To study the variation related to age and sex in the urinary amounts of fluorine (F), calcium (Ca) and phosphorus (P), 24-hour urine for 2 to 4 days in 239 inpatients aged 1 to 80 years at a dental hopital in Sendai were investigated.
The volume of 24-hour urine and the concentrations of F, Ca and P in it were determined, and then the amounts of F, Ca and P in the 24-hour urine of each individual were calculated. The ratios of these substances to body weighht (wt) and urinary creatinine (Cr) amount were also estimated.
In the amounts of F and Ca, there was seldom significant difference between males and females, and these amounts significantly increased with age until 39 years in both sexes. On the other hand, the P amount in males was significantly greater than in females for many age groups under 39 years, and it significantly increased with age until 19 years in males and 14 years in females (Tables 1, 2).
In the ratios of the amounts of F and Ca to body wt and to Cr amount, there was a definite tendency for the ratio in males to be higher than in females in the age groups until 29 years, and the relation was reversed in the age groups over 30 years; significant differences were frequently found between males and females. F/body wt and F/Cr of both sexes, and Ca/body/wt and Ca/Cr of females in many age groups over 30 years were significantly higher than in age groups below 29 years. P/body wt and P/Cr in females in the age groups over 40 years were sometimes significantly higher than in males and these ratios significantly decreased with age until 19 years in both sexes (Tables 5-8).
The coefficients of variation of the amounts of F and Ca in the combined age group of 1 to 9 year-olds were significantly greater than in the combined age group of 10 to 59 year-olds respectively, but no difference was found between the coefficients of varition in the P amounts of the age groups. The coefficient of variation of P amount was significantly less than that of F and Ca in the both age groups. In the combined age groups, the coefficients of variation of the ratios of F, Ca and P amounts to body wt and to Cr amount were similar to the findings related to the amounts of F, Ca and P (Table 9).
The above observations on the urinary F, Ca and P amounts confirm the close correlation between F and Ca metabolism and that P metabolism differs from F and Ca metabolism.

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When fluoride is administered to a living body, a considerable amount is promptly absorbed, resulting in a rise in the serum fluoride concentration. This study discusses the changes in the serum total fluoride concentration and ionic fluoride concentration, as well as in the serum calcium concentration in Japanese white rabbits after fluoride administration by intubation. Rabbits were given an NaF solution containing 1, 2, 4, 6, 8 or 10 mgF/kg body weight. Blood was then taken from a marginal vein and tested. After fluoride intubation, the ionic fluoride concentration and the total fluoride concentration both rose promptly. Furthermore, the greater the fluoride dose, the more rapid the rise in serum ionic fluoride concentration and total fluoride concentration. For all fluoride treated groups, the rises in serum ionic fluoride concentration and total fluoride concentration 4 hours after administration were significantly higher than before administration.
The serum ionic Calcium concentration was decreased 4 hours after fluoride administration, but later returned to normal levels (same as before administration) at 24 hours after administration. There was no significant difference in the serum total calcium concentration in all fluoride treated groups before and after fluoride administration.
Serum phophorus concentration in the fluoride treated groups reached its lowest value 15 or 30 minutes after fluoride administration, but then soon returned to pre-administration values. The phosphorus concentrations at each time after administration were not significantly different from those before administration. On the other hand, blood sugar values determined within 4 hours after administration were significantly higher than those before fluoride administration. In all treated groups, however, blood sugar decreased as time passed after administration and eventually drew near to that of pre-administration values.
The half-life of serum fluoride after administration was determined from the ionic fluoride concentration and total fluoride concentration. The half-life of every concentration increase proportionately to the increase in the fluoride dose.

