Oral mastication is the initial process of digestion, a physico-chemical reaction comprising primarily the law of diffusion. According to the law, the amount of a certain substance dissolved is proportionate to the surface area of particles of the substance. The efficiency of mastication, therefore, may be most properly expressed by the increment in surface area of particles of the material chewed. On the other hand, there is in the field of engineering Rittinger's principle concerning crushing work and the surface area of solid that the amount of work done in crushing is proportionate to the increment of surface area of particles crushed. The authors undertook, therefore, to study experimentally as to whether or not this principle also holds true in the masticatory process of human mouth. 10 grams of peanut selected as a test material were allowed to chew 30 times in 30 seconds, then the products were sieved through 3, 4, 6, 8, 10, 14, 20, 28, 35, 48, 65, 100, 200 mesh sieves successively. Each portion of peanut particles was then dried and weighed, the surface area of which was then calculated respectively as shown in Table I. The results indicated that the number of chewing was in direct proportion to the increment in surface area of the particles. The author suggests that the masticatory efficiency of individual mouth be expressed by the increment in surface area of a test material as produced by definite number of chewing in definite time interval, and wants to call it R, Y, M (Rittinger-Yokota-Method), for the sake of convenience. The author deems that, though theoretically sound at the most, the method lacks as yet many substantiation for the practical application, and further elaborations are now demanded.
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