In considering maximum bone volume, calcium plays an important role. Male Wistar rats, 8-week-old corresponding to human puberty, therefore, were given highly calcium-deficient diet and low calcium-deficiency diet for three weeks and juvenile bone debility was induced in them. Then the food was changed to standard diet and maintained for three weeks. The state of bone architecture was then investigated. The results were as follows : I. Body weight All of the control group, highly calcium-deficient diet+standard diet group, and low calcium-deficiency diet + standard diet group showed gradual increase in body weight through out the experiment period and so significant differences were found among the three. II. X-ray findings A. Macroscopic observation 1. Alveolar bone region and mental region As compared with the control group, the highly calcium-deficient diet+standard diet group showed insufficient thickness of the alveolar bone towards the incisal edge, poor development of the mental ridge, irregular arrangement of trabeculae, and decrease in the number of trabeculae on the whole. The low calcium-deficiency diet+standard diet group, as compared with the highly calciumdeficient diet+standard diet group, showed a tendency to increase in thickness of the alveolar bone towards the incisal edge, more development of the mental ridge, more regularity of arrangement of trabeculae on the whole, and a tendency to increase in the number of trabeculae. As compared with the standard diet group, about the same findings were observed. 2. Mandibular inferior margin As compared with the control group, the highly calcium-deficient diet+standard diet group showed irregular arrangement of trabeculae, extreme decrease in their number, and indistinct masseter muscle ridge. The low calcium-deficiency diet+standard diet group, as compared with the highly calciumdeficient diet+standard diet group, the finding of recovery in bone architecture was marked. B. Bone density by X-ray Significant differences were found between the control group and the highly calciumdeficient+standard diet group (p<0.01), and between the control group and the low calcium-deficiency diet+standard diet group (p<0.05), and the control group showed higher values. Significant differences were also found between the highly calcium-deficient+standard diet group and the low calcium-deficiency diet+standard diet group (p<0.05), and the low calcium-deficiency diet+standard diet group showed higher values. III. Hematologic examinations No significant differences were found in any group in electrolyte and biochemical examinations. Homeostatic mechanism was suggested to be involved in this. IV. Histopathologic findings As compared with the control group, the highly calcium-deficient diet+standard diet group showed many findings of bone resorption and clear decrease in bone volume. The low calcium-deficiency diet+standard diet group, as compared with the highly calcium-deficient diet+standard food group, showed marked findings of recovery of bone architecture and approximated the control group. V. Scanning electron microscope investigation The highly calcium-deficient diet+standard diet group, as compared with the control group, showed enlarged resorption sites of the bone adjacent to the periodontium. On the bone matrix, findings of increase of incomplete bone lacunae were seen on the whole mandibular bone. The low calcium-deficiency diet+standard diet group, as compared with the highly calcium-deficient diet+standard diet group, showed narrower width of the periodontium on the whole, and the bone architecture inside the bone showed recovery similar to the level in the control group. On the basis of the foregoing findings, intake of sufficient calcium and securing maximum bone volume in the growth process in the childhood stage to puberty would enable recovery of bone that may suffer calcium deficiency.

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Mucoepidermoid carcinoma (MEC) has been thought to be common malignant tumors of salivary gland. The biological characteristics, however, has been unclear especially in growth, fibrinolytic and angiogenic activity. Therefore, I established a new cell line (designated IT-2) derived from the metastatic submandibular lymph nodes of a patient with mucoepidermoid carcinoma arising in the mandibular alveolus. The biological characteristics of IT-2 were examined by the following methods ; 1) morphological study, 2) chromosomal analysis, 3) growth curve, 4) DNA synthetic activity affected by some growth factors or their antibodies, 5) angiogenic activity by measuring 3 H-thymidine incorporation of bovine capillary endothelial cells cultured by conditioned medium (CM) with or without neutralizing antibodies against angiogenic factors, 6) fibrinolytic activity by examination of mRNA expression for tissue type and urokinase type plasminogen activator (tPA and uPA) by Northern blot analysis, 7) checkerboard analysis of IT-2 cells migration induced by conditioned medium of human fibroblast cells (hFib-CM), 8) invasive activity into Type I collagen gel and basement menbrane (matrigel) induced by hFib-CM with or without neutralizing basic fibroblast growth factor antibody, 9) collagenolytic activity on gelatin zymography. Growth activity of IT-2 cells seemed to be dependent on epidermal growth factor and platelet derived growth factor-A chain. Angiogenic activity of CM was related to either basic fibroblast growth factor or vascular endothelial growth factor. While mRNA expression of uPA was detected, mRNA of tPA was not. Invasive and migrating activities were enhanced by hFib-CM. IT-2 cells produced matrix metalloproteinase 2 and 9. IT-2 cells seem to be the useful cell line for examination of biology of MEC.

