In recent years, increased attention has been given to allergy to dental metal materials. It has been assumed that the allergic reaction to metals was cell-mediated type hypersensitivity reaction. But it has not yet been clarified in detail. Several traditional techniques have failed to induce contact allergy to metals in the animal. In this study, for the purpose of inducing the experimental allergy to nickel, rats were sensitized to peritoneal macrophages that engulfed nickel particles, as antigen. Rats were inoculated twice at one week interval with the antigen intraperitoneally. A week after the latest inoculation, the rats were inoculated again with the antigen into the gingiva. The rats were sacrificed on 6, 12 and 48 hours after the gingival inoculation. Using immunoperoxidase labeling technique, we examined the distribution of cells which bound anti-interleukin-2 receptor (IL-2R) monoclonal antibodies in the gingival tissues and submandibular lymph nodes, for the purpose of investigating the mechanism of the expression of allergic reaction to metals. In submandibular lymph nodes, IL-2Rs were not or hardly observed 6 hours after the gingival inoculation. After 12 hours, however, IL-2Rs were slightly observed in medulla and were clearly observed after 48 hours. The result suggested that antigen signal was transmitted to submandibular lymph nodes, IL-2R appeared on the surface of T cells, B cells and macrophages, and then T cells proliferated. In gingival tissues, polymorphonuclear leukocytes infiltrated after 6 hours. After 12 hours, mast cells characteristically were distributed and degranulated. The result suggested that antibody dependent type I hypersensitivity was involved in this reaction. After 48 hours, IL-2Rs were clearly observed. The result suggested that sensitized T cells were distributed in gingival tissues, and the cells responded to the antigen and secreted lymphokines. These results suggested that type I hypersensitivity was involved in early experimental allergic reaction to nickel, and type IV hypersensitivity was predominated after that.

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Interleukin 1 (IL-1) and tumor necrosis factor α (TNFα), two major immunoregulatory cytokines which produced by a variety of cells, have been shown to exert and share multiple biological effects on many target cells. Current evidence has demonstrated that their appearance is closely related with a feature of periodontal disease. This study, therefore, was designed to investigate their potential importance in the lesions of periodontal tissues in vitro and in vivo. At first in in vitro experiments, a dose-response and kinetics of IL-1α (like factor) production by macrophages and fibroblasts were investigated by measuring those amounts by ELISA at various time points after stimulation by LPS, heat-killed E. coli and rTNFα. The kinetics of IL-1α production of the macrophages in the presence of LPS differed from those observed in the presense of heat-killed E. coli. When combined at sub-optimal concentrations, LPS and rTNFα synergistically stimulated intra- and extracellular IL-1α production by the macrophages. A combined use of heat-killed E. coli followed with rTNFα (6 hours later addition) seemed to stimulate additively. On the other hand, LPS also increased IL-1α like factor production by the fibroblasts in a dose-dependent manner within a range from 0.1 to 5.0μg/ml. Especially, extracellular IL-1α like factor production by the fibroblasts was detected as early as 6 hours after LPS treatment and then reached a maximum level at 24 hours. No increase in IL-1α like factor production was observed in the fibroblasts stimulated by heat-killed E. coli. Futhermore, in vivo the kinetics of IL-1α like factor and TNFα like factor was studied in the samples extracted from the gingiva and serum after injection into the gingiva of rats with LPS and heat-killed E. coli. In LPS-injection group, the amounts of IL-1α like factor and TNFα like factor in gingival extracts were observed to have two peaks. The first increase reached a peak at 6 hours after injection, and the amounts of IL-1α like factor and TNFα like factor were maintained during the second peak (one day later). In heat-killed E. coli-injection group, a rapid-onset of IL-1α like factor production was observed in the gingival extracts. The first peak was recognized one hour and the second peak 3 days after injection. The amount of TNFα like factor was increased with two peaks. The first peak was observed 6 hours, the second peak one day after injection. Thus, the kinetics of IL-1α like factor production was differed from that of TNFα like factor production in the gingival extracts. On the other hand, no marked IL-1α like factor production was observed and no TNFα like factor was detectable in the serum by immunoassay. These findings suggest the possibility that IL-1 and TNFα may be key mediators in the initiation and regulation of many steps in the inflammatory and immunological response through interaction between cytokines (as a cytokine-network) in the lesions of periodontal disease.

