. II. Surgical recommendations. American Journal of Orthodontics , 86, 407– 418. Google Scholar CrossRef Search ADS PubMed  11. Spencer, H.R., Ramsey, R., Ponduri, S. and Brennan, P.A. ( 2010) Exposure of unerupted palatal canines: a survey of current practice in the United Kingdom, and experience of a gingival-sparing procedure. The British Journal of Oral & Maxillofacial Surgery , 48, 641– 644. Google Scholar CrossRef Search ADS PubMed  12. Sampaziotis, D., Tsolakis, I.A., Bitsanis, E. and Tsolakis, A.I. ( 2018) Open versus closed surgical exposure of palatally impacted maxillary canines: comparison of the different treatment outcomes-a systematic review. European Journal of Orthodontics , 40, 11– 22. Google Scholar CrossRef Search ADS PubMed  13. Chaushu, S., Becker, A., Zeltser, R., Branski, S., Vasker, N. and Chaushu, G. ( 2005) Patients perception of recovery after exposure of impacted teeth: a comparison of closed- versus open-eruption techniques. Journal of Oral and Maxillofacial Surgery , 63, 323– 329. Google Scholar CrossRef Search ADS PubMed  14. Gharaibeh, T.M. and Al-Nimri, K.S. ( 2008) Postoperative pain after surgical exposure of palatally impacted canines: closed-eruption versus open-eruption, a prospective randomized study. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics , 106, 339– 342. Google Scholar CrossRef Search ADS PubMed  15. Parkin, N.A., Deery, C., Smith, A.M., Tinsley, D., Sandler, J. and Benson, P.E. ( 2012) No difference in surgical outcomes between open and closed exposure of palatally displaced maxillary canines. Journal of Oral and Maxillofacial Surgery , 70, 2026– 2034. Google Scholar CrossRef Search ADS PubMed  16. Smailiene, D., Kavaliauskiene, A., Pacauskiene, I., Zasciurinskiene, E. and Bjerklin, K. ( 2013) Palatally impacted maxillary canines: choice of surgical-orthodontic treatment method does not influence post-treatment periodontal status. A controlled prospective study. European Journal of Orthodontics , 35, 803– 810. Google Scholar CrossRef Search ADS PubMed  17. Nordenvall, K.J. ( 1992) Glass ionomer cement used as surgical dressing after radical surgical exposure of impacted teeth. Swedish Dental Journal , 16, 87– 92. Google Scholar PubMed  18. Nordenvall, K.J. ( 1999) Glass ionomer cement dressing for surgically exposed impacted teeth. Journal of Clinical Orthodontics: JCO , 33, 45– 49. Google Scholar PubMed  19. Ericson, S. and Kurol, J. ( 1988) Early treatment of palatally erupting maxillary canines by extraction of the primary canines. European Journal of Orthodontics , 10, 283– 295. Google Scholar CrossRef Search ADS PubMed  20. Gungor, V., Atay, G., Bajin, M.D., Yarali, M., Sarac, S. and Sennaroglu, L. ( 2016) Comparison of various bone cement ossiculoplasty techniques and functional results. Acta Oto-Laryngologica , 136, 883– 887. Google Scholar CrossRef Search ADS PubMed  21. Liu, D.G., Zhang, W.L., Zhang, Z.Y., Wu, Y.T. and Ma, X.C. ( 2008) Localization of impacted maxillary canines and observation of adjacent incisor resorption with cone-beam computed tomography. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics , 105, 91– 98. Google Scholar CrossRef Search ADS PubMed  22. Pearson, M.H., Robinson, S.N., Reed, R., Birnie, D.J. and Zaki, G.A. ( 1997) Management of palatally impacted canines: the findings of a collaborative study. European Journal of Orthodontics , 19, 511– 515. Google Scholar CrossRef Search ADS PubMed  23. McDonald, F. and Yap, W.L. ( 1986) The surgical exposure and application of direct traction of unerupted teeth. American Journal of Orthodontics , 89, 331– 340. Google Scholar CrossRef Search ADS PubMed  24. Zuccati, G., Ghobadlu, J., Nieri, M. and Clauser, C. ( 2006) Factors associated with the duration of forced eruption of impacted maxillary canines: a retrospective study. American Journal of Orthodontics and Dentofacial Orthopedics , 130, 349– 356. Google Scholar CrossRef Search ADS PubMed  25. Fleming, P.S., Scott, P., Heidari, N. and Dibiase, A.T. ( 2009) Influence of radiographic position of ectopic canines on the duration of orthodontic treatment. The Angle Orthodontist , 79, 442– 446. Google Scholar CrossRef Search ADS PubMed  26. Becker, A. and Chaushu, S. ( 2003) Success rate and duration of orthodontic treatment for adult patients with palatally impacted maxillary canines. American Journal of Orthodontics and Dentofacial Orthopedics , 124, 509– 514. Google Scholar CrossRef Search ADS PubMed  © 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 This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The European Journal of Orthodontics Oxford University Press

Glass-ionomer open exposure (GOPEX) versus closed exposure of palatally impacted canines: a retrospective study of treatment outcome and orthodontists’ preferences

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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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Abstract

