This study was made to investigate the influence of gum texture on the chewing motion. The textures of chewed gum (Green gum, LOTTE Co.), the hardness, the cohesiveness, the gumminess, the stickiness and the adhesiveness, were quantified by a texturometer (Zenken Co.), and also the weight measured for 10, 20, 30, 60, 90, 120, 180, 240, 300 and 600 sec in 8 normal subjects and 2 patients with craniomandibular disorders (CMD). Using a kinesiograph (Model K 6, Myo-tronics Co.), the jaw movement of

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... mandible was recorded three-dimensionally during 10min. habitual gum chewing. Multiple regression analysis was applied for investigating the effects of the change of gum texture and weight on chewing motion (criterion variables: chewing movement parameters, explanatory variables: texture and weight factors). The results obtained were as follows: 1. In normal subjects, the closing and the occluding phases were observed high correlations with the hardness and the cohesiveness. On the other hand, the opening phase and the cycle time were not observed correlations with any texture and weight factors. 2. In CMD patients, all parameters of chewing movement were observed high correlations with texture and weight factors. In conclusion, a central pattern generator (CPG), somewhere in the brain stem, is suggested to be responsible for rhythmical jaw movement in normal subjects. In CMD patients, however, jaw movement was easy to be affected by peripheral factors such as gum texture and weight.