Soghra Yassaei - Associate Professor, Department of Orthodontics, Faculty of Dentistry, Shahid Sadoghi University of Medical Sciences and Health Services, Yazd, Iran
Zohre Tabatabaei - Assistant Professor, Department of Orthodontics, Faculty of Dentistry, Shahid Sadoghi University of Medical Sciences and Health Services, Yazd, Iran
Hossein Torabi - Dentist

Aim: Hyoid and its attached muscles involved in three basic functions: deglutition, phonation, respiration and control of pharyngeal spaces. The aim of this study was to valuate hyoid bone position in relation to facial growth pattern in class III malocclusion.Material and Methods: This was a retrospective descriptive analytical study, performed on lateral ccphalograms of fifty patients with class III malocclusion with prognathic profile. Cephalograms were classified to three facial growth pattern groups so each group comprised of minimum ۱۵ samples. T-test and ANOVA were used to compare the difference of mean value of growth pattern groups. P< ۰۰۵ was considered as the level of significance.Results: The difference between means of ANB angle (۰.۷۸ degree) were significant (P=۰.۰۲۷) in three facial growth pattern groups. The indices determining the growth pattern were significantly different in three facial growth pattern groups (P<۰.۰۰۱). The findings showed a significant difference in H-RGN between three facial growth pattern groups and also showed no significant difference in H-Pal P, H-SN, H-Mand P, H-C۳ between three growth pattern groups.Conclusion: The anteroposterior position of hyoid bone related to cervical colunm was not affected by facial growth pattern. But its antroposterior position related to mandible was affected by facial growth pattern. There were significant differences between hyoid bone position in three facial growth patterns. Vertical position of hyoid bone was not affected by facial growth pattern.

Hyoid, Growth Pattern. Class III Malocclusion