The author undertook a series of measurements, with the use of a measuring deviceand method designed by Dr. Takamizawa, on a group of 80 male and 76 female patients, all in the age bracket of 30's, who were the out-patients for treatment of Parodontopathia at Nihon University Dental Hospital, regarding the individual biting forces of each tooth.
In carrying out the measurements, the resorption degreeof their alveolar bone was used as an indication and, thus, correlations between the degrees of resorbed alveolar bone and individual biting forces were studied.
Generally speaking, the individual biting forces of the each proper tooth in the concerned teeth group were reduced than that of the control group, in correspondence to the degrees of alveolar bone resorbed.
As a result with the percentage of the individual biting forces of the concerned teeth group against that of the control teeth group, the author arrived at the following conclusions.
1. With the concerned four groups, A. B. C. and D., the distributions of individual biting forces are as follows. That is, group A refers to patients whose resorption of the alveolar bone was within 1/4 of the total length of roots, group B refers to cases where the resorption of the alveolar bone was anywhere from within 1/4 to 1/2, group C refers to cases where the resorption of the alveolar bone was beyond 1/2 to 3/4, and lastly group D refers to cases where the resorption of the alveolar bone was more than 3/4.
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2. In terms of kg. measurements of individual biting forces of the concerned teeth in the 4 groups, the data are as follows.
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In common with these 4 groups above, there are not observed significant differences in terms of sex, upper or lower jaw(with the exceptions of second premolars in Group A, first molars in Group B, lateral incisors and second molars in Group C) and the side of jaw whether right or left.
On the strength ofthe measurement data give above, it is to be concluded that they will serve as scientific indications of the degree of functional ability in mastication of the teeth, suffering from Parodontopathia.

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Although much published literatures are available which deals with the sensitivity of normal oral mucous membrane of dentulous persons, there is not yf t found any detailed study of sensitivity of mucous membrane under the plate, comparing with that of dentulous persons.
In these studies, the author constructed thecomplete dentures by himself on an edentulous group of 110 patients, on whom theauthor measured the sensory threshold of mucous membrane under the plate to the electric stimuli.
The measurement values thus obtained were comparatively examined with reference to a dentulous group of 50 normal subjects. By these comparisons, it was possible to ascertain in detail changes occuring in mucous membrane under the influence of the complete dentures.
As a result of these studies, the author arrived at the following conclusions.
1. In common to the edentulous and dentulous groups, the sensory threshold of females was definitely lower than that of males. In the former, the sensitivity of mucous membrane had a slight tendency of being more active.
2. Simillary, in common to the edentulous and dentulous groups, mucous membrane of the lower jaw was observed to have less sensory threshold than that of the upper jaw. On the other hand, the sensitivity of lower jaw mucous membrane was somewhat higher than upper jaw mucous membrane.
However, when the mucous sensitivity had been much dulled under the influence of the insertion of complete plates, the lower jaw registered higher sensory threshold.
3. In comparison with normal dentulous subjects, edentulous subjects with complete dentures registered the sensory threshold values which increased in proportion to their age. The dullness of sensitivity to stimuli had advanced also proportionally to their age. In particular, with the edentulous patients in the age from about 60' to over 70's the average sensitivity responsed ecreased by 65% to 50% of normal subjects.
4. The sensory threshold values increased proportionally to the applied length with complet dentures and the mucous sensitivity had dulled correspondingly. From 10 to 15 year's of the applied length the average sensitivity decreased by 65% and, beyond 15 years, by 65% to 50% of normal subjects.
5. The sensitivity of mucous membrane under the complete dentures was measured in various regions of jaw as follows.
i) Mucous membrane in the molar region was duller than that of the anterior region. However, the decreased rate of sensivity of the mucous membrane under the influence of dentures was much recognized in the anterior region than that of posterior.
ii) Order of the degrees of dullness produced under the influence of dentures was labiobuccal, lingual, alveolar ridge, palatal side and palate regions.

