Exploring the Relationship Between Mandibular Morphology, Dental Eruption, and Chronological Age in Modern Human Juveniles Through Geometric Morphometrics

Objective: This study investigated how mandibular morphological shape and dental eruption patterns reflect chronological age in modern human juveniles, using geometric morphometrics. The aim was to assess their variation, covariation, and the accuracy of classifying individuals into age-based groups using combined shape information. Materials and methods: Computed tomography scans from a sex-balanced sample of 48 individuals, aged 4 to 13 years, sourced from the New Mexico Decedent Image Database, were used to generate 3D models of mandibular bodies and permanent dentition (incisors, canines, premolars, and first molars). Mandibular and dental morphology were analyzed using 3D landmark-based methods. Generalized Procrustes Analysis and Principal Component Analysis (PCA) assessed shape variability. Two-block partial least squares analysis evaluated covariation and linear regression tested the age estimation protocol. Results: PCA of combined proxies revealed distinct morphological changes in the mandible corresponding to different phases of dental eruption. In contrast, analyses of separated proxies exhibited high variability, limiting their reliability. The combined configuration demonstrated a strong association between mandibular shape and dental eruption patterns, aligning closely with the chronological ages of individuals in the sample. Discussion: This study highlights the utility of integrating mandibular shape variation with dental eruption as an effective approach for capturing consistent morphological changes during growth. The combined proxies exhibit strong statistical relations with chronological age and reliably identify developmental change (shape change) even within narrow age brackets of 3-6 months, providing a foundation for the development of a standardized age estimation protocol.