Rats were grouped into the standard food group, calcium deficient diet group, vitamin D deficient diet group, and calcium and vitamin D deficient diet group, and changes in bone matrix in the tibia was investigated, with the tibia of the rats in growing stage as specimen. The results were as follows : 1. Findings in bone density No significant difference (p>0.05) was found between the control group and the vitamin D deficient diet group. Among the control group, calcium deficient diet group, and calcium and vitamin D deficient diet group, significant difference (p<0.01) was found and the control group showed higher values. 2. Analytical findings on the X-ray microanalyzer In the quantitative analyses of Ca and P, relative Ca ratio and relative P ratio showed decreasing values in the order of the control group, vitamin D deficient diet group, calcium and vitamin D deficient diet group, and calcium deficient diet group. 3. Histopathological findings In contact microradiogram findings and general tissue findings as compared with those in the control group, the calcium deficient diet group and calcium and vitamin D deficient diet group showed increase in bone marrow in the tibia, decrease in Haversian canals and bone lacunae, and low calcified layers in nearly all bone layers. The tibia in the vitamin D deficient diet group showed about the same findings as those of the control group. 4. Scanning electron microscopic findings As compared with the control group, the calcium deficient diet group and calcium and vitamin D deficient diet group showed about the same findings, and bone resorption exceeded bone formation (area). Bone resorption was shallow in process at most sites. The calcium and vitamin D deficient diet group showed abundant findings of sparse collagen fibril network close to the resorption sites especially. The tibia in the vitamin D deficient diet group showed about the same findings as those of the control group. On the bases of the foregoing findings, calcium deficiency greatly affected the changes in the formation of bone matrix in the vitamin D deficient diet group.

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The purpose of this study was to measure interexaminer agreement for three indices (CPITN, DMFI and DAI) based on International Collaborative Study of Oral Health Outcomes (ICS II). Eight dental students aged 24-27 were examined by two dentists and an expert epidemiologist. These examiners were calibrated for three days before this study began. To evaluate how well the examiners are able to consistently assess these oral conditions according to the criteria, kappa statistics were computed for pairs of examiners for each condition. For DMFI scores kappa values for dental caries were 0.87. Kappas for periodontal conditions and occlusal characteristics ranged from 0.29 to 0.36 and 0.38 to 0.51, respectively. These results suggest that interexaminer agreement after three days calibration, except for DMFI scores, is not adequate. Perhaps calibration for more than three days should be performed in order to raise interexaminer's agreement to satisfactory level in epidemiological study.

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Oral examinations and daily life surveys were made among first grade pupils in the Kitakyushu area on June 2, 1989. The results were as follows : 1. The subjects consisted of 55 boys and 42 girls, a total of 97, of first grade pupils in the Kitakyushu area. 2. Gingivitis (GI) occurred more in the lower jaw than in the upper jaw and at the mesial and median portions of the anterior teeth. 3. Plaque (PLI) was found more on the labial side for both the upper and lower jaws. Dental calculus (CI) was found on the lingual side of the lower permanent central incisor of some boys and on the lingual side of the lower deciduous canine tooth in one girl. 4. Foreign materials were found mostly on the labial side and some on the lingual side. 5. No bleeding from the gingiva was found in the upper jaw. Bleeding was found at the distal side of the lower left and right central incisors in one boy and at the labial side of the right canine tooth in one boy. 6. Eruption of permanent teeth was about 27.2% for the upper central incisor and about 8.1% for the lower central incisor. Change to permanent teeth had not yet started for the canine tooth. 7. Caries (c) averaged 50.8% for the upper deciduous incisor for boys and girls, 2.4% for permanent incisors, and 20.8% for the upper deciduous canine tooth. In the lower jaw, the average was 5.45% for deciduous central incisor for boys and girls, 1.35% for permanent central incisor, and 21.8% for the deciduous canine tooth. 8. As to restoration of the 731 teeth, only partial restoration was seen for 13 teeth. 9. The hour of rising was 6 : 00 hours on the average and 7 : 00 hours on holidays, and bedtime was 21 : 00 hours on weekdays and 21 : 00 hours were more common on holidays. 10. Tooth brushing was twice a day, and vertical and holizontal brushing was predominant after supper. 11. Snack was given once a day, regularly, at a fixed place and in a fixed amount. Chewing gum of first class, chocolate, caramel candy, and ice cream were common kinds. 12. Dental treatment given during the past year was 72.7% for boys and 78.6% for girls.

