[Clinical study of evaluation on masticatory function in complete denture wearers. A comparison of masticatory movements between normal natural dentition and complete denture wearers].

The purpose of this study was to comparatively study and elucidate the characteristics of masticatory function of the subjects with complete denture and those with normal natural dentition. The study were carried out on 20 subjects with normal natural dentition and 30 subjects with complete denture having clinically good prognosis. Masticatory movements were analyzed by electromyograph (EMG) and sirognathograph (SGG) when the subjects were chewing peanuts and kamaboko (boiled fish paste). The results were as follows: 1. The duration of chewing cycle, closing phase, occluding phase, and EMGs burst duration (especially after tooth contact) were significantly longer in the subjects with complete denture. 2. The maximum opening distance was significantly shorter, the maximum opening and closing velocity were significantly slower, in the subjects with complete denture. Further, the standard deviation of the coordinates of the sample points in the occluding phase was indisordered in the subjects with complete denture, and standard deviation of the coordinates of sample points in occluding phase were varied in complete denture wearers. 3. The frontal masticatory pattern tended to unstable and typical tear drop shape pattern was found in about 60% of the subjects with complete denture. 4. Different reactions to the test foods were observed in the subjects with normal natural dentition, while such was not noted in the cases of the subjects with normal natural dentition. These results was suggest that the masticatory function in the subjects with complete denture were obviously differ from those of normal natural dentition due to the difference in the sensory-motor-system.