We examined the effects of various beverages on dental enamel. 1) The pH of 116 brands of beverages except for coffee drinks, milk tea and tea drinks was strongly acidic ranging from 2.3-4.9. 2) Teeth (central incisors) were immersed in 10 brands of beverages and examined by scanning electron microscopy. Decalcification of dental enamel was observed after 1 minute of immersion in beverages with a pH of 2.3-3.7. 3) When teeth were immersed in 1mM, 10mM or 100mM lactic acid and hydrochloric acid and examined by scanning electron microscopy, decalcification of dental enamel was observed in both 1mM lactic acid and hydrochloric acid. The degree of decalcification of dental enamel was stronger in hydrochloric acid than in lactic acid. These findings suggest that the decalcification of dental enamel occurs in strongly acidic beverages with a low pH.

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The purpose of this study was to clarify the relationship between the fluoride sensitivity (F sensitivity) and the cell cycle in cultured human gingval fibroblasts and carcinoma cells. The following results were obtained: 1. The activity of cell growth and DNA synthesis in decreasing order was FGF-4-Y cells (fetal gingiva, PDL ; 10-15), HeLa S3 cells, KU-2 cells (carcinoma) >FGF-4-E cells (PDL ; 35-40) >GF-5-Y cells, GF-12-Y cells (adult gingiva, PDL; 10-15) >GF-5-E cells, GF-12-E cells (PDL ; 35-40). 2. The F sensitivity estimated by measuring the F concentration necessary to inhibit the cell growth and the DNA synthesis was the highest in FGF-4-Y cells, HeLa Ss cells, and KU-2 cells, and was the lowest in GF-5-E cells, and GF-12-E cells. 3. The flow cytometric study showed that although the ratio of number of cells in S phase to cells in G_0/G_1 Gi phase was different among cell types, the rateio of both cells in S phase and 4. FGF-4-cells, HeLa S3 cells, and KU-2 cells, which had higher of cell growth and DNA synthesis, had a higher rateio of cell numbers in S phase and had a lower rateio of cell numbers in G_0/G_1 phase. GF-5-E cells and GF-12-E cells, which had lower activity of those potentials, had a lower rateio of cell numbers in S phase and a higher rateio of cell numbers in G_0/G_1 phase. These results indicate that the F sentitivity of cells cultured under general conditions in probably related to the ratio of number of cells in S phase to cells in G_0/G_1 phase.

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Iron-deficiency anemia is said be the most frequent type of anemia. This study used rats suffering from experimental iron-deficiency anemia to estimate the effect of fluoride prescription on hard tissue using metabolic efficiency rate. 4 weeks age rats were divided into 2 experimental groups. Each was fed an iron deficient diet for 4 weeks with or without addition of 2mg/day fluoride. After that, both groups were fed an ordinary diet for 1 week. The results were as follows. 1. Iron-deficiency rats had lower weight increase than controls through the entire experiment. The fluoride had no effect. 2. The Hb value after the first 4 weeks of iron-deficient diet significantly increased with fluoride intake but had no relation to iron intake. The Ht value was not influenced by fluoride intake. 3. Iron levels in the femur and mandible after the first 5 weeks higher than in the controls. 4. Iron level in hard tissue was not affected by fluoride intake in any material. 5. Fluoride level in molar dentin was less than half of that in the femur due to the low metabolic state. 6. Concentration of blood plasma and iron in blood plasma in both iron-deficient and iron-non-deficient rats were not affected by fluoride intake.

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Metallothionein (MT) is a low molecular mass protein inducible by heavy metals such as cadmium (Cd), zinc, and copper. Because the kidney is the critical organ in Cd poisoning, the effect of Cd on kidney cells has been well investigated in vitro. Chronic exposure of Cd also leads to a golden yellow discoloration of the teeth. However, the effect of Cd on oral soft tissues has not been fully explored. The purpose of this study was to investigate the effect of Cd on human gingival keratinocytes. Keratinocytes were derived from human adult gingiva samples using an explant method. Cells were grown in serum free medium (SFM, Gibco) at 37℃ in a humidified atmosphere of 5% Co_2-95% air. To expose cells to Cd, cells were cultured in medium containing various concentrations of Cd as CdCh. The growth and DNA synthesis of cells were determined to evaluate the effects of Cd. To study the induction of MT, the incorporation of 85S-cysteine into cells was measured. MT was measured by ELISA. DNA synthesis was reduced by 10^<-3> and 10^<-2>mM CdCl_2. The incorporation of <35>^S-cysteine was enhanced by 10^<-6>, 10^<-5>, 10<-4>mM CdC_2. The levels of MT were higher in cells exposed to 10^<-6> and 10^<-5> Mm CdC_2 than in control cells. The results show that MT is induced in human gingival keratinocytes by exposure of the cells of Cd in vitro.

