Arch Widths in Normal Occlusion and Class II Brazilian Youths

OBJECTIVES: The purpose of this study was to compare the possible differences in dental arch widths of Brazilian youths with normal occlusion and Class II, division 1 malocclusions. METHODS: The sample comprised 170 pairs of gypsum dental models of Brazilian youths with permanent dentition, divided into two groups: normal occlusion (76 pairs of models, corresponding to 41 females and 35 females) and Class II, div. 1 malocclusion (94 pairs of models, including 58 females and 36 males). Furthermore, this last group was also divided into two subgroups, that is, Class II without crowding and Class II with crowded incisors. The distances between cuspids, first bicuspids and first molars were measured in both arches and statistically compared between groups and subgroups, by means of student “t” test (p<0.05). RESULTS: In normal occlusion group, the males presented the following significant differences: 1) a greater lower inter cuspids width and a smaller inter upper first bicuspids width for Class II group without crowding; 2) smaller inter first bicuspids and inter molars widths, in upper and lower arches, for Class II group with crowded incisors. As far as it concerns the females, the results showed: 1) smaller inter first bicuspids and intermolars width, only in the upper arch, for Class II without crowding; 2) smaller inter first bicuspids and intermolars width, in both arches, for Class group with crowded incisors. CONCLUSIONS: The Brazilian youths with Class II, division 1 malocclusions revealed a trend towards posterior transversal deficiency in the dental arches, particularly in the Group with crowded incisors.