A changes in hyoid bone position after orthodontic treatment of patients with mandibular deviation.

OBJECTIVES The aim of this study was to observe the influence of orthodontic treatment on the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations. METHODS A total of 60 patients with mandibular deviations, including 30 males and 30 females with a mean age of 15.4 years, were recruited. They were equally divided into average angle, high angle, and low angle groups, with a 1:1 gender ratio. Their hyoid position was measured before and after orthodontic treatment. The data were analysed using paired t-tests and analysis of variance (ANOVA). RESULTS After treatment, the hyoid body in the high angle group presented significant forward and upward movements (p = 0.012 and p = 0.005). The hyoid body in the low angle group exhibited significant forward movement (p = 0.048) and a significant increase in the hyoid inclination (p = 0.00). In the average angle group, the hyoid body significantly moved downward (p = 0.031) and the thyrohyoid moved upward (p = 0.046). The ANOVA showed that orthodontic treatment significantly influenced the vertical position and inclination degree of the hyoid (F = 6.37, p = 0.003; F = 6.204, p = 0.004; and F = 3.393, p = 0.025). The average angle group displayed significant differences in these indices compared with the high angle and low angle groups. Orthodontic treatment significantly influenced the mandibular plane angle in the high angle group (p = 0.012). CONCLUSION Orthodontic treatment influences the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations by varying degrees.