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Three-week old male rats of Wistar strain were given calcium-deficient food and debilitated mandibles were induced in them. The rats were then given a calcium-deficient diet + a high calcium diet or a calcium-deficient diet + a standard diet. The effect on formation of bone matrix in the mandible at growth stage was investigated after five weeks of maintenance. The results were as follows : I. Histopathological findings In the control group, findings of active bone remodeling were observed. At the same time, at the portion corresponding to enamel organ, small resorption cativities were observed in succession. In the calcium-deficient diet group, as compared with the control group, a considerable decrease in bone quantity was seen and the whole of the osseous layer corresponding to enamel organ showed large and small resorption cavities in the whole area. The high calcium diet group, as compared with the calcium-deficient diet group, showed findings of extensive boen remodeling of transition from bone resorption to bone formation. In the standard diet group, as compared with the high calcium diet group, bone matrix became dense and reconstruction of bone construction by bone remodeling was active on the whole. II. Scanning electron microscope findings In the control group, the surface of bone matrix formation was relatively flat and smooth. The surrounding matrix of the bone lacuna was composed of segments of bundles of collagen fibrils. In the calcium-deficient diet group, bone resorption surfaces were more extensively seen than bone matrix formation surfaces. In the high calcium diet group, as compared with the calcium-deficient diet group, collagen fibrils running in a given direction appeared. In standard diet group, as compared with the high calcium diet group, findings of decarease in bone resorption images were seen and collagen fibrils running in a given direction tended to increase. On the basis of the foregoing findings, in calcium treatment for debilitated mandibles, the standard diet group, as compared with the high calcium diet group, showed decrease in bone resorption images and active reconstruction of bone construction by bone remodeling.

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In manufacturing ceramo-metal restoration, the metal coping is subjected to several mechanical and thermal treatments after cast for fusing porcelain. Several reports have demonstrated some changes in the fit of the single ceramo-metal crown during such procedures. The potential disturbance of the fit in the case of the connected crowns was examined in this study. The model was composed of two abutments for connected crowns with an interspace of 1 mm. Both the abutments were of shouldered type, 6 mm in height and 5°in taper. The pattern was prepared using a spacer to ensure the specified thickness for full-baked or veneered type. The investments used were two brands of phosphate-bonded investments-Uni vest non-precious (UN) and Blue vest (BV) having different compressive strength. Nickelchromium alloy was employed as the coping metal. The vertical gap at the margin between the coping and the abutment shoulder was measured after each stage of the procedures : casting, cutting of sprue, treating of metal surface, degassing, fusing of opaque porcelain, fusing of body porcelain, adjusting of body porcelain, and glazing. The as-cast connected crowns were in mesio-distally warped shape showing larger gap at the proximal margin than at the connected margin. The subsequent mechanical and thermal treatments caused deformation of the crowns to correct the warpage to some extent, resulting in the decreased gap as a whole. The largest decrease in the gap was generally found at the stage of sprue cutting, and the second at those of degassing and sandblasting for metal surface treatment. The decrement at each stage was changed by altering the processing order in association with the amount of residual stresses in the casting involving uncut sprue and runner bar, relaxation and release of the stresses, and development of new stresses in the previous treatments. The changes in the fit were marked in the full-baked type with the coping being thinner, especially cast with the investment UN when compared with that in the veneered-type. It is because a larger residual stress might be introduced in the casting with use of the stronger investment UN than BV, which was suggested from the cast tearing test. The compressive strength of BV is intentionally lowered by the manufacturer for the purpose of making it easy to take out the casting from the mold. The lowered strength of this investment showed additional effect of reducing the residual stress and hence minimizing the fit changes in the subsequent procedures. The application of the stress relief annealing to the casting before cutting the sprue was also found to be effective for maintaining the as-cast fit of the casting.

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Recently, polyethersulfone resin (PES) has been utilized as a new denture base material. It has excellent characteristics such as high impact resistance, high wear resistance and high chemical stability and has no harmful effect on the oral mucosa. Therefore PES is expected to overcome the disadvantages shown in polymethylmethacrylate resin (PMMA) which is the most popular denture base material. However, the fit of the PES denture made by press forming method according to the manufacturers' instructions is still unsatisfactory and it has been restricted in its clinical use. The fit seems to be affected by setting and thermal expansion of the model material, the processing shrinkage of PES, the condition of press forming such as pre-heating temperature and time of mold, cooling method after press. In the present study, those factors were examined to find the optimum approach for getting better fit of the PES denture when compared with those of PMMA and polycarbonate resin (PC) dentures. The results obtained were as follows : 1. The setting expansion of the model material was about 0.30%. 2. The thermal expansion of the model material was about 0.40% at 350℃ but decreased to -0.09% by subsequent cooling to the room temperature. Those of the lower and upper investment materials after heated and cooled were -0.63 and -0.35%, respectively, at the room temperature. 3. The processing shrinkage of PES was about 1.0% and it was much greater than that of PMMA. 4. The PES specimens prepared accoding to the manufacturers' instructions showed inferior fit to the master model to those of PMMA and PC. 5. Better fit was obtained by using a model material having larger setting expansion (0.78%). 6. Pre-heating of the upper mold at 220℃ and 350℃ prior to press forming could fairly improve the fit. 7. Marked improvement of the fit was found by slow cooling from the softening temperature or annealing at a little higher temperature than Tg after press forming. Especially the specimen when pressed with the equally pre-heated upper and lower molds and slowly cooled showed the best fit equivalent to that of PMMA.

