A randomized clinical study of two interceptive approaches to palatally displaced canines

This study evaluated the effectiveness of two interceptive approaches to palatally displaced canines (PDC), i.e. extraction of the primary canines alone or in association with the use of a cervical-pull headgear. The randomized prospective design comprised 75 subjects with PDC (92 maxillary canines) who were randomly assigned to three groups: extraction of the primary canine only (EG), extraction of the primary canine and cervical-pull headgear (EHG), and an untreated control group (CG). Panoramic radiographs were evaluated at the time of initial observation (T1) and after an average period of 18 months (T2). At T2, an evaluation of the success of canine eruption was undertaken. Between-group statistical comparisons, Kruskal-Wallis test with Bonferroni correction, were performed on the T1-T2 changes of the diagnostic parameters on panoramic radiographs and the prevalence rates of success in canine eruption. A superimposition study on lateral cephalograms at T1 and T2 was carried out to evaluate the changes in the sagittal position of the upper molars in the three groups. The removal of the primary canine as an isolated measure to intercept palatal displacement of maxillary canines showed a success rate of 65.2 per cent, which was significantly greater than that in the untreated controls (36 per cent). The additional use of a headgear resulted in successful eruption in 87.5 per cent of the subjects, with a significant improvement in the measurements for intraosseous canine position. The cephalometric superimposition study showed a significant mesial movement of the upper first molars in the CG and EG when compared with the EHG.