Abstract
The reduction of the masticatory organs in the process of human evolution is related to the changes in diet during development of the human culture.
The direct cause is considered to be related to the decrease of mastication consequent upon the softening of foods and concentration of nutritive substances by cooking and processing of food materials. This study was carried out to establish the standard for evaluating the amount of mastication for modern Japanese.
For evaluation of the amount and force of mastication, action potentials and their integrated values were recorded electromyographicaly in six young adults with normal occlusion.
As the result, the liquefied or gelatinous foods needed less mastication. Hard and fibrous foods needed much mastication. From the integrated values of the masseter muscles, foods were classified in to 7 groups according to the amount of mastication needed for a bite sized morsel. Using these values, unusual foods can be scored.