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The position where the artificial teeth are arranged to be in harmony with physiological function is named denture space or neutral zone. Their actual state has not yet been clarified. In order to investigate the muscle pressure and morphological characteristics of the neutral zone for lower dentures, muscle pressures exerted on the lower denture flange on swallowing of saliva and warm water were measured. Moreover, the positional relationship of neutral zone to alveolar ridge was discussed. The results were as follows : 1. The muscle pressure of lingual side of the denture flange on swallowing saliva was 1.2 times as large as that of buccal side at premolar region, 1.4 times at molar region when it was measured on imaginary dentition arch (A type). The lingual muscle pressure was significantly larger than the buccal muscle pressure at both regions. 2. The muscle pressure of lingual side of the denture flange on swallowing saliva was 1.4 times as large as that of buccal side at premolar region, 1.0 times at molar region when it was measured on the 2mm outer position at buccal side and 2mm inner position at lingual side than imaginary dentition arch (B type). The lingual muscle pressure was significantly larger than the buccal muscle pressure at premolar region. 3. The muscle pressure of lingual side of the denture flange on swallowing warm water was 1.4 times as large as that of buccal side at premolar and molar regions for A type. The lingual muscle pressure was significantly larger than the buccal muscle pressure at both regions. 4. The muscle pressure of lingual side of the denture flange on swallowing warm water was 1.4 times as large as that of buccal side at premolar region, 1.2 times at molar region for B type. The lingual muscle pressure was significantly larger than the buccal muscle pressure at premolar region. 5. Significant differences were not recognized between the muscle pressure on swallowing of saliva and warm water at every region, except for buccal side at premolar region. 6. The middle point of the neutral zone was 0.3mm more outer than the alveolar ridge at retromolar pad region, and 1.5-1.7mm outer at premolar and molar regions.

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Lipopolysaccharide (LPS) from the wall of gram-negative bacteria plays an important part as an initiative factor in periodontal disease. LPS has various biological activities, and causes cleavage of complement by both the classical and the alternate pathways, production of anaphylatoxins, secretion of lymphokines, chemotaxis of neutrophils, production of prostaglandins, increase of collagenase activity. In initial lesion in periodontitis, complements and prostaglandins may play the role of chemical mediator or chemical modulator. Recently, it was shown that complements promote prostaglandins production, and prostaglandins promote increase of collagenase activity in vitro. Experimental periodontitis was induced by inoculating the gingiva of rats with LPS from E. coli. There were three aims in this study : First, to investigate changes with time in the amount of complement and prostaglandins, and the activities of collagenase in gingiva and serum. Second, to clarify the immunohistochemical localization of prostaglandin E_1. Third, to investigate direct effect of LPS, with and without anti-interleukin 1, on prostaglandin E_1 release from freshly isolated rat peritoneal macrophages and fibroblastic cell ATCC CRL 1213. Results were as follows. 1. There were 2 peaks in amount of C3 c in gingival extracts. The values of C3 c were 1.57 times higher after three hours, 1.02 higher after six hours, and 1.97 higher after 12 hours than the normal level, and were nearly normal level after 72 hours. 2. No marked changes were seen in C3 c in serum. 3. There were 2 peaks in amount of PGE_1 in gingival extracts. The values of PGE_1 were 7.44 times higher after three hours, 2.64 higher after six hours, and 9.81 higher after 24 hours than the normal level, and were nearly normal level after 72 hours. 4. PGE_1 in serum was below the level of detection. 5. There were 2 peaks in amount of PGE_2 in gingival extracts. The values of PGE_2 were 4.98 times higher after three hours, 2.30 higher after six hours, and 12.46 higher after 24 hours than the normal level, and were nearly normal level after 72 hours. 6. PGE_2 in serum was below the level of detection. 7. The immunohistochemistry of PGE_1 in periodontal tissue showed strong PGE_1-positive staining in lamina propria three hours after LPS inoculation. The positive staining decreased greatly six hours after inoculation. 8. In the cell culture experiment, PGE_1 production in cell-free supernatants of macrophages stimulated by LPS increased at 16.6 ng after 360 minutes. Stimulated by LPS in the presence of anti-IL-1, the production increased at 5.9 ng after 60 minutes, and decreased afterward. 9. In the cell culture experiment, PGE_1 production in cell-free supernatants of fibroblastic cell line ATCC CRL 1213 stimulated by LPS increased at 10.25 ng after 360 minutes. Stimulated by LPS in the presence of anti-IL-1, the production increased at 3.10 ng after 180 minutes, and decreased afterward. 10. There was diphasic change in amount of type I collagen in gingival extracts. The values of type I collagen were 0.95 times higher after three hours, 0.90 higher after six hours, and 0.79 higher after 24 hours than the normal level. According to these results, it was shown that LPS stimulate cleavage of complement, production of prostaglandin, increase of collagenase activity. The direct effect of LPS and indirect effect through cells and others resulted in diphasic changes. Cleavage of complement, production of prostaglandin, increase of collagenase activity interact in initial lesion in periodontal disease.

