Effect on Masticatory Function of Changes in Gum Texture during Chewing

Abstract

Since mastication depends on the physical properties of foods, it is very important to know how food texture is changed by chewing. In this study it was assessed how the change in food texture with duration of chewing affected masticatory function.
Eleven normal subjects and 6 patients with masticatory muscle disorders were asked to chew a piece of gum and the texture (hardness, gumminess, cohesiveness and stickiness) was measured by a texturometer at 10, 20, 30, 60, 90, 120, 180 and 240 seconds. The normal subjects showed significantly less hardness and gumminess of gum at 10 seconds.
Masticatory movements and EMG activity were analyzed during gum chewing in 12 normal subjects and 8 patients. Comparisons were made between the early stage of chewing, when the texture varied widely, and the late stage, when the texture had stabilized. In normal subjects, there was considerable variation in masticatory movement and EMG activity between strokes during the early stage. However, the cycle durations were relatively constant throughout chewing. In patients, the cycle durations were constant, and masticatory movement and EMG activity did not vary between the early and late stages. The results showed that although the output of the central pattern generator is influenced by sensory feedback in normal subjects, it is not influenced in patients.