We collected 338 references no the epidemiology of dental fluorosis in Japan, from which we chose 248 articles pertaining to the field work of the disease. We found that reports of dental flurosis had been made in all the perfectures of Japan (46 prefectures) except Miyagi. Of these 46 prefectures, 36 areas in 22 prefectures were examined continuously for a long period. Of the 36 areas in 22 prefectures, 15 areas in 12 prefectures were examined several times by the same researchers. The areas in which the prevalence of dental fluorosis decreased or disappeared were 4 in number; that is, in Aso (Kumamoto Pref.), Funaki (Yamaguchi Pref.), Kasaoka (Okayama Pref.), and Ikeno (Aichi Pref.),
In Japan it was about 1950 that the fluorine concentration of drinking water began to be generally measured.
Before 1949, there were 52 reports made concerning dental fluorisis, but fluoride concentration was measured in only 7 of them, and the others gave no evidence to show that the disease was caused by fluoride. However it was late confirmed that 31 of these reports had correctly examined dental fluorosis.
In and since 1950, 20 reports were made in which there was no description of fluoride concentration, and 11 reports stating that dental fluorosis occurred at 0.3 ppm fluoride concentration and below.
Regarding these 11 reports, we could not confirm that the desease was caused by fluorosis, either because no follow-up survey was made or because it was difficult for us to confirm the validity of the results.
In the literature we gathered the highest concentration of natural content of water fluoride was 23 ppm at Oga (Shiga Pref.), according to the report by Minoguchi and others ('56). In Japan, dental fluorosis, first reported by Fukui ('25), has been examined for 60 years. But 55 % of the literature was pubished during the 10 years from 1950 to 1960.
This fact shows that dental fluorosis studies were of very wide prevalence during that period. This prevalence was noticed not only in the field of dentistry but in medicine and other fields.

View full abstract

The purpose of this study was to investigate what factors influence dental treatment postures in the supine operating system. The postures were studied by moiré topography, which permits dynamic observation and three-dimensional analysis. Eight dentists were photogrophed from the back while seated during treatment. Their backs were marked for analysis beforehand with the five reference marks: the seventh cervical vertebra-, the twelfth thoracic vertebra, the fourth lumbar vertebra, and the spines of the right and left scapula. Four experimental conditions, i. e., the height from the patient's mouth to the dentist, the angles of pitch and roll of the patient's head and the relative positions of dentist to patient at clock face system, were changed. The photographs were analyzed for three kinds of movement, side shift, stoop and torsion, in the trunk of the dentist.
It was observed that the dental operating postures of the trunk were affected by several factors as follows. The side shift was influenced by the rolling angle of the patient's head, the relative positions of the dentist, and the treated locations in the mouth. The stoop was affected by the height of the patient's mouth, and the angle of pitch of the patient's head. The torsion was affected by the rolling angle of the patient's head and the relative positions of the dentist.

View full abstract

In 1979 the dental health of 1132 children, aged 1 to 5 years, was surveyed in three different areas. Seven nursing schools in Chuo-ku (Tokyo), Hiraizumi-cho (Iwate), and Minamidaito-mura (Okinawa) were studied. We compared the oral status of the children in these areas using many indices, such as caries prevalence, mean dmft, the percentage of children with advanced carious teeth, number of advanced carious teeth per person, the percentage of filled teeth in carious teeth, and the percentage of carious types in deciduous teeth.
The children in Chuo-ku were in the best condition, the children in Hiraizumi-cho were average, and the children in Minamidaito-mura had the poorest oral status. This result confirmed recent reports that children in rural areas have more dental caries than those in urban areas. Five-yearold children with poor dental conditions have more erupted first permanent molars and more carious teeth among them.
From these results, where there are severe carious teeth in deciduous molars, there seems to be a tendency for first permanent molars to erupt early and to develop caries. We concluded that the prevention of caries in deciduous teeth is important.

