CBCT-Based Assessment of Tooth Morphology and Dental Arch Dimensions Across Skeletal Class I, II, and III Malocclusions: A Cross-Sectional Study

Background/Objectives: Three-dimensional data that evaluate tooth morphology and dental arch dimensions together across sagittal skeletal patterns are limited. This cone-beam computed tomography (CBCT) study compared tooth morphology and dental arch dimensions among skeletal Class I, II, and III malocclusions and examined their relationships. Methods: This retrospective, cross-sectional study included 111 individuals (37 per group; 24 females and 13 males in each group), selected from archived CBCT records in reverse chronological order with sex-frequency matching. Skeletal class was based on the ANB angle. Crown length, root length, and mesiodistal width of the central incisors, canines, second premolars, and first molars, together with arch perimeter and intercanine, inter-second premolar, and intermolar widths, were measured. Groups were compared using patient-clustered Gaussian generalized estimating equations with Holm-adjusted contrasts and Benjamini–Hochberg false discovery rate (FDR) correction across 35 outcomes; 108 tooth–arch associations were adjusted for class, age, and sex. All analyses were exploratory. Results: Five of 35 outcomes showed nominal class effects (p < 0.05), mainly in the mandible (central incisor and canine crown lengths, arch perimeter, and intercanine width), but none remained significant after FDR correction (q ≥ 0.169). In exploratory contrasts, mandibular arch perimeter was greater in Class III than in Class I (2.20 mm; 95% CI 0.56–3.85). In the primary models, no mesiodistal width or root length differed nominally. Nine of 108 tooth–arch associations remained significant after FDR correction (standardized β 0.27–0.36), six involving premolar and molar mesiodistal widths. Conclusions: No difference in tooth morphology or arch dimensions among skeletal classes remained significant after multiplicity correction; the nominal mandibular findings are exploratory. The findings are descriptive, cannot establish causality, and do not support class-specific treatment recommendations.