Dental and alveolar arch asymmetries in normal occlusion and Class II Division 1 and Class II subdivision...

To compare the degree of intra- and interarch dentoalveolar asymmetry among patients with a normal occlusion, Class II Division 1 malocclusion, and Class II subdivision malocclusion.

The sample comprised dental casts of 150 (72 males [ages 22. 1 +/- 3.11 and 78 females [ages 21.1 +/- 2.1]) normal occlusion subjects, 106 (45 males [ages 17.8 +/- 1.8] and 61 females [ages 16.5 +/- 2.91) Class II Division 1 patients, and 40 (18 males [ages 15.8 +/- 2.8] and 22 females [ages 15.2 +/- 3.3]) Class II subdivision malocclusions. Maxillary and mandibular reference lines were constructed and used for the intraarch asymmetry measurements. Thirty-six width measurements were performed on the dental casts of each subject. Analysis of variance (ANOVA) was used for comparisons of the groups, and Pearson's correlation coefficients were computed to determine the interarch associations.

No statistically significant intra-arch asymmetry was found for maxillary and mandibular dental arch and alveolar width in any of the three groups. All variables were larger on the right side in the normal occlusion subjects. Further, the left side maxillary dental and alveolar arch width measurements were larger in the Class II Division 1 group. None of these differences, however, were statistically significant. In the Class II subdivision group, only the Class II sides' mandibular dental arch measurements were larger (P < .05). Maxillary and mandibular total dental arch and alveolar width dimensions differed among the groups (P < .001). Except for maxillary and mandibular canine alveolar width, opposing interarch dental and alveolar landmarks were significantly correlated with the transverse dimensions.

Although some landmarks in the current study showed statistically significant and insignificant differences, the mean arithmetic differences were small, inconsistent, and not likely clinically important.