Influence of vertical growth pattern on masseter muscle morphology: evidence from cephalometric and ultrasound assessment in eighteen growing subjects

Introduction: The relationship between vertical facial dimensions and morphological-functional features of the masseter muscle in growing patients is of increasing interest in orthodontics. Understanding these correlations may enhance diagnostic accuracy and guide treatment planning, particularly in subjects with altered vertical skeletal patterns. Materials and methods: Growing patients underwent two-dimensional cephalometric analysis and ultrasonographic evaluation of the masseter muscle. Cephalometric variables included SNA, SNB, ANB, SN-GoGn, FMA, AFH, and Go–Me, while ultrasonographic parameters comprised thickness, cross-sectional area (CSA), and volume of the masseter, both at rest and during contraction. Correlations were assessed using Pearson's coefficient, and multiple linear regression was applied to identify predictive associations. A p-value < 0.05 was considered statistically significant. Results: A significant correlation was found between vertical growth pattern and ultrasonographic characteristics of the masseter. Subjects with increased vertical facial dimensions exhibited reduced muscle thickness and volume (p < 0.05). Regression analysis confirmed associations between vertical cephalometric indices (SN-GoGn, FMA) and ultrasonographic parameters, with R2 values ranging from 0.30 to 0.45. Discussion: Findings suggest that vertical skeletal pattern influences masseter morphology, highlighting the role of masticatory musculature in craniofacial development and vertical discrepancies. Conclusions: Integrating ultrasonographic assessment of the masseter with cephalometric analysis may provide clinically relevant insights for orthodontic diagnosis and management in growing patients.