Summary Objectives To investigate which surgical technique orthodontists prefer for exposing palatally impacted canines (PICs), and to compare closed exposure and glass-ionomer open exposure (GOPEX) with regard to pre- and post-surgical orthodontic variables. Materials and methods A questionnaire with 19 questions and three cases visualising superficial, deep, or medial PICs was sent to 48 orthodontists working in a Swedish county. Sixty case records for patients with unilateral PICs from two centres were analysed; 30 patients having GOPEX (Centre A), and 30 undergoing closed exposure (Centre B). Pre- and post-surgical orthodontic variables were collected from the dental records. Results The response rate was 81 per cent. There was an equal distribution of preference between open and closed exposure. Glass-ionomer cement (GIC) was predominately used as surgical packing in open exposure. No active traction was initiated until the canine erupted spontaneously. In the closed exposure cases, traction started shortly after exposure. The clinicians mentioned similar advantages of choosing one technique over the other and the main basis for the decision was the clinician’s preference and not the location of the canine. There were no differences regarding post-exposure complications between the techniques. The overall treatment time was the same but there were fewer appointments and significantly shorter active treatment time with traction of the PIC in the GOPEX group. Limitations Despite the homogeneity of the baseline patient characteristics, pre- and post-surgical orthodontic variables were analysed retrospectively, therefore, it is difficult to assess what impact these confounding factors may have had on the treatment time. Conclusions The choice of exposure technique depends on the clinician’s preferences. The active treatment time is shorter and the number of appointments fewer with open exposure when GIC is used as surgical packing. Introduction Accurate and early diagnosis of palatally impacted canines (PIC) is important, as this condition will lead to permanent impaction (1–3) and on rare occasion’s resorption of adjacent teeth (4, 5). Early interceptive treatment, such as extraction of the deciduous canine, is therefore desirable. Naoumova et al. (6) have shown that early extraction is an effective measure but that it is dependent on the severity of the displacement and the age of the patient. Despite the successful outcome after interceptive extraction, not all canines erupt (7) and other interventions are required. There are various treatment options for the management of PICs, with surgical exposure and a subsequently fixed appliance being a frequently chosen treatment (8). Two different surgical procedures are routinely used to uncover PICs: open and closed surgical exposure. The open exposure technique consists of surgical removal of the tissue covering the tooth, leaving it exposed to the oral cavity. Surgical dressing or packing is often placed over the exposed area for approximately 10 days. The tooth is then left to erupt naturally, or a bonded attachment may be put in place and orthodontic force applied to pull the tooth into its correct position (9). In the closed exposure technique, the palatal mucosa is raised through a flap operation and an attachment, often a gold chain or similar, is bonded to the exposed tooth. The palatal mucosa is then repositioned and sutured, with the chain exiting through the mucosa. Shortly after surgery, orthodontic traction is applied to bring the tooth into its correct position (9). There is no evidence or consensus among clinicians on which surgical technique is the best method. Those advocating the closed technique mention benefits such as patient comfort and post-treatment periodontal status, whereas clinicians favouring the open technique state that the risk of a need for repeated surgical interventions is smaller than with closed exposure. A survey carried out in the UK (10) revealed that 50 per cent of the 325 orthodontists who responded favoured the open exposure technique, and another survey, Spencer et al. (11), showed that there are considerable variations among clinicians in the design of the mucosal flap procedure and the use of surgical dressing and packing. Two systematic reviews have recently been published (9, 12), concluding that there is a lack of evidence on whether the open or the closed exposure technique is the treatment of choice in terms of treatment outcomes. However, it is important to highlight that previous comparative studies (13–16) mainly have focused on exposures where orthodontic traction is applied shortly after, regardless if it is an open or a closed technique. No studies have so far focused on comparing closed exposure to a Glass-ionomer OPen EXposure (GOPEX) where the canine with its glass-ionomer coverage is left for several months to self-erupt before applying the orthodontic traction (17,18). The GOPEX technique may hence shorten the active orthodontic treatment time and also decrease the post-surgical complications compared to a closed exposure. Therefore, the aims of the current study were to: 1. Evaluate which surgical technique orthodontists prefer for treating PIC and the reasons behind their choice; 2. Retrospectively compare pre- and post-surgical orthodontic variables between