View full abstract

A large quantity of coenzyme Q₁₀ (CoQ₁₀) naturally exists in mitochondria of various tissue cells in human beings, and has indispensable functions in the bioenergetics of cells. Some clinical reports have demonstrated that oral administration of CoQ to patients with periodontal disease is significantly effective in some cases. However, basic studies on the relationship between CoQ₁₀ and periodontal disease have not yet been done. The purpose of this study was to investigate the effect of oral administration of CoQ₁₀ on experimental periodontitis in dogs, particularly on the changes in CoQ-dependent enzymes.
Thirty adult dogs were divided into four groups: 1, normal group; 2, CoQ₁₀-treated normal group; 3, experimental periodontitis group; and 4, CoQ₁₀-treated experimental periodontitis group. The experimental periodontitis was induced by placing a cotton-floss ligature subgingivally around the crown of a molar tooth. CoQ₁₀ was administrated orally in a dose of 1.5 mg/kg daily for 2 weeks from the 3rd to the 4th week after the beginning of the experiment. The clinical estimations were performed by using gingival index, plaque index, and pocket depth. The CoQ10 levels in plasma and gingiva were determined by high performance liquid chromatography. The activities of CoQ-dependent enzymes, such as succinate dehydrogenase-CoQ reductase (SD-CoQR), succinic-cytochrome c reductase (S-CCR), and NADH-cytochrome c reductase (NADH-CCR) in the mitochondrial fraction of gingiva were determined in an enzyme assay system in which exogenous CoQ₃ was absent and present.
The results obtained can be summarized as follows:
1. The activity of CoQ₁₀-dependent enzymes such as SD-CoQR, S-CCR, and NADH-CCR were apparently present in the dog gingiva.
2. The oral administration of CoQ₁₀ to the normal group did not alter either the activity of CoQ-dependent enzymes or the level of CoQ₁₀ in gingiva, but tended to elevate the level of CoQ₁₀ in plasma.
3. Both the S-CCR and NADH-CCR activity in experimental periodontitis were significantly higher than in normal group. The CoQ-% deficiency of the S-CCR in the periodontitis group was increased considerably. No significant change was found in the CoQ₁₀ levels in plasma and gingiva of the periodontitis group.
4. The oral administration of CoQ₁₀ to be periodontitis group was effective in suppressing advanced gingival inflammation. The CoQ₁₀ levels in plasma and gingiva of the periodontitis group were significantly elevated by treatment with CoQ₁₀. The administration of CoQ₁₀ enhanced the activities of CoQ-dependent enzymes, and restored the increased CoQ-% deficiency of S-CCR to normal level.

View full abstract

Sodium lauryl sulfate (SLS) and sorbic acid (SA) were selected because of the dental utility of dextranase (α-1, 6-glucanase) produced by Chaetomium gracile, and their inhibitory effects on plaque and caries formation were investigated. 6 experimental groups of 9 rats each, were prepared to examine the effect of each agent and the combined effect of the reagents by randomized complete block design. The influence of the reagents was estimated by plaque score and caries score and the correlation between the two scores was also investigated. The results are
1. The inhibitory effect of dextranase on plaque formation was satisfactorily significant against the control group (reduction rate; 30.8 %). SLS and SA dosed with dextranase tended to inhibit the plaque formation (reduction rate; 44.6 %) but they showed no inhibitory effect without dextranase.
2. Analysing these results according to site, plaque formation, and caries incidence, the relations were as follows, mandible>maxillary, right side=left side, and first molar>second molar>third molar. All experimental sites of the dextranase dose groups had less plaque formation and caries incidence than in the control group,
3. The correlation between plaque and caries score was significant based on the data from rats (n=54) and experimental sites (n=72) (p<0.01).
It appears that dextranase has a direct effect on plaque and also has the potential to prevent caries.
The inhibitory effects of dextranase produced by Chaetomium gracile on the development of dental plaque and caries.

View full abstract