Influence of vertical skeletal patterns on cancellous bone volume in the mandibular ramus relevant to sagittal split...

To determine whether the vertical skeletal pattern influences cancellous bone volume and related ratios in sagittal split ramus osteotomy (SSRO)-relevant regions of the mandibular ramus in skeletal Class III patients, and to quantify covariate effects.

This single-center retrospective study included 112 patients (224 rami). Cone-beam computed tomography-based 3D segmentations quantified cancellous volume (ROI.S), cortical volume (ROI.C), total bone (TB), and ratios S:C and S:TB within a standardized ramal ROI. Because each patient contributed bilateral rami, within-patient correlation was accounted for using mixed-effects models (random intercept) for ROI.S, ROI.C, TB, ln-transform for S:C, and generalized estimating equations with an appropriate link were used for the bounded proportion S:TB (0-1). All models adjusted for sex, age, BMI, and side. Omnibus pattern effects were tested, with Bonferroni-adjusted pairwise comparisons reported when applicable. Intra- and inter-observer intraclass correlation coefficients (ICCs) were assessed in a 10-patient subset.

Vertical skeletal pattern was not associated with ROI.S (P = 0.17). Omnibus effects were observed for ROI.C (P = 0.04) and TB (P = 0.03), but no pairwise contrast remained significant after Bonferroni adjustment. The ratios showed no pattern effect (ln[S:C], P = 0.69; S:TB, P = 0.64). Males had larger ROI.S, ROI.C, and TB and a higher cancellous proportion.

Vertical skeletal pattern does not materially influence cancellous volume or its ratios within SSRO-relevant ramal ROIs, whereas sex shows consistent volumetric and proportional differences.

Patient-specific CBCT volumetry provides reproducible quantitative information beyond skeletal pattern classification and may aid SSRO planning by identifying patients with relatively limited cancellous support.