Purpose: Various methods of evaluating the ability of mastication have been reported, most of which involve evaluating of the ability to comminute foods. In this study, a new method of evaluating the ability of mastication focusing on bolus formation was applied to denture wearers.
Methods: One hundred and twenty-five subjects (71 males and 54 females) using removable dentures and receiving follow-up in the Niigata University Hospital were selected. This group was categorized by Eichner's classification, and investigated for the effect of prosthetic treatment by counting the number of chewing strokes until the first swallow of rice crackers.
Results: It was clarified that the number of chewing strokes until the first swallow counted by visual observation agreed well with the number of chewing strokes counted by electromyogram wave of masseter muscle, laryngeal motion, and swallowing sound, as a preparatory experiment. Using the method of counting chewing strokes by visual observation, the effect of prosthetic treatment was evaluated, and the results were as follows. 1)There is a significant difference in the number of chewing strokes without dentures between the Eichner A group, B group, and C group. 2)There was no significant difference in the number of chewing strokes with dentures among the three groups. 3)A significant decrease in the number of chewing strokes was proven by the use of removable dentures. 4)Both the improvement rate of chewing strokes (the ratio of the number of chewing strokes with dentures until the first swallow to that without dentures) and the difference of chewing strokes increased significantly in the order of Eichner A, B, and C.
Conclusion: It was clarified that the effect of prosthetic treatment can be quantitatively evaluated by counting the chewing strokes of rice cracker. Moreover, it was suggested that the condition of prosthetic treatment can be evaluated by analyzing the improvement rate of chewing strokes.