Abstract
Aims: The aim of this study was to determine the mesiodistal tooth width of the permanent dentition, interarch tooth size ratios and to compare these variables between genders and among different maloc-clusion and normal occlusion groups for Iraqi adolescent in Mosul City. Materials and Methods: 141 orthodontic models of school students aged 13 – 16 years of different occlusal relationships (class I normal occlusion, class II (division 1 and 2) and class III malocclusion). Mesiodistal width of teeth were measured by using dental vernier. The mean and standard deviation were calculated. Student's t –test, analysis of variance, Duncan's multiple analysis range test and Pearson's correlation coefficient were used for the statistical analysis. Results: Although the males had a larger mesiodistal width of most of the teeth than those in the females, but some of these measurements were not significantly different par-ticularly in class I normal occlusion, while the most significant gender differences were found in class II division 1. Class I normal occlusion showed a tendency toward small teeth than the malocclusion groups particularly in males group, while the class III malocclusion showed a tendency toward larger teeth than the other occlusal categories specially in females group. The class I normal occlusion had a higher ante-rior tooth ratio than that in class III malocclusion and a higher overall tooth ratio than that in the maloc-clusion groups in females. While in males the overall tooth ratio was smaller in class II division 1 than that in class I normal occlusion. No gender difference for the tooth ratios in all occlusal categories ex-cept in class II division 2 malocclusion. Conclusions: It was concluded that interarch tooth size rela-tionships are population specific and there is a gender specific for mesiodistal width of some teeth par-ticularly in class II division 1, and these ratios may be one of the important factors in the cause of ma-locclusion, thus, this study proved the fact that Bolton's analysis should be taken into consideration dur-ing orthodontic diagnosis and therapy.
