We surveyed whether water used for dental treatment met the water quality standard and chlorine residue concentration rule stipulated in the Water Supply Law Enforcement Regulation in 20 dental clinics in Japan between Nov. 1999 and Jul. 2000. The water was collected at the shut-off valve and the tip of the air and water syringes in each clinic. Immediately after routine use at the end of the day or before the first treatment of the next day, the collected water was evaluated for chlorine residue concentration and the number of bacteria. The results of our tests showed that 45% of the water surveyed met regulation standards, but that, all the clinic had a chlorine residue concentration of less than 0.1 ppm, which is below regulation standards bacteria were found at the shut-off valves at the end of the day (n=5), but in all institutions bacteria was found in the tips of the air and water syringes (n=5). In the first water flow measured the next day (n=15), bacteria was found at the shut-off valves in 70% of clinics and at the tips of the air and water syringes in 77% of clinics. Although there have been several studies regarding the quality of dental treatment water, none of them discussed any fundamental counter-measures to address the issue of bacteria growth in the water piping system. In order to improve water quality, we devised a unique chlorine residue concentration compensator and evaluated its effectiveness in clinical use. The results were very successful : the water at all of the institutions surveyed met both the water quality standard and the chlorine residue concentration rule, and no bacteria were found.

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We investigated the condition of occupational oral health promotion as assessed by health care staff using a questionnaire in workplaces that employed more than 50 workers in Kagawa prefecture, as a part of a study on how to promote oral health services more efficiently (total 853 workplaces). The results were as follows : Dental examinations for workers were offered in only 33 workplaces and we judged knowledge of dental health was "not enough." Only a small number of workplaces gave positive answers in regard to having a schedule promoting oral health and services. The results of this study showed that, in places where occupational health nurses were employed, the dental examinations were made more readily available for the employees, and that the occupational health nurses played a major role in convincing the employer of the importance of employees' oral health. Where dental examinations were offered, follow up health care was offered in only 8 workplaces (24.2%). If dental examinations were offered, oral health care was thought of as the individual is responsibility in 48 workplaces (26.4%), and these workplaces gave a negative answer about promoting oral health and services. We concluded that the promotion of oral health in the workplace is insufficient. The workplaces that employ occupational health nurses were positive for the promotion of oral health, and their employment was one factor for the promotion.

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This study evaluated the clinical efficacy of the dentifrice on the improvement of mild gingivitis containing exothermic zeolite. Seventy subjects who had mild gingivitis were selected and divided into two groups for 32 days-clinical test by a randomized method. One group used the dentifrice containing 0.01% benzethonium chloride, 0.1% dl-α-tocopheryl acetate and 0.01% β-glycyrrhetinic acid (the control dentifrice), and another group used the dentifrice containing 20% exothermic zeolite in addition to the ingredients indicated above (the test dentifrice). During brushing with the test dentifrice, the temperature of the papilla between the maxillary canine and lateral incisor remained 38.5±0.7℃. For the control dentifrice, the temperature remained 34.6±0.5℃. There was a significant difference between the test dentifrice and the control dentifrice (p<0.05). After 32 days, both dentifrices caused a significant decrease in the modified gingival index (MGI) (p<0.05) and plaque score (Quigley & Hein's Plaque Scoring System) (p<0.01). In the case of the test dentifrice, MGI was decreased significantly at sites with bleeding after 10 days, and decreased significantly at the sites without bleeding after 32 days, whereas there was no significant difference for control dentifrice. These results show that the dentifrice with exothermic zeolite improved mild gingivitis, and was more effective than the dentifrice which contained only anti-inflammatory and anti-microbial agents. It suggests that the thermal stimulation derived from the exothermic effect of the zeolite may be related to the improvement of gingivitis.

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This study was carried out to investigate current reasons for tooth extraction in Okayama Prefecture. A total of 1,046 dentists belonging to the Okayama Dental Association were requested to file a recording sheet for each tooth extracted during a two-week period in July 1998. Within the period, 399 of the dentists returned the forms. The following results were obtained. 1. The dentists had extracted 4,594 teeth, with a mean of 5.76 teeth per week. 2. Periodontitis accounted for 46.1% of the teeth extracted, while 42.1% of teeth were lost due to dental caries. 3. The mean age of patients was 53.3 years old for dental caries and 58.8 years old for periodontitis. Except for the third molar, the subjects had their upper first premolar extracted prematurely, followed by the upper second molar and the lower second molar. 4. In patients under 45 years old, extractions for dental caries were predominant. In the age over 45 years old, periodontitis was dominant. 5. Compared with the previous investigation in 1986 and 1987, the number of teeth extracted per dentist had decreased. The mean age of the patients was higher, and the primary reason for extraction changed from dental caries to periodontitis.

