Effects of Bite Opening on Masseter and Geniohyoid Muscles: A Randomised Clinical Trial

Objective: To evaluate the effects of anterior bite plane on the masseter and geniohyoid muscle thickness. Materials and Methods: 14 subjects who needed bite opening were allocated as a single group with mean age of 17.4± 3.4 years and mean overbite of 5.3±0.2 was treated with a fixed anterior bite plane (ABT). The pre-treatment (T1) and post-treatment results (T2) was compared to study the effect of Bite opening. The ultrasonographic imaging was used to evaluate masseter muscle thickness (clenched and relaxed) and geniohyoid muscle thickness.  Results: The study showed, the right masseter muscle thickness (RMT) in (R) at T1 was 8.68 ± 1.13 mm, T2 was 7.68 ± 1.14 mm and in (C) 0.72 ± 1.39 mm and 9.86 ± 1.35 mm respectively While left muscle thickness (LMT) was at 8.54 ± 1.3 mm and 7.68 ± 1.3 mm respectively.  The mean geniohyoid muscle thickness before treatment was 6.58 ±0.69 mm and after treatment was    7.40 ± 0.69 mm with an increase in thickness of 0.8 ±0.04 mm. Conclusion: Bite opening procedure influence the muscles thickness, with reduction of masseter muscle thickness and increase in geniohyoid muscle thickness.