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The elastic and creep properties of commercial denture soft liners were evaluated through static and dynamic creep test. The materials employed were an acrylate (Soft-liner : SL) as a tissue conditioner or a functional impression material, a fluoropolymer (Kurepeet Dough : KD) and four silicones (Neo-snugger : NS, Evatouch S : ES, Evatouch H : EH, Mollosil : ML) as resilient liners. Their changes in surface aspect in water were also examined with a scanning electron microscope. The findings obtained were as follows : 1. In the early stage of aging, SL showed larger viscous flow and creep favorable for conditioning unsound tissues or taking functional impression. However, it would no more effectively serve as those uses over the third day because of its markedly decreased thickness, loss of flow and creep rates, and increased surface roughness. 2. The resilient liners used were classified into two groups by the deformation under static compressive loading ; one involved KD and ML showing large elastic deformation and the other NS, ES and EH showing smaller deformation, less than a half the values for KD and ML. 3. The dynamic compressive creep linearly increased with increase in the repetition number of loading in the silicone materials, while KD maintained smaller level of creep. 4. All the resilient liners exhibited good elastic recovery even after six-month aging or repeated compressive preloading by 540, 000 times corresponding to the average number of mastication for a six-month period. 5. The surface roughness and pore exposure were increased by aging in water in the silicone materials. On the other hand, little change was found in the surface of KD.

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Three-week-old rats of Wistar strain were given a calciumdeficient diet for three weeks and experimental condition of bone dibility was induced in them. The rats were then given a normal diet containing calcium and 1 α-OH-D_3, a physiologically active substance, was administered at the same time for two weeks, and the effects of the administration on the mandibular condyle at growth stage were examined. The results were as follows : 1. General tissue findings In comparison with the controls on a normal diet, the calcium-deficient diet group showed irregular borders between erosive zone and hypertrophic zone. Bone trabeculae of subchondral bone formation zone decreased in number. The calcium-deficient diet + a normal diet group showed active subchondral bone formation and many findings of hypocalcification of bone layers. Although bone trabeculae were thin, they increased in number and increase in osteoblasts on the surface of trabeculae was marked. The calcium-deficient + a normal diet + Vitamin D_3 group showed decrease in number of hypertrophic chondrocytes, but increase in volume ofcalcified matrix surrounding hypertrophic chondrocytes and in findings of erosions of calcified matrix by chondroclasts. Subchondral bone formation was active and bone trabeculae were more in number, but they were still thin. 2. Transmission electron microscopic findings In the calcium-deficient diet group in comparison with the controls on a normal diet, osteoblasts were fewer in number and presented fibroblasts-like morphology. The cytoplasm showed marked swelling of mitochondria and a marked increase in cristae. Osteocytes were found in spacious bone lacunae, had well-developed rough surfaced endoplasmic reticulum, and showed unclear lamina limitans in part. Osteoclasts were more in number and many ruffled borders were well developed and active in bone resorption. In the calcium-deficient + a normal diet group in comparison with the calcium-deficient diet group, osteoblasts increased in number and the organelle were active. Young osteocytes increased and osteoclasts also increased in number. In the calcium-deficient diet + a standard diet + Vitamin D_3 group, osteoblasts were about circular in form and increased in number. They showed marked development of rough surfaced endoplasmic reticulum and mitochondria. Osteoblasts in close proximity of osteoclasts increased in number and many findings of increased distances between osteoblasts were seen. Significantly, osteocystes ranged from the young to the matured.

