LOESS-Based Cephalometric Growth Curves for Clinical Assessment of Craniofacial Development: A Cross-Sectional Study

Background/Objectives: This cross-sectional study aimed to estimate the Locally Estimated Scatterplot Smoothing (LOESS)-smoothed percentiles for growth trajectories and evaluate age-related tendencies across groups using visual cross-sectional graphs. Methods: A total of 1147 patient records were analyzed, including 648 females and 469 males aged 5-20 years, with a mean age of 11.9 (SD ± 3.8) years. Twenty-seven cephalometric variables were organized into six measurement domains: cranial base, maxillary complex, mandibular complex, occlusal plane, vertical relationship, and sagittal relationship. Percentile curves were generated using LOESS regression across an age range of 5-20 years. Results: The LOESS-smoothed curves showed age-related trends across age groups. An upward trend in the curves was observed for the anterior and posterior cranial bases between 5 and 12 years of age, a plateau indicating reduced age-related change across groups during mid-adolescence. Maxillary measurements showed a similar pattern, with a clear upward tendency during childhood and reduced age-related change after approximately 12 years. Mandibular length and projection showed increasing trends during childhood, followed by a plateau or reduced slope across later age groups. The occlusal plane and vertical dimensions showed consistent patterns that approached a plateau around 12 years, indicating minimal age-related differences between groups. Changes in the ANB angle and Wits appraisal reflected a progressive forward tendency of the mandible across childhood age groups, followed by reduced age-related change during adolescence. Conclusions: These findings suggest that many craniofacial measurements show an upward trend during childhood followed by a plateau or reduced age-related change across age groups between approximately 12 and 14 years. The percentile-based growth curves presented here offer a practical reference for clinicians to evaluate craniofacial growth trajectories as population-level approximations derived from cross-sectional data in the pediatric population.