closed exposure and glass-ionomer open exposure (GOPEX). Materials and methods Questionnaire A questionnaire was sent to all orthodontists with at least 1 year of specialist experience working in the county of Västra Götaland, Sweden. The questionnaire was answered anonymously. Two reminders were sent with a 1-month interval to those who had not responded. No further attempt was made to contact the non-responders. The questionnaire consisted of 19 questions divided into two categories: open questions and questions with response categories followed by three cases: one case with unilateral and two cases with bilateral impacted maxillary canines (Supplementary Appendix). The impaction of the canines in the three cases was judged as superficial (canine overlapping the lateral incisor and located at the cemento-enamel junction of the lateral incisor), deep (canine overlapping the lateral incisor and located at 1/3 of the apical part of the root of the lateral incisor), or medial (canine overlapping the central incisors and located at the middle of the root of the central incisor) (Figure 1). In all three cases, the participants were asked which surgical technique they would prefer and why. The remaining questions concerned gender, age, number of years of work as a specialist, the location and type of clinic, the number of orthodontists at the clinic, the number of PICs treated per year, access to CBCT/CT machines and which radiographs they thought were needed for the treatment planning of PICs. The participants were also asked which surgical exposure technique(s) they normally prefer, who decides and performs the surgical procedure and what the advantages of the chosen technique are. If the participants preferred open exposure, they were asked to specify the surgical dressing that was used, the time it was applied and whether spontaneous canine eruption was awaited. Those who preferred closed exposure were asked to specify the material that was used for bonding the canine. Participants using both surgical techniques were asked to explain when they would choose one technique over the other. Figure 1. View largeDownload slide The three cases in the questionnaire. Case 1: superficially located unilateral impacted maxillary canine on the left side. Case 2: medially located bilateral impacted maxillary canines. Case 3: deeply located bilateral impacted maxillary canines. More detailed information about the cases is given in the Supplementary Appendix. Figure 1. View largeDownload slide The three cases in the questionnaire. Case 1: superficially located unilateral impacted maxillary canine on the left side. Case 2: medially located bilateral impacted maxillary canines. Case 3: deeply located bilateral impacted maxillary canines. More detailed information about the cases is given in the Supplementary Appendix. Dental records survey Patient records and radiographs from two orthodontic clinics in the county of Västra Götaland, Sweden, were retrospectively reviewed. The specialist clinic in Gothenburg (centre A), which mainly performs GOPEX, and the specialist clinic in Skövde (centre B) that mainly performs closed surgical exposure. The dental records of 30 patients with unilateral palatally impacted maxillary canines were selected between January 2012 and July 2013 from Centre A, and 30 patient records were selected between October 2008 and September 2013 from Centre B. Out of this total of 60 patients, 30 were treated with GOPEX (Figure 2) and 30 with the closed technique. Figure 2. View largeDownload slide A clinical case with bilateral palatally retained canines. Left picture: open exposure with glass-ionomer cement covering the exposed canines. Middle picture: the canines have spontaneously erupted and the glass-ionomer cement has been removed and an eyelet is bonded directly on the buccal surface and orthodontic traction is applied. Right picture: canines correctly positioned in the dental arch. Figure 2. View largeDownload slide A clinical case with bilateral palatally retained canines. Left picture: open exposure with glass-ionomer cement covering the exposed canines. Middle picture: the canines have spontaneously erupted and the glass-ionomer cement has been removed and an eyelet is bonded directly on the buccal surface and orthodontic traction is applied. Right picture: canines correctly positioned in the dental arch. The inclusion criteria were patients with a unilateral palatally impacted maxillary canine, and younger than 20 years. Patients with craniofacial syndromes, including cleft-lip-and palate, odontomas, supernumerous teeth, or other pathological conditions in the maxillary anterior region were not considered eligible for the study. The following pre-orthodontic treatment variables were registered: − Patient characteristics: gender, age on exposure, side of impaction, malocclusion, dental deviations, or eruption disturbance other than palatally impacted maxillary canines, and the need for orthodontic extraction of teeth other than the maxillary canines; − Radiographic images used for treatment planning and surgical exposure; − Exposure technique and sedation administered before