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Estimating the lead absorption of lead workers is necessary for their health care. It is necessary to make clear the relationships between body absorption level of lead and related biological parameters, such as lead concentration in blood and urine, urinary coproporphyrin and δ-aminolevulinic acid, free erythrocyte porphyrin, erythrocyte δ-aminolevulinate dehydrase activity, Zn erythrocyte porphyrin.
Especially, a number of reports have been published concerning the measurement of concentration of lead in blood for monitoring the exposure level. Recently, not only blood or urine but also saliva has been used as a biological fluid for monitoring the level of exposure to lead.
I first attempted fundamental research on measuring the lead content in used mouth rinse, because mouthrinsing has been used to eliminate lead contamination from the oral cavity of lead workers.
Then I investigated, regarding lead workers in a battery factory, the relationship between lead content in used mouth rinse, and lead concentration in air, urine and dental plaque, and specific gravity of the blood.
The results were as follows.
1. Lead content in mouth rinse used by subjects who were not exposed to lead occupationally, was under 0.5μg, when they rinsed with 0.2% acetic acid solution (30ml) for 30 seconds. This amount did not vary significantly in several consecutive rinses.
2. The geometric average of lead content of used mouth rinse from 126 lead workers was 1.18μg (^×_÷2.7) and that from 9 non-lead workerswas 0.41μg (^×_÷1.19).
3. The geometric average of lead content in the mouth rinse from lead workers in every work area showed close correlation with the lead concentration in the air of their work area (r=0.73).
4. Lead content in the mouth rinse from individual lead workers did not show any correlation with the lead concentration in their urine.
5. Lead content in the used mouth rinse from lead workers was not correlated with lead concentration in their dental plaqe or the specific gravity of their blood.
6. In conclusion, lead content in the used mouth rinse from lead workers reflects the concentration of lead in the air, and it can be one of the parameters indicative of the body's absorption of lead.

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The problem of intramural infection has come to claim our attention in hospitals and dental clinics, and the importance of sterilization and disinfection has been given a new emphasis. In actual dental practice, the admixture of various substances adversely affects the antibacterial effect of disinfectants. These various substances include tooth cutting powders, alginate impression-taking material, saliva, serum, resin for immediate polymerization, and zinc phosphate cement. For this reason, in the present study, these materials were mixed with various disinfectants that has been diluted to 900 to 1024, 00 times (chlorhexidine, benzalkonium chloride, cresol, and irgasan DP-300) and a series of experiments were carried out to study the influences on their antibactrerial effects.
The following were the salient results obtained from the present study.
1. The substances that particulaly reduced the effects of these disinfectants were tooth cuttings, alginate impression-taking material, and serum.
2. The sterilized saliva, either 1) reduced the antibacterial effect, 2) increased it or 3) had no influence at all.
3. Resin powder, sometimes reduced the antibacterial effect and sometimes not.
4. Dental cement powder either increased the antibacterial effect or had no influence at all.
5. Resin and dental cement liquid did not cause an increase in the growth of bacteria at any concentration.
6. The effect of saliva samples collected from 12 subjects, showed wide individual differences. Cresol was the most prominent by offected, followed by irgasan DP-300. The influence on chlorhexidine and benzalkonium chloride was more or less the same.
7. The pH values of the admixtures of various substances were pH 2.2 in the case of a dental cement, and from pH 7.1 to 7.4 in the case of the other substanses.

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The purpose of this study was to evaluate the possibility of clinical use for fluoride topical treatment of a phosphoric acid-acidified ammonium fluoride solution, in which fluoride concentration and pH was similar to a conventional APF solution. Experiments were performed in vitro using a solution of phosphoric acid-acidified NH₄F (9000ppm of F^-, pH 3.4) and APF (Acidulated phosphate fluoride solution, 9000ppm of F^-, pH 3.4).
In the experiments with intact enamel, morphological observation, acid solubility test and fluoride uptake on enamel blocks following topical treatment (for 60 min at 20°C) with fluoride solutions were studied by means of the scanning electron microscope, chemical analysis, and electron probe X-ray microanalysis (Experiment 1). In the experiments with powdered enamel, chemical analysis and identification of reaction products using X-ray diffractometry were carried out in enamel following the application of fluoride solutions (for 25 min at 37°C) (Experiment 2).
In order to observe the relationship between CaF₂ formation and reaction times, enamel powder was treated with fluoride solutions at 37°C for 2, 4, 6 and 10 minutes. CaF₂ in enamel was determined by internal standard technique used X-ray diffraction. Retention of CaF₂ in enamel and fluoride released from enamel into distilled water were determined by X-ray diffractometry and chemical analysis (Experiment 3).
Scanning electron microscopic examination of enamel surfaces treated with NH₄F revealed heavy deposits of crystalline material, whereas after treatment with APF, the deposit was homogeneous material. Acid solubility test proved the aquisition of acid resistance by the enamel. In the electron probe X-ray microanalysis, the fluoride uptake of NH₄F-treated enamel surface was a few times higher than that of APF-treated enamel. X-ray diffractometry showed that CaF₂was formed in the experimental groups, and a large amount of CaF₂ with high crystallinity was formed in NH₄F treated enamel. In NH₄F-treated enamel, about two times more CaF₂ was formed than at the same reaction time in APF-treated enamel. The retention of CaF₂ in enamel treated by washing was higher in NH₄F-treated enamel than in APF-treated enamel because of the large amount of CaF₂ formation with high crystallinity.
Therefore, since phosphoric acid-acidified ammonium fluoride solution (9000ppm of F^-, pH 3.4) produces a large amount of CaF₂ with high crystallinity in enamel, the CaF₂ will effectively a prevent caries as a source of dilute fluoride supply. NH₄F can be expected to have the same effect as APF with a shorter time of application or at a lower concentration.

