In order to evaluate the relationship of the hickness of the substance being chewed, occlusal force, and deformation of the cervical vertebrae, we measured deformation of the left and right lamina of the vertebral arch of monkeys from the first to third cervical vertebrae. This was done by electrically stimulating the anesthetized animal's bilateral masseter muscles to in-duce the left first molars to occlude on 3 and 7 mm thick chips of wood with mild, intermediate, and strong force. Because the head tilts toward the working side when the animal bites a 3mm thick chip of wood with the first molars, the working side of the first cervical vertebra is strongly compressed and the nonworking side extends vertically. The amount of deformation on the sorking side of the second cervical vertebra was very small, and the direction of deformation varied with the biting conditions. There was significant extension vertically on the working side and this tendency became marked with increases in induced occlusal force. When the animals occluded on a 7mm thick chip with the first molars, this tendency became more pronounced, and the nonworking side of the second cervical vertebra was markedly deformed in the horizon-tal plane. As the thickness of the chip and the occlusal forces increased, the first cervical verte-bra tended to incline toward the working side, while the second cervical vertebra inclined toward the nonworking side to compensate for the inclination of the first cervical vertebra. Because this phenomenon is mediated by the odontoid process of the second cervical vertebra, it is clear that the odontoid process plays an extremely important role in maintaining posture during occlusion and mastication.

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The muscle activity voltage and rhythm pattern by the masticatory electromyograph measurement have been reported numerously as 1 piece of the function evaluation law in the stomatognathic function. However, as for these the object the actual condition is not clear with 3〜30 subjects. I studied of masticatory electromyographs during tapping movements, and ana-lyzed the distribution of parameters in young adults of 22 to 23 years of age. The frequency distribution in the histogram was expressed with the relative ratio, to com-pare and examine the distribution of each 114 parameters. Also stomatognathic function is in-vestigated by the questionnaire and divide into the unsymtom group and symptom group and did the test for equal with SPSS. Cycle time understood that is receiving the influence of interval from duration. Duration and interval adjusting it mutually for the acquisition of cycle time rhythm in, CV of each parameter it became with clear to be being. Each parameter of masticatory electromyograph of tapping movement showed the distribu-tion that has a characteristic. It was difficult nature, to do the normal value that the individual was limited and was have from the distribution of each parameter that was displayed detection. However, it was consid-ered to be useful for the research of the objective evaluation of jaw mouth function condition, that distribution condition was diferent in the particular parameter of masticatory electro-myograph, with symptom group.

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Calcium phosphate crystalline ceramics are castable ceramics with good translu-cency and superior mechanical properties. I measured the amoun of wear and loss of gloss on the surface of this material after 40,000 cycles of toothbrus abrasion, and determined the width and depth of wear on test specimens after 200,000 cycles using the two-body sliding wear test. Mechanically fine polished calcium phosphate crystalline ceramics or add-on material of calcium phosphate crystalline ceramics, and maintained their original gloss similar to hybrid ce-ramics. The difference between the wear depth in glazed calcium phosphate crystalline ceram-ics and that in natural enamel when both were subjected to abrasion with Au-Ag-Pd alloy was not statistically significant. However, the abrasion in porcelain was significantly less. The wear resistance was similar between mechanically fine polished calcium phosphate crystalline ceram-ics and natural enamel, and differences in the hardness of the two materials were not statisti-cally significant.

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We investigated the adsorption of glycosaminoglycans(GAG) to non-treated titanium powder(Ti) and calcium-treated titanium powder(Ca-Ti). Two milliliters of aqueous solutions of the GAG, hyaluronic acid(HA), chondroitin 4-sulfate(CS) and dermatan sulfate(DS) were re-acted with 1g samples of the two materials for 24 hours at room temperature. Residual GAG was detected as hexuronic acid using the carbazoler reaction of better and muir in the superna-tant following recovery of the TiO_2-GAG complex by centrifugation at 5000 G for 1 min. We also examined overlap adsorption of GAG to titanium powder and used cellulose acetate electropho-resis to establish the presence of GAG. The adsorption of GAG to Ca-Ti was significantly greater than to Ti for all soluions. HA ad-sorption was less than that for CS and DS for both Ti and Ca-Ti. The overlap adsorption of CS to materials that already adsorbed HA was greater to Ca-Ti than to Ti. The overlap adsorption of DS to materials that already adsorbed both HA and CS was also greater to Ca-Ti than to Ti. Cellulose acetate electrophoresis indicated that there was no advanced adsorption of GAG in the supernatant. These findings suggest that the divalent cation Ca facilitates bridging of the polyanionic sur-faces of titanium oxide and GAG, and that adsorption of Ca to Titanium in human alveolar bone may be important in the interaction of GAG with titanium oxide.

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The elk-1 oncogene is a member of the ets family and regulates gene expression in a variety of biological processes. We used molecular biological techniques to investigate he ex-pression pattern of the elk-1 gene in mice and in human oral precancerous lesions and squamous cell carcinomas. Expression of elk-1 mRNA was moderate in erythroplakia and leukoplakia, weak in normal gingive, and pronounced in squamous cell carcinomas. In addition, elk-1 mRNA was detected in mice from 8 to 12 days of gestation. It was weak in the ovaries, and was not detected in the intestine, stomach, uterus, kidney, spleen, liver or testes.These re-sults suggest that elk-1 may play an important role in the embryo and in development of oral precancerous lesions and squamous cell carcinomas.

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We examined the effect of clonidine with CFA (complete Freund's adjuvant) on neuritis in Sprague-Dawley rats us-ing behaviorassays. The animals were anesthetized and the common sciatic nerves were exposed bilaterally after in-traperitoneal injection of 50 μg / kg clonidine or saline. The left nerve was wrapped in a band of sterile hemostatic oxi-dized cellulose saturated with 50μL CFA. The right nerve was only exposed. Intraperitoneal injection of clonidine or saline were administered every 12 hours for a total of eight times. The response of the rats was checked 12 hours af-ter the last injection. We found that cold-allodynia and mechano-hyperalgesia, but not mechano-allodynia, were de-pressed in the rats that had received clonidine.

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I observed 252 postoperative maxillary cysts clinically and with the electron microscope. In 49 of the cases, the cysts were in the immediate proximity of teeth. There were three categories of cysts: type I, where the root was in the cyst cavity, type II, where the cyst wall was fused to the tooth, and type III, where the socked extended to the cyst cavity. Type I is referred to as the postoperative radicular cyst. Eighty of the 252 cysts were observed by scan-ning electron microscopy, and these were divided into five types based on the number of ciliated epithelial cells. Al-though ciliated epithelial cells were observed in 57 cysts, there were large variations in the number of cilia. Although the onset and development of the unilocular cyst might be explained by the sinus obstruction theory, this is not the case for multilocular cysts.

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We investigated the relationship between the human life span and the life of the average tooth. Although Japanese woman live longer than man, the opposite is true for their teeth. We also foung that longevity was different for each tooth. During the six years from 1987 to 1993 the increase in longevity of the average Japaneese tooth was three times greater than the increase in the average life span. In order for people to achieve the goal of having 20 teeth by age 80, they must consider different preventive measures for each tooth.

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