A water-insoluble glucan (IG) -synthesizing glucosyltransferase (GTase-I) and two kinds of water-soluble glucan (SG) -synthesizing glucosyltransferases (GTase-Sa and GTase-Sb) were purified from the culture supernatant of Streptococcus sobrinus strain MT 3791 (serotype g) by chromatofocusing on a Polybuffer exchanger PBE 94 column.
A fractionation of the reaction products of the enzymes indicated that the main products of GTase-I, GTase-Sa and GTase-Sb were IG, low-molecular-weight SG (75% ethanol precipitates), and high-molecular-weight SG (50% ethanol precipitates), respectively. The glucosyl transfer reactions and the transferring efficiency of GTase-I and-Sb were extremely enhanced in the presence of dextran. On the other hand, the most effective acceptor for those of GTase-Sa was isomaltotriose. Thus, in the absence of an exogenous dextran, the synthesis of SG was enhanced in a synergistic manner by the combined action of GTase-Sa and GTase-Sb. The synergistic effect for the IG production was also observed in the presence of all of these three GTases.
A quantitative analysis of the reaction products of the enzymes also revealed a difference in mode of effect between α-D-xylosyl β-D-fructoside (XF) and α-isomaltosyl β-D-fructoside (IMF) on the enzyme reaction of each GTase. IMF acts as an alternative acceptor for the glucosyl transfer reaction of each enzyme and stimulates the transferring activity of the enzyme. XF, on the other hand, competitively inhibits the sucrose-splitting activity of each enzyme as an analog to sucrose, and thereby diminishes the synthesis of glucans.
The Km values for sucrose and Ki values for XF of GTases in the presence of dextran T10 were 0.8 and 0.3mM for GTase-I, 0.7 and 0.05mM for GTase-Sa, and 2.8 and 1.0mM for GTase-Sb, respectively.

View full abstract

In the countries where dentistry is developed, the number and quality of dentists, the economic conditions of the people, dental education and many other factors influence the oral condition of the people: food style and the natural environment no longer have much effect on oral conditions. On the other hand, in areas where no dentist exists and where people live on natural foods, food style and the natural environment are the most important factors which influence the oral condition.
We made an oral survey of the Tibetans in three quite different areas and got interesting results. With the eruption of wisdom teeth, it is very important to know whether the jaw develops well or not. People whose jaw develops well can grow four normal wisdom teeth. Japanese can not have four normal wisdom teeth any more because of lack of space for wisdom teeth. Only a few modern Japanese can have four normal teeth.
On the other hand, Tibetans have many normal wisdom teeth. The results were as follows: 1) 80% of the 20-years-old villagers in Karakoram (Goma village, 1974) had four normal wisdom teeth. No horizontal or half impacted wisdom teeth were found there. Old people lost many teeth including wisdom teeth because of a high degree of abrasion and the lack of oral hygiene. 2) In northwest Nepal (a very poor village, 1983), many wisdom teeth could not erupt at 20 years of age, but after 25 years 50% of the villagers had four normal wisdom teeth. Even old people still had wisdom teeth probably because of the very low amount and poor quality of the food. 3) In Yunnan (at a Tibetan village, 1989), where villagers can eat a rather large amount of refined and well cooked food, about 40% of the villagers had four well erupted wisdom teeth. Old people lost wisdom teeth because of a high incidence of tooth caries. The causes of tooth caries were lack of oral hygiene and the consumption of rich food.

View full abstract

The time and order of eruption of the permanent teeth were studied from the records of longitudinal surveys of 8, 839 students. They were born in 1967-1968, 1970-1971, 1973-1974 and 1976-1977. The mean eruption times were estimated using an arithmetic probability paper. Longitudinal changes in time and order of eruption were determined.
The results were as follows:
1) The estimated mean time of eruption could be substituted for the mean time of eruption.
2) The mean time of eruption was earlier in females than in males.
3) Little difference was-found in mean time of eruption between the right and the left.
4) The eruption time of central incisors, lateral incisors and first molars tended to be earlier with time. Canines, first premolars and second premolars tended to erupt later.
5) The eruption time of lower central incisors tended to precede the lower first molars. Upper second premolars tended to erupt later than upper canines.

