Nine years ago, we began giving oral health examinations with oral health consultations for employees at various companies in west Tokyo. At present, we examine about 60, 000 persons every year. From the data from 9 companies which we visited every year, we obtained the following results.
1. The mean number of untreated teeth decreased each year. This is an effect of the examination and recommended treatment.
2. The complaints of foul breath and bleeding or uncomfortable feeling in the gums decreased with each successive year.
3. The periodontal diseases including gingivitis decreased and oral hygiene was improved. We consider this an effect of the consultation and oral examination.
4. Persons who brushed their teeth frequently had better oral health than those who brushed less frequently. We concluded that the oral examination and consultation for employees at companies contributed to their oral health.

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A dental health examination of 908 inhabitants, 40 years of age and over, of Ueno, Okinawa, was carried out in concurrence with a general health examination.
This study is deals especially with dental caries and general diseases. The prevalence of dental caries was 81.8%, and the prevalence of untreated dental caries was 42.6%, and these decreased with advancing age. This tendency was particularly marked in those aged 70 years and over, and also indicated the influence of the high rate of missing teeth in inhabitants of this age. The ratio of carious teeth, the ratio of untreated teeth, and the ratio of missing teeth increased with advancing age. This tendency was particularly marked in those aged 80 years and over.
Some general diseases were present in 55.5% of the inhabitants examined, 36.4% of whom were suffering from two diseases or more. Particularly in subjects aged 60 years and over, the prevalence was as high as 67.6%, 58.9% of which were evaluated as requiring treatment. The incidence of locomotorial, connective tissue and cardiovascular diseases, and nervous, sensory diseases was high, and 28.1% of the sujects with carious teeth requiring treatment were also suffering from gneral diseases for which treatment was necessary. The incidence of general complications in the subjects aged 60 years and over was particularly high, 37.7%. These results suggest that it is necessary to formulate a new medical examination system that will be able to accomodate general conditions in the aged for the establishment of dental science and treatment in this group.

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Epidemiological analyses in connection with DMFT index and length of stay were performed on 948 subjects receiving further dental examinations beyond an initial admission examination among 1107 mentally retarded individuals who were admitted to the Niigata Prefectural Institute of Total Training for the Mentally Retarded, Colony Niigata Shiroiwa-no-Sato during the years 1971-1988.
(1) The 948 subjects were distributed into 3 groups based on the length of stay, i. e., 1-5, 6-10, and 11 years and longer. The DMFT index showed a tendency of increasing with age in all 3 groups. The DT index showed values blow 2.46 in 15-year-olds and over, and decreased in longer stays. The FT index in all of the 3 groups classified by length of stay was in the range of 3.31-7.60 in almost all age groups (over 15 years of age). The MT index was 1.66-3.17 in 20-24-year-olds and 2.00-11.00 for subjects in their 40's in all of the 3 groups classified by length of stay.
(2) In the DMFT index by sex in 1971-1975 newcomers, females had a higher index than males, and it was the same in 1976-1981. This difference may disappear as the length of stay increased, and the difference in the MT index by sex, also higher in females, was gone within 5 years of admission. The difference in the DMFT index by sex in 1976-1981 newcomers disappeared within 5 years. No difference was noted afterwards in 1982-1988 newcomers.
(3) While the DMFT index remained stable, a decrease in the DT index and a corresponding increase in the FT index was seen in females as the length of stay increased. In males the DMFT index was raised by an increase in the FT index as the length of stay increased.
However, this increase in the FT index immediately after admission in males was accompanied by gradual decreases in the DT and MT indices and consequently by a decrease in the DMFT index in 1971-1975 newcomers when they stayed longer than 6 years, as compared to the data of 1977-1988 admissions as a control.

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The purpose of this study was to examine the glaze-like substance which formed on enamel surface treated with titanium fluoride compounds.
Specimens of intact enamel and powdered enamel were treated with solutions of (NH₄) ₂TiF₆, TiCl₃, APF, NH₄F, or TiCl₃ followed by treatment with APF solution and 48 hour washing with 1M KOH solution. Fluoride concentration of each solution was 0.9%, and pH was 3.4, except for TiCl₃ (4000ppmTi, pH 1.0). Intact enamel was observed by scanning electron microscopy (SEM), electron microprobe analysis (EPMA), and microbeam X-ray diffractometry. In the experiments with powdered enamel, the fluoride uptake and retention in enamel were studied by chemical analysis, and X-ray diffraction analysis was performed.
SEM images showed that the surfaces treated with (NH₄) ₂TiF₆ solution had a tenacious coating which remained after washing. However, SEM image of cross sections did not show the existence of a glaze layer and only enamel apatite was detected by microbean X-ray diffractometry. TiCl₃ treatment and TiCl₃ pretreatment followed by APF treatment resulted in enamel etching, and reaction products were deposited on the enamel surface which were totally removed by washing. No glaze-like substance was detected. APF and NH₄F treatments formed a large amount of CaF₂, which was totally removed by washing. EPMA showed significant retention of fluoride and titanium at the depth of 10μm in (NH₄) ₂TiF₆-treated enamel surface. On the TiCl₃-APF treated enamel surface, a titanium and fluoride-rich layer was observed, which was totally removed by washing. However permanently bound fluoride and titanium retained in the surface. This fact suggests the possibility of glaze-like substance formation.
In the chemical analysis of enamel powder, (NH₄) ₂TiF₆-treated enamel showed lower fluoride uptake, but considerable higher retention of fluoride after washing, and higher fluoride uptake was found in the other fluoride-treated enamel. Most of these fluorides was released by washing.
X-ray diffraction analysis showed that only enamel apatite was detected in (NH₄) ₂TiF₆-treated enamel, and a large amount of CaF₂ was formed in the other fluoride-treated enamel.
I concluded that the glaze formation peculiar to titanium fluoride compounds were caused by coreaction of titanium and fluoride, and not by titanium reaction alone. Titanium forms an organometalic bond with the enamel protein and fluoride called ‘glaze’.

