Tongue thickness is associated with masticatory performance of perioral muscles: Ultrasonographic study of perioral muscle characteristics in healthy young subjects

Mastication is a complicated task that involves the teeth and perioral muscles, such as the tongue and lip. Previous studies have shown correlations between masticatory performance and perioral muscle strength (eg tongue pressure) and between masticatory performance and occlusal forces.To investigate the relationships between masticatory performance and perioral muscle characteristics.Forty-nine healthy young subjects (men: 24 and women: 25) with Eichner classification group A were included in this cross-sectional study. Age, body weight, masticatory performance, masseter muscle thickness, masseter muscle echo intensity, cross-sectional area of geniohyoid muscle, geniohyoid muscle echo intensity, tongue thickness (TT) and tongue echo intensity were assessed. Masticatory performance was evaluated using a colour-changeable chewing gum. The thickness and echo intensity of the masseter muscle, geniohyoid muscle and tongue were observed using an ultrasonic diagnostic apparatus. Stepwise multiple regression analysis was conducted to examine relationships between perioral muscle characteristics and masticatory performance.Tongue thickness (P < .01) was the sole significant explanatory variable for masticatory performance. The standard partial regression coefficient was 0.47. The multiple correlation coefficient (R) was .47, and the adjusted R2 was .20; the variance inflation factor was 1.0. This study showed that TT was related to masticatory performance, whereas perioral muscle quality was not. Moreover, perioral muscle quantity was highly correlated with perioral muscle quality.Tongue thickness is a predictor of masticatory performance in healthy young subjects. An ultrasonic diagnostic apparatus is useful in the evaluation of perioral muscle characteristics.