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The shrinkage of demineralized enamel and dentine lesions due to dessication was evaluated, The lesions were formed in 6 % carboxymethylcellulose containing 0.1mol/L lactate (pH 5.0) for 10 days. The degree of shrinkage was determined with a magnescale (LU10A 1G5P, Sony), the difference between the resin references and lesion surfaces was measured in μm for 24 hours. The shrinkage of demineralized enamel samples under dessicating conditions ranged from 3 μm to 5μm and was always greater than under wet conditions. The relative shrinkage of the enamel lesions was approximately 5 %. In demineralized dentine samples, the shrinkage was nearly 20μm after 15 minutes exposure to air (p<0.01). The tendency of the shrinkage showed a similar pattern. The relative shrinkage of the dentine lesions was approximately 25%. The shrinkage of dentine lesions was 5 times greater than that of enamel lesions. However, a significant recovery of the shrinkage in dentine lesions occured following 24 hours exposure to wet conditions. This investigation suggested that the shrinkage of demineralized dentine sections during micro-radiography can be avoided by simply wrapping the sections with polyester sheet.

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The purpose of this study was to learn the relationship between tooth crowding, dental plaque accumulation, and gingivitis using various indices. 173 young adults were investigated for malocclusion, oral hygiene, and gingival status using the Orthodontic Treatment Priority Index (TPI), Occlusal Index (OI), Occlusion Feature Index (OFI), Malalignment Index (MI), Plaque Scoring System (PSS), Debris Index (DI), and PMA Index (PMA). Correlation with each index was evaluated and screening level was set for identifying high risk group of plaque accumulation and gingivitis. The sample rate with normal occlusion was 8.7% and no crowding ratio was 20.2 %. All of the sample had plaque accumulation and 52 % the of sample had gingivitis. The value of MI and PSS in males was significantly higher than in females. There was significant internal correlation among 4 indices. MI had significant correlation with DI and PMA. When the sample with a DI score of less than 2 was set as no plaque accumulation, a screening level with a MI score of less than 2 was best. The same result was found when 0 PMA score was set as normal gingival status. When DI was treated as an objective variable and rotation and displacement by MI were treated as explanatory variable, multiple regression analysis indicated that rotation in males and displacement in females had a higher relation with the DI score. When the PMA scorewas treated as an objective variable, the same analysis indicated that displacement in male and females had significant relation with the DI score. Therefore, teeth crowding has significant correlation with plaque accumulation and gingivitis.

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Since the Japanese word ha (tooth) is a basic word for persons concerned with dentistry, I became interested in its uses in folklore and chose the complete works of Kunio Yanagita, a well-known folklorist, I made an index of his works. I found 30 words that concerned with the word ha. I classified them into the various areas of folklore and was able to grasp the situations in which they were used. In the future, indexing of texts will be facilitated by the use of computers.

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In a previous study we reported that we made self-administered questionnaires that consisted of 6 scales and 48 questions for diagnosis and health education considering several factors which influence periodontal diseases. The present study examined the reliability and validity on this questionnaire in different population. The reliability and the stability was examined by factor analysis (Varimax rotation method) and Cronbach's a reliability coefficient, and the validity was checked by the relations between the questionnaire and the oral health condition, PMA or presence of periodontal pockets from CPITN criteria. Each question included in a scale aopropriately converged into one or two factors in different population, and the reliability coefficient in each scale also showed comparatively high values. . Accordingly, the stability and the reliability that a scale in the questionnaire had to get were kept up. The discriminant analysis using presence of periodontal pocket as dependent variables indicated that each of the scales except for "oral health condition" scale as an independent variable did not contribute much to the distinction of periodontal disease, and the percentage of cases correctly classified (65.3 %) was not sufficient. Therefore, the inventory using this questionnaire was less valid. However, there was still a possibility that we can use this questionnaire in health education considering multi-factors, because there is statistically significant correlation among several scales. It is necessary to reconsider each question in the scale and set up new scales in order to improve its diagnostic ability and make a ideal questionnaire.

