Quantitative analysis of the maxilla and the mandible in hyper- and hypodivergent skeletal Class II pattern.

Nair R, Deguchi T Sr., Li X, Katashiba S, Chan YH To examine the volumetric (size) difference in the maxilla and the mandible of hyper- and hypodivergent skeletal patterns in Angle class II malocclusion. Descriptive retrospective study. The hypothesis is that a hypodivergent mandible has a larger size than a hyperdivergent mandible. Using cone-beam computed tomography, 20 subjects with Angle class II malocclusion were classified into two groups; 10 of 20 subjects formed a hyperdivergent group while the rest formed a hypodivergent group. Cone-beam computed tomography images were obtained and processed and 3D volume data was measured by one clinician. Dahlberg's technique was used to assess the measurement error and significant difference was set at p < 0.05. No significant differences were found between the volumes of the maxilla and mandible in both groups. Differences were observed in the ratio of mandibular/maxillary volumes. The hypodivergent group had a significantly larger (p = 0.014) ratio than the hyperdivergent group. Maxillary and mandibular volumes differ between hyper- and hypodivergent skeletal patterns.