Prevalence of Palatally Displaced Canines in a Kentucky Orthodontic Population

Most reported prevalence rates of palatally displaced canines (PDC's) range from 1-3%. Recent studies suggest hypodontia and PDC's may be related; other studies have shown that hypodontia is more prevalent in KY than the U.S. Therefore, it is likely KY PDC prevalence is higher as well. Objectives: (1) Identify prevalence of PDC's in KY (2) Determine vertical and anterior-posterior skeletal distributions in patients with PDC's. Methods: 731 consecutively treated patients (>/=6yrs) from the University of Kentucky orthodontic clinic were examined in a retrospective chart review (excluding dento-alveolar clefts and syndromes). Panoramic, periapical and lateral cephalometric radiographs were examined for PDC's and hypodontia (excluding third molars). A random sample of 100 patients without PDC or hypodontia were selected as controls for comparison. Results: Hypodontia rate was 7% (+/- 1.7%) consistent with reported rates for KY. PDC prevalence was 5% (+/- 1.6%), which was higher than the reported rates of 1-3% (p<0.05). There were significant differences in the distribution of PDC, hypodontia, and control cases among the atnerior-posterior and Vertical skeletal classes (Chi-square, p<0.05). Similar rates of skeletal Class I were observed for hypodontia and control (50%) patients, while PDC and control cases had more similar rates (20%) for Class III. Three groups differed in rates of Class II. PDC had slightly higher observed rates of balanced bites (62%) compared to hypodontia (47%) and controls (48%). Similar rates of deep-bites were observed in the groups (PDC: 33%, Hypodontia: 40%, Control: 27%), but differed in the rates of open-bites (PDC: 5%, Hypodontia: 13%, Control: 25%). Conclusion: This sample exhibited a hypodontia rate similar to previously reported KY rates. A higher prevalence of PDC's compared to most published rates supports the hypothesis of a relationship between hypodontia and PDC's. However, this relationship does not appear to be due to vertical or anterior-posterior patterns.