The conical telescopic system (Konuskronen) developed by Körber, as ridged support retainers for removable partial dentures, has rapidly increased popularity in Japanese dentistry because of its many clinical advantages.
In spite of these advantages, this system still poses some problem in its clinical application. One of them is the necessity of highly skilled technique in adjusting the outer crown to the inner one to control the retentive force. Patients often complain that they can not remove the denture by themselves. On the contrary, some dentures are easily drifted in the oral cavity. Every prostheses should stay in place tightly during function, and should be able to be removed easily in need. If the patient has an effective means to remove the prosthesis, a very rigidly supported denture can be provided.
For this purpose, a specific denture remover has been developed introducing the impact force mechanism which is very effective to separate these telescopic systems. As the remover is designed very compact, it is easy to carry with the patient.
From the fundamental experiment and clinical trials, this new denture remover has been found to be a very useful apparatus.

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The purpose of this study was to investigate the influence of the vertical dimension of dentures on pronunciation.
The results were as follows:
1. The maximum tongue pressures tended to be greater in more posterior palate in the normal vertical dimension, just as in normal subjects.
2. The maximum tongue pressures tended to decrease in anterior palate and increase in posterior palate with increases in vertical dimensions, just as in normal subjects. But, conversely, some of them had a tendency peculiar to complete denture wearers to increase in anterior palate for sounds /asa/, /asi/, etc.
3. Tongue contacts usually started from posterior palate to anterior palate in the normal vertical dimension, just as in normal subjects. But the timings between sounds and tongue pressures weren't consistent with increases in vertical dimensions.
4. The incisor position of mandible tended to be downward and back with a decrease in vertical dimension, and to be located differently with increases in vertical dimensions, just as in normal subjects.
5. Changes in maximum tongue pressures with varying vertical dimensions were related to those of simultaneous mandibular movements, just as in normal subjects. In some cases, including/asa/ and /asi/, a correspondence peculiar to complete denture wearers was found.

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Experimentally thermal expansion inhibited investment was produced to discuss a problem, the compensation of metal casting shrinkage is to be dependent upon setting expansion. Using the various concentration of colloidal silica solution as mixing liquid, idealized full cast crowns were made, the each size were measured and the following results were obtained.
On this investment:
1. As the more concentration of silica, the more expansion appeared.
2. The shrinkage in cooling is slight.
3. The expansion in ringless method is greater than that of ring method.
On the deformation of crowns:
1. In the external width, both ring and ringless method in 10% and 20% showed shrinkage, the more concentration, expansive tendency appeared. The inhibition of expansion appeared in 40% by ring method. The expansion of cervical showed larger than occlusal.
2. Internal width in 10% appeared shrinkage by both methods, they showed more expansion, increasing of concentration. The internal tendency appeared that occlusal was greater than cervical. The expansion of internal showed greater than external.
3. Despite of methods the more expansion appeared, increasing concentration. The more expansion appeared in the internal height than in external.
The mention above following conclusion were obtained.
It was cleared that the various deformation of crowns appeared due to the setting expansion of investment alone. Accordingly it was considered that the deformation occur in the stage of setting expansion before thermal stage in the present dental casting procedure. It can be said that the setting expansion is the great factor of the deformation in cast crowns.

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It is important to grasp the functional characteristics of open bite, because those who are open bite have problems on anterior guidance and many of them show TMJ dysfunction. However the effect of open bite on stomatognathic function has not been clarified.
The purposes of this study are to investigate 1) the characteristics of chewing patterns in subjects with open bite and 2) the relationship between each chewing pattern and the location of open bite.
14 normal subjects were selected as a control group, and 14 open bite subjects were selected and clinically classified by the location of open bite, as follows
1) anterior open bite
2) anterior and posterior open bite
Chewing movements of each subject were recorded and qualitatively analysed by Sirognathograph Analysing System II.
As a result, characteristic chewing patterns were observed in subjects with open bite, and some of which have relationships with the location of open bite.

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This investigation compared the effects of types of alloy on the bond strength of the porcelain fused to metal complex, by using a shearing test method.
Eight commercial alloys (Au-Pt-Pd, Au-Pd, Pd-Ag, Pd, Ni-Cr (2 types), Co-Cr, Ti) and two porcelain brands were chosen in this study.
The highest values were found in the Co-Cr alloy samples. The bond strengths of the Ti samples were recorded medium values.
Diffusion profiles of elements of those alloys and porcelain which existed at the interface between metal and porcelain were obtained by using the scanning electron microscope (SEM) and the X-ray microanalyser (XMA).
High amounts of tin were found at the interface between metal oxide and porcelain in the case of Ni-Cr alloys.