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After participating in a dental examination for children aged 18 months or 3 years at a health center in central Tokyo, we carried out a follow-up study in order to determine the changes in the incidence of caries at 18 months of age and at 3 years of age in the same individual children. Mothers were asked to fill in a questionnaire concerning the daily dental hygiene of their children at home. The children were assigned to the high and low caries risk groups based on their daily tooth-brushing habits, times of tooth brushing, snacking habits and types of snacks eaten between meals, and the presence or absence of plaque. The relationship between these factors and the prevalence of 3-year-old df children as well as the validity of the screening parameters were evaluated.
The incidence of df was significantly lower in children with O₁-type caries than in those with O₂-type caries (p<0.01). The dft and dfs incidences were also lower in the former than in the latter, but siginificantly. The df incidence in the high caries risk group was significantly correlated with the habit of snack eating (p<0.05), the type of snacks eaten (p<0.01), and the presence of plaque (p<0.01). With respect to the validity of the screening parameters, both the Youden index and the predictive value were high for the presence of plaque. The predictive value was also high for the O₁ and O₂-type screening.
These results indicate that the presence of plaque and the habit of snack eating deserve particular attention, and suggest the validity of the O₁ and O₂-type screening.

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The purpose of this study was to investigate the age specific distribution of salivary bacteria. From birth to senility, 1127 subjects in 14 age groups were analysed ecologically with regard to the numbers and occurrences of S. mutans, Lactobacilli, Actinomyces and total microorganisms in saliva.
The number and occurrence of Streptococci in newborn babies were significantly lower than in the other age groups. 4-5 days after birth, Streptococci reached high levels and became established in 90 % of the subjects. However, Lactobacilli and Actinomyces occurred transiently and in very low numbers in both groups. Establishment of Lactobacilli and Actinomyces in oral flora was presumed to attain 4-5 years and 3 years, respectively. S. mutans was not recovered from infants. At 1-2 years of age, however, S. mutans was recovered from all subjects and tended to increase gradually to 7 years of age. Total microorganisms appeared regularly in newborn babies except in one of two babies born by cesarean. The Mean number of viable cells was 10³ in newborn babies. 4-5 days after birth, the total microorganisms reached high levels (10⁶-10⁸) and could be cultured usually at these levels up to adults.
A relationship between S. mutans and Lactobacilli was found and the number of both types of bacteria was similar. The number and occurrence of Streptococci was relatively constant after 1-2 years. At 16 years of age decrease in the number of Streptococci and Actinomyces was found and Lactobacilli increased the number. The number of S. mutans was higher and the number of Actinomyces was lower in pregnant-women than in 20-year-olds. The number of S. mutans and Lactobacilli in the elderly wearing fulldentures was lower than in the elderly with their own teeth. These variations were statistically sigificant (p<0.05).

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Significantly high fluoride concentrations (0.3-1.1 ppm) in drinking water obtained from deep wells ranging 200 to 300 meters in depth were detected. The possible influence of soil fluoride on fluride concentration in drinking water was investigated.
Soil samples obtained during deep well (250 m) boring from the area where frequent dental fluorosis occurred were employed in determining total soil fluoride concentration using sulfuric acid steam distillation and a fluoride specific ion electrode.
Total and ionizable fluoride concentrations in the soil samples ranged from 59.0 to 211.0 ppm (Mean±S.D.: 130.3±43.1 ppm) and from 6.2 to 92.0 ppm (Mean±S.D.: 37.4±24.8 ppm). The percentage of ionizable to total fluoride concentration was significantly higher (over 70%) in the sandy siltstone of the water-bearing stratum than in other rock strata. Much rapid fluoride release from sandy siltstone was found.
These findings strongly imply that soil fluoride influences fluoride concentration in drinking water.