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Matrix vesicles are membrane invested vesicles that initiate mineralization in the extracellular matrix of various calcifying tissues. Alkaline phosphatase (ALP) has been used as the marker enzyme of matrix vesicles, because matrix vesicles isolated from mineralizing tissues contain very high level of ALP in association with the plasma membrane of the cell. However, ALP is unsuitable as the marker enzyme of matrix vesicles because of its localization not only in the plasma membrane but also in other subcellular organelle membranes. Recently lactate dehydrogenase (LDH) isoenzymes were found to be located in matrix vesicles of the epiphyseal growth plate of young rabbit leg bones [Hosokawa et al. (1988) J. Biol. Chem. 263, 10045-10047]. In the present study, identification of lactate dehydrogenase isoenzymes in matrix vesicles was carried out with use of the epiphyseal cartilages from 6 different mammals. In some mammals, enzymatic properties of matrix vesicles in the growth cartilages were compared with those in the resting cartilages. 1. Matrix vesicles were isolated from the epiphyseal growth plates of 6 different young mammalian (dog, cat, rat, chicken, pig and monkey) rib bones. LDH activities were detected in the isolated matrix vesicles only in the presence of Triton X-100 but not in the absence of Triton X-100, showing that LDH is located in the matrix of the matrix vesicles. 2. The epiphyseal cartilages of young rat rib bones were divided into the growth zone and the resting zone, followed by the isolation and identification of matrix vesicles after collagenase treatment. Matrix vesicles with both ALP and LDH were also detected in the growth zone but were not detected in the resting zone. In contrast and surprisingly, LDH containing vesicles without ALP were found in the resting zone but not in the growth zone. The same results were obtained with the growth and resting cartilages of other young mammalian (dog, pig and monkey) rib bones, suggesting that LDH containing vesicles without ALP are also present in all mammals including humans. 3. Chondrocytes were prepared from the growth zone and the resting zone of the epiphyseal cartilages of young rat rib bones, homogenized with isotonic solution and subjected to sucrose density gradient centrifugation. In each case, LDH activity was recovered only in the soluble top fraction and not in sediment, showing that LDH is present only in the cytosol of chondrocytes but not in the plasma membrane and intracellular organelles. The results show that LDH in the vesicles is not from the plasma membranes and the membranes of intracellular organelles. 4. In both the growth and resting zone cartilages of young rat rib bones, isoenzyme patterns of LDH in the two different vesicles were identical with those of cytosolic LDH of chondrocytes. 5. Other cytosolic enzymes such as aldolase, aspartate : 2-oxoglutarate aminotransferase and alanine : 2-oxoglutarate aminotransferase were not detected in the two different vesicles from the growth and resting cartilages, suggesting the presence of a mechanism for the specific uptake of cytosolic LDH.

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Experimental segmental resection including teeth was performed in the range from canine median mandibular through right lower central, intermediate and angular teeth, and the stumps were put together firmly in bolt fixation, being kept at a deformed healing state. The influence of subsequent malocclusion on temporomandibular joint was examined pathohistologically. The results obtained are as follows : 1. The articular fossa・lateral angular region showed bone resorption from the 5th postexperimental day and its peak on the 240th day on the left side and on the 30th∿90th day on the right side. Bone resorption decreased thereafter and disappered. 2. The articular fossa cartilaginous layer became thicker as a whole on both sides at lateral angular region from the 5th to 90th day and thereafter gradually decreaseed to return to the original on the 240th day. Tr-z was scarcely noted throughout the period, while Ca-z was noted partially hypertrophic on the 365th and 90th days on the left and right sides, respectively. 3. The articular disc began to show uneven stainability and thickness on both sides from the 5th day and to a remarkable extent especially internal-externally, with the occurrence of interfiber bundle bending, dispersion and occasional rupture. 4. Bone resorption which gradually started following the start of the experiment at condyle head・inter-external angular region increased in scope and depth with time, reaching its peak at the both sides, and disappeared from the 240th day on. 5. Osteoplasty was noted on the left side at condyle head・lateral angular region on the 60th day and to an extensive and thick extent on both sides on the 240th day. 6. The condyle head tended to project externally. 7. The condyle head cartilaginous layer tended to be hypertrophic for Ta-z in the whole regions, and to remarkable extent especially at lateral angular region. Tr-z and Ra-z were scarcely noted in any one of the regions, and Ca-z, though partially hypertrophic, tended to be decreasing. 8. No distinct difference in these findings was noted between both temporomandibular joints. The above results suggest that earlier and more remarkable changes occur in temporomandibular joints in case of malocclusion due to mandible deformed healing than in case of malocclusion due to the loss of the tooth. However, it was also revealed that all of condyle head, articular fossa and articular disc proceeded in reconstruction and functioned as integrated temporomandibular joints while adapting themselves to any abnormal environment.

