Several glycosyltransferases which play important roles in the biosynthesis of oligosaccharide chains of glycoprotein have been demonstrated in various animal tissues and fluids including those of humans. The purpose of this study was to determine the presence of α-_L-fucosyltransferase which specifically catalyzed the transfer of _L-fucose from GDP-fucose to glycoproteins and/or oligosaccharides, and to clarify its binding form in human parotid and submaxillary-sublingual saliva.
Saliva samples from four adults with different ABO secretor phenotype were tested. Fresh parotid and submaxillary-sublingual saliva was collected by the methods of Keene and Stephan, respectively. As acceptors for the assay of fucosyltransferase, fetuin, porcine submaxillary mucin, and/or human milk oligosaccharides were prepared. The α-_L-fucosyltransferase in both types of saliva catalyzed the transfer of _L-fucose to an asialo-fetuin, but did not transfer to an asialo-afuco-porcine submaxillary mucin. The α-_L-fucosyltranserase in both types saliva apparently transfered _L-fucose to 2′ fucosyllactose, and this phenomenon was confirmed by the chromatograhic mobility using known substrates. The α-_L-fucosyltransferase activity was also found in both saliva samples when lacto-N-tetraose was used as an acceptor, and the radio-active product corresponding to lacto-N-fucopentaose II was detected. However, lactose and 3-fucosyllactose were not found to be the acceptors. The fucosyltransferase activity in parotid saliva was higher than in submaxillary-sublingual saliva, even when the acceptors described above were used. The occurrence of the fucosyltransferase activitiy was independent of ABO secretor status. This study has clearly demonstrated the presence of α-3-_L- and α-4-_L-fucosyltransferase activity in both parotid and submaxillarysublingual saliva, but α-2-_L-fucosyltransferase activity was not detectable in either type of saliva.

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The dental health care system for the developing children needs to be rearranged from a widely comprehensive standpoint. This is because dental health care and treatment do not always follow an uniform principle, when pathogenic and symptomatic commonness among dental diseases and the variety of their symptoms with age and social background were considered. Dental health examinations for school children are centered on dental caries today, and periodontal diseases and malocclusions are neglected.
Recently, we carried out dental health examinations for 1627 children at a kindergarten, an elementary school, and junior and senior high schools affiliated to a University in the Tokyo area. From the results of these examinations, we attempted in the present paper to discuss the effective objectives of the care and treatment system for dental diseases in the developmental stage, as well as directions for the improvement of dental health education.
The necessity of dental care before three years of age is suggested from the rapid increase in untreated carious teeth during the period from three to four years of age. Further improvement of the dental health education program through the school ages and its successful enforcement before adolescence is also recommended from the fact that there was dominant increase of serious carious teeth in senior high school students. Since gingivitis was observed in 25.7% of the children even at three years of age, and in 62.1 % at four years of age followed by continuous increase in seriousness with the progress of school years, it seems very important to change the teaching objectives of tooth brushing in the early stage of development, to prevent not only dental caries but also periodontitis. Additionally, there seemed to be three important times to examine for malocclusions, namely, three years of age in kindergarten, the 2nd or 3rd year in elementary school, and the 3rd year in junior high school or the 1st year in senior high school. The necessity of providing a criterion for examination of occlusions in dental health care system, which includes the evaluation of their severity, is pointed out.

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The serological detection of virus hepatitis has made it possible to use the serological method clinically as well as epidemiologically. In order to clarify the infection rate of hepatitis A among Japanese practicing dentists, the anti-hepatitis A antibody positive rate was investigated.
The following conclusions were obtained:
Anti-hepatitis A antibody positive rate (total & age-groups) among Japanese practicing dentists was approximately the same as in the controls.
Thus, hepatitis A was not characteristic of dentists. From the consideration that the infection rate of hepatitis B among Japanese practicing dentists was characteristic, and that non-A and non-B hepatitis has not been clarified yet, it seems reasonable to conclude that the virus hepatitis infecting Japanese practicing dentists is hepatitis B, not hepatitis A.

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The cellular fatty acid composition of B. matruchotii #13 was determined by gas chromatography and mass spectrometry (GC-MS). Non-polar and polar fatty acids were detected by thin-layer chromatography (TLC) of fatty acid methyl esters from B. matruchotii #13. Hexadecanoic acid (C_{16: 0}), octadecenoicacid (C_{18: 1}), and octadecanoic acid (C_{18: 0}), were found in non-polar fatty acids. Polar fatty acids were identified as mycolic acids by mass spectrometry. Even-numbered fatty acids such as C_{32: 0}, C_{34: 0}, and C_{36: 0} occurred in polar fatty acids.

