Age‐Related Osseous Measures of the Temporomandibular Joint and Mandibular Ramus During Childhood Assessed by Magnetic Resonance Imaging

Objective This study aimed to provide age‐related osseous measures of the temporomandibular joints (TMJs) and mandibular ramus in asymptomatic children and adolescents and to develop percentile reference data for ramus height. Material and Methods A retrospective cross‐sectional study was conducted on 133 asymptomatic participants (67 males, 66 females; age range 0–19 years) who underwent magnetic resonance imaging of the head, including the TMJs and posterior parts of the mandible. Mandibular ramus height, glenoid fossa depth, articular eminence inclination angle, and condylar dimensions (mediolateral and anteroposterior) were measured. A single observer assessed 266 TMJs, and a second observer repeated measurements for 80 TMJs to evaluate intra‐ and inter‐observer reliability using the intraclass correlation coefficient (ICC) and Bland–Altman plots. Age‐related growth curves were estimated using the Box‐Cox Cole and Green (BCCG) distribution, modeling median, coefficient of variation, and skewness as cubic spline functions of age. The optimal spline degrees of freedom were selected using the Bayesian information criterion. Percentile curves were derived, and biannual lookup tables were provided. Results Ramus height, glenoid fossa depth, articular eminence angle, and condylar width increased with age, whereas condylar depth exhibited variable patterns during adolescence. Intra‐observer reliability was excellent for all measurements. Ramus height and condylar width measurements demonstrated excellent inter‐observer reliability, while glenoid fossa depth, articular eminence inclination angle, and condylar depth measurements showed good inter‐observer reliability. Conclusion This study provides age‐related osseous measures of the TMJs and mandibular ramus in asymptomatic children and adolescents aged 0–19 years. The percentile curves for mandibular ramus height may aid in assessing growth in children with juvenile idiopathic arthritis for monitoring disease activity and treatment responses.