The purpose of this study was to evaluate the possibility of use for fluoride topical treatment of a dilute ammonium fluoride solution, in which the fluoride concentration was 1/5 times lower than that of APF solution.
Human enamel powder (200 mesh passed) was treated with solutions of NH₄F (1, 800ppmF^-, pH 3.4) and APF (9, 000ppmF^-, pH 3.4) for 5min. at 37°C. A part of the specimen was washed with 1M KOH solution for 72 hours.
In experiment 1, fluoride uptake by enamel powder was determined by means of chemical analysis and identification of reaction products using X-ray diffractometry.
In experiment 2, the relationship between CaF₂ formation and release into synthetic saliva, the increase of permanently bound fluoride, and acid solubility in enamel were observed by means of chemical analysis and X-ray diffractometry. In order to identify fluorapatite formation, variance of line profile, peak shift and a-axis lattice parameter of enamel apatite were examined using X-ray diffractometry. Crystallite size and β-TCP formation during heating at 1, 000°C were determined to evaluate the crystallinity of enamel apatite. The acid solubility test was performed by messuring calcium released into 0.4M acetate buffer (pH 4.0) from enamel.
In experiment 3, scanning electron microscopic observations were made and the infrared spectra of the enamel powder were studied.
The following results were obtained.
The fluoride uptake of NH4F treated enamel was higher than that of APF treated enamel. X-ray diffractometry showed that CaF₂ was formed in the experimental groups, and a large amount of CaF₂ with high crystallinity was formed in NH4F treated enamel (experiment 1).
CaF₂ formed in emanel was released into synthetic saliva and permanently bound fluoride increased with time. Hydroxyfluorapatite was indicated in the line profile of fluoride-treated enamel powder. Peak shift and decrease of the a-axis lattice parameter also showed the formation of hydroxyfluorapatite. The amount of β-TCP produced by heating in fluoride-treated enamel decreased in enamel immersed in synthetic saliva, and the crystallinity of enamel apatite was increased. The acid solubility test proved an acquisition of high acid resistance by the enamel powder treated with fluoride (experiment 2).
Scanning electron microscopic observation of enamel powder treated with NH4F revealed larger deposits of crystalline materials than that treated with APF. Infrared spectra of enamel powder treated with fluoride revealed the formation of fluorapatite (experiment 3).
I concluded that a dilute ammonium fluoride solution (1, 800ppmF^-, pH 3.4), in which fluoride concentration was 1/5 times of APF solution, had the same effect on enamel powder as conventional APF solution. I suggest that a dilute ammonium fluoride solution is useful as safe agent for fluoride topical application in clinical use.

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Sorbose is a 2-ketohexose, differing from fructose in configuration at C-3 and C-4. It is obtained through a cultivation of sorbitol and Gluconobacter (Acetobacter) suboxydans. The sugar is about 80-90% as sweet as sucrose and is also non-hygroscopic. The effect of sorbose on the cariogenicity of mutans streptococci (serotype a-h) and certain oral microorganisms was studied. Sorbose was not utilized as a substrate for the growth, lactic acid production, and plaque formation of mutans streptococci (serotype a-h). It did not serve as a substrate for cellular aggregation of mutans streptococci and was not utilized in water-insoluble glucan synthesis and cellular adherence by glucosyltransferase from Streptococcus mutans PS-14 (c) or S. sobrinus 6715 (g). Sorbose was also not utilized for the growth and lactic acid production of certain oral microorganisms although some growth was seen with Lactobacillus casei and L. acidophilus. Two groups of SPF SD rats infected with S. mutans PS-14 were fed with a diet containing 30% sorbose and 30% sucrose for 58 days. A significantly (p<0.01) lower caries score (mean±SE; 17.5±2.0) was obtained in the rats fed with a diet containing 30% sorbose than in the rats fed with a diet containing 30% sucrose (82.1±4.4). The caries inhibition rate was 78.7%.

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The aim of this study was to develop a new classification of carious incidence patterns in children. The subjects were 702 children aged 18/19 months and 378 aged 24/25 months. The children's teeth were examined and they were grouped by their carious tooth types at 40/41 months of age the mean dmft and mean dmfs were compared between groups. The following results were obtained.
The children with caries at the age of 18/19 months could be divided into two classes, i. e., children who had carious teeth in only upper anteriors (class 1-A) and those who had carious teeth in molars or lower anteriors (class 1-B). The children with caries at the age of 24/25 months could be divided into four classes, i. e., children who had carious teeth in only the upper incisors or lower molars (class 2-A), those who had carious teeth in the upper cuspids or upper molars but not in the lower anteriors (class 2-B), those who had carious teeth in the lower incisors but not in the lower cuspids (class 2-C), and those who had carious teeth in the lower cuspids (class 2-D).
When the classifications were applied and the carious scores compared between classes at the age of 40/41 months, the children of class 1-A had statistically lower carious scores than those of class 1-B. The children of class 2-A had the lowest carious scores, and those of class 2-B, class 2-C, and class 2-D had significantly more carious teeth in ascending order.
From these results, we suggest that the newly proposed carious incidence patterns of children aged 18/19 months or 24/25 months is useful for predisting the caries prevalence at the age of 40/41 months.

