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?

Abstract

To analyse whether extraction of the deciduous canines facilitates eruption of the palatal displaced canines (PDCs), and to analyse root resorption in adjacent teeth caused by the PDCs. Eligibility criteria for participants were as follows: children at age 10-13 years with either maxillary unilateral or bilateral PDC, persisting deciduous canine and no previous experience of orthodontic treatment. Sixty-seven patients (40 girls and 27 boys; age: mean ± standard deviation: 11.4±1.0) with unilateral (45) or bilateral (22) PDCs were consecutively recruited and randomly allocated using permuted block randomization method to extraction or non-extraction. No patients dropped out after the randomization or during the study. Patients underwent a clinical examination and cone beam computed tomography at baseline (T0), after 6 (T1) and 12 months (T2). The total observation time was 24 months. Outcome measures were eruption, positional changes, length of time until eruption, and root resorption of adjacent teeth. The baseline images were measured blinded while the 6- and 12-month control images were not, since it was not possible to blind the extracted canine. Significantly more spontaneous eruptions of the PDCs were seen in the extraction group (EG) than in the control group (CG), with rates of 69 and 39 per cent, respectively, with a mean eruption time of 15.6±5.6 months in the EG and 18.8±5.8 months in the CG. Significant differences in changes between the groups, in favour of the EG, were found for all variables except for the sagittal angle. In the EG, the changes in the distances of the canine cusp-tip were larger during the first 6 months, while the change of apex was larger between 6 and 12 months. There were no significant differences in resorption of adjacent teeth between the groups. Imputation values were used for the PDCs who had erupted at T2, since no x-rays were taken for ethical reasons, which might have given uncertainty in the positional changes between T1 and T2. Extraction of the deciduous canine is an effective treatment in patients with PDCs. Significantly more positional changes and shorter mean eruption time were seen in the EG. Resorptions of lateral incisors were seen in both groups, but none exceeded grade 2 (resorption up to half of the dentine thickness to the pulp). This trial was registered in "FoU i Sverige" (http://www.fou.nu/is/sverige), registration number: 40921. The protocol was not published before trial commencement.