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The purpose of this study was to evaluate the possibility of clinical use for fluoride topical application of dilute ammonium fluoride soluion, in which fluoride concentration was 1/3 times lower than that of APF solution.
Experiments were performed in vitro and in vivo using a solution of phosphoric acid-acidified NH₄F (3000ppm of F-, pH 4.4) and APF (9000ppm of F-, pH 3.4). In the experiments on intact enamel, fluoride uptake, acid solubility, and morphological changes in enamel blocks following topical treatment (for 60min. at 37°C) with fluoride solutions were studied by chemical analysis, scanning electron microscopy, and electron probe X-ray microanalysis. In experiments on rats, the cariostatic effect of ammonium fluoride solution was investigated. Eighteen-day-old male Sprague-Dawley rats were infected with Streptococcus mutans GS-5 for three days and fed a cariogenic diet (Diet 2000 No. 3) during the experimental period. Experimental groups were given topical application of each fluoride solution twice a week. Caries prevalence was examined using a standardized photograph (×50) of the rat jaw, and then caries scores (caries incidence and caries extent) were calculated from these data.
The fluoride uptake of NH₄F-treated enamel surface was a few times higher than that of APF-treated enamel. In the electron probe X-ray microanalysis, the same results were obtained. The acid solubility test proved the acquisition of acid resistance by the enamel. SEM images showed heavy deposits of crystalline material on NH₄F-treated enamel surface, whereas the deposit was homogeneous in APF-treated enamel.
Both caries incidence and caries extent were clearly reduced, and significantly lower values were found in the fluoride groups than in the control group. The fluoride groups had very few serious grade lesions, whereas the control group had many collapsible lesions.
It is concluded that the topical application of dilute NH₄F solution leads to uptake of fluoride into the enamel surface and proves the acquisition of acid resistance by enamel in vitro, and is effective in reducing caries incidence and inhibiting caries progression in rat experimental caries in vivo. A dilute NH₄F solution can be expected to have the same effect as APF in topical application for caries prevention.

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The clinical retention of a multiple application of a pit and fissure sealant was evaluated at every 3 months after sealant treatments on the early carious first permanent molars in grade one or two elementary school children during school based fluoride mouthrinsing (daily; 0.05% NaF). Maxillary and mandibular teeth, CO and C₁ teeth at sealant treatment, occlusal mesial and occlusal distal sites for maxillary teeth, and occlusal and buccal sites for mandibular teeth were differentiated and evaluated. Maxillary palatal sites were not evaluated because no early caries was detected in these sites.
The ratio of teeth retaining sealant was 78.7% at the final examination. Sealant materials had not come away in 53.4% of sealed teeth during this survey period. The rate of teeth retaining sealant was significantly reduced after 15 months compared to at 3 months. The retention ratio of CO teeth and the site retention ratio of maxillary occlusal distal site were not significantly reduce dat any period compared to at 3 months.

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The purpose of this study was to search for demineralizing conditions which did not cause erosion on human enamel surface. Twenty human premolar enamel surfaces were divided into two groups. In one the original enamel surface was ground down about 400μm (Group A), and in the other it was not ground (Group B). Two types of 0.1M lactic acid buffer, pH4.5 and 4.0, were also prepared for demineralization. Both buffers contained 3.0mM Ca, 1.8mM P and 1.0% carboxymethylcellulose. Exposure times were 6, 12, and 18 hours for Group A, and 1 day and 1 week for Group B. The degree of demineralization was evaluated by microradiograph using calculated mineral content.
Subsurface enamel lesions were seen in Group B. The minimum mineral content in the body of lesions was 7.2% when exposed for 1 week in lactic acid buffer at pH 4.0. This showed the possibility of complete demineralization in the body of the lesions.
Softened enamel lesions were seen in Group A. Erosions of the surface enamel were observed in all cases at pH 4.0 and after 18 hours demineralization at pH 4.5. These results indicated that the demineralizing conditions without erosion were less than 12 hours exposure at pH 4.5.