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Male Wistar rats three-week-old corresponding to the human weaning period and fiveweek-old corresponding to the early childhood were given calcium deficient food and low calcium food, and bone debility was induced. Then food was changed to balanced standard food and the effect of food on ossification in the cartilage in the mandibular condyle at the growth stage was investigated. The results were as follows : I. Roentgenological findings As compared with the control groups of 9-week old and 11-week old rats, the low-calcium food group showed decrease in trabeculae and irregular running. As compared with the calcium deficient food group, the state of bone construction in the mandibular condyle cartilage was improved. In comparison of the 9-week old group with the 11-week old group, the 9-week old showed clear dense osseous layers, increase in trabeculae, and regularity. II. Histopathological findings As compared with the 9-week old and 11-week old control groups, in the low calcium food group, calcification of cartilage matrix in the chondrocyte layers and growth of the mandibular condyle were still restrained. As compared with the calcium deficient food group, in the low calcium food group, demarcation of chondrocyte layers became clear ; especially, maturing of chondrocytes (A) and promotion of chondroclasts (B) were seen ; calcification of cartilage matrix was active ; and the trabeculae in the subchondral bone formation zone became thick. In comparison of the 9-week old with the 11-week old, in the 11-week old, growth of the mandibular condyle was expedited. III. Scanning electron microscope findings The low calcium food group, as compared with the 9-week old and 11-week old groups, did not yet show sufficient recovery. As compared with the calcium deficient food group, however, demarcation of chondrocyte lacunae became clear ; fusion of clacospherites was strong ; bone resorption surfaces decreased in the subchondral bone formation zone ; smooth bone formation surfaces were formed actively ; and bone construction was expedited in the low calcium food group. In comparison of the 9-week old with the 11-week old, the 11-week old showed more calcification, more matured bone matrix, and active reconstruction of bone construction. IV. Hematological findings Serum Ca of the 9-week old control group showed high values. The low calcium food group of the 11-week old showed high GOT values. Between the 9-week old group and the 11-week old group, significant differences were found in serum Ca and ALP values between the control and calcium deficient food groups, and in serum P values between the calcium deficient food group and the low calcium food group On the basis of the foregoing findings, storing in the body sufficient calcium in the early childhood and balanced dietotherapy would expedite growth and bone construction of the mandibular condyle once fell into debility.

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In August to September of 1995 the authors conducted an anthropometry of the head and face and measurement of the dental arch on Chinese Liao-Ning (66 males and 83 females), and the results were discussed. Furthermore, the correlations between the measurements of head and face, and those of dental arches and palate height were studied. The main results obtained are as follows : 1) Head length : the mean value for the male is 181.0mm and for the female 170.4mm. Both belong to Middle type. 2) Head breadth : the mean value for the male is 155.3mm and for the female 151.6mm. Male belong to Middle type and females belong to Wide type. 3) Bizygomatic breadth : the mean value for the male is 140.3mm and for the female 133.5mm. Both belong to Middle type. 4) Morphological face height : the mean value for the male is 124.0mm and for the female 114.6mm. Both belong to High type. 5) The head-type of the Chinese Liao-Ning belongs to Hyperbrachycephalic type and the face-type to Leptoprosopic type. 6) Correlation : The significant positive correlation is noted between the morphological face height and lower dental arch length only in the male, while that between morphological face height and palate heght is noted in both male and female.

