Comparison of Hyoid bone Position, Soft Palate Position and Head Posture in Class III Growing Patients with Maxillary Protraction treatment with or without Expansion.

Abstract

Objective: To assess changes in hyoid bone position, soft palate angle, and head posture  after maxillary protraction in class III Growing patients using lateral cephalograms between expansion group with facemask and the group without expansion.

Methods: The study was composed of 30 growing patients with Class III malocculsion treated in orthodontics department of the Faculty of Dentistry, Dental Clinic, and a number of private clinics in Hamadan, Iran. For data collection, lateral cephalograms were collected from each of the patients before and after treatment, after which the patients exhibited positive overjet. After radiography scan (using Microtech Scan Maker 48bit color.i800) for patients without electronic radiographs (CD), the cephalograms were all resized at a certain dpi. The length of the ruler was considered to be the factor for resizing the scanned images. After collecting the electronic files of lateral cephalograms and the cephalometric scan for patients without the files, the images were traced using Orthosurger X software,Iran.. Statistical evaluation was performed using SPSS 23.

Result: Pm-U variable in control group increased after treatment.(P˂0.05), downward movement of hyoid bone was significantly increased in both groups but there was no difference between two groups. No change happened in head posture during treatment in both groups

Conclusions: No difference was found between two groups and expansion seems to have no effect on airway size.