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The purpose of this study was to determine whether the level of cariogenic bacteria in saliva was related to clearance ability of sucrose from the oral cavity and the salivary flow rate. Subjects were 43 dental college students. In this study, it was shown that sucrose clearance ability had a significant relation to the number of mutans streptcocci in saliva (p<0.001). On the other hand, sucrose clearance was not related to the number of anaerobes, lactobacilli, or streptococci. A significant negative correlation was found between resting salivary flow rate and the level in mutans streptococci (p<0.01). Change of mutans streptococci counts was influenced by sucrose clearance ability that malinly originated in the resting salivary flow. These findings suggest that subjects with a low sucrose clearance may have a high risk for dental caries in view of host and parasite factors.

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This study was made from 1980 to 1989 regarding holiday dental clinical service by the Yamato Dental Association. The number of outpatients was 5086, consisting of 3045 men and 2041 women during 10 years. 65.6 percent of the outpatients came from Yamato city, and 19.2 percent from Ayase city. In monthly distribution, 18.6 percent of outpatients visited clinics in December, followed by January and May. The highest number of outpatients, was in their thirties (22.7 percent) and the second highest was in their twenties (18.6 percent) 37.6 percent of the outpatients were a members of socio-medical insurance. The chief complaint and the main disease regarded the first molar in the lower iaw, was periodontitis apicalis, followed by endodontic treatment. The holiday dental clinical service was known by 60 percent of inhabitant who answered the questionnaire, and only 2 percent of them had visited this clinic for emergency service.

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Analysis of 25 brands of commercial bottled water and 21 brands of canned tea was carried out to obtain information on their fluoride concentrations. In 13 of 17 domestic Japanese brands of bottled water, fluoride concentration was less than 0.1ppm, and the maximum value was 0.76ppm. In 4 of 8 imported brands of bottled water, fluoride concentration was less than 0.1ppm, and the maximum value was 0.70ppm. In domestic bottled water, Ca content was 1.14-58.81mg/l; and Mg content was 0.70-7.93mg/l. In imported bottled water, Ca content was 8.13-88.78 mg/l; and Mg content was 1.07-25.86 mg/l. Several kinds of tea and other infusion beverages were investigated. Fluoride concentration was highest in the coarse tea called ban-cha: 1.29ppm. In green tea, it was 0.53-0.90ppm. In oolong tea, it was 0.75-1.50ppm. In black tea, it was 0.47-2.19 pm. In barley tea and the infusion known as duzhong tea, it was less than 0.1ppm. These results clearly show that the amount of fluoride and other minerals in bottled water and canned infusion beverages differ from brand to brand. Further clarification of the ingredients of these beverages is needed to determine their efficacy as sources of fluoride and minerals.

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For the purpose of re-examination of Koch's Dropping Method (Koch method) which is simple and useful for continuative management of airborne bacteria in a dental hospital, climatic, environmental and airborne bacteria were measured using an SY type pinhole sampler method (SY method) and a Koch method for 3 years (1988, 1990, 1991) in five clinics at Asahi University dental hospital. Analytical points were as follows : 1. Floating airborne bacteria colonies (SY method) were estimated with the climatic and environmental factors, and dropping airborne bacteria colonies (Koch method) by multipule regression analysis. The effect of addition of dropping airborne bacteria colonies on the accuracy of the equation of multipule regression was evaluated. 2. A correlation between the number of airborne bacteria by SY method and by Koch method was made, and a predicted section of a value of dropping airborne bacteria colonies corresponding to the clean standard value (0.2 CFU//) of floating airborne bacteria colonies was estimated. The following results were obtained, 1. The addition of dropping bacteria colonies to floating airborne bacteria colonies increased the estimated accuracy of the equation of multipule regression. It is concluded that the Koch method is useful for simple air pollution monitoring. 2. The correlation between the number of airborne bacteria obtained by the SY method and by the Koch method had a high coefficient of 0.439-0.606 (p<0.01). The estimated value of dropping airborne bacterial colonies corresponding to the clean standard value of floating airborne bacterial colonies was 0.755-1.333 CFU and the upper limit of a predicted section with 95% reliability was 2.161-4.116 CFU. Therefore, the clean standard value of dropping airborne bacterial colonies was about 4.1 CFU, and the Koch method is useful for simple air pollution screening. Thus, we confirmed that the Koch method is useful for continuative management of airborne bacteria in a dental hospital.

