咀嚼機能の模型化による咀嚼粉砕の基礎実験

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Attempt to measure the efficiency of human mastication on a quantitative basis is an important task assigned to dentistry to which many workers have contributed. These studies, however, have been done in vivo on human or animal mouth where various factors involved in the mastication and their iudividual effects on its efficiency could not be clearly understood. The author attempted to study the specific effect of these factors by making a model apparatus for the grinding mechanism of mastication. It is hoped that by this apparatus the three major factors, as the author arbitrarily enumerated, i. e. masticatory pressure, occlusal surface, and food carrying action besides other factors such as duration of chewing and amount as well as nature of saliva may be studied independently as to their effects on the efficiency of mastication. 1 MODEL APPARATUS OF MASTICATORY GRINDING The masticatory pressure of human individuals was recorded osillographically (Fig. 4), and a press machine equipped with a pounder exerting the same operating load was devised. This machine was conneted with a kymograph to make automatic recording of the pounder's movement. When necessary, the machine afforded to make alterations in the contact surface of the pounder and the state of food migration. The set of these equipments is shown in Fig. 3. 2 EXPERIMENTAL The grinding tests in wet and dry processes were done on peanut, raw rice and dried rice. In the wet process of grinding, load equivalent to 2.2 kilograms, in the dry process, load equivalent to 5.8 kilograms were applied on the pounder having the standard surface of 1 square cm.for each pounding, and 25, 50, 100, 200 and 400 times of pounding were respectively carried out. The particles of the materials obtained by each test were divided in portions by 8, 10, 28, 48, 100, and 200 mesh sieves successively. Since the author had been aware of the imperfectness of the sieving procedure hitherto commonly used, he has newly prepared an apparatus by which each stage of sieving was carried out simultaneously in water. On this apparatus the food particles in each mesh sieve were impregnated in water and agitated 3000 times automatically and successively. The particle distributions obtained from the above mentioned procedure showed the following results. 1) In peanut grinding, it was noted that considerable weight loss of the material occurred due to diffusing away of the peanut oil which occupies 20 to 30 percent of the material. The loss had been supposed by previous authors as due to swallowing down of fine particles by mouth experiment. The author confirmed that this is not the case, and therefore, data from these mouth experiments on peanut would be far from representing the masticatory efficiency. Besides the disadvantage, peanut undergoes remarkable denaturation in the water, and not at all suitable for the experiment as the test material, 2) As test material, dry and wet rice had similar nature to peanut. Rates of oil diffusion and water dissolution were small, but denaturation by water was not negligible in these materials. Both were better than peanut but not sufficient. 3) The particle distributions obtained in peanut and rice experiments do not seem to conform to the exponential law of Rosin and Rammlar as well as to the probability law of Austin. 4) The author plotted the correlations between the particle distributions and the amounts of work done in grinding the materials, and from the graphs, it was believed, the efficiency of grinding would be quantitatively known by examining the particle distribution of the material.
九州歯科学会の論文
1954-12-30

咀嚼機能の模型化による咀嚼粉砕の基礎実験

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