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The present study was performed to confirm the usefulness of four parameters for the reevaluation of the Stephan curve after giving three subjects three types of foods. The four parameters were (1) minimum pH, (2) the time required to reach the minimum pH, (3) the time required to return to the fasting pH, and (4) the area between the Stephan curve and the fasting pH level (pH changed area). The experimental design was set up using a table of orthogonal arrays (L₉ (3⁴)).
Dental plaque pH was determined in vivo by using a glass microelectrode with a Beckman pH meter before and after eating.
The following results were obtained.
1) In general, all subjects showed a classical “ Stephan curve ”. Dental plaque pH fell (within 25min.) after eating and gradually returned to the fasting pH.
2) Dental plaque pH fell greatly after drinking orange juice or eating chocolate, but the pH did not fall after eating potato chips.
The Stephan curve produced by orange juice was different from that of chocolate. The former showed a rapid pH fall and a quick return, whereas the latter showed a slow fall and a slow return to the fasting pH.
3) The Stephan curves showed considerable difference among three subjects. One of the subjects showed a great change after eating, but the others showed only a slight change.
4) The differences between foodstuffs and between individuals had more effect on the Stephan curve than the differences between the time of pH measurement.
5) It was concluded that the four parameters were useful for the quantitative analysis of the Stephan curve.

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This paper reports the type analysis of foodstuffs using four parameters: (1) minimum pH, (2) the time required to reach the minimum pH, (3) the time required to return to the fasting pH, and (4) the area between Stephan curve and fasting pH level (pH changed area).
A total of 21 snacks and beverages were tested. Plaque pH was measured by the method reported in the previous paper.
The following results were obtained.
1) Four types of Stephan curve were produced by eating: an acid type (A) showed a pH decrease, a basic type (B) showed a pH increase, a mixed type (AB) initially showed pH increase and then pH decrease, and an indefinite type (C) showed no definite pH change.
2) The acid type (A) was further classified into three subtypes: a small pH-change type (A1: ex. potato chips), a rapid pH-change type (A2: ex. orange juice), and a slow pH-change type (A3: chocolate).
3) Cheese gave a typical example of the basic type (B), ice cream of the mixed type (AB), and senbei (rice crackers) of the indefinite type (C).
4) Minimum pH was correlated with the differences between individuals, and the time required to return to the fasting pH and the pH changed area were correlated with the differences between foodstuffs.
5) There was correlation between the pH changed area and the carbohydrate content in foods, and also between the sucrose content in foods and either minimum pH or the pH changed area.
6) There was correlation between the concentration of sucrose solutions and the time required to return to the fasting pH.

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It is important to know the individual differences of dental caries activity (susceptibility) especially from the standpoint of dental practice and dental public health. The Stephan curve is thought to be useful as a cariesactivity (susceptibility) test.
In two previous papers. I reported that four parameters were useful for the quantitative analysis of the Stephan curve, and by using these parameters, Stephan curves were classified into four types: (1) acid type (A), (2) basic type (B), (3) mixed type (AB), and (4) indefinite type (C).
The present study was undertaken to know the individual differences among Stephan curves produced after eating three types of foodstuffs (potato chips, orange juice, and chocolate).
The following results were obtained.
1) Minimum pH and the area between Stephan curve and fasting pH level (pH changed area) were correlated greatly with the differences between individuals, and the time required to reach the minimum pH and that required to return to the fasting pH level were correlated stronglywith the differences between foodstuffs.
2) There were great differences among the Stephan curves of five subjects. They were classified into three types using the four parameters for Stephan curve analysis: a safe type (S), a slightrisk type (SR) and a risk type (R).
3) There was correlation between minimum pH and the flow rate of saliva for all foods. There was correlation between the viscosity of saliva and minimum pH for two foods (orange juice and chocolate) and the pH changed area for one food (chocolate). There was no correlation between the four parameters and the buffer capacity of saliva.
4) It was concluded that the present study gave basic information about individual differences in the Stephan curve.

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Twenty seven strains of oral streptococci were examined for capacity of protease production, and some properties of extracellular protease from S. sanguis ATCC 10557 were studied.
The streptococcal strains were grown in brain-heart infusion broth at 37°C for 18hr. The resulting cultures were separated by centrifugation into two fractions, i, e., the supernatant and the whole cells. Both fractions were searched for protease activity at three different pH, 4.0, 6.5, and 8.5, using succinylated hemoglobin as substrate. At both pH 6.5 and 8.5, the activity was found in many strains of cell fraction, and in only three strains of extracellular (culture supernatant) fraction. No protease activity was found at pH 4.0 in either fraction.
Extracellular fraction from S. sanguis ATCC 10557, which showed the highest activity, was concentrated by ammonium sulphate precipitation, and applied to a Sephadex G-200 gel column. Fractions which possessed protease activity were collected, and then frozen and dried. This sample was used for the determination of some properties of the protease. Optimum pH of the protease was 6.5, and the activity was strongly inhibited by phenylmethane sulphonylfluoride. This enzyme hydrolyzed succinylated hemoglobin specifically higher than the other substrates tested. The activity for mucin preparation was less than one tenth of the succinylated hemoglobin.