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To improve the surface quality and roughness of die stone poured into the alginate hydrocolloid impression, the surface of impression was pretreated with the concentrated calcium chloride solution, ranging from 5 to 40% by weight, for 30 seconds.
The SEM observation and the surface roughness measurement for the stone surfaces which was set on the modified impressions revealed that the dihydrate crystals grew more densely at the surface than that for the stone surfaces which were produced from the impressions not pretreated or pretreated with the conventional fixing solutions, 2% potassium sulfate solution or 2% zinc sulfate solution, and that the excellent smooth surface comparable to the stone surface from addition silicone impressions was obtained by the pretreatment with 10-20% calcium chloride solution.
It was suggested that the die stone poured into the alginate hydrocolloid impressions pretreated with the new fixing solution was availabe as a working model in dental pracitice.

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Since the auditory brainstem response (ABR) is representative of action poten tials generated by sound stimulation from the auditory pathway in the cochlea. peripheral sensorium, cochlear nerve, and brainstem, the appearance of abnormal ABR waves may indicate the presence of some abnormality in the auditory pathway and its surroundings, or in the entire brains tem. It is also presumed that an abnormal change in the masticatory system, including the temporoman-dibular joint, could be detected by the observation of ABR, because the temporomandibular joint is closely related anatomically and embryologically to such peripheral auditory sensoria as coc hlea and auditory ossicles, resulting in the involvement of such abnormal change in the audi tory pathway.
In this study, an occlusal interference was experimentally imposed to normal subjects, and its effects were examined after 24 hours for the purpose of obtaining a data on ABR responses in the presence of abnormal change in the masticatory system. As a result, a peak latency of wave I was unilaterally prolonged in comparison with that seen before the administration of interfer ence, indicating that an abnormality in the stomatognathic system caused damage not only to the stomatognathic system, but to the cochlear nerve as well through various pathways. Therefore, it was confirmed that the diagnosis, treatment and analysis of an abnormality in the stomatognathic system should be carried out in close cooperation with adjacent territories, by but other territories as well.

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It is very important for clinical diagnosis to record, and analyze condylar movements in cranio-mandibular disorders.
I have developed a simple device which substitute the palpation of the posterior aspect of the TMJ. I modified the Cardiokymograph which used electro-magnetic field, and tested many electrical characteristics of this device. The results obtained were satisfying, as the first report.
I tried to use this device for the purpose of recording a feature of condylar movement of normal subjects and patients with TMJ dysfunction.
The following conclusion were obtained:
1. The obtained waveforms of normal subjects were smooth, and these shape were constant. Each waveforms in the right and left external auditory meatus were same size, and there weren't a time lag at the start of the recorded each waveforms.
2. The waveforms of patients were not smooth, and were changeable when condylar movement changed a speed. A place which the change appear in the waveforms is related to an amount of condylar movement.
3. I compared this waveforms with the data by the system of measuring movements of any point of the mandible. And It became evident that this device could detect a feature of condylar movement.
4. It was proved that this device was validity for clinical diagnosis.

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Radiopacity of the denture base resin has significance in X-ray search for swallowing or aspirating of denture. However, there have been few reports concerning the radiopacity of the denture base resin.
In this study, we examined the radiopacity of 69 type of 39 commercial denture base resins and evaluated factors in high radiopacity.
Radiopacity was not different in the same product with different shade. Radiopacity was not different among materials when the sample thickness was 1mm, but Sumiply^®(Polyethersulfone), Polysulfone, Epolex^®and Triad^®showed good radiopacity when the sample thickness was 5mm or 10mm.
In light curing denture base resin with high radiopacity, silica fillers contained in them are considered to be related to the radiopacity of the materials. The high radiopacity of Smiproy and polysulfon may be explained by their high density.

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In this studies, the author investigated changes in upright posture in 5 healthysubjects while the mandibular position altered for 1 and 5 minutes in a horizontal direction at the distances of 2.5 and 5.0mm. Namely, loci of gravity fluctuation were examined under analysis system in order to reveal what effect were given upon the upright posture. At the same time, electromyograms were obtained from mascles of masticatory system, neck and lower extremity for the observation of the effects on gravitymuscles. The results obtained were as follows:
1. Loci of gravity fluctuation
1) Loci of gravity fluctuation tended to increase beyond the normal range when the mandibular position was horizontally changed for 1 and 5 minutes at the distances of 2.5 and 5.0mm.
2) Changing amounts were less in the anterior direction than in the right and left directions.
2. Activities of antigravity muscles Although muscular activities showed similar tendencies to those of loci of gravity fluctuation they showed individual differences
3. Since these results revealed that horizontal changes in mandibular position influenced both loci of gravity fluctuation and muscular activities, it was suggested that changes in the stomatognatic system are involved the systemic condition, and that the recovery of adequate function of the stomatognatic system is essential to the maintenance of systemic harmony.