or during the surgical exposure. The following orthodontic treatment variables were collected: − Treatment time (treatment start and treatment completion in terms of bonding and debonding of orthodontic appliances); − Number of visits, divided into: o Active: appointments including bonding, cementing, active traction of the canine, adjustments of the appliance, debonding; o Passive: appointments without orthodontic treatment; i.e. consultation, clinical and radiographic examination, removal of sutures or glass-ionomer packing (GIC); o Emergency appointments. − Number of missed and/or cancelled appointments; − Complications during treatment; − Time to spontaneous canine eruption; − Type of orthodontic appliance. Statistics The statistical analyses were performed using SPSS software. The Chi-square test was used to determine differences between categorical variables, while Student’s t-test was used for continuous unpaired variables with approximately normal distributions to test the significance of mean differences. The level of significance was set at P < 0.05. Results Questionnaire The survey was sent to 48 orthodontists and 39 of them responded, resulting in a response rate of 81 per cent. The majority of the orthodontists had worked more than 10 years (62%), and all except one had undergone postgraduate training in Sweden. All clinics had more than at least three orthodontists. Thirty-three of the respondents treated more than 10 impacted canines per year (Table 1). Paedodontic specialists or oral and maxillofacial surgeons usually performed the surgical procedures, while the type of exposure, open or closed, was generally chosen by the orthodontist. Eighty-five per cent of the respondents had access to CT/CBCT machines, but these were mostly used ‘sometimes’, while intraoral radiographs and panoramic radiographs were taken ‘always’ in almost 90 per cent (Table 1) of the cases. Table 1. Questions about impacted canines with response options and percentages. Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  CT/CBCT, computed tomography/cone beam computed tomography; PAN, panoramic radiograph. View Large Table 1. Questions about impacted canines with response options and percentages. Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  Question  Response options  Percentage  Number of surgical exposures of impacted canines/year  0–5  21  6–10  44  11–15  18  More than 15  15  No reply  2  Operator performing the exposure  Orthodontist  0  Paedodontist  82  Oral and maxillofacial surgeon  49  Other; if so, who?  3  Operator deciding on the exposure technique  Orthodontist  82  The relevant operator  13  Orthodontist with relevant operator  0  No reply  5  Access to CT/CBCT  Yes  85  No  13  No reply  2  Radiographs needed for therapy planning of surgical exposure of impacted canines  Intraoral X-ray: always  87  Intraoral X-ray: sometimes  8  Intraoral X-ray: never  0  No reply  5  PAN: always  95  PAN: sometimes  2  PAN: never  0  No reply  2  CBCT/CT: always  0  CBCT/CT: sometimes  92  CBCT/CT: never  2  No reply  5  CT/CBCT, computed tomography/cone beam computed tomography; PAN, panoramic radiograph. View Large Forty-eight per cent of the orthodontists used both open and closed procedures in the treatment regimens. An equal distribution of the respondents preferred only one of the methods. Twenty-eight per cent chose the open and 23 per cent the closed method. No orthodontist used any other method than open or closed exposure. Those who worked with more than one surgical technique preferred open exposure in cases where the tooth was judged as superficial on the radiograph, while closed exposure was chosen in deep/medial cases. The advantages of open and closed exposure, respectively, as described by the respondents, are shown in Table 2. Table 2. Advantages of open and closed exposure, as expressed by the respondents. Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  View Large Table 2. Advantages of open and closed exposure, as expressed by the respondents. Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  Advantages of open exposure  Advantages of closed exposure  Shorter orthodontic treatment  Earlier start of pulling the canine, especially if the canine is near the root of the incisors  Easier to decide traction direction  Easier to control the traction direction  Easier orthodontic treatment  Less risk that the canine erupts in the anterior cross-bite position  Less pain during orthodontic treatment  Less pain during the exposure  Fewer complications post-surgery, such as no loose chains, fewer re-operations  Fewer complications post-surgery, such as fewer re-operations and less granulation of the soft tissue  Better periodontal status after orthodontic treatment  Better periodontal status after orthodontic treatment  No need for radiographs during orthodontic treatment  Easier to clean during the orthodontic treatment  View Large The surgical dressing or packing used in the open exposure cases to prevent gingival healing or overgrowth was glass-ionomer cement (GIC) in 72 per cent , followed by Coe-pakTM in 3 per cent of the cases. In 25 per cent of the