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We compared the oral health status of the schoolchildren in two primary schools and one junior high school and of all the preschool children of HIRAIZUMI-cho in IWATE prefecture after 4-year dental health activities. (1978-1981) Our activities were dental health education, topical application of Ag (NH₃) ₂F, the filling of earlv carious lesions in permanent teeth, and the extraction of advanced carious teeth.
In preschool children, the mean dmft, the number of advanced carious teeth per person, and the number of children with advanced carious teeth decreased considerably.
On the other hand, in school children, the caries prevalence rate, the mean DMFT, showed no marked difference, but the restoration rate was significantly higher due to the early treatment.
We studied the dental caries of upper anterior teeth by tooth surface in schoolchildren from the 4th grade of primary school to the 3rd grade of junior high school.
Caries prevention was most effective on the labial surface, and secondly on the proximal surface, and pit caries on the lingual surface was the most difficult to prevent.
Dental plaque on the tooth surfaces and gingivitis were also decreased.

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The distribution of Streptococcus, Lactobacillus, Veillonella, and Granular organisms in the oral cavity of 40 adults was examined. The results are as follows.
1) The isolation frequency of Str. mutans was high in the pits and fissures of the molars, but low on the lingual smooth surface of the lower incisors and the surface of the tongue.
2) The isolation frequency of Granular organisms (Actinomyces viscosus) was high on the lingual smooth surface of the lower incisors
3) Positive correlations between Streptococcus, Veillonella, and Granular organisms were comparatively clear on the lingual smooth surface of the lower incisors, but not clear in the pits and fissures of the molars.
The distribution of Str. mutans in the dental plaque of different tooth sites and different age groups was examined. The results are as follows.
1) In the permanent dentition, the isolation frequency of Str. mutans was highest in the pits and fissures of the molars. In the deciduous dentition, it was highest on the proximal surface of the upper incisors.
2) In 1st and 2nd grade children of primary school, the isolation frequency of Str. mutans was higher on the labial surface of the upper incisors than on the proximal surface of the upper incisors, but in 5th and 6th grade children of primary school this was reversed.
3) There was tendency for the isolation frequency of Str. mutans on the labial surface of the upper incisors to decrease with age.
4) Str. mutans (serotype H1) was predominant in all tooth sites.
5) The isolation frequency of Str. mutans (serotype H2) on the proximal surface of the upper incisors was higher than in other sites.
6) Str. mutans (serotype R) was not detected in any tooth sites.

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Induced mutants (mutational phases) were isolated from representative strains of every serotype of Streptococcus mutans using mechlorethamine HCI. The phases were divided into phase I, phase II, and phase III according to their properties. Phase I induced a firm and adhesive plaque, and severe caries in experimental animals. Phase II showed unstable properties. Phase III did not show adhesive plaque formation, and lost its cariogenecity in experimental animals. In the presence of phases I and III, plaque formation and proliferation in phase I were strongly suppressed in vitro.

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A clinical trial of daily mouth rinsing with 9% D-galactose solution or 0.01% saccharin as a placebo was conducted for twenty-six young students from 18 to 23 years of age. Three-day examinations showed significantly lower Plaque Index scores for the group rinsing with D-galactose than the group rinsing with placebo.

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The present study was made to examine the effects of fluoride mouth rinsing solutions on the powdered enamel by chemical analysis and X-ray diffractometry. Experiments were done in vitro with the powdered enamel (200 mesh) as material. Phosphoric acid-acidified NaF solutions (100 ppm of F^-; pH 5.0, 250 ppm of F^-; pH 5.0) were used as the mouth rinsing solutions. Fluoride, calcium, and phosphor, us contents in enamel were determined by using an ORION ion meter (model 901), anatomic absorption spectrophotometer (HITACHI polarized zeeman 180-80), and Dryer's method, respectively.
X-ray diffractometry was performed with an automatic recording X-ray diffractometer to observe the crystallinity and identify the reaction products in enamel following the application of fluoride solutions. For the observations of crystallinity, the half-maximum breadth (β1/2) was measured, and the values calculated from Scherrer's equation were defined as the parameters of crystallinity. The reaction products were studied by identification with the ASTM indexes, observations of alterations in the diffraction line profiles and peak shifts at diffraction angles of 50-59 degrees (20). Determination of β-tricalcium phosphate produced by heating treatment (1000°C, 5 hours) was carried out using X-ray diffractometry.
In the experiments with fluoride mouth rinse, the fluoride content of enamel increased with time. The Ca/P mol ratio of fluoride treated enamel was similar to that of control enamel. Chemical analysis and X-ray diffractometry showed that no CaF₂ was produced, while a large amount of hydroxyfluorapatite with considerably high crystallinity was pruduced. The amount of β-tricalcium phosphate produced by heating treatment decreased with time. Thus it appears that the imperfect apatite decreases following rinsing with fluoride solutions. Thus the effect of dilute fluoride mouth-rinsing solutions on powdered enamel is quite high in spite of the fact that the concentration of fluoride was lower than in conventional mouth-rinsing solutions.
In other words, the repeated application of fluoride mouth rinse with dilute fluoride solutions over a long period will produce hydroxyfluorapatite with high crystallinity without CaF₂ formation. Therefore, the dilute fluoride solution for mouth rinse is an effective caries perventive.

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