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A longitudinal study was carried out to evaluate the trends of the mean DMFT of 12-year-olds in areas (73 municipalities in total) focusing the effects on caries prevention by school-based fluoride mouthrinsing (FMR) in Niigata Prefecture. The data of caries prevalence from 1982 through 1993 were obtained from the Community Organization Data Base (CODE). The subject areas were divided into four groups : F ['70] group-the municipalities in which the FMR was began before 1977, F [82-85] group-the municipalities in which the FMR was began between 1982 and 1985, F [86] group-the municipalities in which the FMR was began in 1986, and F [-] group-the municipalities in which the FMR had never been implemented. In the F [-] group and F ['70] group, caries prevalence decreased slightly but steadily. The DMFT of the F ['70] group was markedly lower than that of the F [-] group through all the study term. In the F [82-85] group and F [86] group, the DMFT significantly decreased year by year since the FMR was began. Correcting for the natural change in DMFT, the percentage of the difference in the DMFT between baseline and 1993 was 45.1 % in the F [82-85] group, and 31.1 % in the F [86] group. In conclusion, the effects on caries prevention by the FMR program have been clearly recognized at the community level.

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The aim of this study was to make a health care plan for pregnant women, by investigating periodontal disease prevalence and treatment needs in pregnant women. Oral examination was carried out using the "CPITN", indices for gingivitis, periodontitis, and calculus deposition and the "VPI" by inspection. A total of 1,612 subjects participated, all pregnant women who received oral examinations while attending classes for new mothers at health centers from 1990 to 1993. The average number of weeks into pregnancy for the subjects was 19.6 weeks. The average age of the women was 26.8 years. Most of the pregnant women, of all CPITN age groups, were coded 2, and a small fraction were coded 3 or 4, 94.2 % of these were found to be in need of some treatment. Almost all were aged 20〜29 years, and they were classified by the number of pregnancy weeks, and divided into 10 categories. 1. CPITN code 2 was most common during all pregant stages, especially at 23〜25 weeks. 2. Gingivitis G+ G++ G+++ also tended to increase at 23〜25 weeks of pregnancy. 3. Although the ratio of VPI Fair and Poor become high during weeks 23〜25 of pregnancy, VPI and degree of calculus appeared to recover in the later stages of pregnancy. 4. The ratio of CPITN code 2 and Cal+ showed the same tendency during the pregnancy stages. 5. The ratio of code 3 and 4 was very low, and there was no change during the pregnant stages. That is, it was comfirmed that gingivitis was not worsened by pregnancy. 6. Gingivitis during pregnancy showed a profound relationship between VPI and calculus, and it seemed to be affected by the condition of oral hygiene. In conclusion, to prevent the development of gingivitis especially during the intermediate stages of pregnancy, oral examinations at an early stage and instructions in oral hygiene are very important.

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The aim of this work was to obtain further information about the mechanisms of fluoride profiles in cementum. Fluoride was administrated to rats at varying doses (0, 50, l00ppmF in drinking water) and for different lengths of time (4, 13 and 25 weeks). A series of fluoride concentrations across the full thickness of molar cementum in rats were measured by means of an abrasive microsampling technique. The average fluoride concentrations in cementum increased significantly with each increasing dose and length of fluoride administration. The relative reductions of the average fluoride concentrations were 94.2〜36.5% at 50ppmF and 62.2〜49.0 % at 100ppmF in the outer layers (1〜60μm) and 91.5〜24.1 % at 50ppmF and 74.1〜7.6% at 100ppmF in the middle (61〜120μm) layers of the cementum after stopping fluoride administrations. The reduction rates were more related to the duration of cessation than to the fluoride concentrations in drinking water or regions of cementum. Two possible reasons are that the new cementum formation occurred after the withdrawal of fluoride administrations and that some fluoride release occurred from cementum surfaces when the fluoride supply was stopped. I conclude that the fluoride concentration in rat molar cementum were related to the length of fluoride cessation and regions of cementum.

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To investigate how the school dental health examination and post-examination care are actually carried out, we sent questionnaires to primary and junior high schools throughout the nation. A total of 398 schools responded to our survey. The found that all the schools conduct dental health examination on a regular basis, and that, in 90 % of the schools infirmarians receive instructions and guidance from school dentists based on the results of examinations. Most of the schools tell students and their parents about the examination results and, if necessary, advise them to go to the dentist. However, the survey found that many schools do not do anything about students who were absent from school on the very day of the examination. As many as 50 % of the junior high schools had this attitude. Nearly half of the school principals and upwards of 50 % of class teachers did not know of school dentists instractions. Again, over 50 % of the schools were not interested in epidemiological analysis of dental examination results. More than 30 % of the schools did not inform the school dentists of the final analyses of the data. Our findings suggested that school dental health examination are conducted only as part of mandatory health management in many schools. Few schools have a health program harmoniously incorporating health education and health management with dental hygiene. In this paper, we discuss what schools should do and what school dentists activities should be, on the basis of our findings.

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