In 1985 an epidemiological survey of dental caries, periodontal disease and oral hygiene status was performed in 185 college students (96 males and 89 females) between 18 and 24 years of age in Taichung, Taiwan. The aim of this survey was to compare the changes in dental caries in children who were previously reported to have a low prevalence of dental caries and the present adolescents, as well as to compare changes in periodontal disease. The final goal of this study was to analyze the correlation between oral health status and oral hygiene behavior using the questionnaire method, and to clarify the causes of dental caries and periodontal disease prevalence in order to contribute to public dental health care in Taiwan. The mean number of DMF teeth was 8.85 in Chinese males and 9.16 in Chinese females, significantly lower than that in Japanese males and females. The mean number of missing teeth was similar in Chinese and Japanese. The mean number of decayed teeth was significantly higher, but the mean number of filled teeth was significantly lower in Chinese males and females that in Japanese males and females, respectively. Oral Hygiene Index (OHI) was 4.74 in Chinese males and 4.02 in Chinese females, significantly higher than that in Japanese males and females. The high OHI value in Chinese adolescents resulted from the large amount of dental calculus deposit compared with Japanese. PMA Index was 15.01 in Chinese males and 13.48 in Chinese females, significantly higher than in Japanese males and females. Subjects who received topical fluoride application, had a between-meal habit, and ingested sweet snacks were significantly fewer, but subjects ingesting sweetened beverages and beverages containing raw or killed Lactobacilli were significantly more numerous among Chinese adolescents than in Japanese. In Chinese adolescents, the mean numbers of DMF teeth and DMF tooth-surfaces were significantly higher in subjects frequently ingesting sweet snacks than in those ingesting no sweets. But the numbers were similar in subjects frequently ingesting sweetened beverages and in those who rarely ingested them. The percentages of persons with uncomfortable feelings of gingiva, swelling, bleeding, and pus discharge from gingiva, tooth mobility, and food impaction were significantly higher in Chinese than in Japanese adolescents. In Chinese adolescents, the mean number of sextants exhibiting periodontal disease was similar in subjects having subjective symptoms of this disease and in those having no subjective symptoms. Length of toothbrushing time was similar but frequency of toothbrushing was lower in Chinese adolescents than in Japanese. In Chinese adolescents, the prevalence of dental caries and periodontal disease was not related to subjects' frequency of toothbrushing, toothbrushing time and toothbrushing methods. These findings indicated that an increase of dental caries and periodontal disease prevalence resulted from the inconsistency of knowledge concerning dental disease prevention and oral hygiene behavior. An increase in sugar consumption in Taiwan, however, was partly responsible.

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The fresh isolates of mutans streptococci (two strains of Streptococcus mutans serotype c and a strain of Streptococcus sobrinus serotype g) from the human oral cavity were subcultured one hundred times in brain heart infusion broth. Considerable changes were found in the virulence-related factors of mutans streptococci during repeated subculture. The results were summarized as follows. 1. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and radioimmunoassay showed that the amount of a cell-surface protein antigen with a molecular weight of 190, 000 (PAc) of S. mutans serotype c, which is considered to be important in the sucrose-independent cellular adherence, exhibited considerable changes after repeated subculture. Moreover, there was a correlation between the cell-surface hydrophobicity and the amount of PAc on the cell surface. On the other hand, the amount of a cell-surface protein antigen with a molecular weight of 210, 000 (PAg) of S. sobrinus serotype g was not influenced during repeated subculture, and the cell-surface hydrophobicity was relatively constant. In addition, changes in the expression of several cell-surface proteins and extracellular proteins other than the protein antigens were noticed after repeated subculture in S. mutans and S. sobrinus. 2. Changes in the glucan-synthesizing ability, which is known to be important in the sucrose-dependent cellular adherence, was also found after subculture in S. mutans and S. sobrinus. There was a correlation between the cell-associated 1N NaOH-soluble glucan-synthesizing ability and the in vitro sucrose-dependent cellular adherence ability. 3. Almost no change was observed in the abilities for acid production and cell growth. 4. The cariogenicity of S. mutans in hamsters was reduced after repeated subculture. It was suggested that the reduced cariogenicity might be ascribed to the changes of the PAc expression and the cell-associated 1N NaOH-soluble glucan-synthesizing ability.