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The aim of this study was to compare dental attendant behavior in female office workers and male worker's spouses. Dental attendance and food intake behavior were analyzed in terms of four components : (1) the mean number of dental care bills per year ; (2) the mean number of dental consultation days per year ; (3) the mean insurance score of the dental care bills per year ; and (4) responses from a self-reported questionnaire. Statistical analysis of these data was performed using the Mann-Whitney's U test and chi-square test. The results were as follows. The mean number of dental care bills per year in the 50-54 yrs group was 1.40 in female office workers and 2.21 in male worker's spouses. The mean number of dental consultation days per year in the 50-54 yrs group was 2.89 in female office workers and 5.58 in male worker's spouses (p<0.05). The mean insurance score of the dental care bills per year in the 50-54 yrs group was 1,752 in female office workers and 3,016 in male worker's spouses (p<0.05). In questionnaire responses, male worker's spouses revealed significantly higher rates (p<0.05) of eating between meals and dental attendance during clinical hours than female office workers. These results suggest that its necessary to provide oral health instruction not only for employees but also for male worker's spouses.

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Many cases of contact allergy due to dental metals have been reported, and several in vitro or in vivo tests have been used for the screening of the allergenic epitopes. One of the in vitro methods is the lymphocyte stimulation test, which can reveal the sensitization of T-cells by an enhanced proliferative response of peripheral blood lymphocytes to a certain metals. In this study, to evaluate the lymphocyte stimulation test as a screening method for metal allergy, an intradermal patch test was performed in 410 subjects, of whom 17 subjects with or without experience of metal allergy, also received a lymphocyte stimulation test of mercury, nickel, chromium, cobalt, gold, titanium and DNCB (1-Chloro 2, 4-dinitrobenzene). In the case of DNCB, positive responses to both patch test and the lymphocyte stimulation test were found in only one subject who was occupationally exposed to the chemical and showed allergic symptoms. Cobalt, chromium, gold and titanium caused positive proliferation in patch test-positive subjects with or without allergenic experience, and the stimulation index (SI) values were lower than 180 in patch test-negative subjects. Thus, we suggest that the lymphocyte stimulation test was a reliable in vitro method for identifying chemical sensitivity. However, in the case of mercury and nickel, the SI values between the patch test-positive and negative cases did not differ significantly, and the values of all subjects were higher than 181. So we speculate that the T-cell of all subjects were sensitized to mercury and nickel because those metals are used widely in daily tools. Particularly high SI value was found in the subject who had been occupationally exposed to mercury, but had negative responses in vivo. This finding suggests that a positive response in the lymphocyte stimulation test may also have been caused by immunological tolerance, even if the subjects showed a negative response in vivo. Therefore, for identifing mercury and nickel hypersensitivity, the lymphocyte stimulation test was not a sufficiently accurate method and we recommend using a different functional test.

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This study was undertaken to investigate both the oral microbial flora and salivary functions in diabetes mellitus (DM) patients for preventing the onset of the oral infections. A total 129 DM patients (the mean age ; 54.0 years old, HbA_1C 9.3%, FBS ; 187.9 mg/dl) were divided into 2 groups by the level of HbA_1C (HbA_1C ≧8% group or HbA_1C 8% group). The statistic correlations were observed between the periodontal status and the incidence of periopathic bacteria, and between the number of lactobacilli and that of mutans streptococci. HbA_1C ≧8% group showed a lower number of sound teeth, while showing higher levels of PD, lysozyme in saliva, Candida on the tongue and total bacteria in the periodontal pockets than those of HbA_1C8% group. These findings suggest that poor controlled DM patients may have a high risk of candidiasis. Oral microbial flora and salivary functions before and after FBS control were investigated in 27 out of 129 DM patients and these findings were compared. After FBS control, the salivary buffering capacity and the number of lactobacilli and mutans streptococci in saliva were significantly improved from the pre-FBS control. These findings indicate that FBS control may reduce the pathogens of oral infections. In conclusion, both the dentist and physician should work in closer cooperation for preventing oral infections connected to diabetes mellitus.

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To investigate whether osteoporosis is a factor affecting periodontal disease, we investigated the relationship between periodontal condition and bone mineral density (BMD) of the calcaneus in 233 residents of Nagoya City (33 males and 200 females) aged 17 to 87 years. BMD was measured using an ultrasonic method and periodontal conditions were evaluated using the Community Periodontal Index of Treatment Needs (CPITN). Although the rate of periodontally diseased sextants (ROPS) showed a significant correlation with BMD in both males (r=-0.34, p<0.05) and females (r=-0.34, p<0.01), the association was not significant when the ROPS was regressed by multiple factors such as age, frequency of toothbrushing, menstrual status and body mass index (BMI) together with BMD. Only the number of toothbrushing was a significant factor in the premenopausal group. In the postmenopausal group, age had a significant relationship with periodontal condition. Menopause is only slighty associated with ROPS (OR=2.6, 95% CI : 0.9-7.4, 90% CI : 1.1-6.3). The results of this study suggest that factors such as age, frequency of toothbrushing and menopause might play roles in the initiation and progression of periodontal disease.

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