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In recent years, the problem of the air pollution in dental clinics, has received much attention in particular, pollution by air-borne bacteria. For this reason, we conducted studies for a year with SY type pinhole sampler (SY method) and Koch's dropping (Koch method) method in the Preventive Dental Clinic and the waiting room at Tsurumi University, School of Dental Medicine, Kanagawa Prefecture. As a result of the study, we obtained the following conclusions:
1. The room temperature was 23.3-28.4°C, humidity was 45-77% and the air current was 0.06-0.20m/sec.
2. The number of persons in a clinic was anywhere from 2 to 26 people.
3. The bacterial count was from 0.03 to 0.52 colonies per liter with the SY method and 0.58 to 5.33 with the Koch method.
4. Thers was no statistical relation between the number of air-borne colonies and the temperature, humidity, or air current.
5. There was a high statistical relation between the number of colonies and the number of people in the clinic, with a coefficient of 0.666 in the SY method and a coefficient of 0.590 in the Koch method.
6. The correlation between the number of air-borne bacteria of the SY method and those of the Koch method had the high coefficient of 0.814.

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In a two-year doubleblind cohort study, the caries-inhibiting effect of a dentifrice containing 0.4% stannous fluoride and 1% sodium phytate in a silica abrasive system (SnF₂-phytate dentifrice) was compared to an active control containing 0.4% stannous fluoride dentifrice and a placebo. 998 children, aged 6 to 11 years, were involved in this study.
The SnF₂-phytate dentifrice proved to be significantly effective in caries reduction when compared to both the placebo and the SnF₂ dentifrice. Reductions ranged from 21% for all teeth (ΔDMFT rate) to 47% for anterior teeth (ΔDMFT).
The SnF₂ dentifrice showed significant caries reduction for anterior teeth (40%, ΔDMFT) but not significant reduction for all teeth (9%, 21DMFT rate) in comparison with the placebo.
A significant difference was obtained in DMFS rate reduction for molar teeth between the SnF₂ dentifrice (-1%) and the SnF₂-phytate dentifrice (13%).
The results indicate that the caries-inhibiting effect of a SnF₂ dentifrice is significantly improved by the addition of sodium phytate.

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On the basis of previous findings, the effectiveness of a tea drinking program for caries prevention was tested in the primary schools of two typical Japanese farm villages for five years. Caries lesions on the pit/fissure (CF) and approximal sites (CA) were detected with the point of a No. 1 sewing needle by clinical criteria. The average number of carious lesions in both villages decreased in the first program year and reduction rates were almost constant thereafter. The reduction rates averaged 22.1% in CF and 26.1% in CA.
The program was evaluated from three angles, accessibility, availability, and acceptability. The monetary accessibility was considered very good because the above reduction rates were attained by the expense of only 1.5 yen for a cup of Bancha tea. Yearly production of Bancha in Japan would cover about 4.5 times more children.
In order to assess the objective acceptability, a new scale called the epidemiological susceptibility of the caries risk (ESF and ESA) was derived from the caries experience (CF and CA) divided by the caries risk which was half the number of existing teeth (D) multiplied by the dentitional age of the permanent teeth (T) of a child. The reduction rate of the susceptibility of the caries risk averaged 19.5% in ESF and 21.3% in ESA respectively. No signs of the mottling such as discoloration and disfiguration of the teeth were found on the lower front teeth.
It was stressed that dental caries produced by multifactorial causes should not be prevented by use of a single agent, but accomplished by a combination of multiple anticaries agents in order to avoid overdosage.

