In order to verify the influence of aging, nutrition, dietary and occlusal support loss-related changes on endurance performance and bone mineral density in old male rat, 99 Wistar male old rats were divided into the following groups, the control group (fed with a solid diet), the soft diet group (fed with powder diet contaning the same components as the solid one), the molarless group (at molar were removed at 45 weeks and then fed with a powder diet), the low calcium solid diet group (fed with solid diet low in calcium-deficient and in vitamin D) and the molarless with low calcium diet group (all molars were removed at 45 weeks and the rats were fed with a powder diet low in calcium-deficient and in vitamin D). Exercise-physiologic, biochemical, histomorphometic studies were performed.
The results obtained were as follows:
1. The weight of the soft diet group at 75 weeks was higher than that of the control group at 75 weeks, showing a statistical significance (P<0.01)
2. Bone mineral density at the condyle and the femur in the molarless with low calcium diet 75 weeks group was lower than that of all the other groups, showing a statistical significance (P<0.01)
3. Endurance performance (exhaustion time in a swimming-exercise) and the value of serum indices (creatine phosphokinase, free-fat acid and alkaline phosphatase type III) after the swimming-exercise in aged rats were considerably influenced by nutrition, dietary and occlusal support alteration in addition to aging.
These results suggested that the soft diet, malnutrition and the decline of occlusai-masticatory function caused by teeth loss could accelerate osteoporotic changes of the mandibular bone and femur, besides decreasing the bodily activities.

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Candida species commonly inhabit the oral cavity and are implicated in a variety of diseases.
Antifungal therapy is useful in the prevention and treatment of oral candidosis, and ismost important in keeping the oral cavity clean. There is a natural self-cleansing action of themouth. It is estimated that this action is influenced by diet. However the elderly tend to have asoft diet. The purpose of the present study is to investigate the relationship between the dietform, salivary flow rate and the quantities of Candida species on the dorsum of tongue.
In this study, the subjects were 46 women and 59 men who were in-patients suffering fromdementia or stroke, with ages ranging from 62-97 years (mean age 80). The coat of the tonguewas collected by the sterilized swab from the dorsum of tongue. The sample was evaluated bya simplified culture (STOMASTAT^TM). Whole saliva was stimulated by paraffin wax chewingand the flow rate was measured.
There were high candida levels in 24.5% of the solid diet group and 65.4% of the soft dietgroup.There was a significantly high candida level in the soft diet group.The salivary flowrate was significantly reduced in the soft diet group.These results indicate that taking a softdiet causes increased Candida species on the dorsum of the tongue.

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There has been a recent trend in human dietary habits toward a semi-fluid diet. Thoughtherehave been many studies on the effect of a semi-fluid diet on various biological functionsand the development of the oral and maxillofacial unit, no studies havebeen conducted onregressive changes in the jaw and masticatory muscles of the elderly who are forced to switchto a semi-fluid diet due to reductions in oral functions caused by aging. Therefore, the presentstudy was conducted to investigate the effect of a semi-fluid diet on the masticatory musclesof aged rats. Male Wistar rats were used in the present study. They were raised on a hard dietfor four months until they were fully grown, and were then allowed to freely eat powdered foodhaving the same composition as the hard diet until reaching the age of 21 or 30 months (experimental groups). For comparison, rats were raised on a hard diet until reaching the ageof 21 or 30 months (control groups). The temporal muscle and the superficial and deep layersof the masseter muscle were removed from each rat and stained using actomyosin ATP ase todetermine the mean ratio of the components of muscle fibers, the mean ratio of the area ofmuscle fibers, and the mean of minor-calibers muscle fibers. Type-1 fibers were not detectedin the temporal muscle or the superficial and deep layers of the masseter muscle in the presentstudy. The glycogenase activity of fibers of types 2A and 2B was high, and anaerobic ATPsynthesis was active. In particular, the oxidase activity of type-2Afibers was high, indicatingthat these fibers were durable and highly resistant to fatigue.The findings of the study wereas follows:
(1) The composition ratio of type-2A fibers decreased in the superficial layer of the masseter muscle in both the experimental and control groups, but increased in the deep layer of themasseter muscle in the control groups. The mean ratio of the area of muscle fibers decreasedin the superficial layer of the masseter muscle in the experimental group.
(2) The mean caliber of fibers of types 2A and 2B decreased in the control group over time, and these decreases were marked in the deep layer of the masseter muscle.
(3) Although there were significant differences between the experimental and control groups 21 months after birth, virtually no differences were seen between the two groups30 months after birth.
These findings suggest that the mastication of a hard diet has some effect on the maintenance of occlusal force, and that regressive changes in masticatory muscles are mainly attributable to the aging process after a certain age.

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[in Japanese]

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