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Apoptosis is a crucial element in the behaviour of mammalian cells in many different situations. Firstly we show that the cell death of WEHI-231 cells induced by specific inhibitors of vacuolar type H^+-ATPases (V-ATPases), concanamycin A, occurs through apoptosis. CD40 is involved in regulating B cell activation and differentiation, including blocking apoptosis of germinal center of B cell. It is well known that ligation of CD40 by antibody or soluble CD40 ligand (CD40L) rescues anti-IgM-induced apoptotic cell death of murine WEHI-231 B lymphoma cells. In this study, we examined the role of CD40-CD40L interaction in controlling B cell apoptosis mediated by concanamycin A. Here we show that CD40 is linked to induction of Bcl-2 and Bcl-X_L proteins of WEHI-231 cells. CD40 ligation was found to rescue apoptotic cell death of WEHI-231 cells induced by concanamycin A as shown by a decrease in the proportion of fragmented DNA. In addition, gel electrophoresis of cellular DNA showed that CD40 ligation strongly suppressed concanamycin A-induced apoptosis in WEHI-231 cells. WEHI-231 cells overexpressing Bcl-2 were resistant to apoptosis induced by concanamycin A. However, overexpression of Bcl-X_L was unable to block concanamycin A-induced apoptosis in WEHI-231 cells. These results suggest that constitutive expression of Bcl-2, but not Bcl-X_L, induced by CD40 signaling in WEHI-231 cell is a key modulator in apoptotic cell death induced by V-ATPases inhibitor, concanamycin A.

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In order to demonstrate regulation of retrograde transport by synaptic inputs, we examined effects of transection of the lingual nerve on retrograde transport of HRP in the rat masseter and hypoglossal motoneurons. Rats were performed transection of the unilateral lingual nerve and then HRP was injected bilaterally into the masseter and tongue muscles. Sixteen hours later brainstems were removed and serial frozen 60 μm sections of brainstems were processed for HRP activity. The amount of transported HRP in the masseter and hypoglossal motoneurons was measured by using an image processing system. The number of HRP-positive cells was also counted. The values were compared between the control and transected sides. The transection of unilateral lingual nerve decreased significantly the retrograde transport of HRP in the ipsilateral hypoglossal motoneurons although certain change in the masseter motoneurons was not detected.

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The purpose of this survey was to compensate for the lack of information on the relationship between saliva and oral malodor from the epidemiological point of view, and to get more details about periodontal factors. 408 people aged 35 to 64 were measured for oral malodor using a portable sulfide monitor detecting the volatile sulfur compounds (VSC). In addition, tongue coating (TC), hemoglobin concentration in saliva, stimulated salivary flow rate and buffer effect of saliva were also assessed. Periodontal conditions including pocket probing depth, loss of attachment, and bleeding on probing (BOP) were assessed. Before clinical examination, subjects were interviewed about their medical history, self-diagnosis of bad breath, smoking habit and frequency of tooth brushing per day. Correlation was found between hemoglobin concentration in saliva and periodontal conditions. 37% of subjects showed the VSC values above the suggested socially acceptable limit (75ppb). There were significant differences observed in VSC values of hemoglobin concentration in saliva, with or without BOP or TC. Correlation was found between VSC and BOP, and VSC and TC. The stepwise multiple regression between VSC and parameters was analyzed. TC was found to have significant influence. The stepwise multiple regression between VSC and parameters except for TC was analyzed. Hemoglobin concentration in saliva was found to have significant influence. In conclusion, VSC was influenced by BOP, a parameter for inflammation of periodontal tissue, and especially TC. Saliva didn't have a great influence on VSC.

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It is practically difficult to properly seat the full cast crown on the prepared tooth by means of a luting cement. We have devised the double-crown system consisting of an inner crown and an outer crown to aid better seating of the crown restoration. It can minimize the elevation of the inner crown at the margin, because its open occlusal plane allows the cement slurry to easily overflow. Although the inner crown should be very thin, it is not easy to fabricate it precisely by casting. In this study, therefore, the application of the sintering procedure by powder metallurgy to the formation of the inner crown was evaluated in terms of marginal fit before and after cementation and surface aspect. The results obtained were as follows : 1. There were no significant differences in the try-in marginal fit between the full cast crown, cast inner crown and sintered inner crown. 2. Both the cast and sintered inner crowns showed a small elevation at their margins by cementation, while significantly larger elevation was found in the cast full crown. 3. The surface roughness test and SEM observation revealed no obvious differences in the metal surface aspect between the sintering and casting method procedures. It was suggested from the foregoing results that the powder metallurgy could be effectively available for easily making the inner crown in the double-crown system.