questionnaires, the orthodontist did not indicate which packing was used. In the majority of cases, the dressing was left on until the tooth had erupted. In open surgical cases, 23 per cent of the orthodontists did not wait for the canine to erupt before they started pulling the tooth with an appliance, 28 per cent waited until the tooth could be bonded, and 15 per cent waited approximately 3–6 months (Figure 3). A gold chain was bonded in 95 per cent of the closed surgical exposure cases. In 5 per cent of the cases, this question was not answered. Figure 3. View largeDownload slide Distribution of waiting time for spontaneous canine eruption until active pulling is initiated. Figure 3. View largeDownload slide Distribution of waiting time for spontaneous canine eruption until active pulling is initiated. Case 1: superficially located impacted canine Sixty-four per cent would have chosen open exposure and 31 per cent closed exposure. The rest of the orthodontists did not state a preference. The reasons for choosing open exposure were superficially positioned canine, familiarity with the open exposure procedure, and shorter orthodontic treatment. The orthodontists who chose closed exposure also mentioned familiarity with the surgical technique, to possibility to start to distalize earlier the canine post-surgery, thus minimizing the resorption risk of the adjacent teeth, and better periodontal status after the orthodontic treatment. Case 2: medially located impacted canines Forty-six per cent would have chosen open exposure for 13 and 54 per cent a closed procedure. Almost the same distribution was seen for 23 (open, 59%; closed, 41%). The reasons for choosing open exposure for both canines were the same: easier and shorter orthodontic treatment, familiarity with open exposure, superficially located canine, and less pain during the orthodontic treatment. Five respondents would like a modified version of open exposure with glass-ionomer dressing and a gold chain, in order to start distalizing the canine earlier. Those choosing closed exposure mentioned benefits such as less pain during surgery, possibility to start distalizing the canine earlier to minimize the risk of resorption of the adjacent teeth, better periodontal status after the orthodontic treatment and familiarity with the technique. Case 3: deeply located impacted canines Almost the same distribution was reported for both canines: 13 (open, 44%; closed, 46 %; no reply, 10%) and 23 (open, 44%; closed, 41%; no reply, 15%). The same reasons were given for choosing open exposure for both 13 and 23: easier and shorter orthodontic treatment and familiarity with the technique. The same reasons were also given for choosing closed exposure for both 13 and 23: deeply located canine, need for distalization post-surgery due to the risk of resorption of adjacent teeth, familiarity with the closed technique and difficulty of performing open exposure of deeply located canines. Dental records The baseline demographic and clinical data for the 60 patients recruited from the two centres are listed in Table 3. There were no differences between the centres at baseline for age, gender distribution, and side of canine impaction or severity of canine impaction, dental deviations/other eruption disturbances, need for orthodontic extraction of other teeth than the impacted canine, and malocclusion Classes II or III. However, there were significantly more CL I cases in Centre B than in Centre A (P < 0.05). Table 3. Baseline data of the patients from Centres A and B.   Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS    Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS  NS, not significant. *Statistical significance P < 0.05. View Large Table 3. Baseline data of the patients from Centres A and B.   Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS    Centre A glass-ionomer open exposure (GOPEX) (n = 30)  Centre B closed exposure (n = 30)  P-value  Age (years): mean ± SD  14.0 ± 1.6  13.9 ± 1.6  NS  Gender      NS   Female  18  20     Male  12  10    Side of impaction      NS   Right (13)  14  18     Left (23)  16  12    Severity of impaction according to Ericson and Kurol (19)   Alpha angle (mean ± SD)  30.9 ± 8.9  33.8 ± 12.3  NS   Vertical height in mm (mean ± SD)  15.6 ± 3.6  15.5 ± 3.3  NS   Sector (mean ± SD)  3.4 ± 0.9  3.0 ± 0.8  NS  Dental deviations/eruption disturbance   Agenesis  3  1  NS   Ectopic eruption  1  2  NS  Angle’s classification   Class I  21  28  *   Class II  7  2  NS   Class III  2  0  NS  Necessity of orthodontic extraction  7  8  NS  NS, not significant. *Statistical significance P < 0.05. View Large Radiographic images taken for treatment and surgical exposure planning included two-dimensional imaging (intraoral radiography, lateral cephalogram, and panoramic radiographs) and/or three-dimensional imaging (CBCT) in both centres (Figure 4). Significantly more 2D images were taken in Centre B (P < 0.01), while in Centre A, significantly more 2D in combination with 3D were taken (P < 0.01). Neither centre used only 3D images. Figure 4. View largeDownload slide Two (2D) and three-dimensional radiographs (3D) required