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In view of the high prevalaence of periodontal disease, it is important for us to detect and treat the disease as early as we can. Therefore, using salivary occult blood test paper (Salivaster Bld), I examined gingivitis screening in a group of 117 employees of a company (average age 42.6 years). The results of the phenolphthalin method and the Salivaster Bld were the same in both the conventional 5-step evaluation and the 3-step evaluation. Therefore, the 3-step method is suitable for gingivitis screening, and gargled liquid should be used as specimens because its evaluation is simple and is subject to in mass applications.
In most cases, a low correlation was noted between Salivaster Bld and each of the indexes indicative of the condition of gingivitis and periodontitis. However, since a high correlation (0.3-0.7) was noted with many of the indexes for a group of subjects up to their thirties, compared with lower values noted for older subjects, the application of Salivaster Bld appeared to be effective for those agegroups which have a high incidence of gingivitis.
No sex difference was noted in the indexes.

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The purpose of this study was to determine the percentile curves for the numbers of permanent teeth and to examine their significance in oral health promotion and their utilization in oral health education for adults and elderly people.
The percentile curves were estimated by cumulative frequency distribution of missing permanent teeth from 10, 249 subjects aged 10-79yr, reported by the National Survey of Dental Disease (Japan, 1987). The results were as follows.
1) Age differences in missing teeth were observed clearly on the rate of persons with a few numbers of missing teeth (less than approximately 5 teeth, Fig. 1) and high percentile levels (more than 50 percentile level, Fig. 2) when the subjects were divided into two age groups of less or more than 40-44years.
2) Regression analysis showed that the percentile values of missing permanent teeth were in conformity with an exponential curve (Fig. 2).
3) Percentile curves for the numbers of permanent teeth were widely distributed and divided into the areas between 3-97 percentile curves with similar intervals (Fig. 3).
4) The percentile curves showed profiles similar to the survival rate curves of human life and reflected suitably the trends of aging in oral health status and the present distribution in permanent dentition.
These results show that the percentile curves for the numbers of permanent teeth are a useful index for planning and evaluting oral health promotion and are an effective parameter in the counselling for oral health.

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The biochemical and serological characteristics of Streptococcus salivarius were investigated. Strains used included S. salivarius ATCC 7073, ATCC 9222, ATCC 9758, ATCC 9759, ATCC 13419, ATCC 25975, ATCC 27945 and ATCC 31067 as reference strains, and 72 oral isolates from healthy adults and 6 oral isolates from patients with Behcet's disease. Eight reference strains and all except 4 of our 78 isolates of S. salivarius were biochemically classified into 4 biotypes, A to D, according to their carbohydrate fermentation profiles. S. salivarius was also serologically heterogenous, and 4 serotypes were indentified by immunodiffusion in agar gel with antigens extracted with nitrous acid by Kholy's method and anti-sera against whole cells of S. salivarius. Although 8 reference strains could be classified as each of 4 serotypes, all of our isolates belonged to either serotype II or III and none belonged to serotype I or IV.
This study also showed that biochemical and serological characteristics of S. salivarius isolates from patients with Behcet's disease were not distinct from them of S. salivarius isolates from healthy adults, and it seemed that S. salivarius isolates from the two origins were indistinguishable.

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A T cell line (CCRF-CEM cells) derived from human acute lymphocytic leukemia was cultured in a medium containing 0.26mM fluoride for 125 (CEM-5F-25 cells), 250 (CEM-5F-50 cells) or 375 (CEM-5F-75 cells) days serially.
The growth, DNA synthesis, protein synthesis and surface antigens of the cells were measured.
1) There were not any differences in growth pattern between CEM cells and fluoride treated cells.
2) The 24hr treatment with 0.26mM fluoride enhanced DNA synthesis and protein synthesis to 122% and 110% of the control, respectively. However, these potentials of cells were not affected by treatment of fluoride with 125, 250 and 375 days.
3) Surface antigens on cells determined in this study were not affected by treatment with fluoride for 125, 250 and 375 days.
In conclusion, the results suggested that the long-term treatment (375 days) with 0.26mM fluoride did not inhibit the function of CCRF-CEM cells.

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