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Prostaglandin E_2 (PGE_2), interleukin-1 (IL-1), and lipopolysaccharide (LPS) are the candidates for the inducers of osteoclastic bone resorption accompanied with periodontal disease. The purpose of this paper is to show the effect of these substances on osteoclast formation in cell culture. Mouse bone marrow cells were prepared, and the cells were cultured with IL-1 and LPS in the presence of PGE_2. After the culture, tartrate-resistant acid phosphatase positive cells were scored as osteoclasts. The results obtained were as follows : 1. IL-1 increased the multinuclear osteoclast formation in the culture in the presence of 0.1μM PGE_2. 2. The multinuclear osteoclast formation was increased in the culture with IL-1 added in the second half culture period as much as in the culture with the addition throughout the culture period. The multinuclear osteoclast formation decreased in the culture with IL-1 added in the first half culture period. 3. Mononuclear osteoclast formation was increased in the culture with LPS added in the first half period of the culture with 0.1μM PGE_2. Multinuclear osteoclast formation was increased by LPS added in the second half period with 0.1μM PGE_2. 4. Mean nuclear number of multinuclear osteoclasts formed by IL-1 or LPS in the presence of 0.1μM PGE_2 was much higher than that by 0.1μM PGE_2 alone. Mean nuclear number of multinuclear osteoclasts by 1μM PGE_2 alone was much less than that by 0.1μM PGE_2. These results show that osteoclasts are formed by IL-1 and LPS in the presence of low concentration of PGE_2. This suggests the possibility that PGE_2, IL-1 and LPS induce or enhance bone resorption, through osteoclast formation, accompanied with periodontal disease.

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In the recent reports, the tonsillar instillation of sheep red blood cells was an effective method to induce specific IgA in saliva. The level of the specific antibody was much higher than those of oral and nasal administration. The purpose of this study is to examine that the instillation of whole cell suspension of formalin-killed Streptococcus mutans (S. mutans) or Streptococcus sobrinus (S. sobrinus) into the palatine tonsil may induce specific antibody in saliva. In the 6th week after the instillation, agglutination titers of saliva and blood plasma to S. mutans and S. sobrinus increased significantly. Specific IgA concentration in saliva after the instillation also increased to 1.5μg/ml in the 6th week. The antibodies in saliva induced by the instillation of S. mutans and S. sobrinus did not cross-react with other streptococci. The antibodies only reacted with some mutans streptococci, including the instilled bacteria and those who are seorogically related with the instilled one. Thus, the results show that the tonsillar instillation is effective in immunization of mutans streptococci, and the instillation may be useful for preventive vaccination to dental caries.

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Caries is multi-etiogenic disease affected by various factors, especially dietary habit. A deluge of processed food and fast food has caused drastic changes in diet for contemporary children. This investigation was undertaken with 126 children aged from six to fifteen years old who received treatment in the department of pediatric dentistry, Kyushu Dental College Hospital. The investigation included taking questionnaire and examination of the oral cavity in order to observe the effect of dietary habit on immature permanent teeth. The results were as follows : 1. Most children had a regular schedule for meals, but not for snack in more than a half of them. The prevalence of caries in these children eating snack adlibitium was high. 2. Although the frequency of eating-out was low, processed food was used occasionally. 3. 103 children indicated their preference for sweets. Of these, 45 said that they had sweets every day. 4. 54 children were careful about eating sweets. 77 children knew about low-and noncariogenic sweetening but the frequency of its use was low. 5. As to drinks, most children had tea and milk with a third to a quarter of them drinking sport drink, fruit beverages, or carbonated drink more than twice or three times a week. A high frequency was shown for the use of no sugar in drinks among the caries-free children. 6. Most children indicated "a little" or "average" in response to the inquiry about their likes and dislikes. Vegetables were high proportion among the itmes disliked by children. However, about a half of the caries-free children indicated their liking for vagetables. 7. No definite relationship was found among adhesion of plaque, cariosity, and dietary habit. The foregoing findings show the characteristics of children's dietary habit at the time of the eruption of the immature permenent teeth. It is necessary to give guidance on food intake on the basis of these tendencies.

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