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Chemotherapy, surgical therapy, and radiotherapy are the methods currently employed for treatment of oral cancer. For the oral cavity, however, extensive surgery and radiotherapy face considerable limitations because its anatomical complexity. Also, speedy healing of wounds is desirable and restoration of the morphology and functions must be achieved as early as possible. It is therefore important in the postoperative chemotherapy to prevent local recurrence and metastasis by keeping the side effects of anticancer agents to a minimum and providing an extended administration of the agents. Wounds were experimentally made in the tongue in domestic rabbits and the effect of anticancer agents (Bleomycin and Mitomycin C) on the healing process was investigated histopathologically and histochemically. The results were as follows : I. Histopathological findings A. In Bleomycin group (3.0mg/kg/day), with increase in the number of administration, proliferation and maturity of epithelial cells, granulation tissues, and fibroblasts were retarded and healing of wounds in the epithelial layer in particular was retarded markedly. B. In Mitomycin C group (0.5mg/kg/day), with increase in the number of administrations, epithelialization of the epithelial layer and proliferation and maturity of granulation tissues and fibroblasts under the epithelial layer were retarded. II. Enzyme-histochemical findings A. In Bleomycin group, along with the retardation of healing wounds in the epithelial layer, Lactate Dehydrogenase (LDH), Succinate Dehydrogenase (SDH), Alkaline Phosphatase (ALP), Acid Phosphatase (ACP) and Non-specific Esterase (EST) gradually decreased in reaction. About in coincidence with the proliferation and maturity of granulation tissues and fibroblasts, LDH, ALP, ACP and EST decreased in reaction. SDH however did not show much change in reaction. B. In Mitomycin C group, along with the retardation of proliferation and maturity of fibroblasts and granulation tissues, LDH, SDH, ALP, ACP and EST decreased in reaction. However, decrease in reaction of each enzyme in the new epithelial layer was relatively slight. C. The foregoing changes in enzyme reactions were especially marked in the epithelial layer, granulation tissues, and the layer of fibroblasts, and the reactions increased with increase in the number of administration. In comparison with the control group, however, the reactions decreased markedly. Also, these changes about coincided with the histological retardation of healing wounds. III. On the basis of the foregoing experimental results, administration of Bleomycin and Mitomycin C in the healing process of tongue wounds not only retarded healing of wounds because of proliferation and maturity of epithelial cells and granulation tissues but also decreased enzyme reactions of oxidase and hydrolase. Their administration therefore was thought strongly affect the functions of mitochondria related with wound healing, maturity of collagen, metabolic mechanism of cells such as functions of lysosome.

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For the purpose of investigating the effect of marginal morphology of crown prostheses on the periodontal tissue, four types of cast crowns, with the finishing line at 0.5mm below the gingival crest, were made and a setting experiment was conducted in the premolar of the dog. The following crowns were used ; Group I : The fit of crown margin was confirmed at wax pattern taking and polishing, under the stereoscopic microscope ; Group II : The margin of the crown for Group I was grounded slightly with silicon points to make it smooth and round ; Group III : The fit of the margin was confirmed macroscopically ; Group IV : Marked overhang was provided at the margin. Observations were made for 1, 3, and 12 months and histopathological changes, due to difference in fit of the margin, in the periodontium were examined. Furthermore, microstructural changes in the epithelial layer of the gingival sulcus and at the cervical margin were observed under the scanning electron microscopy. The results were as follows : 1. In Groups I and II, no changes in the tissue structure in three months were as in controls. In 12-month cases, inflammatory cells were found in the lamina propria under the epithelial layer of the gingival sulcus. However, no difference was found between the two group. 2. In Groups III and IV, changes in the tissue structure were seen since early stages and inflammation extended with time. Greater inflammatory changes were found in Group IV than in Group III. 3. The thickness of the cementum layer at the margin averaged 58.3μm in Group I, 52.8μm in Group II, 113.3μm in Group III, and 125.6μm in Group IV. 4. The surface of the epithelial layer of the gingival sulcus in Groups I and II was relatively flat and cell borders were relatively clear. The portion corresponding to the crown margin was protruded in Group III and depressed in Group IV. In both groups cell borders were unclear and cellular space was expanded. 5. The margins were sharp like a knife-edge in Group I and round and smooth in Group II. Neither group showed deposits such as plaque on the margin. In Groups III and IV, the margins were irregular, and grinding scratches were found. Deposits increased with time. 6. Deposits were found on the surface of cementum in every group and increased markedly with time in Groups III and IV.

