Evaluation of arch width among Class I normal occlusion, Class II Division 1, Class II Division 2, and Class III...

To test the hypothesis that there is no difference between Class I (CI) normal occlusion, Class II division 1 (CIId1) and CII division 2 (CIId2), and Class III (CIII) malocclusion with respect to arch widths, width of the maxillary and mandibular arches, gender dimorphism within groups, and gender comparisons.

Samples of 40 CI subjects, 40 CIId1 subjects, 40 CIId2 subjects, and 34 CIII subjects were studied. All subjects were Indians with no history of orthodontic treatment. An analysis of variance and Duncan's test statistically compared the groups and genders.

CIId1 malocclusion showed the narrowest maxillary arch compared with the other types of malocclusions. CIII malocclusion showed largest mandibular arch than other types of malocclusions. Gender dimorphism is more commonly seen in CI normal occlusion than other types of malocclusions. Gender dimorphism is not observed in CIId1 group. Gender comparisons revealed arch width differences between different types of malocclusions more pronounced in males than in females. The maxillary/mandibular intermolar width difference is positive for CI normal occlusion and negative for CIId1, CIId2, and CIII malocclusions, which suggested, the presence of crossbite tendency in CII and CIII malocclusions.

The hypothesis is rejected by the findings of this study.