To Örebro University

OBJECTIVES: The early interceptive treatment of palatally displaced canines (PDCs) has for decades been based on their position in panoramic radiographs. In the 1990s, cone-beam computed tomography (CBCT) started to become popular in cases with PDCs. The aims of this prospective study were to evaluate the agreement of PDC sector position and angle to midline between panoramic radiographs and CBCT scans.

METHODS: PDC sector and angle to midline were measured in panoramic radiographs and CBCT scans in 58 consecutive patients with 64 PDCs. Kappa with linear weighting was used to assess the agreement between the measurements of PDC sector position and Bland-Altman limits of agreement to assess the agreement between the PDC angular measurements in the 2 methods.

RESULTS: PDC sector position and angle to midline had systematically higher values in panoramic radiographs compared with those in the CBCT scans. The agreement of sector position between the methods was fair: weighted kappa 0.36 (95% CI 0.24-0.49). The mean difference in angle was almost 7° (95% CI 5.9°-7.9°) higher in panoramic radiographs compared with CBCT.

CONCLUSIONS: Panoramic radiographs overestimate PDC sector and angle to midline position, compared with the use of CBCT scans, but clinically the differences are quite modest. Panoramic radiographs could be considered good enough for rendering PDC position when the need for 3D information is not crucial for treatment planning.

Background: Closed and open surgical techniques are two different main approaches to surgical exposure of palatally displaced canines (PDCs). Because there is insufficient evidence to support one technique over the other, there is a need for randomized controlled trials.

Objectives: To compare surgery time, complications and patients' perceptions between closed and open surgical techniques in PDCs.

Trial design: The trial was a multicentre, randomized, controlled trial with two parallel groups randomly allocated in a 1:1 ratio.

Material and methods: Study participants were 119 consecutive patients from 3 orthodontic centres, with PDCs planned for surgical exposure, randomly allocated according to a computer-generated randomization list, using concealed allocation. Full-thickness mucoperiosteal flap was raised, and bone covering the canine was removed in both interventions. In closed exposure, an attachment with a chain was bonded to the canine and the flap was sutured back with the chain penetrating the mucosa. In open exposure, a window of tissue around the tooth was removed and glass ionomer cement placed on the canine crown, to prevent gingival overgrowth during spontaneous eruption. Patient perceptions were assessed with two questionnaires, for the evening on the day of operation and 7 days post-surgery.

Blinding: It was not possible to blind either patients or care providers to the interventions. The outcome assessors were blinded and were unaware of patients' intervention group.

Results: Seventy-five girls and 44 boys, mean age 13.4 years (SD 1.46) participated in the study and got either of the interventions (closed exposure, n = 60; open exposure, n = 59). Surgery time did not differ significantly between the interventions. Complications though were more severe in bilateral cases and the patients experienced more pain and impairment in the open group.

Conclusion: There were no statistically significant differences regarding surgery time between the groups. Postoperative complications were similar between the groups in unilateral PDCs, but more common in the open group in bilateral cases. More patients in the open group experienced pain and impairment compared to the closed group.

Trial registration: Trial registration: ClinicalTrials.gov, ID: NCT02186548 and Researchweb.org, ID: 127201.

OBJECTIVES: To compare treatment time, patients' perceptions during orthodontic treatment, dental fear and side effects, between open and closed surgical exposures in patients with palatally displaced canines (PDCs).

TRIAL DESIGN: Multicentre, randomized controlled trial, with random 1:1 allocation of two parallel groups.

MATERIALS AND METHODS: One hundred and twenty patients from three different orthodontic centres were randomized into one of the two intervention arms, open or closed surgical exposure. Both techniques had mucoperiosteal flaps raised and bone removed above the PDCs. In open exposure, tissue was removed above the canine, and glass ionomer - reaching above soft tissue - was built on the crown. The canine was then left to erupt spontaneously, prior to orthodontic alignment. At closed exposure, a chain was bonded to the canine and orthodontic traction was applied under the mucosa until eruption. Orthodontic alignment of the canines was undertaken after eruption into the oral cavity, with fixed appliances in both groups. All participants were treated according to intention to treat (ITT).

BLINDING: Due to the nature of this trial, only outcome assessors could be blinded to the intervention group.

RESULTS: One hundred and seventeen patients completed the trial. All PDCs were successfully aligned. Total treatment time was equal in the two techniques, mean difference -0.1 months (95% CI -3.2 to 2.9, P = 0.93). The closed group experienced more pain and discomfort during the active orthodontic traction. Dental fear, root resorption and periodontal status did not show any clinically significant differences between the groups.

GENERALIZABILITY: Results of this randomized controlled trial (RCT) can be generalized only to a similar population aged 9-16 years, if exclusion criteria are met.

CONCLUSION: The closed exposure group experienced more pain and discomfort mostly during active orthodontic traction. All other studied outcomes were similar between the two exposure groups.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02186548 and Researchweb.org, ID: 127201.

OBJECTIVE: To evaluate the costs of open and closed surgical exposure and subsequent orthodontic treatment for the correction of palatally displaced canines (PDCs).

TRIAL DESIGN: A multicentre, two-arm parallel group randomized controlled trial.

METHODS: One hundred twenty adolescents between 9 and 16 years of age, from three orthodontic specialist centres, were randomized to one of the two surgical exposure interventions. The randomization was conducted according to a two-arm parallel group 1:1 allocation ratio, using computerized lists with block randomization. In both the surgical techniques, whole mucoperiosteal flaps were raised, and bone covering the PDCs was removed. In the open technique, glass ionomer was built up on the PDC crown - reaching above the mucosa through a hole punched in the flap - to allow the canine to erupt autonomously. After eruption, the canine was orthodontically moved above the mucosa. In the closed technique, an eyelet was bonded onto the PDC, the flap was repositioned and the canine was orthodontically moved beyond the mucosa. The trial ended when the PDC was successfully aligned in the dental arch.Cost analysis was performed including costs for surgery, orthodontic treatment, emergency visits, and material, as well as costs for transports and time spent in connection with every appointment.

BLINDING: Patients and caregivers could not be blinded due to obvious limitations of the clinical setting, while outcome assessors and data analysts were blinded.

RESULTS: A cost-minimization analysis was performed since both exposure groups succeeded equally well in terms of treatment effects. The two different surgical exposures and following orthodontic treatments did not differ significantly in terms of costs.

GENERALIZABILITY AND LIMITATIONS: Costs are estimated in the Swedish setting, which needs to be considered if applying the results in other settings. Calculations of total cost do not include finishing, debonding, retention, and follow-up.

CONCLUSION: There is no significant difference in costs between closed and open surgical exposure with following orthodontic treatments in PDCs.

TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02186548.