Digital Orthodontic Assessment of Mandibular Morphology Using Orthopantomograms: Correlation and Symmetry Analysis of Bilateral Gonial Angles, Bigonial Width, and Bilateral Ramus Heights.

Background/Objectives: Precise evaluation of mandibular morphology is essential for orthodontic diagnosis, growth assessment, and treatment planning. While lateral cephalograms are traditionally used for angular measurements, orthopantomograms (OPGs) allow side-specific assessment of mandibular structures. This study aimed to analyze bilateral gonial angles, bigonial width, and ramus heights on OPGs using artificial intelligence (AI)-assisted tracing, with a focus on symmetry, sex-related differences, and clinical applicability. Methods: A cross-sectional study was conducted on 78 Romanian patients (46 females, 32 males; mean age 22.8 ± 8.7 years) seeking orthodontic treatment. Standardized OPGs were obtained and analyzed using WebCeph AI-driven software. Bilateral gonial angles, bigonial width, and ramus heights were measured. Symmetry between sides and differences between sexes were evaluated, and correlation analyses were performed. Inter-rater reliability was assessed using intraclass correlation coefficients (ICCs). Results: The mean right and left gonial angles were 126.3° and 127.1°, respectively, with no significant sex- or side-related differences (p > 0.05). Bigonial width averaged 134.9 mm, being slightly larger in males, although not statistically significant (p = 0.240). Ramus heights were comparable bilaterally (right: 48.4 mm; left: 48.3 mm), with males showing slightly greater values. Correlation analysis demonstrated strong bilateral symmetry for gonial angles (r = 0.795) and ramus heights (r = 0.895). Negative correlations were observed between gonial angles and both bigonial width and ramus height, whereas bigonial width correlated strongly with ramus height. Measurement reproducibility was high (ICC > 0.75). Conclusions: OPGs, when combined with AI-assisted analysis, provide reliable and reproducible measurements of gonial angles and ramus heights, comparable to cephalometric values. Their ability to assess right and left sides separately enhances clinical utility in detecting asymmetries and monitoring mandibular growth. However, caution is advised when interpreting transverse parameters such as bigonial width, where CBCT remains the gold standard. AI-driven OPG analysis represents a cost-effective, accessible, and low-radiation diagnostic tool with significant potential for precision orthodontics.