for treatment planning and surgical exposure of maxillary impacted canines in Centres A and B. Figure 4. View largeDownload slide Two (2D) and three-dimensional radiographs (3D) required for treatment planning and surgical exposure of maxillary impacted canines in Centres A and B. Prior to the surgical exposure, different types of medication were administered in the two centres; either an analgesic agent alone (n = 15, Centre A, 0; Centre B, 15), sedative agent alone (n = 10, Centre A, 4; Centre B, 6) or in combination with an analgesic agent (n = 23, Centre A, 21; Centre B, 2). The types of sedative agents included general anaesthetics, nitrous oxide, and oral premedication. Twelve patients (Centre A, n = 5; Centre B, n = 7) were not given any medication prior to the surgical exposure. Significantly more patients were only given analgesics in Centre B than in Centre A (P < 0.001). However, significantly more analgesics in combination with oral premedication (P < 0.001) or analgesics in combination with both nitrous oxide and oral premedication (P < 0.05) were prescribed in Centre A than in Centre B. Nine complications were noted after the surgical exposure (Centre A, n = 3; Centre B, n = 6). In Centre A, the complication was loss of the surgical dressing between 20 and 40 days post-surgery. None of the cases needed re-operation. The complications in Centre B included loss of the suture or gold chain 3–6 days post-surgery. All the gold chains had to be rebonded; i.e. re-operations were carried out. The patients in the two centres were treated with different orthodontic appliances, such as a fixed appliance in the maxilla only or in combination with the mandible and/or with an anchorage device as extraoral traction, a goshgarian, a transpalatal bar, a lingual arch, and a transpalatal bar connected to a temporary anchorage device. Statistically significantly more patients in Centre A were treated with fixed appliances in both jaws (P < 0.01), whereas statistically significantly more patients in Centre B had a fixed appliance in the maxilla in combination with an anchorage device (P < 0.001) (Figure 5). Figure 5. View largeDownload slide Distribution of patients according to the different type of orthodontic appliance used during the orthodontic treatment in Centres A and B. Figure 5. View largeDownload slide Distribution of patients according to the different type of orthodontic appliance used during the orthodontic treatment in Centres A and B. The number of appointments was significantly higher in Centre B, where the closed surgical procedure was applied (Figure 5). This was due to a larger number of active appointments when the appliances were activated. There were no differences in the number of passive appointments between the two centres, but the number of missed and cancelled appointments was significantly higher in Centre A than in Centre B (Figure 6). Figure 6. View largeDownload slide Distribution of the number of passive [appointments where no orthodontic treatment was performed; i.e. consultation, clinical and radiographic examination, removing sutures, or glass-ionomer cement (GIC)], active (appointments including bonding, cementing, active traction of the canine, adjustments of the appliance, debonding), emergency, missed and cancelled appointments, as well as the total number of absent appointments (missed and cancelled appointments) in Centres A and B. Figure 6. View largeDownload slide Distribution of the number of passive [appointments where no orthodontic treatment was performed; i.e. consultation, clinical and radiographic examination, removing sutures, or glass-ionomer cement (GIC)], active (appointments including bonding, cementing, active traction of the canine, adjustments of the appliance, debonding), emergency, missed and cancelled appointments, as well as the total number of absent appointments (missed and cancelled appointments) in Centres A and B. The overall treatment time did not differ between the open and closed procedure (Centre A; 28.0 ± 9.7 months; Centre B, 27.1 ± 8.4 months). However, when the treatment time was analysed in greater detail, some significant differences were seen. Traction of the impacted canine started earlier in the closed cases (P < 0.001), and active treatment time from the start of canine traction until debonding was shorter in the open cases (P < 0.05). The waiting time for spontaneous eruption after surgery was longer in the open cases (P < 0.001), and active treatment also started later after surgery in the open cases (P < 0.001) (Figure 7). Figure 7. View largeDownload slide Orthodontic treatment time measured in days and divided into different stages: canine traction debonding; i.e. start of canine traction to completion of the whole treatment; exposure bonding; i.e. time from exposure to start of active treatment (appointments including bonding, cementing); exposure debonding; i.e. the time from exposure to completion of the whole treatment. The duration of canine eruption; i.e. waiting time for spontaneous eruption after surgery, was also measured in days. Figure 7. View largeDownload slide Orthodontic treatment time