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Dental Au-Ag-Pd alloy is usually melted by a gas-air blow torch in air and cast with a centrifugal machine. In this study, the possibility of improving the characteristics of the alloy castings was investigated for some other casting methods. The casting machines used were Castmatic CM-230 (CM) : arc heating in Ar gas and suction-Ar gas pressure type ; Argoncaster-DX・S (AC) : induction heating in Ar gas and vacuum-Ar gas pressure type ; Caspac-MK3 (CP) : resistance heating in carbon crucible and vacuum-air pressure type ; and Sure CV-51 (SR) as a control : gas-air flame heating in air and centrifugal pressure type. The vacuum-pressure type machines, AC and CP, showed superior ability to cast the alloy into thinner detail. The ability was the worst in the suction-pressure type, CM. It may be atributed to its insufficient suction effect through the investment mold. The roughness value of the as-cast crown surface became the largest with AC and smallest with CP and SR. It was found from SEM observation and X-ray microanalysis that the roughness on AC casting was caused by dendritic structure with less oxide formation while the smoother surfaces on CP and SR castings were due to the thick oxide formed on the dendrite. There were more micro porosities and oxide inclusions in the casting with CM than those with the other machines probably because CM tended to cause overheating of the alloy and poor suction effect. Marked increase in pores was observed when the alloy was repeatedly cast with this machine. The presence of such pores and oxide inclusions were reflected in lower elongation of the castings with CM and SR in tensile test. The casting with CP having few pores and inclusions showed highest elongation. No significant differences in the dimensional change of the cast crown were found among the casting machines. It is summerized from these results that the castings with AC and CP at mold temperature of 700℃ were superior in several important characteristics to those with CM and SR. Although CM has some advantages such as ease of manipulation and short-time completion of the casting process, it may be necessary to improve its suction effect for producing better castings.

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When providing prosthetic treatment for the cases of loss of occlusal height or loss of the anterior teeth, functions and esthetics must be restored. A yardstick in restoration of esthetics is that harmony is established between the upper half and lower half of the face and between the face and dentition. The present author therefore made an investigation to determine to what extent golden proportion can be applied in restoration of facial esthetics. For this investigation, dentulous adult males with individual normal occlusion were used and the lengths and widths between various parts of the face and the widths between various parts of the anterior teeth were measured and examined. The results were as follows : In the lengths of various parts of the face, approximation to golden proportion was found in subnasal point-submental point length and pupil point-lip conjugate point length to pupil point-submental point length, in subnasal point-submental point length and pupil point-lip conjugate point length to pupil point-subnasal point length, in lip conjugate point-submental point length to subnasal point-submental point length, in lip conjugate point-submental point length to subnasal point-submental point length, and in pupil point-lip conjugate point length to lip conjugate point-submental point length. Among the widths of various parts of the face, internal ocular angle width and ala width to right internal ocular angle-left external ocular angle width approximated golden proportion. Significant correlation was found in the former but not in the latter. Among the widths of various parts of the mandibular anterior teeth to those of the maxillary anterior teeth, the width approximated golden proportion in mandibular inter-central-incisor width and mandibular inter-canine-cuspis width to maxillary inter-central-incisor width, in mandibular inter-lateral-incisor width to maxillary inter-canine-cuspis width, and in mandibular inter-canine-cuspis width to maxillary inter-canine width. However, no significant correlation was found. Among the widths of various parts of the maxillary anterior teeth to those of various parts of the face, the width approximated golden proportion in maxillary inter-canine width to right internal ocular angle-left external ocular angle width. Significant correlation also was found.

