Three-dimensional relationship between the hyoid bone and the stylohyoid complex: a cone-beam computed tomography study introducing a novel angular parameter

BACKGROUND: This study aimed to evaluate the relationship between hyoid bone morphology and stylohyoid complex morphometry using cone-beam computed tomography and to investigate the influence of age and sex on these characteristics. METHODS: A retrospective cone-beam computed tomography analysis of 338 individuals was performed to evaluate hyoid bone morphology, styloid process length, angulation, elongation type, and calcification patterns. The lesser horn-body angle was measured as a novel angular parameter to assess its relationship with the stylohyoid complex anatomy. RESULTS: The study included 338 individuals (226 females, 66.9%; 112 males, 33.1%) with a median age of 43 years. No significant associations were found between hyoid bone morphology and styloid process length, angulation, elongation type, or calcification pattern (p > 0.05). Type U was the most common hyoid bone morphology overall and in males, whereas Type B predominated in females; however, the association between hyoid bone morphology and sex was not statistically significant. Although the highest lesser horn-body angle difference was observed in Type H and the lowest in Type B, these differences did not reach statistical significance (p = 0.076). Styloid process length, medio-lateral angulation, and antero-posterior angulation were significantly greater in males than females bilaterally (p < 0.05). Type I (elongated) and Type II (partial calcification) were the predominant stylohyoid complex elongation and calcification patterns, respectively, both showing bilateral symmetry. Age-related differences were identified among styloid process elongation types on both sides, with Type III (segmented) occurring at younger ages on the right side (p = 0.006) and Type I (elongated) being associated with older age on the left side (p < 0.001). No significant associations were found between hyoid bone morphology and styloid process length, angulation, elongation type, or calcification pattern (p > 0.05). CONCLUSIONS: CBCT demonstrated bilateral symmetry in stylohyoid complex morphology and angulation. Significant sex and age-related differences were observed in selected stylohyoid complex characteristics, whereas no association was found between hyoid bone morphology and stylohyoid complex morphometry. The lesser horn-body angle exhibited high reproducibility and bilateral consistency, although its significance remains unclear.