Assessment of hyoid bone position among different skeletal patterns

Abstract

PurposeTo determine the hyoid bone position in subjects with various skeletal patterns. Materials and methodsConventional pre-treatment lateral cephalograms of 100 subjects aged 18–25 years were selected from the files of orthodontic patients based on anteroposterior skeletal pattern and facial divergence pattern. Subjects with Class I skeletal pattern (ANB 1–4°) were categorized into group A and group B depending on the measurements of Frankfort Mandibular Plane Angle (FMA) of 22–30° (normo divergence) and greater than 30° (hyper divergence) respectively. Likewise subjects with Class II skeletal pattern (ANB >4°) were categorized into group C and D, based on the above same divergence. The angular and linear measurements were recorded and measured. Statistical assessments include unpaired Student t-test and one-way analysis of variance (ANOVA). ResultsThe vertical position of hyoid bone was not affected by nature of horizontal or vertical growth pattern of the face. The mean anteroposterior position of the hyoid bone among the 4 groups of subjects was statistically significant (p<0.05). The position of hyoid bone in group D was significantly backward compared with the subjects in group A (p<0.05) or group C (p<0.05). The mean hyoid axis angle among subjects in the hyper divergent group (group B and group D) was high but insignificant. ConclusionThe position of hyoid bone was most posterior in subjects with skeletal Class II malocclusion associated with mandibular retrognathism.