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Several polymerizing methods are available for fabricating acrylic resin denture. In this study, some characteristics were compared among heat-cured, cold-cured and microwave-cured resins for plate specimen and lower complete denture model. Three different heating processes were adopted for the heat-curing resin : conventional 70℃-2h and successive 100℃-0.8h heating, 80℃-8h heating and 60℃-8h heating in water. Pour type and injection type resins were employed for cold-curing. In the microwave-curing resin, the microwave was irradiated for three minutes. The results obtained were summarized as follows. 1. The temperature of the heat-curing and cold-curing resins during polymerization almost followed the environment temperature for curing, while in the microwave-curing resin the temperature rose rapidly to about 130℃. 2. The specific volume of the heat-cured resin was increased as the curing temperature was lowered. The microwave-cured resin showed about the same value as that of the heat-cured resin processed at 100℃. In the cold-cured resin, the pour type showed larger value than the injection type. 3. The residual amount of monomer was about 2% in the heat-cured resin processed at 100℃ and the microwave-cured resin, 3 to 5% in the 80℃-8h heat-cured resin and the cold-cured resins, and as high as 8% in the 60℃-8h heat-cured resin. The residual monomer showed slight decrease with time, and the decrement was generally larger in the specimens stored in water than in air. 4. The contraction of the specimen measured just after deflasking was the largest in the microwave-cured resin and the smallest in the injection type cold-cured resin. 5. When the specimen was stored in water, further contraction by stress release occurred during a few days after deflasking and then expansion by swelling appeared in all the resins. 6. When the specimen was stored in air, on the other hand, all the resins always tended to contract by stress release and elimination of water. The contraction was marked during the five days after deflasking. 7. When the specimen was stored in water and in air alternately, all the resins showed a gradual decrease in dimension as a whole by repeating a small contraction and expansion alternately. 8. In the lower complete denture model, the dental arch width at the molar region decreased by processing and storing after deflasking, showing about the same tendency as the plate specimen mentioned above.

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Three-week-old male rats of wistar strain were given a calcium-deficient diet and experimental osteoporosis was induced in them. These rats were then given 1α-OH-D_3 orally (0.05μg/kg and 0.1μg/kg), an analogue of active type vitamin D_3, three times a week. The rats were grouped into normal diet control group (control group), calcium-deficient diet group (deficient group), calcium-deficient diet with 0.05D_3 group (0.05D_3 group) and calcium-deficient diet with 0.1D_3 group (0.1D_3 group). The effect on the alveolar bone and tibia was investigated for weight and radiologically, photographically, photo-densitometrically, x-ray microanalytically, histopathologically, scanningelectron-microscopically, and hemologically. The results were as follows : 1. The body weight showed more increase, though slight, for 0.05D_3 and 0.1D_3 groups than for deficient group, in comparison with control group. 2. Light-microscopically, the densitometric curves of the alveolar bone for 0.05D_3 and 0.1D_3 groups were lower than those for deficient group. The widths of interosseous cortex and medial cortex of the tibia were about the same as those for deficient group. However, the densitometric curves of patterns of arrangement of trabeculae were irregular. 3. Photo-densitometrically, the bone densities of the alveolar bone and tibia were lower for 0.05D_3 and 0.1D_3 groups than those for deficient group. 4. X-ray microanalytically, the relative ratios of Ca and P by quantitative analysis to those of control group showed that Ca in the alveolar bone was higher for 0.05D_3 and 0.1D_3 groups than for deficient group. The relative ratios of P were high for 0.05D_3 group, Deficient group, and 0.1D_3 group, in descending order. In the tibia, the relative ratios of Ca were higher for 0.05D_3 and 0.1D_3 groups than for deficient group. The relative ratios of P were higher for 0.05D_3 group and deficient group than for 0.1D_3 group. 5. Histopathologically, contact microradiogram (CMR) findings in the alveolar bone showed more increase in thickness of the alveolar bone and more increase in resorption lacunae and Haversian system for 0.05D_3 and 0.1D_3 groups than for deficient groups. General tissue findings in alveolar bone showed increase in osseous layers in the alveolar bone, haversian canals, bone cavities, resorption lacunae, bone marrow, osteoclasts, and hypocalcification layers. Diminution of trabeculae was seen. Scanning-electron-micros-copically, osseous layers were incompletely formed and osseous layers on the side of the alveolar crest were formed wider in 0.1D_3 group than in deficient group and 0.05D_3 group, and the resorption lacunae were many and shallow. In the tibia, CMR findings and general tissue findings were similar to those in the alveolar bone. 6. Hemologically, electrolytic serum Ca and the ratios between serums Ca and IP in 0.05D_3 and 0.1D_3 groups, and serums IP and Cl in 0.1D_3 group were low. Biochemical AL-P, GOT and GPT were high in the examination of endocrine functions, N-PTH and CT were high and C-PTH was low.