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Matrix vesicles, membrane invested vesicles, are generally accepted to initiate mineralization in the extracellular matrix of calcifying tissues except enamel. Matrix vesicles contain high alkaline phosphatase activity and related phosphatase activities associated with the plasma membrane ; this may be because matrix vesicles may be formed by budding from the plasma membrane of calcifying cells. Recently, lactate dehydrogenase (LDH)-containing vesicles were found in the epiphyseal growth cartilage [Hosokawa et al. (1988) J. Biol. Chem. 263, 10045-10047] and the resting cartilage [Ohashi-Takeuchi et al. (1990) Biochem. J. 266, 309-312], and in the calvaria of mice [Naito (1992) J. Kyushu Dent. Soc. 46, 345-354]. However, it is unknown what true function of LDH-containing vesicles is and there is no report on the presence of LDH-containing vesicles in calcification sites of developmental tooth germs. In the present study, LDH-containing vesicles were found to be present in odontoblast layer and ameloblast layer of bovine tooth germs, as follows. 1. The extracellular matrix vesicle fraction was prepared from odontoblast layer of bovine tooth germs. Only in the presence of detergents, LDH activity was detected in the extracellular matrix vesicle fraction, showing that LDH is located in the vesicles. 2. The extracellular matrix vesicle fraction of bovine odontoblast layer was subjected to sucrose density gradient centrifugation. LDH activity was detected in the presence of Triton X-100 but not in the absence of Triton X-100. The sedimentation profiles of LDH in the presence of Triton X-100 were different from that of alkaline phosphatase, showing that LDH-containing vesicles were different from matrix vesicles. 3. Odontoblast fraction from bovine tooth germs was homogenized with isotonic solution and then subjected to sucrose density gradient centrifugation. LDH activity was recovered only in the soluble top fraction, but not in sediment, showing that LDH in the vesicles is not simply encapsulated by vesicles from the plasma membranes or membranes of intracellular organelles. 4. Electrophoretic profiles of LDH isoenzymes from the extracellular matrix vesicle fraction of bovine odontoblast layer were similar to those of cytosolic LDH of bovine odontoblast, suggesting that the presence of a mechanism for the specific uptake of cytosolic lactate dehydrogenase into vesicles. 5. Furthermore, LDH-containing vesicles were found in the ameloblast layer of bovine enamel organ. The existence of LDH-containing vesicles in bovine ameloblast layer, where calcification is not initiated by matrix vesicles, suggests the possibility that LDH-containing vesicles have a specific role different from matrix vesicles.

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In daily clinical work, at the time of enucleation of salivary calculus in sialolithiasis or of a mucous cyst occurring on the oral floor, injuries to the salivary gland tissue are often experienced. At present, however, histological characteristics of repair and regeneration of severed or injured salivary gland have not yet been clarified sufficiently. Yet, it is important to have a sufficient grasp of effects of various surgical operations on salivary gland tissue and healing process. Partial extirpation of the submandibular glands of Wistar rats was performed and an investigation of wound healing and effects on the remaining salivary glands was conducted. The results were as follows : 1. The portion near the excretory duct of the submandibular gland of Wistar rats was partially extirpated and the healing process of wound was investigated. At the early stage, persistence of blood clots, formation of fibrin, and inflammatory cell infiltration were observed. Thereafter, increase with time in glannulation tissue and then replacement by fibrous scar tissue occurred. II. Remaining salivary gland tissue A. In the terminal portion, atrophy, destruction, disappearance, pyknosis, and deformation of acinous cells were seen, and along with these regressive changes, decrease in secretory granules was observed. Decrease in stainability was also seen in Periodic Acid-Schiff (PAS) stain and Azan stain. B. In the striated ducts, regressive changes such as atrophy, pyknosis, and deformation of epithelial cells and granular duct cells of striated ducts were seen. Especially in the granular duct cells, azocarmin chromatophilic secretory granules decreased or disappeared and stainability also decreased. C. These findings were markedly observed first in the salivary gland tissue adjacent to the extirpation wound and gradually in the surrounding salivary gland tissue also. Although most marked regressive changes were seen in the cases from 4 to 6 days after operation, changes were hardly seen in the whole submandibular gland. At the same time, many findings of disappearance of acinous cells due to atrophy, deformation, and destruction were seen, but the regressive changes such as atrophy and deformation in the epitherial cells and glanular duct cells of striated ducts were relatively slight and disappearance was hardly seen. D. In the cases from 7 days after operation, undifferentiated cells appeared in the epitherial cells of striated ducts and granular duct cells in which regressive changes had occurred. The cells showed with time cell nidi like acinous cells of the terminal portion and duct-like structures, gradually increased in regular arrangement, and formed relatively clear submandibular gland lobulus. In the cells like acinous cells of the terminal portion, secretory granules showing positive reaction in PAS stain gradually increased. III. On the basis of the foregoing experimental results, the wound by partial extirpation of rat submandibular gland underwent fibrous scar healing and the remaining salivary gland tissue was subjected to considerably severe regressive changes. However, it was suggested that repair and regeneration start from the remaining striated ducts and the injured salivary gland tissue recover morphologically and functionally. Repair or regeneration of salivary gland however was not observed in the defect by extirpation during this experiment.

