Difference in discrepancies of mandibular incisor compensation relative to Menton deviation between Class III roll- and yaw-dominant asymmetries.

Objectives: To compare mandibular incisor compensation relative to Menton (Me) deviation between skeletal Class III patients with roll- and yaw-dominant mandibular asymmetries.

Materials and methods: Sixty skeletal Class III patients (21.62 ± 2.69 years) with facial asymmetry were divided into roll- or yaw-dominant asymmetry groups. Mandibular skeletal and incisor measurements were carried out using cone-beam computed tomography data, and values were compared between the two asymmetry groups or between moderate and severe asymmetry subgroups using independent t-test or Mann-Whitney U-test. The relationship between skeletal and dental measurements was assessed using Pearson correlation coefficient.

Results: Relative to the mandibular midsagittal plane, the yaw-dominant group presented significantly greater mandibular dental midline deviation in distance (LI-mid deviation, 2.15 mm) and angulation (4.20°) toward the nondeviated side than the roll-dominant group (P < .001). The ratio of amount of LI-mid deviation to Me deviation was significantly greater in the yaw-dominant group (26.44%) than in the roll-dominant group (1.76%; P < .001). In the yaw-dominant group, the LI-mid deviation was significantly greater in the severe asymmetry subgroup than in the moderate asymmetry subgroup, and the amount of mandibular incisor compensation was positively correlated with Me deviation and mandibular yaw.

Conclusions: Mandibular incisor compensation differed significantly between the roll- and yaw-dominant asymmetry groups. The yaw-dominant group demonstrated significant mandibular dental midline deviation, and dental compensation of the anterior teeth was positively correlated with Me deviation and mandibular yaw.