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Lipopolysaccharide (LPS), Protein A and activated T cells were added to cultures of peritoneal macrophages from rats and the cells were incubated for several hours, and the degree of activation of the macrophages by bacterial antigens (LPS and Protein A) and activated T cells was studied. The degree of the activation was expressed as the proportion of Ia positive cells by count by the fluorescent antibody technique and as the amount of interleukin 1 (IL-1) secreted into the culture medium by ELISA. Results obtained were as follows : 1) The proportion of Ia positive cells and the amount of IL-1 were maximum when LPS and Protein A were added to the cultures at a concentration of 5 μg per ml and the cells were incubated for 6 hr. 2) After LPS addition, the proportion of the cells which expressed Ia antigen during incubation for 1, 2, 3 and 6 hr was 9.5%, 6.3%, 11.6% and 13.8%, respectively. The amount of IL-1 secreted from the cells which were incubated for 1, 2, 3 and 6 hr was 0.57, 0.47, 0.53 and 0.58, respectively. There is a positive correlation between the proportion of Ia positive cells and the amount of IL-1 in the case of the addition of LPS. 3) After the addition of Protein A, the proportion of the cells which expressed Ia antigen during incubation for 1, 2, 3 and 6 hr was 9.2%, 4.5%, 12.7% and 14.9%, respectively. The amount of IL-1 secreted from the cells which were incubated for 1, 2, 3 and 6 hr was 0.75, 0.64, 0.71 and 0.60, respectively. There were no correlations between the proportion of Ia positive cells and the secretion of IL-1. 4) After the addition of activated T cells, the proportion of the cells which expressed Ia antigen during incubation for 1, 2, 3 and 6 hr was 26.0%, 16.7%, 23.0% and 28.0%, respectively. The amount of IL-1 secreted from the cells which were incubated for 1, 2, 3 and 6 hr was 0.69, 0.65, 0.60 and 0.72, respectively. It seemd that the change in the amount of IL-1 was similar to that of the proportion of the cells expressing Ia antigen. 5) The proportion of Ia positive macrophages was 2-3 fold higher in the case of the addition of activated T cells than that in the case of the addition of bacterial antigens. The results that activated T cells cause macrophages in cell culture to activate effectively, probably by the mediation of lymphokins, suggest that the activated T cells will also cause the cells in organs to activate and to modulate immunological response.

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The development of the taste pore which is the receptor of gustation in the soft palate of the rat was observed by the optical, scanning electron and transmission electron microscopy. The specimen were excised from 60 Sprague Dawlay rats at birth, 1 day, 3 days, 5 days and 14 days after birth, and highly differentiated taste buds were selected. The results obtained were as follows, 1. Under the optical, scanning electron and transmission electron microscope, the taste pore in the soft palate of the rat didn't open at birth. And then it opened at 1 day after birth, and with the development of the taste buds, the taste pore was formed at 14 days after birth. 2. In the process of forming of the taste pore, the microvilli reached to a higher level of the pore, but at 14 days after birth it terminated within the pore. From at birth to 14 days after birth, microgranules and vesicles were seen around the microvilli in the pore region, and they increased with the progress of the formation of the taste pore. 3. The epithelium which covered the taste buds turned into thin type, and the intercellular gap became wide with the beginning of the formation of the taste pore. Subsequently desquamation was seen at the surface layer of the epithelium. 4. In the transmission electron microscopic observation, large amount of mitochondria, free ribosome and a small amount of rough surfaced endoplasmic reticulum, lipid granule, vesicle and substance like multivesicular body were seen in the cytoplasm of the taste cell immediately after birth before the taste pore opened. After 1 day after birth, these structures increased at the beginning of the formation of the taste pore. At the apex of the gustatory cell, microvilli were formed and they gathered and intruded into the taste pore. In the epithelium which covered the taste buds, formation of the taste pore was in progress before it opened, and cytoplasm in its epithelium was homogenous and nonstructured as a whole to the aged 5 days, and lysosome-like structures were seen in relatively large quantities and decreased slightly at postnatal 14 days. Since these structures could be seen in the taste pore, it is speculated that those structures closely participate in the formation of the taste pore.

