A structural equation modeling approach to determine the correlation between the vertical and sagittal skeletal patterns and posterior basal bones mismatching in patients with skeletal Class III malocclusion

Abstract

Matching the maxillomandibular basal bone width is essential to the stability of orthodontic treatment. We aimed to determine the relationship between basal bone width mismatching and the vertical and sagittal skeletal pattern in patients with skeletal Class III malocclusion through shape analysis and structural equation modeling (SEM). Cone-beam computed tomography images were collected from 45 men and 51 women. Width mismatching of the basal bone was determined using generalized Procrustes analysis. Twenty-two parameters from the synthesized cephalogram were measured, followed by factor analysis and SEM. Mismatch occurred at the second molar (men, -4.29 ± 4.32 mm; women, -5.55 ± 4.43 mm) and retromolar regions (men, -8.49 ± 5.11 mm; women: -8.93 ± 5.25 mm). The sum of angles had the largest loading for vertical-1 (extracted from 18 vertical cephalometric measurements) (men, 0.9477; women, 0.9489), followed by MP-SN angle (0.9408) in men and N-Me/S-Go (0.9342) in women. Wits appraisal and anteroposterior dysplasia indicator were largest for Sagittal-1. SEM showed a positive effect of male vertical-1 and 2 on width difference in the retromolar region (P<0.001; B>0). Female vertical-1 had a significant positive effect on DW7 (P<0.001; B= 5.535) and DWR (P= 0.016; B= 3.427) as vertical-2. Sagittal-1 showed a negative correlation with DW7 in both genders (P<0.05; B<0) and with DWR in men. Basal bone width mismatching occurred at the second molar and retromolar regions, especially in low-angle and patients with severe skeletal Class III malocclusion.