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The purpose of this study was to analyse the effects of daily habits on deciduous molar caries by the cohort method. The incidence and the severity of molar caries were studied by analysis of variance.
The analyses were performed on the different effects from each ca ies score, which was determined by differences in the individual daily habits.
These were studied by using Hayashi's Quantification Scaling Type 1. The results were as follws:
1. As caries scores, we recorded the following items: the dmft of deciduous molars, the dmt of high grade molar caries, the dmfs of occlusal, smooth, and proximal surfaces, the dmfs of the distal surface of the first deciduous molar and the mesial surface of the second deciduous molar at the age of six.
The correlation between the individual caries scores and the daily habits of the subjects was studied by analysis of variance.
It was, obvious that caries inductive factors from different individual inake of sweetened beverages influenced the dmfs of smooth surfaces, and the different individual intakes of sweets influenced the dmfs of occlusal surfaces.
Therefore, these two factors showed a difference in the effective period of time in regard to deciduous molar caries.
2. Selected factors from previous studies had less than 5 percent singnificance and were determined as “explanatory variables” by analysis of variance. Each caries score was selected as a“criterion variable”for Quantification Scaling Type 1. Then the incidence and the severity of deciduous molar caries were analysed in detail by using each category of daily habits.
3. The incidence of dmft of deciduous molar carise was influenced by sweetened beverages and sweets intake as a positive caries factor, and milk intake as a negative caries factor at the age of three.
Nevertheless, there was no effect on caries control from the improvement of the sweets intake. But the effect on caries control from improvement of the sweetened beverage intake was very clear.
4. As regards the severity of molar caries, there was an effect on caries control from the improvement of sweets intake. It was also clear that the constant restriction of sweetened beverages controls the severity of molar caries. Since these children received an periodical oral examination along with fluoride application and the consultaion for dental hygiene more than 4 times, fewer severe molar caries teeth were seen in these children.
5. As regards the occlusal surface caries, there was no effect on caries control from improvement in sweets intake. On the other hand, there was a clear effect on caries control from improvement of sweetened beverage intake on the smooth surface caries. The effect on caries control was seen on smooth surface by the restriction of sweets intake at the the age of three. However, to this effect was not seen when improvement of sweets intake was established after the age of three.
6. There was no effect on caries control on the distal surface caries of first deciduous molar from improvement of sweets intake.
On the contrary, control of mesial surface caries of second deciduous molar was accomplished by the improvement of sweets intake as well as reduction in the severity of molar caries. This accomplishment was made after the age of three.
7. These findings suggested that effective period of time for molar caries occurence from sweets intake was earlier than that from sweetened beverage intake. This is a very important factor for establishing the prevention of various surface caries in deciduous molars, of which the most susceptable period of time was different.

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The purpose of this study was to investigate the effects of 7 days of washing on fluoride and titanium uptake, glaze formation and acid solubility. Specimens of human enamel were treated for 60 minutes with solutions of (NH₄) ₂TiF₆ (0.9% of Fluorine, pH 3.4) or APF as control, followed by 7 days of washing with distilled water. These specimens were investigated for fluoride and titanium uptake by means of electron probe X-ray microanalysis and observations of their surface structure were made by scanning electron microscopy. Some specimens were etched for 15 seconds with 0.5 M HCIO₄ to examine their acid solubility and were then observed by SEM. The calcium released from the enamel surface into distilled water during every 24hr period was determined by means of atomic absorption spectrophotometry.
In the electron probe X-ray microanalysis, fluoride and titanium in the enamel surface layer remained even after 7 days of washing, but the CaF₂ formed on the enamel surface in APF-treated enamel was washed away. The glaze formation on enamel surfaces caused by the effect of titanium showed a strong resistance to washing and acid etching. Calcium content in distilled water released from enamel surface treated with ammonium titanium fluoride was lower than in the control group.
Therefore, it appears that the amorphous coating on titanium fluoride-treated enamel surface known as “glaze” is very resitant to washing and acid etching, and that the permanently bound fluoride and titanium in the enamel may contribute to the acquisition of caries resistance in human enamel.

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Streptococci resembling Streptococcus sanguis were isolated from dental plaque of MCLS patients and their mothers. The biochemical and serological characteristics of these organisms were examined in this study.
These organisms were found to synthesize extracellular glucan, to give rise to haemolysis and to ferment melibiose and cellobiose, but they failed to hydrolyse arginine and esculine, suggesting that they were similar to biotype B strains of S. sanguis.
Serological studies of these organisms revealed that they gave rise to cross-reactions with S. sanguis serotype I strain when the cell-surface substance of these organisms was used as antigen. However, they were separated into new two serogroups when the heat-extracted substance was used as antigen.

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