Comparison of tooth size discrepancies among different malocclusion groups

SUMMARY This retrospective investigation was designed to compare tooth size discrepancies among subjects with different skeletal malocclusions in an orthodontic population. The study employed the pre-treatment models of 200 patients (100 males, 100 females, aged from 14 to 20 years) selected from the records of the Orthodontic Department, Shiraz Dental School. The subjects were from four malocclusion groups, Class I, Class II division 1, Class II division 2, and Class III, with the corresponding skeletal characteristics. Each group comprised 50 healthy individuals (25 males, 25 females). The mesio-distal dimensions of teeth were measured using digital electronic callipers (accurate to 0.01 mm) and the Bolton indices were determined. The data were statistically analysed using analysis of variance and Duncan’s multiple range test, with the level of signifi cance set at P < 0.05. The results revealed that the mean anterior ratio (79.01) for the whole sample was statistically signifi cantly different from Bolton’s (77.2) but no signifi cant difference was found for the overall ratio. The posterior and overall ratios of the Class III malocclusion group were statistically greater than the other malocclusion groups ( P < 0.05). The mean anterior ratio of the Class III group was greater than that of the Class II group. However, there was no difference when compared with the Class I malocclusion group. For the two types of Class II malocclusion, no signifi cant ratio differences were observed