This study is based on the notion that the mandibular oscillation, which is part of mandibular fluctuation at the lower incisal point, reflects the functional condition of the stomatognathic system. The purpose of this study was to investigate the significance of the mandibular oscillation in functional diagnosis of the stomatognathic system.
The subjects of this study were 7 males with a normal tooth alignment and normal occlusion and 2 males with some clinical dysfunctional symptoms in stomatognathic system. The equipment of this study, appling a MKG, is able to record a mandibular oscillation and interocclusal distance. Recordings were made on 7 normal subjects 5 times within one day, at the same time on every 5 days period, before and after tooth contact, with voluntary changing vertical and lateral jaw positions, and on 2 subjects with stomatognathic dysfunction before and after Myo-monitor pulsing and insertion of occlusal splint. The analogue data obtained during these recordings were observed visually, and in addition correlation analysis was performed on them, then the following results were obtained.
1. Variation was found, in all 9 subjects, of each mean amplitude of mandibular oscillation at rest. Those mandibular oscillations were made up of several frequencies of oscillation, therefore, mandibular oscillations in 7 normal subjects were more periodic than those in 2 subjects with stomatognathic dysfunction.
2. Intraindividual variations of mandibular oscillations at rest both within one day and over a period of 5 days were found to be small compared to those of free way space.
3. Mandibular oscillations at rest after tooth contact would become aperiodic for a while and then became periodic again.
4. Mandibular oscillations became aperiodic with changing vertical and lateral jaw positions.
5. Mandibular oscillations at rest after Myo-monitor pulsing became more periodic than before pulsing, and the free way space also increased.
6. After insertion of an occlusal splint, mandibular oscillations became periodic, and the free way space also increased.
7. The difference of the periodicities of mandibular oscillations could be significant with better objectivity if correlation analysis of the signals is employed in this study.

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In order to establish direct firing method of precise porcelain jacket crown, some points were investigated using several investments as the direct refractory dies of porcelain jacket crowns.
The following results could be drawn.1.The dimensional change rates of directly fired porcelain jacket crowns were much correlated to the total expansion rates of refractory die materials.
2.The refractory die for direct firing method should have equal or slightly small heating expansion rate on cyclic heating compared with the porcelain.We could not make porcelain jacket crown on refractory dies which have more than 2.0% heating expansion.
3.All directly fired porcelain jacket crowns have a tendency to transform opening at cervical part. The degree of transformation became higher when total heating expansion rates of refractory dies grew larger.
4.When we use porcelain which have 0.88-1.11% heating expansion rates on cyclic heating, it would be possible to use investments which have 0.92-1.09 heating expantion rates as refractory dies for direct firing method.

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Recently, various kinds of resins are in the market. Among several resins for the artificial denture base, the heat-curing methacrylic resin made by mixing monomer and polymer has widely been used.Despite its favorable characteristics of being supple, the heat-curing methacrylic resin has an unescapable defect of shrinkage at the time of heating.
An attempt was made to overcome the defect of the methacrylic resin in a simple way.Special attention was paid to eliminate the unfit at the mucous side of a denture base caused by the shrinkage at the time of heating. The heat expanding microcapsule (Matsumoto Microsphere F-30) was used as heat expanding mold seal, thus making the unfavorable shrinkage or gap minimum.Basic experiments were conducted on the expansion of the heat expanding microcapsule and on the shrinkage of the resin.Further experiments were conducted on the effect of contraction control of the resin made by conventional heat-curing method and applied with heat expanding mold seal.
The following were the results of the present study.
1.The rate of polymerization shrinkage was about 20% with L-Resin, Urban, and MMA monomers, and the rate slightly decreased as the content of crosslinking agent increased.
2.The rate of heat expansion at the same temperure increased as the content of F-30 in the thin film increased.
3.In the experiment of applying thin films of the heat expanding mold seal to the resin block, the gap distance at the plaster surface decreased as the content of F-30 in the thin film increased.
4.Applying the heat expanding mold seal to the lower complete denture improved the fit at the mucous side and at the junction of porcelain teeth.

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Panoramic radiographs were used to survey the location of the mental foramen horizontally and vertically of the dentulaus subjects. It was reviewed whether the relationship of the mental foramen to the inferior border of the mandible remain relatively constant before and after the loss of teeth.
The results are as follows:
1. Probably almost the mental foramina were located horizontally just under the mandibular second premolar, and 90% of the mental foramina were located from the middle area of the first and second premolar to the area just under the second premolar.
The mental foramen of male subjects had a tendency to be located anteriorly than that of female subjects.
The vertical relative ratio of the distance from the inferior border of the mandible to the center of the mental foramen versus the distance from the inferior border of the mandible to the upper edge of the alveolar crest through the center of the mental foramen vertically was 0.442 for male subjects and 0.432 for female subjects. It was significant.
The vertical relative ratio of vertical position of the mental foramen increased 0.0001 for male, 0.0002 for female for aging process.
2. The distance from the inferior border of the mandible to the center of the mental foramen was not significant for aging but significant for sexual difference.
In partial edentulous case of the same subject, the distance was not significant for sex and dentition.

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Panoramic radiographs were used to survey the resorption of the alveolar ridge and the mandible of the edentulous subjects and to compare the vertical position changes of the mental foramen before and after the loss of teeth.
The results are as follows:
1. The vertical position of the mental foramen was described 0.590 for male and 0.636 for female subjects by the use of the vertical relative ratio (ratio of the distance from the inferior border of the mandible to the center of the mental foramen versus to the distance from the inferior border of the mandible to the upper edge of the alveolar crest through the center of the mental foramen vertically). It was significant for age and sex.
The vertical relative ratio is proved to be increasing with age, 0.0026 for male and 0.0013 for female subjects.
2. The distance from the center of the mental foramen to the inferior mandibular border was not significant with difference of age, but significant with sexual difference.
The valuale deviations were considered existing both between the edentulous and the dentulous, and male and female subjects.

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