measured in days and divided into different stages: canine traction debonding; i.e. start of canine traction to completion of the whole treatment; exposure bonding; i.e. time from exposure to start of active treatment (appointments including bonding, cementing); exposure debonding; i.e. the time from exposure to completion of the whole treatment. The duration of canine eruption; i.e. waiting time for spontaneous eruption after surgery, was also measured in days. Discussion This study aimed to compare whether open (GOPEX) or closed exposure is the most favourable treatment in PIC, in terms of treatment outcomes and in the view of the orthodontists. The open exposure method (GOPEX) where GIC is used instead of conventional dressing or packing has been used in Gothenburg since the 1980s. Glass-ionomer cement is used as bone cement in ear, nose and throat surgery and also as a retrograde filling material after apicoectomy (20). The material is considered as a biocompatible material which does not cause any tissue inflammation or reaction. The thoughts behind the method is that the glass-ionomer cement coverage, penetrates the gingival surface and thus lets the biological dental emergence system believe that the tooth has emerged and thus will continue to erupt in a normal way. The glass-ionomer coverage can sometimes be reduced by drilling if it becomes too protruded and irritates the tongue. The choice of the respondents yielded an equal distribution of the open (28%) and closed (23%) surgical method, and almost half of the respondents used both methods (49%). These results differ from a survey carried out in the UK, revealing that 50 per cent favoured open exposure (11). The main finding in the present study was that personal preferences, such as, ‘I’m used to work with this technique,’ was a decisive factor for choosing the method of exposure. To assess if the severeness of the canine position based on its location horizontally and vertically, may affect the orthodontist choice of exposure technique, three clinical cases were added in the survey. However, the majority of the orthodontist preferred the surgical technique they usually work with in all cases irrespectively of the canine position. Several randomised controlled trial (RCT) studies (13–16) have shown that there are no differences in post-operative pain, periodontal health, or aesthetic impact between open and closed exposure of palatally impacted maxillary canines. Despite this, those who worked with both techniques preferred open exposure for superficially positioned canines, as it was easier to monitor the direction of traction and it was presumed to be less painful for the patients. It was also believed to lead to easier and shorter orthodontic treatment. For deeply located canines, the need to distalize the canines post-surgery due to the risk of resorption of adjacent teeth, easier control of the direction of traction, better anticipated periodontal status after the orthodontic treatment, and less pain during surgery, were reasons for choosing the closed exposure technique. Since, as far as we know, there are no studies in the literature that have investigated the operator’s reasons for choosing the appropriate surgical exposure technique, it is not possible to compare our findings with previous studies. CBCT has been recommended in severe PIC and for those with a high risk of incisor root resorption (21), as it provides the clinician with a comprehensive radiographic image in three planes. In the present study, however, the dental records showed that neither centre used 3D images as a standard procedure for treatment planning; instead, 2D images were the first-hand choice, sometimes in combination with 3D imaging. Significantly more 3D images were used in Centre A, which could be explained by Centre A being a University Clinic, while Centre B is a regular orthodontic clinic. In addition, the questionnaire, which was sent to both Centres, showed that 2D images were ‘always’ taken in almost 90 per cent of the cases for diagnosis and treatment planning, while CT/CBCT, to which 85 per cent had access, was used only ‘sometimes’ (Table 1). According to the literature, surgical exposure is generally performed by oral and maxillofacial surgeons under local or general anaesthesia (14–16). According to the questionnaire, paedodontic specialists or oral and maxillofacial surgeons usually performed the surgical exposure, but the technique was generally chosen by the orthodontist. Many different types of surgical dressing, such as Whitehead’s varnish, Coe-pakTM and SeptoplastTM, are used as packings in open exposure of teeth. These dressings are usually sutured and removed after 1–2 weeks (14–16). When conventional surgical packing is removed, there is always a risk that the opening to the tooth heals, especially if the tooth is deeply positioned in the alveolar process. Glass-ionomer cement, on the other hand, is known to bond to enamel or dentin without etching and post-operative discomfort, and complications are uncommon (17,18), even if the packing is left for several months during which the tooth can continue to self-erupt. A