STUDIES ON THE MASTICATORY EFFICIENCY

Abstract

As the preliminary stages for research in masticatory efficiency of denture wears, the author has made experiments to obtain on persons with natural teeth the basic informations requiring for establishment of a method to measure all inclusive masticatory ablilty in the stand point of biochemical digestive process in mastication which has never been reported enough previously.The author paid attention to amylohydrolytic activity of salivary amylase which plays the chief part in digestive function of oral cavity. He has investigated the influences of mastication upon the digestion of Japanese rice on the basis of glucose from polished rice with a few types of preparation by mastication in human oral cavity under several conditions (differences of frequency, periods and tempo of mastication).Glucose and maltose as glucose in the supernatant, obtained by 20 min. centrifugal separation under 6.99×103g, from masticated rice in which the salivary amylase activity was stopped with acid, were detemined by Somogyi-Nelson method. Maltose was determined as glucose after hydrolysis by 1, 000mg/dl Maltase, 37°C, 60min., The quantity of ‘glucose+maltose’ as glucose is called in this study “total glucose”.In this research, the term “masticatory performance” is defined to total glucose from rice after mastication and the term “high or low masticatory efficiency” is defined to the case in which masticatory performance is high or low under the same masticatory condition.The author thinks that the effect of mastication should be determined by the difference of total glucose under the same condition between the case in which the test food is masticated and the case in which the test food in the mouth is never masticated.To express definitely the relationship between masticatory times and periods in a test, a term “masticatory tempo” is used by the author; for example, tempo (M. M.) =60 means 60 times mastication per a minute.“His or her own tempo” is used to mean the tempo in which he or she masticates freely without any control.The results obtained from the author's investigations were as follows:1. It is possible to judge the masticatory efficiency and masticatory performance by the author's biochemical method.2. As masticatory test food, washed rice, boiled rice and boiled-dried rice are available.3. The idea that masticatory performance is related with the increase of contact area with saliva bringing the increase the number of test food's particle is certified from the author's result that the increased masticatory frequency (times) and the increased total glucose are in direct proportion in over 50% of cases.4. A person's own masticatory tempo against the same test food is nearly constant.5. In the case of a person's own and adjacent tempo, the masticatory efficiency is the highest.6. In all test food, masticatory efficiency, in slow tempo (M. M.=30) is higher than in quick tempo (M. M.=120).7. There is seen no difference in a person's mastication during a short period (about one week), but a few difference during a long period of time (about one year); especially inFeb. and Aug., masticatory efficiency is lower and in April and June higher.8. There is seen a few difference in masticatory efficiency in a day; especially at 11.00 O'clock, it is highest.9. There is seen a few difference in masticatory efficiency between the right and the left masticatory side. Masticatory efficiency on a person's habitual masticatory side is higher than on his nonhabitual side.10. There is seen no constant relationship between masticatory tempo and the volume of secreted saliva, but the types of preparation of rice influence the volume of secreted saliva; the harder the food is, the larger the salivary volume is.