Jaw‐movement smoothness during empty chewing and gum chewing

Abstract

A major goal of motor coordination is the production of a smooth movement. Jerk‐cost, which is an inverse measure of movement smoothness, has been evaluated during gum chewing in previous studies. However, the effect of the gum bolus is still unclear. The aims of this study were to compare the jerk‐cost values of normal gum chewing with those of empty chewing. Thirteen subjects undertook, empty chewing, then chewing of gum, and then a second empty chewing. Jerk‐cost was calculated from an accelerometer attached to the skin of the mentum. There was a significantly higher smoothness (i.e. lower jerk‐cost, P < 0.05) during the opening and second‐half closing phases in empty chewing compared with gum chewing. There were no significant differences in jerk‐costs (i.e. opening or closing) between the first and the second empty‐chewing sequences. These results suggest that the influence of the mechanical effects of tooth contact on jerk‐cost is not restricted just to the occlusal phase of chewing, but rather the effect influences the entire opening and closing phases of chewing.

The three‐axial gyroscope sensor detects the turning point between opening and closing phases of chewing

“…The waveforms obtained from the three‐axial accelerometer (Minami et al, ; Minami et al, ) are also able to detect the boundaries between fast‐ and slow‐opening phases and fast‐ and slow‐closing phases (Ross et al, ), as well as the intercuspal phases. The present study demonstrates that the three‐axial gyroscope sensor is able to detect the turning point between the opening and closing phases of chewing.…”

“…The sensor was secured by means of double‐sided adhesive tape placed onto the surface of medical tape (Fixomull stretch; BSN Medical, Hamburg, Germany) that was attached to the skin on the chin of each participant, with the same method as described previously (Minami et al, ; Minami et al, ; Molenaar et al, ). The output from the three‐axial gyroscope provided angular velocity along three orthogonal axes (Figure ).…”

“…These five sessions were performed unilaterally on the preferred chewing side. For each participant, the five strokes after an initial three strokes were used for calculation, in accordance with previous studies (Minami et al, ; Minami et al, ; Minami et al, ; Molenaar et al, ), and the middle three sessions were used for further processing.…”

“…Data collection would be facilitated, particularly in the elderly, if the device for measuring masticatory function was easily transportable and simple to setup. Recently, an accelerometer attached to the skin of the chin has captured jaw movement smoothness for the evaluation of movement variability (Minami et al, ; Minami et al, ; Minami et al, ; Yashiro, Yamauchi, Fujii, & Takada, ). This device is portable and easy to setup and use and with minimal interference to the participant.…”

“…This device is portable and easy to setup and use and with minimal interference to the participant. This system can detect the tooth contact phase of the chewing cycle, as well as jerk‐cost, an inverse measure of movement smoothness (Minami et al, ; Minami et al, ; Minami et al, ; Molenaar et al, ).…”