View full abstract

[in Japanese]

View full abstract

Epidemiological analyses of tooth DMF rate and 4 related indices in connection with the length of their stay, were performed on 948 subjects who received dental examinations after the initial admission examination. They were among a group of 1107 mentally retarded individuals who were admitted to the Niigata Prefectural Institute of Total Training for Mentally Retarded, Colony Niigata Shiroiwa-no-Sato during the years 1971-1988.
(1) The 948 subjects were categorized into 3 groups on the basis of the length of stay: 1-5 years, 6-10 years, and 11 years and longer. The tooth DMF rate showed a tendency to increase with age and had values in the range of 24.3-64.5%, in the ages between 15 and 49 years in all 3 groups. The tooth mortality rate (TMR) and the tooth fatality rate due to dental caries (TFR) exhibited a tendency to increas with age but had fluctuations based on the age group. TMR and TFR were between 3.1-39.7% and 10.9-70.7%, respectively, in all 3 of the groups. The treated tooth rate (TTR) and the restorative index (RI) was approximately the same with age in all 3 of the groups and rose slightly as the length of stay increased. These two indices were in the ranges of 13.6-43.2% and 57.3-100.0%, respectively.
(2) The difference in the tooth DMF rate by sex was recognized in stays longer than 11 years in the 1971-1975 newcomers (p<0.001). Females had a higher index than males in the tooth DMF rate, TMR, TTR, and RI. These were independent of the period of admission. The difference in TMR was greater in the length of stay between 6-10 years (p<0.05) and disappeared after that. There was no recognizable difference in TFR based on the admission time of subject. A difference in TTR was recognizable in stays longer than 11 years (p<0.001) but a difference in RI was not. Differences in the tooth DMF rate, TMR, and TTR by sex in 1976-1981 newcomers existed 1-5 years after admission but these differences disappeared after that. No difference was noted after 1-5 years of stay in 1982-1988 newcomers.
(3) Although a decrease was found in males and an increase was found in females, there was almost no significant difference in the tooth DMF rate in comparison to the newcomers of the same ages admitted at the time of examination. Increases in TTR and RI were remarkable. Decreases in TMR and TFR were seen in males as their length of stay increased.
(4) In comparison to the averages of all Japanese, studied in the Survey of Dental Diseases taken by the Ministry of Health and Welfare, the tooth DMF rate was almost equal in males and was lower in females. Higher values in TMR were found than in the Survey. Increases in TTR and RI were also higher in relation to the length of stay in the institute.

View full abstract

Golden hamsters are often used as an animal model periodontal disease. They were examined for the relationships among bone resorption, root surface caries, and a change in oral microflora caused by the introduction of D#2000.
The present study consisted of two experimentations to investigate those relationships. One was to investigate relationships in two groups: an experimental group started on D#2000 at the age of 5 weeks for 8 weeks, and a control group fed on CE-2 powder for the same period. The other was to investigate the influence of aging on bone resorption, and the changes in microflora by changing the time of starting feeding with D#2000.
The results were as follows.
1) Root surface caries and alveolar bone resorption were obviously increased by feeding D#2000.
2) There was no difference in growth condition between the experimental and control groups, but the level of blood sugar in the experimental group was slightly higher than in the control group.
3) The oral microflora of the golden hamsters contained a variety of bacterial species and was similar to that of human beings. Gram-negative cocci were predominant in the experimental group, and Gram-positive cocci were predominant in the control group.
4) The later the start of giving D#2000, the greater was the incidence of root surface caries and bone resorption. Although there was no statistically significant difference, an increase was seen in the number of Fusobacterium and Bacteroides as the start of feeding was postponed.

View full abstract

[in Japanese]

View full abstract

Elderly people with less than ten missing teeth can masticate any food as well as younger people.
We found that the average number of missing teeth per persons increases in a sigmoid curve with age using the “Report on the survey of dental diseases (1987, Japan) ”.
Next we determined the theoretical average number of missing teeth per person by sex and age by means of cubic logit-log polynomial regression analysis.
To achieve less than ten missing teeth at the age of eighty, we estimate the intermediate objective number of missing teeth at the intervals of five years for the people who begin their effort at the age of thirty or forty.
Because the report “To maintain twenty present teeth at the age of eighty” was published by Ministry of Health and Welfare Japan, intermediate objective of number of present teeth per persons to achieve this objective (less than eight missing teeth) was evaluated using our theoretical curve.

View full abstract

The purpose of this study was to examine the availability of the CPITN and the B.I. (Bleeding Index) for adults in the dental health administration system of preventive dental clinics. At the outpatient clinic in the hospital of Nagasaki University School of Dentistry, we have managed to control periodontal disease using a maintenance dental care system consisting of oral examination, motivation, tooth brushing instruction, scaling, and periodic recall based on an original screening method.
We analyzed the data obtained over a 2-year period from 472 patients (aged 15 to 70, who were new cases from April, 1984 to September, 1986). As the result of continuous administration of this dental care system, the B.I. decreased to about half the value of the first examination. In addition, we could easily estimate the manpower necessary to provide preventive treatment of periodontal disease to the public. If a dental team composed of one general dentist and two dental hygienists works 6 hours a day, 5 days a week, they can offer this program to 1, 167 people, excluding serious patients with CPITN code 4.
We concluded that the application of CPITN with B.I. was useful in the screening of patients, the evaluation of prognosis at each recall examination, and the estimation of manpower.