study by Nordenvall (17) showed that only three out of 35 (8.5%) GIC were lost during the first post-operative month, which is regarded as the most critical period. In another study by Nordenvall (18), no GIC was lost during the critical initial healing period, and only 2 of 30 were lost during the 3–9-month follow-up period. About 72 per cent of the orthodontists in the present study responded that they use GIC in open exposure cases, i.e. GOPEX, until the tooth has erupted spontaneously. The dental records from Centre A confirmed use of GIC as the wound dressing in all open exposure cases. Loss of a GIC dressing occurred in three cases (10%), two during the critical initial healing period, and one 38 days post-surgery. None of the cases needed repeated surgery. These results conform with the data published by Nordenvall (17). The overall failure rate reported in the study by Parkin et al. (15) was 6–9.6 per cent, where Whitehead varnish or Coe-pack surgical dressing was sutured in place but only applied for 1–2 weeks. According to the dental records, a golden chain was bonded to the canine in the closed exposure technique, which was also stated in the questionnaires. Complications included loss of sutures or chains 3–6 days post-surgery. Out of the six cases with complications, three were due to loss of the gold chain (10%). All chains except one (the canine was visible and an eyelet was bonded instead) had to be rebonded; i.e. required repeated surgery. Failure rates of 11.4–30.7 per cent for closed exposures have been reported (22,23); however, these results were published many years ago, and bonding techniques and materials have developed considerably since then. A more recent study had a failure rate of 2.9 per cent in a closed exposure group (14), which is less than in our study. The higher failure rate found in the dental records may be explained by the clinical experience of the clinicians performing the surgical technique. In this study, the clinicians carried out the closed exposure under local anaesthesia, while in the study by Parkin et al. (15), the surgery was performed under general anaesthesia. A wide range of average treatment times has been reported in previous studies, extending from 17 to 28 months, depending on the age of the patients, whether the cases concern unilateral, bilateral PIC or buccally impacted canines, but also on the location of the canine mesiodistally and in relation to the occlusal plane (1, 24–26). The total treatment time in this study was within the same time range as in the studies mentioned above. In addition, the total treatment time was the same, regardless of the surgical technique (Centre A, 28.0 ± 9.7 months; Centre B, 27.1 ± 8.4 months). However, the active treatment time was shorter and the number of active appointments fewer in the GOPEX cases. Furthermore, the canine traction time until completion of the orthodontic treatment was more than four months shorter when GOPEX was employed. This is due to the different treatment approach in the open exposure cases where natural eruption of the canine is awaited before the active part of the orthodontic treatment is initiated. The homogeneity of the baseline patient characteristics, with respect to age, sex, the need for orthodontic extraction and the location of the canine in relation to the occlusal plane and the mesiodistal location as seen on radiographs, is a strength of this study. The only difference seen between the two centres was significantly more CL I cases in Centre B. For this reason, and the fact that pre- and post-surgical orthodontic variables were analysed retrospectively, it is difficult to assess what impact these confounding factors may have had on the treatment time. Therefore, further studies with a prospective design are required to report on treatment outcomes accurately when performing open versus closed exposure. An RCT study comparing GOPEX with closed exposure of PIC is currently the subject of a prospective trial at our clinic. Conclusion The choice of surgical exposure technique depends on the clinician’s preference. The duration of active treatment and the active traction time for PICs is significantly shorter and the number of appointments significantly fewer with glass-ionomer open exposure (GOPEX). Supplementary material Supplementary material is available at European Journal of Orthodontics online. Funding Public dental service, Region Västra Götaland. Conflict of interest None to declare. Acknowledgment The authors wish to thank all the orthodontists for responding to the survey. References 1. Stewart, J.A., Heo, G., Glover, K.E., Williamson, P.C., Lam, E.W. and Major, P.W. ( 2001) Factors that relate to treatment duration for patients with palatally impacted maxillary canines. American Journal of Orthodontics and Dentofacial Orthopedics , 119, 216– 225. 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Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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The European Journal of OrthodonticsOxford University Press

Published: Jun 1, 2018

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