EVALUATION OF HYOID BONE POSITION AND ORIENTATION TO THE CRANIAL BASE, MANDIBLE, AND THIRD CERVICAL VERTEBRA IN DIFFERENT ANTEROPOSTERIOR SKELETAL MALOCCLUSION: AN OBSERVATIONAL STUDY

Background:The aim of this study was to evaluate the hyoid bone (HB) position and it’s orientation to cranial base,
mandible, and third cervical vertebra in different anteroposterior skeletal malocclusion.
Materials and Methods: This retrospective study included 90 lateral cephalometric radiographs of Yemeni patients
distributed into 3 groups with different skeletal classes of malocclusion aged between 18-30 years. All radiographs
were traced manually by a researcher. The recorded data was collected, tabulated and analyzed by statistical program
SPSS.
Results:The S-N (Sella-Nasion) distance, was low in Class III (69.5 mm) and the Hy-D distance was slightly higher
in Class III. For, angular measurements, the NSAr (Nasion-Sella-Articulare angle) was high in Class III (128.2°) and
SNA (Sella-Nasion-A point angle), was about 78.6 in Class III. A statistically significant difference was found in the
S-N length (p = 0.03), indicating a longer cranial base in males. In females, the S-N distance correlated strongly with
C3-HY (r = 0.73), while in males, C-Xi had a high correlation with Hy-D (r = 0.82). Angular measurements also
showed strong correlations, such as SNA being negatively correlated with ArGoMe (-0.91) in females and NSAr
negatively correlated with SNA (-0.77) in males, indicating cranial base influence on mandibular position.
Conclusions:The positioning of HB in different classes of skeletal malocclusion is a critical consideration in
orthodontic therapy. The findings indicate significant variations in HB position and its orientation to other structures,
emphasizing the need for clinicians to account for these differences during treatment planning.