These experiments were carried out for the purpose of investigating causes of exfoliation of the oral mucosa after use of dentifrice.
Exfoliation of the oral mucosa is considered to be mainly due to the surfactant of dentifrice components.
The perfumes influence exfoliations of oral mucosa when surfactants co-exist with them.
Combinations of perfume and surfactant are mainly divided into two types.
The first ; surfactants themselves cause small amount of exfoliations oral mucosa and even when perfumes co-exist, they do only a same size of exfoliations.
The second ; surfactants themselves have properties of exfoliations and when perfumes coexist, exfoliations is varied with their type.
On the other hand, exfoliations are influenced with quantity of perfumes.
Differences of exfoliations volumes come not from depthes of exfoliations tissues but from sizes of exfoliations tissues.
Exfoliations are caused by swelling of the upper layer of tissues, which due to dentifrices.

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A caries preventive method by filling the pit and fissure in the occlusal surface with Ethyl-2-eyanoacrylate and Polymethylmethacrylate has been developed by Takeuchi and others, based on Takeuchi's Epidemiological principles of dental caries attack.
Contrary to a suspicion that the filled material will soon come off or abrade after exertion of this procedure, all the results of previous studies for testing its effectiveness indicated that this method is good for caries prevention for at least more than six months. This study, therefore, was made to observe the positions in the pit and fissure where the filled material might remain if abrasion or coming off should occur, and to presume the reason of its remaining in respective positions.
Materials and methods : sixty extracted teeth, that is, twenty each of invested wisdom teeth, the upper, and the lower first premolars, were used. After the routine procedures of sealing of the pits and fissures with resin adhesives, the teeth underwent the most severest condition that might occur in the oral cavity, a thermal changes at 0°C and 60°C. Then, by tensile force destruction of the material was induced in the pits and fissures. The teeth were ground buccolingually, taking series of continued pictures of the sections at 50 μ intervals, and enlarged tracings were obtained from these films.
Results : observations made from varying standpoints resulted in the findings that even by the tensile force, the material came off, being fractured around the basal line of measurement, an imaginary fundus of the fissure ; and that a major reason of this retention lies in the existence of continuous formation of undercuts in the direction of the tensile destruction observed in three consecutive sections, that is, within the thickness of approximately 150 μ. Unhomogenous physico-chemical distribution of the filling material and the stress upon the filling are also considered as another reason of the retention.

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On Aug. 1, 1963, President of the Japan Dental Association submitted “Present Status of Japanes Periodontal Diseases” to Japanese Society for Dental Health. And then, Japanese Society for Dental Health accepted this matter, and established Committee of Survey of Periodontal Diseases. The Committee dispatched a special investigational group, and the study was performed on the entity of the said disease in Japan from an independent standpoint of the Society. As for the objects employed and the methods of the present investigation, 10 areas were selected from among the those investigated on dental diseases in all over Japan by Ministry of Health and Welfare, Japan, in Nov. 1963. And, the mass clinical examination was performed on 955 persons with their age more than 10, living in the above 10 areas regarding 4 symptoms of the abnormality of periodontal diseases such as redness of periodontal tissue, swelling of periodontal tissue, exposed dental root and loosening of teeth.
As the result, the following findings were obtained. Among the patients having the above 4 symptoms, the rate of those who have one and or more than one symptom was 97.38%.
In view of the classification by each symptom, the average number of existence of teeth per person was 12.2 teeth on the redness of periodontal tissue, and 11.3 teeth on the swelling of periodontal tissue, 2.5 teeth on the exposed root of teeth, and 1.4 teeth on the loosening teeth.
Also, the rate of existence of teeth present was 52.82 % on the redness of periodontal tissue, 48.95% on the swelling of periodontal tissue, 11.46% on the exposed root of teeth, and 6.15 % on the loosening of teeth.
In the classification by age-group consisting of every 5 years older persons, redness and swelling of periodontal tissue were observed in nearly equal number on the above each age-group, showing marked increasing tendency in the group of their age up to 34, but decreased in the group of their age more than 35.
Exposed root of teeth and the loosening of teeth were observed increasingly in the group of the higher age, but the exposed root of teeth was observed more increasingly than the loosening of teeth.
The comparison on the above 4 symptoms by sex in each age-group was attempted while observing each symptom in classification by the kind of teeth, and those sexual comparison showed specific values classified by teeth and sexual differences.

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