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The induction ability of dentinal caries by Streptococcus salivarius, Actinomyces viscosus, Streptococcus mutans and Lactobacillus casei were studied in vitro. The dentin blocks, extracted human caries-free premolars prepared with class I cavity (depth : 2mm), were incubated anaerobically with these four bacterial strains respectively. In addition to the monoinfective groups, mixed culture of L. casei with S. mutans or A. viscosus was also performed. One half of the culture broth was replaced by fresh medium and the pH of the culture medium was measured every 3 days through the experimental interval. After 4 weeks or 12 weeks, these dentin blocks were investigated with SEM, CMR, as well as with Brown-Brenn stain and enzyme immunohistochemical staining for light microscopical observation. The final pH of the S. salivarius group showed the highest value of 5.1, was higher than those of others, around 4.3. In every experimental specimen inoculated with bacteria, decalcification of dentin was observed in various degrees under the surface of the cavity. The bacterial invasion into dentinal tubules was observed in all of the experimental groups except S. salivarius group. When monoinfected, the bacterial invasion ratio was highest in the S. mutans group, followed by the A. viscosus group and the L. casei group. In the two mixed infection groups, high invasion ratio was also observed. However, it was revealed by the enzyme immunohistochemical staining that the invasion of S. mutans and A. viscosus were not observed but that of L. casei only. Meanwhile, the invasion ratio of L. casei was higher in mixed infection group with either S. mutans or A. viscosus, than that of monoinfection. These results suggest that lactobacillus may play an important role in the development of dentinal caries. Furthermore, the presence of other bacteria may promote the induction ability of dentinal caries of this bacterium.

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The fungiform taste buds and some mechanosensory endings in rabbits, which are supplied with chorda tympani and lingual nerves, were examined by means of light and electron microscopy. Three to seven taste buds were present in the dorsal epithelium of a fungiform papilla. The taste bud was composed of the type I, the type II, the type III cells and the basal cells. The type III cell was characterized by the presence of dense-core vesicles and synaptic vesicles, and showed afferent synaptic contact with nerve endings. Thus, it was suggested that the type III cell is involved in the chemoreceptive function. The presence of numerous free nerve endings in the extragemmal epithelium and mechanosensory endings, and of encapsulated corpuscles and Ruffini-like endings in the connective tissue of the fungiform papillae suggested that the fungiform papillae of the rabbit were highly adapted to both taste and mechanical sensation. The fungiform papillae were examined by light and electron microscopy from 1 week to 6 months after denervation followed by microsurgical reinnervation of both chorda tympani and lingual nerves. Further, these results were compared with those of experiments which were carried out in the same manner except for the microsurgical reinnervation. The first remarkable finding was the appearance of an ulcer in the dorsal surface of the tongue of the denervated side after the first week following denervation. The ulcer remained visible for about 10 weeks after the operation, and a severe defect of the tongue of the denervated side was observed occasionally. Taste buds and mechanosensory endings in fungiform papillae disappeared completely after the first week following denervation. The dorsal epithelium of the fungiform papillae showed filiform-like structures because of the hyperparakeratotic changes. However, 15 weeks after denervation followed by microsurgical reinnervation, the fungiform papillae regained their normal appearance. Encapsulated corpuscles and Ruffini-like endings regenerated in the connective tissue of reinnervated fungiform papillae in this experimental period, although these nerve endings were small in size and in number. 5 months after microsurgical reinnervation, regeneration of the taste buds was observed in the dorsal epithelium of the fungiform papillae. Ultrastructure of regenerated taste buds was essentially identical with that of normal taste buds, although the numbers of regenerated taste buds and their constituents were smaller than those of normal fungiform taste buds. In groups where no microsurgical reinnervation was carried out, regeneration of mechanosensory endings in the connective tissue was observed 5 months after denervation. Regeneration of taste buds, however, could not be observed during the experimental periods, even 6 months after denervation. The present study showed morphologically that the rapid and reliable regeneration of taste buds and mechanosensory endings in denervated fungiform papillae by chorda tympani-lingual nerves could be expected only when the proximal and distal cut ends of these nerves were repaired microsurgically.