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For the purpose of examining the influence of an implant body on stress distribution in alveolar bone, we carried out a two-dimensional photoelastic experiment using different shapes of the wing portion of the implant body and different conditions of its union with the supporting alveolar bone (e. g., presence of connective tissue between the implant body and alveolar bone, etc.), as well as different implant directions (i. e., vertical vs. 10°-nclined implantation).
The results obtained were as follows:
1. The use of implants with a curved lower margin and a silicone-coated surface led to a shift was not observed in the absence of silicone at the interface.
2. Shaping of the lower margin of the implant body curve resulted in a more even distribution of the stress, and this effect depended upon the presence of the silicone at the interface, direction of the implantation, and the degree of curvature of the lower margin.
3. Vertically placed implants showed an even stress distribution on both sides of the wing portion, as compared with the uneven stress found for the inclined ones. Furthermore, the presence of silicone at the interface caused the stress to be concentrated mainly at the lower margin of the wing portion, while implants without the silicone showed stress concentrated at not only the lower margin, but also at the neck portion.

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To analyze the influence of craniofacial morphology on the functions of stomatognathic system, dentulous subjects in the normal face group were selected and had been engaged in vertical clenching to measure the magnitude and direction of bite force as well as the EMG activity of masticatory muscles. The correlation was studied among them.
The results were as follows:
1. The correlation curve of temporal muscle was hyperbolic. The correlation curves of masseter muscle and medial pterygoid muscle were linear.
2. The ratio of the EMG activity of the increasing part was equal to or higher than that of the holding part at 25-100%MC.
3. A significant correlation was observed between θ' and 4 angle measurements. The correlation of 13 items of the craniofacial measurements and direction of bite force was investigated with the EMG activity per 1kgf. A significant correlation was observed between the EMG activity per 1kgf and several items of craniofacial measurements.

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We conducted color stability tests on three new resilient lining materials for three months. These materials, Polyorefin, Silicone resilient materials and Polyphosphazine fluoroelastomer were immersed in four aqueous solutions and one oleaginous solution. The aqueous solutions included saline, turmeric, instant coffee and red color No.102. The oleaginous solution consisted of olive oil plus β-Carotene.
The results were as follows:
1. Severe color change was observed in the Polyorefin resilient material immersed in the olive oil plus β-Carotene solution.
2. Although the Silicone resilient material immersed in the oleaginous solution changed moderately, severe color change was observed in the Silicone resilient material immersed in the turmeric and the instant coffee solutions.
3. The color change in Poryphosphazine fluoroelastomer was less than that of the other two materials except in the case of immersion in turmeric. These results suggested that the degree of color change depends on not only consistency of test solutions but also some physical properties, i. e. water absorption, solubility, swellings, and surface roughness.

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Three mandibular edentulous patients treated with osseointegrated implants were reported. They were treated in the department of Oral Surgery, Nagoya University Hospital and followed for three years. In this paper the relationship between bone quality and degree of bone resorption around the fixtures was analysed.
Results were summarized as follows:
1. The cases were one male and two female and aged 66, 64 and 50 years old.
2. The bone qualities of each case were analysed by DIP method preoperatively. The bone densities were 2.98, 1.98 and 3.10.3. Six fixtures were installed in each case and one fixture of case 2 failed to osseointegrate. Final survival rate of the fixtures was 95%.
4. The degree of bone resorption in the low DIP case was greater than that in the high DIP case.
5. The degree of bone resorption were almost equal in any site of mandible.
6. The degree of bone resorption in high Plaque Index case was greater than that in the low Plaque Index case.

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This study was designed to investigate the effect of an air-powder abrasive system on the surface texture of implant materials.
Single-and poly-crystalline alumina, hydroxyappatite, partially stabilized poly-crystalline zirconia and pure titanium were used in this study. Before and after one minute of air-powder jetting, the surface roughness and contact angle were measured. The surface was also examined by scanning electron microscopic observation.
After jetting, the surface roughness was increased in hydroxyapatite and pure titanium, decreased in zirconia but not changed in alumina. The contact angle was decreased in hydroxyappatite and pure titanium, increased in zirconia but not changed in alumina. In scanning electron microscope observation, the surfaces of all the materials examined were free from the effect of jetting.
These results indicate that there is no problem in air-powder abrasive system for these implant materials.