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The purpose of this survey was to quantify potential relationships between dmft (dmfs) scores at 3.5 years of age and sociodemographic variables, parental characteristics, nutritional characteristics, oral health practice, and fluoride application.
Dental health services for children 1.5 to 4 years old are provided at a health center in Niigata City. The dental health program is based on a six-month recall system. The program is composed of dental examinations, obtaining information through a questionnaire on the above-mentioned variables, individual dental health education for mothers based on the information obtained by the questionnaire, and fluoride application for children who desire it.
This survey was conducted longitudinally in the program on children from 1.5 to 3.5 years of age. The information was obtained by examinations of tooth surfaces and by questionnaires on the abovementioned variables.
The subjects analyzed were 286 children who received dental examinations and dental health services more than four times from 1.5 to 3.5 years of age.
Stepwise multiple regression analyses (step up method) were used to develop models which are useful in explaining dmft (dmfs) scores by various combinations of independent variables. Eight dependent variables were analysed. These variables were dmft scores, upper anterior dmft, molar dmft, first molar dmft, second molar dmft, buccal-lingual dmfs, proximal dmfs and pit-fissure dmfs. The 23 independent variables were adopted from the information accumulated by the questionnaires filled out for children up to 3 years of age and were each indicated by a constant value, mode, or mean in character with these variables.
The results showed that the independent variables (multiple correlation coefficient R=0.46, p<0.01) associated with dmft scores at 3.5 years of age were ‘Region’, ‘Sweets and beverages’, ‘Method of infant feeding’, ‘Parents and guardians’, ‘Mother's DMFT score’, ‘Period of infant feeding’, ‘Frequency of snacks’, ‘Age at start of weaning’ and ‘Experience of fluoride application’ in order of the highest partial correlation coefficient.
The independent variables associated with the seven other dependent variables, which were the dmf scores according to tooth groups, tooth types, and tooth surfaces, were different according to the dependent variables. If the independent variables were the same, the order of the partial correlation coefficients in which the independent variable was associated with the dependent variable was different.
The independent variable ‘Region’ was highly associated with the dmf scores of all tooth types and all tooth surfaces. Children from the urban area had lower dmf scores than children from two rural areas.
The variables in relation to infant feeding habits, ‘Method of infant feeding’ and ‘Period of infant feeding’, were concerned with dental caries in teeth which erupted during the period of infant feeding. The longer children were fed, the higher the dmft score was. The number of dental caries was higher in breast-fed children.
In the variables concerning sweets and beverages, ‘Frequency’, ‘Sweets and beverages’ and ‘Sucrose intake from foods which have a long clearance time’ were associated with dental caries. These variables are known to have an influence on the cariogenicity of foods containing sugar. ‘Mother's DMFT score’ was associated with her child's dental caries in molars. It is supposed that the occulusal form is likely to be inherent.
‘Frequency of fluoride application’ was related to the prevention of dental caries in first molars which had optimum oppotunities for fluoride application from the time of eruption and had relatively more caries on the proximal surfaces.

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The purpose of this study was to derive a method for predicting children at high risk of caries at the 1.5 year-old dental examination in order that preventive measures might be taken.
The subjects were 286 children who received dental examinations when they were 1.5 years and 3.5 years old.
The 36 independent variables used to predict children at high risk were comprised of variables obtained from a baseline questionnaire (21 items) and variables obtained from a baseline dental examination (15 items). The variables based on the questionnaire included sociodemographic variables, parental characteristics, nutritional characteristics, oral health practice, etc.
Discriminant analysis was used to determine the discriminant function by which those variables as a whole discriminated between the true high and the non-high risk groups as defined. True high risk children were difined in two ways: the highest 25% of children based on the dmft scored at 3.5 years of age (dmft≥7) and the new dmft scores from 1.5 years to 3.5 years of age (new dmft≥6). Using the dmft score as an indicater of true high risk there were nine baseline variables, which were ‘Classification of OABC’, ‘Period of infant feeding’, ‘Sucrose intake from foods which have a long clearance time’, ‘Mother's DMFT score’, ‘Tooth brushing habits’, ‘Order of birth’, ‘BL-dmfs’, ‘Age at start of weaning’, and ‘Weight at birth’, obtained from each child for use in prediction. Then a discriminant function comprised of the nine variables was made. Children predicted to be at high risk were determined by discriminant scores which were higher than the discriminant boundary score -0.434.
The result of the discriminant analysis showed that sensitivity was 71.2% and specificity was 71.8%. It was clear that this screening model comprised of nine variables showed higher validity in prediction, and higher sensitivity than the model comprised of only the one variable, ‘Classification of OABC’ (sensitivity: 22.7%, specificity: 97.3%). The results indicate that in predicting the prevalence of dental caries, which is a disease associated with a multiplicity of facters, these collective variables increase the validity in prediction.
Using the new dmft score as an indicator of true high risk there were eight variables obtained from each child for use in prediction. A discriminant function comprised of eight variables was made. Children predicted to be at high risk were determined by discriminants scores which were higher than the discriminant boundary score -0.187. The result showed that sensitivity and specificity was 70.7% and 59.7%, respectively. It was found that the screening model using the dmft score as an indicator of true high risk was more effective than that using the new dmft model.

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