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A consciousness survey concerning the demand for and supply of dental care was conducted among the inhabitants in Miyazaki city having an excess of dentists, in Kitagawa-chohaving no dentist and in Nichinan city which is the intermediate type between the above two areas. As a result, the inhabitants in Miyazaki city were quantitatively satisfied with the provision of dental care, while there was an extremely high demand for the care in Kitagawa-cho. In Nichinan city, the degree of satisfaction with the dental care tended to be the same as that in Miyazaki city.

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In order to investigate the mandibular movements and function after sagittal split ramus osteotomy for prognathism, occlusal contact area and points, distance of mandibular border movements, myographic activity of masseter and temporalis, biting force and masticatory efficiency were measured before and 3, 6, 12 months after surgery. Postoperative evaluation under the consideration of fixation method of bone segments and with or without orthodontic therapy was carried out. The results were as follows : 1. Occlusal contact area and points tended to increase from 3 months after surgery compared with preoperative level and they indicated a significant increase 12 months after surgery. 2. Maximal distance of opening mouth indicated a significant decrease 3 and 6 months after surgery compared with preoperative level. Significant difference however was not recognized 12 months after surgery. Distance of anterior and lateral border movements showed an increasing trend from 6 months after surgery and the distance of left border movements indicated a significant increase 12 months after surgery. 3. Myographic activity of bilateral masseter decreased 3 months after surgery compared with preoperative level. A significant increase was recognized 12 months after surgery. Myographic activity of bilateral temporalis showed an increasing trend from 3 months after surgery compared with preoperative level. Twelve months after surgery a significant increase was recognized. 4. Biting force on both sides decreased 3 months after surgery compared with preoperative level, but 12 months after surgery it indicated a significant increase. 5. Masticatory efficiency tended to increase from 3 months after surgery compared with preoperative level. Six months after surgery significant increase was recognized. 6. Significant correlation of masticatory efficiency was recognized with occlusal contact area, points and myographic activity of temporalis preoperatively and with all examined items except distance of anterior and lateral border movements postoperatively. Correlations between left and right in myographic activity and biting force, as well as between masseter and temporalis in myographic activity strengthened with the passage of time after surgery. 7. Screw fixation was superior to wire fixation in occlusal contact area, distance of anterior border movements, and myographic activity of masseter. On the contrary wire fixation was superior to screw fixation in myographic activity of temporalis and left biting force. Occlusal contact points and masticatory efficiency showed equal improvement of function. 8. The group combined with the orthodontic therapy was superior to the group without it in occlusal contact area and points, myographic activity of right masseter and temporalis, right biting force and masticatory efficiency. On the contrary in the group without the orthodontic therapy, nothing was superior to group with it. From the above results, it was suggested that application of sagittal split ramus osteotomy for prognathism is very meaningful for not only esthetic and morphological improvements but also improvement of mandibular movements and function.

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A case of cementoma in the 〓 region of a 15-year-old boy was reported with a discussion on histopathological consideration about it. Histopathologically, the mass consisted of a normally formed crown and abnormally formed root, and showed abundant findings by the site, i.e., like cemental hyperplasia, cementoossifying fibroma, apical cemental dysplasia etc. Above-findings indicated that Ishikawa's vision of cementoma is more oppropriate than Bhaskar's one.

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