engleski

Tooth size discrepancies among different occlusion groups

AIM: To compare Bolton anterior, posterior and overall ratio among different occlusion groups in the Croatian population. MATERIALS AND METHOD: Pre-orthodontic records were systematically collected of 301 subjects (127 boys, 174 girls) from each occlusion group (112 subjects with a Class I, 109 with a Class II and 80 with a Class III malocclusion). The mesiodistal crown diameters of all teeth were measured using digital callipers. Anterior, posterior and overall ratios were calculated according to Bolton’s formula. The mean, standard deviation and range were calculated separately for girls and boys, in each malocclusion group. The differences between genders were tested using a t-test. Differences among the malocclusion groups were tested with ANOVA and post hoc Scheffe tests. RESULTS: Anterior ratio of 78.1 (±2.6), posterior ratio of 104.9 (±3.1) and overall ratio of 91.6 (±2.0) were found. All ratios showed higher values and standard deviations than in the original Bolton’s study. Anterior ratios were lower in girls, and the difference was statistically significant (P = 0.017). Between malocclusion groups a statistically significant difference was found for posterior ratio between Class II and Class III malocclusions (P = 0.014), for overall ratio between Class II and Class II malocclusions (P = 0.035) and between Class II and Class III malocclusion groups (P = 0.031). Subjects with a Class I occlusion had the lowest (104.3%) and the subjects with a Class III malocclusion the highest (105.6%) posterior ratio. The lowest value for overall ratio was found in subjects with a Class II (91.1%) and the highest in subjects with a Class III (92.1%) malocclusion. Correlating with Bolton’s sample, 4.98 per cent of examinees had anterior ratios below 2SD and 16.28 per cent anterior ratio above 2SD. For overall ratio, 2.33 per cent of were below and 4.32 per cent above 2SD. CONCLUSIONS: Anterior, posterior and overall ratios had higher values in this sample than in the original Bolton study. Tooth-size discrepancy was found to be more frequent in the posterior region, which has great influence on the overall ratio. Consequently, specific standards should be used for Croatian population.

Bolton analysis; tooth size discrepancy

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