Recently, according to the change of the social environment, the opportunity for needing hand work in human life lessens.
Therefore, people in the industrial world have felt the crisis to the field of producing since many years ago. And they have developed a CAD/CAM system to a wide scope, by transplanting the technology of skilled workers to the machine of controlled by computer.
We had crisis to the future dental medicine occupied by hand work. Consequently, members of the School of Dentistry of Hokkaido University introduced a progressive CAD/CAM system in the industrial world, with a special view to improving the average result of dental treatment, and have begun research and development about mechanical process of crown in 1973.
The characteristic of this research is that as the origin of mechanical process. We recognized the shape of teeth by the data of three dimensions not by feeling.
Consequently, we researched the way of measure to get the data, developed CAD that could design to make crown form (for making crown) by the wax. In case of CAM, we applied technology of existing NC-processing machine.
By the support of Japanese government and the company, we made laser-measuring equipment, CAD that could design crown form around the abutment tooth and exclusive NC processing machine.
Therefore, we could make a crown precisely by only a mechanical process, instead of by hand work. Because of this research, the CAD/CAM system was put on the market by the maker and put into practical use.

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Patients: We describe a 51-year-old woman who presented with tongue pain in 1987. Five months before presentation, she began to wear a mandibular denture. The denture was repeatedly adjusted because of a burning feeling of the tongue and entire gingiva. The patient was treated for tongue pain at the department of oral surgery, and was introduced to the department of prosthetic dentistry because of severe discomfort. However, we were asked to give treatment, because the symptoms were suspected to be related psychosomatic disease. The patient was a methodical person who complained in detail about the denture. We explained the possible relation to psychological problems, but the patient did not recognize this and refused medication. In 1998, the patient had difficulty coming to the hospital because of physical weakness. She then began to talk about her worries concerning the denture. Despite 12 years of treatment at the department of prosthetic dentistry, the symptoms did not improve. Since the patient was a perfectionist and was easily irritated, she started to recognize the relation to psychological problems.
Discussion: We conclude that the methodical personality of the patient led to psychological problems instigated by dental treatment. A persevering response to her dental complaints and careful listening, until the patient becomes aware of her problems, will most likely lead to improvement.
Conclusion: We described our experience with a patient who had psychosomatic disease with denturerelated symptoms and oral discomfort. This case illustrates the importance of psychosomatic treatment.

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Purpose: The purpose of this study was to evaluate biological effects (i. e. cytotoxicity and interleukin 1β production) of eluates from commercially available denture adhesives (7 cushion-types, 5 creamtypes, 1 powder-type, and 2 seal-types) on human gingival fibroblasts.
Materials and Methods: To achieve this purpose, defined amounts of commercially available denture adhesives were dialyzed (cut-off MW: 12, 000 to 14, 000) against Dulbecco's Modified Eagle Medium for one or two days. The cytotoxicity and interleukin 1β inductions of these eluates were analyzed by aqueous soluble tetrazolium/formazan assay (MTS assay) and enzyme-linked immunosorbent assay (ELISA), respectively.
Results: The cytotoxicity against human fibroblast cells of the materials was varied, to a lesser or greater extent, depending on the type of materials. Particularly, cream-type denture adhesives caused much population of cell death, whereas cushion-type materials showed neither cytotoxicity nor induction of interleukin 1β. Though several materials acidified the dialysates, such a pH change was suggested to have no effects on cell viability.
Conclusion: The results of this study implied that several commercially availfable products of denture adhesives may be cytotoxic to human oral tissues in vivo.

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Purpose: Tooth transplantation and replantation are increasingly attracting attention in prosthetic treatment, because transplant and replant teeth possess periodontal ligament and are able to restore healthy and physiological occlusal function with better harmony. Although the prognosis of transplant and replant teeth depends on how well the periodontal tissue is stored, a method for long-term storage of periodontal tissue has not yet been established. Thus, the purpose of this study was to establish a long-term storage method of teeth for transplantation and replantation.
Methods: It was transplanted by the extracted teeth that had been stored refrigerated, frozen, or at a controlled freezing point for 4-6 weeks, and comparatively investigated their prognoses based on tooth mobility, and on radiographical and histological findings.
Results: The mobility of the teeth stored at a controlled freezing point for 8 weeks was grade 1, and the same as before extraction, whereas the mobility of the teeth stored refrigerated or frozen was grade 0. Radiographical observation showed ruptured periodontal spaces in the teeth stored refrigerated or frozen, but the teeth stored at a controlled freezing point had periodontal spaces throughout the circumference of the root. Histologically, ankylosis was observed between the alveolar bone and the dentin in the teeth stored refrigerated or frozen. In the teeth stored at a controlled freezing point, no ankylosis was observed, and fibrous connective tissue was regularly and functionally arranged between the transplant tooth and the alveolar bone.
Conclusion: These results suggest that controlled freezing point storage allows long-term storage of teeth to be transplanted and replanted, and that this method of storage can be applied to clinical practice.

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