Abstract
Purpose: The purpose of this study was to characterize masticatory function in patients with myotonic dystrophy (MyD) and to clarify the masticatory disturbances that might be encountered in these patients.
Methods: Eighteen patients with MyD with an average age of 54.1 years were enrolled as the subjects of this study. Factors such as activities of daily living (ADL), occlusal contact area, number of foods that were easy to chew, maximum bite force, and muscle activity in the temporal and masseter muscles during one chewing cycle were investigated, and the correlations among these factors were evaluated in these patients.
Results: The ADL score was significantly correlated with only the occlusal contact area. A significant negative correlation was observed between the muscle activity in the temporal and masseter muscles and the maximum bite force (P<0.05), as well as between the muscle activity and the number of foods that were easy to chew (P<0.01). A significant positive correlation was observed between the maximum bite force and the number of foods that were easy to chew (P<0.01), as well as between the maximum bite force and the occlusal contact area (P<0.01).
Conclusion: These results suggest that patients with MyD find only a few types of foods easy to chew because of their weak bite force, and that they compensate for the weak bite force by greatly increasing their temporal and masseter muscle activity while chewing. Also, patients with MyD with a low ADL score frequently have a small occlusal contact area.