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The dental arch and palatal traits in the Goto population were reported. Ninety-seven persons over 16 years of age, having normal dentition and few decayed teeth were selected for study from 224 persons who had impression taken and plaster models made. In the Goto population, dental arch length tended to be longer in males than in females, although the difference was not significant. Dental arch breadth (upper jaw) and palatal height (posterior) were significantly greater in males than in females. These findings indicated similar features of the Goto population and other populations in various regions of Japan. The morphology of dental arch and palate in the Goto population showed little difference when compared with Kitakyushu, north Shikoku, Nagashima, Koshikijima, Tanegashima, and Okinawa populations. For example, the lower dental arch tended to be shorter and narrower, palatal height tended to be greater, and the length of sutura palatina mediana tended to be longer.

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Extracted maxillary and mandibular molars with the curved fine root canals untreated were employed. Enlarging and preparation of the root canals were made with K-files after the root canals were filled with distilled water. Two cleansers, NaOCl (1.25%, 2.5%, 5%) and EDTA (1.875%, 3.75%, 7.5%), were used in combination for ultrasonic cleansing and the inner walls of the root canals were observed by SEM. The results were as follows : 1. When the canals were cleansed with water only, or with 1.25% NaOCl and 1.875% EDTA, smeared layer was observed in mid-canal and root apex ; the root canal could not be cleansed sufficiently. 2. When the canals were cleansed with 2.5% NaOCl-3.75%EDTA and 5.0% NaOCl-7.5% EDTA, cleansing effect was sufficient at mid-canal but insufficient at root apex. No significant difference was found between the two. 3. In order to increase cleansing effect on root canals, abundant use of the irrigation agents and extension of time for cleansing appear to be necessary.

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Three isomeric cresols were compared on their irritant and corrosive effect with use of LP as a positive control by means of the Evan's blue test. When the paper discs of 6 mm diameter in size and soaked with 30μl of one of the test drugs were kept secured on the dorsal skin of the rabbits for 30 minutes, the following results were obtained : (1) Difference in intensity either of dye exudation or of skin corrosion was scaresly found among the three isomeric recsols, when the skin reactions were scored on a scale ranging from 0 to 4. (2) The areas of the dye exudation caused by the isomeric cresols were nearly equal to each other. The ratio of the area by each isomer to that by LP was 0.9. (3) The lowest concentrations of the isomeric cresols causing dye exudation were found at the same dilution of 1 : 2^4 (6.25%), and those causing corrosion were also the same dilution of 1 : 2 (50%). (4) Concerning their lowest concentrations either for dye exudation and for corrosive reaction, the three isomeric cresols were at the same level as LP. From the above, it is confirmed that the three isomeric cresols are equal, a little milder than LP and a little more serious than guaiacol in injurious effects.

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It is said that dental plaque or bacteria consume complement in periodontal disease. Complement system plays very important part in initial lesion in periodontitis. In periodontal therapy, initial preparation plays an important role. The purpose of the present study was to examine whether or not successful periodontal treatment resulted in alternations in the level of complements, C3, C3a, and C3c in gingiva. Eleven patients with periodontitis and five with healthy periodontium were subjected to this study. The patients were divided into two groups, group I and group II. The individuals in group I did not have oral hygiene and initial preparation, and those in group II have them. Periodontally healthy ones formed group III. Seven gingivae were extracted from group I, six from group II, and five from group III. The presence and levels of C3, C3a, C3c were determined by enzyme linked immunosorbent assay. The results were as follows : 1. C3 levels were significantly elevated in group I as compared with group II (p<0.05). No significant differences were detectable in other groups. 2. C3a levels were not significantly different among all groups, although there seemed to be higher C3a in group I as compared with group II or group III. 3. C3c levels were not significantly different among all groups, although there seemed to be higher C3c in group I as compared with group II or group III.

