The fact that the compressed distortion of the seat mucosa of complete dentures (just the seat mucosa will be substituted for the seat mucosa of complete dentures in subsequent sentences) varies from an area to another is considered one of the primary factors to adhesive retention, stabilization and masticating efficiency of dentures and problems of the seat mucosa.
Some researches have been already reported on the compressed distortion of the mucosa, is rather difficult to find any clinically significant values in them form the following 1) they measured just strain under a given load, whereas load itself varies regionally mucosa. 2) they have not represented accurate relationship between load and strain condition of the compressed distortion under various loads.
Since the new type transducer was designed and developed by the auther, it became measure both the load and strain simultaneously in a given condition of the seat mucosa also to compare physical hardness and tension of the mucosa at different regions.
The following conclusions were obtained.
1) The simultaneously measured load and strain of the seat mucosa were shown in Tables -4. It was obvious that the load and strain of the seat mucosa were different regionally and they were summarized as follows.
a) Both the load and strain of the seat mucosa of anterior alveolar ridge were greater than those of the seat mucosa of posterior alveolar ridge.
b) In the mucosa of palate, the load in anterior region was greater than it in posterior and the strain increased with a small difference in turn in the region of middle palate, rugae and foveola palatini. And the strain in those three regions were with significance smaller than those in the palatal side of the region of premolar and in the region of posterior palatine foramen where the greatest strain was acquired from.
c) When comparison was made between the load in the region of alveolar ridge and it in the region of palate, and the strain in those two regions:
i) The load in anterior ridge had a tendency to be slightly smaller than it in theregion of rugae, but to be greater than it in the region of middle palate, the palatal side of the region of premolar and the region of posterior palatine foramen, and was distinctly greater than it in the region of foveola palatini.
The load in posterior ridge had a tendency to be slightly greater than it in the region of rugae, although the differen between the two was little, and was obviously greater than it in the other regions, that is, middle palate, foveola palatini, palatal side of the region of premolar and posterier palatine foramen.
ii) The strain in anterior ridge had a tendency to be slightly smaller than it in the region of rugae and was obviously greater than those in the region of middle palate, foveola palatini, palatal side of the region of premolar and posterior palatine foramene.
The strain in posterior ridge had a tendency to be greater than it in the region of rugae and middle palate, but a tendency to be smaller than it in the region of foveola palatini and was obviously greater than those in the palatal side of the region of premolar and in the region of posterior palatine foramen. It was a trend in the aged person over 60 years, however, that difference of strain in anterior ridge, in the region of middle palate and foveola palatini became on the decrease.
3) The load and strain of the seat mucosa increased with age. It was, especially, evident in the load in posterior alveolar ridge and in the region of palate. And the strain in anterior ridge and in the region of rugae remarkably increased with age.
4) The load in upper alveolar ridge was significantly greater than it in lower. On the other hand, the strain in upper ridge had a tendency to be greater than it in lower, but no significant difference between the two was found.

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The seventy persons (38, 32), who were between 20 and 28 years old and had late persistent second deciduous molars, were found in 28, 580 people over the age of 20 (16, 830, 11, 750), who were examined at random.
On those subjects and the 143 late persistent second deciduous molars had, the author conducted clinical examinations, roentgenograms, measuring the individual biting forces and the comparison of those on one side in a person and those of the second permanent premolars on opposite.
For measuring biting forces, the biting forces measuring appartus with four strain gauges attached and Multiplex monitor-recorder (RM-150 type) made by Nihon Koden co. were used, and the following results were obtained.
1) The seventy subjects with those deciduous molars were found in 28, 580 people exmined. It is ratio to the total number of the people examined was 0.25 per cent.
2) Those subjects were 38 men from 16, 830 examined and 32 women from 11, 750. It is ratio to the total number was 0.23 per cent in male and 0.27 pe cent in female. But there is no significant difference between in male and female.
3) The subjects with two persistent molars to the total number of the subjects were about 66 per cent, those with one about 20 per cent, those with four about 10 per cent and those with three about 4 per cent, least.
4) When observed the kind of the late persistent second deciduous molars, the following finding were obtained.
E. 32 (22.4 per cent) E. 36 (25.2 per cent)
E. 39 (27.3 per cent) E. 36 (25.2 per cent)
There were no significant difference between those.
5) The late persisent second deciduous molars without second permanent premolars to the total number were141/143 (98.6 per cent) and those with second permanent premolars were 2/143 (1.4 per cent).
6) When the relationships between maxilla and mandibule, and right and left sides of jaws were observed based on #4 findings, the late persistent second deciduous molars were found 47.6 per cent in maxilla and 52.4 per cent in mandible. There was no significant difference between those. And there was also no significant difference in per cent of the persitent molars between right and left sides of in maxilla and in mandible.
7) The subjects for either type of E/E and E/E to the total number of the subjects were 21.4 per cent (15/70 in number), 10.0 per cent (10/70 for either type of E/E and E/E E/E 8.6 per cent (6/70) for either type of E and E, 5.7 per cent (4/70) for E/E types, 4.3 per cen (3/70) for either type of E/E and E/E/E, 2.9 per cent 2/70 for E/E type and 1.3 per cent (1/70) for either type of E and E.
8) The individual biting forces of the persistent molars, when observed by each group, were as follows.
The mean value of the individual biting forces of each persistent molar in group [A] (male and female involved), which is vital, and without dental caries and any restorations except light attrition, and has neither resorption of dental root nor permanent premolars in roent genograms, was as follows:
E: 36.7Kg, E: 35.2Kg, E: 37.7Kg, E: 37.1Kg
There was no significant difference in biting forces between maxilla and mandible, and between right and left sides of jaws, among the four values above.
Then mean value of the individual biting forces of each sex was as follows:
E: 38.1 Kg 34.9 Kg
E: 36.0 Kg 34.3 Kg
E: 38.9 Kg 36.4 Kg
E: 39.1 Kg 35.3 Kg
There was a tendency which the biting force in male was greater than in female, but no significant difference was found between them. And also there were no significant differences between kind of tooth, and in maxilla and mandible, and right side and left side.
9) The individual biting forces of the late persistent second deciduous molars which were restorated with amalgam, gold inlay and gold crown were about 5-7 Kg less than those of #8 findings.

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In order to estimate the long-term clinical effects of wearing partial dentures, the authorsundertook follow-up on2140dentures with which1564patients 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. 722 cases received re-examination and590partial dentures of them were used at that time. We examined the fractures in these dentures.
The following results were obtained:
1) The denture fractures were observed in96cases (16.3percent) of the examined partial dentures.These fractures occurred in39cases (6.6percent) at the denture base, in25 cases (4.2percent) at the artificial tooth and in 38 cases (6.4percent) at the retainer.In73 cases of590cases (12.4percent) occurred the deformations of the retainers.On the other hand the repairs of the dentures were observed in23cases (3.9percent).
2) The denture fractures, especially the fractures of the denture bases, occurred more in male than in female.
3) Comparing the upper partial dentures with the lower partial dentures, the denture bases and the retainers fractured more in the latter than in the former.
4) The fractures of the denture bases occurred more in the anterior and posterior dentures than in the anterior dentures or the posterior dentures.
5) The rate of the fractures at the denture base increased with the decrease of remaining teeth.
6) The examined dentures were divided according to their antagonistic teeth into full denture, partial denture and natural teeth.Their rates of the fractures were not significantly different.
7) The rate of the denture fractures did not increased with the lapse of time after their insertion.

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[in Japanese]

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