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Abrasion of denture liners was studied using three kinds of resilient lining materials. The weight was markedly decreased with the frequency of brushing in polyolefin and silicone materials. Decreases in weight were hardly recognized in polyfluoroethylene material.
The mean roughness and maximum height were markedly increased with the frequency of brushing in polyolefin and silicone materials. On the other hand, these were hardly increased in polyfluoroethylene material.
Scanning electron microscopy after 100, 000 times of brushing revealed the appearance of distinct line-like marks in polyolefin and silicone materials, while such marks were not observed in polyfluoroethylene material.
In scanning electron micrcscopy, the surface texture of the three resilient denture lining materials were not changed after dipping in a denture cleaning-solution for one month.
These results suggest that mechanical brushing and chemical soke-cleaning are suitable for Cleaning of polyfluoroethylene material, while chemical soak-cleaning is suitable for polyolefin and silicone materials.

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We have researched how a change in occulusion influences the maintenance of equilibrium function and determined the influence of the gravity fluctuation on the upright posture objectively and quantitatively with a gravity fluctuation analyzing system: then, the results have been reported in some papers.
There are, however no available report, except ours, concerning to the relation between the vertical mandibular relation and gravity fluctuation. We also think that the upright posture can be discussed more precisely by researching gravity fluctuation and the muscular activity of antigravity muscles together.
Now, for researching the relation between the stomatognathic system and the systemic condition, I study the influence of bite raising for vertical position (2, 5 and 10mm) on the gravity fluctuation and antigravity muscles on the upright posture in 5 normal subjects as using the trace of gravity fluctuation and the electromyograms of antigravity muscles.
The following conclusions suggest that the influence of bite raising for vertical position not only the stomatognathic system but also the systemic condition, particularly the upright posture.

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Mandibular movement and variations in the discharge activity of the opening and closing muscles were determined in 18 healthy men 22-24 years old performing the occ cycle at a frequency of 30, 60 or 90 strokes/min, and the following results were obtained.
1. The prescribed degree of opening at a frequency of 30, 60 or 90 strokes/min during the occ cycle provided practically identical subject populations for statistical analysis, showing hight reproducibility.
2. The subjects were divided into three groups according to the degree of opening; group A showed the greatest degree of opening, being significantly different from group B. As the frequency of the cycle increased, the degree of opening became significantly smaller in group A, whereas it remained largely unchanged in group B and C.
3. The time lag between the discharge activities of the opening and closing muscles became smaller in group A as the frequency of the cycle increased, whereas it remained largely unchanged in group B. Overlapping was seen in the time lag between the end of the discharge of the opening muscle and the onset of the discharge of the closing muscle.
4. All groups showed a similar time lag between the discharge activity of the opening or closing muscle and the mandibular movement, regardless of the cycle frequency.

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Our recent report of this study described the development of a small size and powerful dental magnetic attachment showing that it had cleared most clinical requirements, ascertained through many fundamental investigations. This article describes the clinical and laboratory procedures used with the system.
One of the elements;“keeper” is cast-weided to the metal-coping which is cemented on the decoronated tooth. Another element;“magnetic assembly” is fixed in the denture base fabricated in a usual manner, by using self-curing acrylic resin. Because of its minute size, this attachment can be used on almost any root-filled teeth.
A dentist has many choices in fabricating a denture with the magnetic attachment. He can set the metal-coping installed the keeper prior to the denture base construction; after the denture is completed; or simultaneously.
The magnetic attachment can be used weather singly, or with other conventional retainers such as the clasps or the telescope crowns. This system is simple; requires no special skills; and can be followed using standard equipment, materials, and techniques.

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The automatic masticatory movement analyzing system was used to investigate the pattern of masticatory path in 78 normal subjects. After classifying the pattern, examining the frequency of each pattern, and investigating the opening and closing angle the following results were obtained.
1. 8 patterns (I-VIII) were observed.
I: smooth opening toward working side, and convex closing.
II: opening similar to I, but concave closing.
III: opening toward working side after initially toward non-working side, and convex closing.
IV: opening similar to III, but concave closing.
V: convex opening, and closing with similar path.
VI: opening more toward working side than closing. VII: crossing.
VIII: creating a line.
2. The catalog for classification was composed of 4 combinations.
3. The most frequent pattern on the habitual, non-habitual, and both side was I, followed by III, II, etc. Also I through IV constitute 85.3%, and I and III constitute 71.8% of the total.
4. The most common pattern in individual subject was I for both side, followed by III for both.
5. The opening angles for I, II or III, IV were similar. The closing angles were significantly smaller in II, IV than in I, III. Also the closing angle for I, III was 47.3±7.6°.
6. It is suggested that a normal mastication was mainly I or III, must exhibit convex closing path, with a functional anterior guidance (Iateral incisal path) of approximately 40-55° to mid plane (35-50° to horizontal plane).

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