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It is suggested that Interleukin-1 (IL-1) is associated with the destruction and restoration of periodontal tissues. The purpose of this paper was to establish an assay system of IL-1 in human gingival tissue. We quantitatively measured IL-1 in the extract from human gingival tissue by an enzyme-linked immunosorbent assay (ELISA). The assay procedure is composed of 5 steps : 1) incubation of experimental gingival extract diluted with PBS from 1 : 2500 to 1 : 1000000 for 2h at 37℃ ; 2) washing with PBS containing 0.1% Tween 20 three times, followed by coating with Block Ace at a 1 : 4 dilution with distilled water for 1h at 37℃ ; 3) washing three times, followed by incubation with rabbit anti-human IL-1 at a 1 : 1000 dilution with PBS for 2h at 37℃ ; 4) washing three times, followed by incubation with peroxidase conjugated anti-rabbit IgG at a 1 : 1000 dilution with PBS for 2h at 37℃ ; and 5) washing three times, followed by addition of the substrate solution and incubation for 1h at 37℃. The absorbance at 405 nm was measured using EIA-READER (BIO-RAD). The absorbance increased linearly in the range of 0.2-0.9 as concentration-dependent manner in each extract. The result showed that ELISA was a useful method for the quantification of IL-1 in human gingival tissue. A close correlation between the amount of IL-1 and alveolar bone loss was found.

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1. On the attrited enamel surface of deciduous teeth, many striations running irregularly were observed. Fissures, furrows, flanked pits, and defects also were observed. Where steps were formed, cut ends of enamel rods were found. A thin membrane of thin organic fibrous materials and bacteria covered the surface. 2. On the attrited surface of dentin of deciduous teeth, dentinal tubules showed openings of various sizes from large to small in diameter and were obliterated completely or partially. The surface was covered with attachments of matrix fibers and bacteria. 3. On the longitudinal surface of sclerotic dentin at attrited sites, the interior of dentinal tubules was occupied by ruptured processes of odontoblasts, collagen fibers, and bacterium-like substances. Most crystals were aggregations of rhombic crystals.

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The purpose of this study is to investigate clinical effects of "GP-solvent" as a new solvent to remove root canal filling materials. The results were summarized as follows : 1. With clinical use of GP-solvent in the 43 cases which required endodontic retreatment, the average number of visits for total endodontic treatment was 3.5 in 4 acute periapical periodontitis cases, 2.8 in 39 chronic periapical periodontitis cases. 2. The average time was 4.3 minutes per 1 root canal for K-files to arrive presumably at the root canal filling materials, and it was 8.4 minutes per 1 root canal before the root canal filling materials were thought to have thoroughly been removed. 3. According to the radiographic judgement on the degree of removal of root canal filling materials, 29 teeth (67.4%) were good, 14 teeth (32.6%) were fair and no tooth was poor. 4. As to the reactions to the smell of GP-solvent, 14 (48.3%) of a total of 29 patients were good, 15 (51.7%) were fair and no discomfort was complained. The above results and biological safety in preliminary studies show that GP-solvent is an effective root canal material solvent for clinical application.

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Dental cements have been widly used as lining materials, for composite resin restoration. They have some problems in handling and esthetics. To solve these problems, polymer type cavity liners have recently been developed. In this study, the applicability to composite resin restoration was evaluated for three polymer liners : an exclusive lining material for a composite resin product, "Liner", a traditional varnish, "Copalite", and a cyanoacrylate agent available as an adhesive. "Liner" seemed to be preferable, showing better abilities to chemically bond with HAp and to inhibit the penetration of monomers from resin into dentin tubules. The cyanoacrylate agent was found to be also applicable owing to its better abilities to inhibit monomer penetration and higher resistance to acid attack. On the contrary, "Copalite" showed inferior properties as a liner under composite resin placement.

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