View full abstract

The purpose of this study was to investigate the incidence of congenital abnormalities of deciduous teeth including fused teeth, congenitally missing teeth, peg-shaped teeth, and supernumerary teeth, and their relation to maternal and child conditions during pregnancy or delivery. The abnormalities were also studied from the hereditary aspect. The subjects were 12, 812 children aged three years who visited the East Health Center in Fukuoka City for dental health examination during 1983-1990.
Fused teeth had the highest incidence. The incidence of fused teeth was 4.77%, including the incidence of congenitally missing teeth. Fusion of central and lateral incisors was observed with the highest freqency. Total rate of incidence of congenital abnormalities was 4.89%. No significant longitudinal changes in the rate of incidence were seen during the period of investigation. However a marked elevation of the rate of incidence of abnormalities during the past 50 years was suggested by comparison with data reported previously in Japan. Most of the abnormalities (91.5%) were found in the lower teeth. Incidence on the right side was significantly higher than on the left side. Incidence of abnormalities in deciduous teeth has no significant relation to maternal abnormalities during pregnancy, maternal age, or the weight of the child at birth. Bilaterally occurring abnormalities and fusion of canine and lateral incisors showed stronger hereditary influence than other types of abnormality.

View full abstract

In many animal models for the study of dental caries, caries is induced by exogenous inoculation with cariogenic bacteria such as Streptococcus mutans. However, it is important to establish a caries model without inoculation, because dental caries is an endogenous infectious disease. Previously we showed that ICR, C57BL/6N, C3H/HeN, and BALB/cA mice fed on a caries-promoting diet, Diet-2000, for 3 months developed fissure caries without prior inoculation. This study was to determine the details of the formation of these carious lesions in C57BL/6N mice. The results were as follows.
1) All experimental groups (Diet-2000 containing 56%, 30%, 10%, and 0% sucrose) developed fissure caries. Sucrose in the diet influenced the progress of caries rather than the caries incidence.
2) Fissure caries developed after only 4 weeks in mice fed on Diet-2000 containing 30% sucrose. The extent of the caries increased with the experimental period.
3) Three- to 4-week-old mice developed the fissure caries effectively. Older mice showed less susceptibility to caries.
This experimental system is suitable model for the study of dental caries as an endogenous infectious disease, and can be used for gaining knowledge of caries etiology, immunology, genetics, and prevention.

View full abstract

The purpose of this study was to evaluate acidogenicity of chewing gum sweetened with palatinose or/and maltitol in pH-response of dental plaque.
The subjects of six volunteers, four males and two females, aged 23 to 31 year, were participated in this study. An IS-FET pH electrode was used to monitor changes in plaque pH on the buccal site of the mandibular fist molar. Plaque pH was measured in the utilization of plaque which had accumulated on the electrodes for four days. Chewing gum was tested individually and subjects had consumed only water for two hours before measurement. The gum was chewed for 4 minutes and then taken out. The pH measurement was performed for 30 minutes. Unstimulated salivary secretion rate and salivary secretion rate stimulated by the chewing gum were measured by Curby cup. Salivary mutans streptococci level was scored by the semi-quantitative method. A paired t test, ANOVA, multiple range test, t test (LSD), Tukey's studentized range (HSD) test were performed for six variables: Minimum pH, ΔpH, maximum rate of pH drop, maximum H⁺, total H⁺, and maximum rate of H⁺ production. Repeated measures analysis were performed for the pH-values, at 0 to 10, 15, 20, and 30 minutes. The same statistical analysis was performed for H⁺.
Individual variation of plaque pH-response after chewing of the test gum was observed. Values of minimum pH for palatinose or/and maltitol chewing gum were significantly higher than for sucrose chewing gum and did not drop below pH 6.0 (p<0.0001). The other two variables were significantly lower than in sucrose chewing gum (p<0.0001). Plaque pH-values at 3 to 30 minutes for palatinose or/and maltitol-chewing gum were significantly higher than for sucrose chewing gum (p<0.001). Similar findings were obtained by using maximum rate of H⁺. production. Mutans streptococci level was partially associated with plaque pH drop, but there was no correlation between salivary secretion rate and three different pH variables.
The findings indicate that chewing gum sweetened with palatinose or/and maltitol is non-cariogenic. Individual variation might be explained by mutans streptococci level and salivary factors such as buffering capacity.

View full abstract