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Pleomorphic adenoma occurring in the oral cavity is neoplastic salivary gland tumor originating from the major and minor salivary glands and has the most frequent rate of occurrence among salivary gland tumors. Although this tumor is said to be benign clinically, it presents various structures, and recurrence and malignancy occasionally occur. Many reports therefore have been made on this tumor as a disease of interest. However, there are still many matters yet to be clarified such as correlation between clinical symptoms and histopathological structures, histogenesis, and hitological types. A sufficient grasp of this tumor has not yet been attained. A clinicopathological and immunohistochemical investigation therefore was performed to elucidate these matters. The results were as follows : 1. In histopathological types of the 32 cases of pleomorphic adenoma, cellular type was most frequent with 15 cases (46.9%), followed by simple type with 10 cases (31.3%), and adenomatous type with 7 cases (21.9%). 2. As to histological types and sites of occurrence, simple type and cellular type occurred more at the palatal mucosa and adenomatous type at the palatal mucosa or buccal mucosa in many cases. 3. Regarding histological types and age of occurrence, simple type occurred in ages from thirties to sixties, adenomatous type in forties, and cellular type in fifties in many cases. 4. Although no differences were seen between histological types and tumor sizes, cellular type was seen in relatively larger tumors in many cases. In histological types and tumor hardness, simple type was elastic soft and adenomatous type was elastic hard, in many cases. 5. In histopathological structure of the 32 cases, chondroid pattern accounted for 18 cases (56.3%), myxomatous pattern 15 cases (46.9%), and cartilage pattern 10 cases (31.3%). Squamous cell metaplasia was seen in 8 cases (25.0%). Recurrence was seen in 3 (9.4%) of the 32 cases and findings of myxomatous pattern were found in the 3 cases. Capsule was incomplete. In treatment of this tumor, therefore, enough care must be given to presence or absence of formation of capsule and of extracapsular infiltration as well as histological types and histopathological structure, and surgical extirpation as wide as possible is desirable. 6. In histochemical investigation of this tumor, Periodic Acid Schiff (PAS) stain showed positive reactions at the portions of squamous cell metaplasia, myxomatous pattern, and cartilage pattern. Mucicarmin (MC) stain and Alucian-Blue (AB) stain showed positive reactions at the portion of myxomatous pattern. 7. In immunohistochemical investigation of this tumor, S-100 protein reacted negatively to normal myoepithelial cells and positively to tumorous myoepithelial cells and cartilaginous myoepithelial cells. Carcinoembryonic antigen (CEA) reacted positively to tumorous cells showing squamous cell metaplasia. Furthermore, localization of Keratin (KER) was suggestive of differentiation tendency toward squamous epithelia of tumorous myoepitherial cells. On the basis of the foregoing investigation results, it was suggested that epithelial cell of the intercalated duct is the histogenesis of pleomorphic adenoma.

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We have experienced a case of immature permanent teeth 〓 with traumas in an eight year old boy. 1. Clinical findings showed invagination of about a half of the crown of 〓 and extrusion of about 3 mm of 〓. 〓 showed two degrees of mobility and caused spontaneous pain. 2. For treatment, reduction and fixation by resin wire of 〓 was done because of their mobility. During the observation of course, 〓 showed resorption of its dental roots and was therefore given root canal treatment and root canal filling was done. 3. At present, a year and a half after treatment, prognosis is good. 4. Because discoloration appeared, closing of the root apex will be done at an appropriate time and whatever clinical actions necessary will be taken.

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