Transverse Growth and Torque Compensation of First Molar in Adolescents Using 3D Digital Dental Analysis

Background To investigate age-related changes in transverse intermolar width and crown torque of maxillary and mandibular first permanent molars in adolescents, and to explore torque as a compensatory mechanism for asymmetric transverse skeletal growth. Methods A total of 470 dental casts and corresponding posteroanterior cephalograms from 124 subjects (43 males and 81 females) aged 8–18 years were analyzed using a cohort-based design, incorporating repeated records when available to evaluate transverse growth. Maxillary and mandibular basal bone widths were measured on posteroanterior radiographs. Dental casts were digitized and analyzed to obtain intermolar width and molar crown torque. Statistical analyses included independent t tests, one-way ANOVA with Bonferroni correction, and Pearson correlation analysis. Results Both maxillary and mandibular basal bone widths increased with age, with mandibular basal growth exceeding maxillary growth. Despite this skeletal pattern, maxillary intermolar width increased more than mandibular intermolar width (3.16 mm vs. 1.44 mm). Maxillary intermolar width showed a moderate correlation with maxillary basal bone width (r = 0.552), whereas the corresponding mandibular correlation was weaker (r = 0.330). No significant association was observed between maxilla–mandible basal width ratios and intermolar width ratios. Maxillary first molars exhibited progressive palatal uprighting totaling 7.43°, while mandibular first molars demonstrated buccal uprighting of 14.04°. Conclusions During adolescence, transverse skeletal growth of the mandible exceeds that of the maxilla, whereas maxillary intermolar width increases more than mandibular intermolar width. Coordinated molar torque adjustments appear to compensate for this skeletal–dental discrepancy and contribute to transverse occlusal coordination, emphasizing the clinical relevance of physiologic torque compensation in orthodontic treatment planning.