Relationship between Tongue Volume and Condylar Position in Skeletal Class I and Class II Subjects: An MRI Study

Introduction Tongue morphology and mandibular condylar position are important components of the craniofacial complex and have been independently associated with sagittal skeletal discrepancies. However, the relationship between tongue volume and condylar position remains unclear. This study evaluated the relationship between tongue volume and mandibular condylar position in skeletal Class I and Class II subjects using magnetic resonance imaging (MRI). Methods Forty subjects were equally divided into skeletal Class I (10 males, 10 females) and skeletal Class II (10 males, 10 females) groups. Tongue volume was measured from three-dimensional MRI reconstructions. Superior Joint Space (SJS), Anterior Joint Space (AJS), Posterior Joint Space (PJS), Condylar Position Index (CPI), and Condylar Height (CH) were assessed on sagittal MRI sections. Intergroup comparisons were performed using independent t-tests or Mann-Whitney U tests. Correlations between tongue volume and CPI were evaluated using Spearman’s rank correlation analysis. Reliability was assessed using the Intraclass Correlation Coefficient. Results Tongue volume was significantly greater in skeletal Class I subjects than in skeletal Class II subjects (p < 0.001). Skeletal Class II subjects demonstrated significantly larger SJS (p < 0.001) and PJS (p = 0.010), smaller AJS (p = 0.022), lower CH (p < 0.001), and a relatively more anterior condylar position as indicated by CPI (p < 0.001). Male subjects exhibited significantly greater tongue volumes than females in both skeletal groups (p < 0.001). No significant correlation was found between tongue volume and CPI in either skeletal Class I (r=-0.056, p = 0.813) or skeletal Class II subjects (r=-0.208, p = 0.378). Conclusion: Skeletal Class I subjects exhibited significantly greater tongue volumes and condylar heights, whereas skeletal Class II subjects demonstrated larger joint spaces and a relatively more anterior condylar position. However, no significant association was observed between tongue volume and condylar position in either skeletal pattern, suggesting that factors other than tongue volume may contribute to condylar positioning within the glenoid fossa.