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It was the purpose of this study to estimate the long-term clinical effects of wearing partial dentures of the various types.Six months to five and a half years follow-up was undertaken on 2149 dentures with which 1564 patients were fitted at Tokyo Medical and Dental University. They comprised 908 maxillary and 1210 mandibular dentures. According to the denture materials they were divided into 853 dentures made of cast cobalt-chromium or gold alloy skeleton with acrylic resin saddles and 1238 in acrylic resin with clasps and bars in wrought metal.Eight hundred and seventy eight appliances of them were provided for men and 1222 provided for women.
Clinical examinations were performed at the time when the dentures were inserted. Six months to five and a half years thereafter a questionnaire was sent to each case in order to ask chiefly the question which dentures had, or had not, been worn, and the re-examination was carried out.1158 cases (53.89 percent) replied to the questionnaries, and 772 of them (35.92 percent) attended for the reexamination.But 655 cases (30.48 percent) did not reply, and 336 cases (15.64 percent) were untraceable.
The responses were obtained only from about a half of patients, and therefore it may be questioned that a series of cases responding to the survey did not differ from the whole in the distribution according to, for example, age, sex, denture materials, denture types, maxillary and mandibular dentures, number of remaining teeth, and the length of time which had elapsed since the dentures had been provided. With the exception of the distributions in denture materials and the years since the dentures had been provided, the series of responding cases, compared with the whole statistically on the basis of the chi-square test, was not different in the above-mentioned distributions.

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In order to estimate the long-term clinical effects of wearing partial dentures, the authors Undertook follow-up on 2140 dentures with which 1564 patients were fitted at Tokyo Medical and Dental University.Clinical examinations were performed at the time when the dentures were inserted.Six months to five and a half years thereafter a questionnaire was sent out to each case to ask several simple questions on the dentures, and to attend for re-examination.1158 cases replied to the questionnaires, and 772 of them appeared for re examination.
As based on the results derived chiefly from the replies to the questionnaires, the following conclusions were drawn:
1.The patients were asked if they were wearing their dentures.The 28.03 percent of examined partial dentures were discarded.In these examined dentures the 21.78 percent of the dentures made of cast cobalt-chromium or gold alloy skeleton with acrylic resin saddles were discarded, and also the 32.56 percent of dentures in acrylic resin with clasps and bars in wrought metal discarded.The rate of discarded dentures in the former was remarkably higher than in the later, and the chi-square test at 5 percent level showed a significant difference between them. But in the rate of discarded dentures was no discrepancy between maxillary and mandibular dentures, among dentures provided for patients of different ages, and between those of men and women.
The rate of discarded dentures remained about 10 percent for a year and a half after the examined dentures were inserted.But afterwards it increased to 30 percent after three years and three months following their insertion. And it approached 40 percent after four years and nine months.Furthermore it increased rapidly to 64 percent after five years and three months.
In unilateral free-end posterior dentures, unilateral bounded posterior dentures and unilateral combined posterior dentures, the rate of discarded dentures reached 30 percent as early as two years after they were inserted.But in bilateral combined posterior dentures the rate increased to 30 percent after three years following their insertion, and in both bilateral free-end posterior dentures and bilateral bounded posterior dentures, it rose rather slower to 30 percent until fourth year. With the exception of unilateral combined anterior and posterior dentures in which the rate rose to 30 percent after three years, the rate of anterior and posterior dentures increased considerably slower to 30 percent. Namely the rate of bilateral combined anterior and posterior dentures reached 30 percent after four years.In both bilateral free-end anterior and posterior dentures, and bilateral bounded anterior and posterior dentures, it increased to 30 percent until fifth year. In unilateral free-end anterior and posterior dentures, and in unilateral bounded anterior and posterior dentures, the rate of discarded dentures did not reach to 30 percent within five years following their insertion, although a small number of them.

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