From the late 1960s through to the end of the 70s, dental schools were rapidly established throughout Japan as part of a national policy dealing with dentist supply and demand. The number of dental schools in the country increased from 6 to 29 (12 national/public, 17 private) during this period. However, this policy was dramatically reversed in the mid 1980s, when the government switched to a policy of restraint. A 20% reduction in the number of new dentists was achieved, and, beginning in 2004, an effort was made to improve the national dental examinations and restrict the number of successful applicants. However, it is clear that these two methods alone are insufficient to control the number of dentists. That being the case, the purpose of this study was to demonstrate the statistical relationship, in each of the 47 prefectures, between the change in the number of dentists per 100,000 people during a 20-year period (1982-2002), the type of management (national, public, private) of the dental schools, and the geographical characteristics of the dental schools (e.g., average distance from the center of the prefecture). Analyses of the factors affecting the number of dentists in each prefecture were performed using the GLIM (Generalized Linear Models) method developed by P. McCullagh and J. A. Nelder. The future number of dentists in each prefecture was estimated by extrapolation using the linear regression line. Specific measures for regulating the number of dentists are also discussed in this study. The results show that the trend of the number of dentists during these twenty years was nearly linear (r≧0.96) and there was no reduction of the differences among the prefectures. The outcome of the GLIM analyses strongly indicates that the existence of national or public dental schools corresponds to a steep increase in the number of dentists who work at the clinics or hospitals. In other words, national and public dental schools are strong attractive forces for the recruitment of new dentists. However, the extension of this effect to neighboring prefectures was, contrary to expectation, not significant. These results indicate that, in order to fully understand the variety of functions and characteristics of dental schools, more accurate studies on the dynamics of dentist recruitment at each school and municipalities are needed. If the threshold point at which the supply of dentists is considered in excess is fixed at 80 dentists per 100,000 people, about 30% of prefectures will cross the threshold in 10 years, and 50% will cross it in 20 years. Based on these results, we propose that legal measures to disperse post-graduate dental trainees to prefectures with no dental school would be a more effective method of regulating the supply of dentists.

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The objective of this study was to compare the effects of four pastes-regular toothpaste as a control (CT), regular toothpaste containing either dipotassium glycyrrhizinate (GLY), dipotassium glycyrrhizinate with Create Ion^[○!R] High Power (HP), or dipotassium glycyrrhizinate with Create Ion^[○!R] Number One (No 1), on periodontitis in the rat model. In addition, the effects of mechanical stimulation of gingiva when combined with the pastes were also evaluated. Under general anesthesia, lipopolysaccharide and bacterial protease solution were applied once a day into the palatal gingival sulcus of the upper right and left first molars of 40 male Wistar rats to induce periodontitis for 8 weeks. From the 5th to 8th week, 4 toothpastes (n=10) were applied in the gingivae of the right and left maxillary first molar once per day for 10 minutes respectively. Also, the palatal gingiva of the left molar was stimulated once a day using a power toothbrush. After 8 weeks, the teeth and gingivae were fixed, decal-cified and embedded in paraffin. Buccolingual sections were evaluated using hematoxylin-eosin staining. Statistical differences among the 4 groups and between stimulated and non-stimulated sides were tested by the ANOVA or Kruskal-Wallis test, and the Student's t-test or Mann-Whitney test, respectively. In the No 1 group, the number of polymorphonuclear leukocytes in the junctional epithelium was significantly decreased. In the HP group, the number of polymorphonuclear leukocytes in connective tissues was significantly less than that in the other groups. The stimulated side had a lower number of polymorphonuclear leukocytes in the junctional epithelium and connective tissue than the non-stimulated side in the GLY group, and the values were similar to those for the stimulated sides of the HP and No 1 groups. In conclusion, Create Ion^[○!R] High Power and Create Ion^[○!R] Number One with dipotassium glycyrrhizinate reduces polymorphonuclear leukocyte infiltration into connective tissues and junctional epithelium, respectively. Mechanical stimulation of gingiva combined with dipotassium glycyrrhizinate reduces polymorphonuclear leukocytes in junctional epithelium and connective tissue as strongly as dipotassium glycyrrhizinate and Create Ion^[○!R] without mechanical stimulation.

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Gingival crevicular fluid (GCF) contains a variety of inflammatory substances resulting from the host response to microbial challenge in the periodontal pocket. Thus, laboratory tests of GCF could be utilized for the early detection of periodontal inflammation and/or motivation of workers with respect to the modification of unfavorable health behavior. We investigated the association of inflammatory substances in the GCF with the oral health status and lifestyle of workers in order to examine the potential of the laboratory test of GCF for worksite health promotion. GCF was collected with standardized filter paper at one fixed site for 921 employees. Hemoglobin (Hb), α1-antitrypsin (AT), lactoferrin (LF) and IgA levels were determined at a commercial laboratory. Logistic regression analyses of the levels of these substances as dependent variables showed negative associations for all tests with the number of existing teeth. Levels of Hb, AT and LF were positively associated with individual scores of the Community Periodontal Index. Individual scores of plaque accumulation were positively associated with levels of AT, LF and IgA. Although current smoking was significantly associated with the level of Hb, smokers were less likely to have high levels of Hb in the GCF than their non-smoking counterparts. The Oral-Health Practice Index was negatively correlated with levels of AT and LF. These results indicated that the levels of GCF contents were associated with the oral health status and oral-health related lifestyle of workers. Profile records of the laboratory GCF test could be used for the explanation of periodontal inflammation and oral health status, even though the sample was drawn from one site from the mouths of workers. The results also suggested that the Hb level in the GCF should be used carefully in the case of current smokers. Further studies are needed to develop GCF tests which could be related to the lifestyle of workers.

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In 1993, a daily fluoride mouth rinsing program and biannual oral examination were started at the nursery school, elementary school and junior high school of the K District, Tokushima Prefecture. In this study, the longitudinal change of caries development in elementary school students was evaluated. Caries development by tooth type in schoolchildren of the 6th grade was evaluated, and furthermore, the relationship between deciduous tooth caries in 1st grade students and caries development in permanent teeth in 6th grade students was also elucidated. After starting the daily fluoride mouth rinsing program, caries development in the permanent teeth of the low grade children of the elementary school began to decrease first, followed by that of the high grade children, and then, the junior high school students. It was revealed that the strong suppression of caries development in the 1st molar was reflected in a decrease in total caries development in the 6th grade schoolchildren. In addition, a significant relationship between DMFT in the 6th grade schoolchildren and the number of deciduous tooth caries or the number of deciduous teeth in the 1st grade schoolchildren was detected. These results suggest that a fluoride mouth rinsing program before school age is effective for caries prevention in the 1st molar, but, in order to effectively prevent permanent tooth caries, a high risk strategy is needed for children with deciduous tooth caries.

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The purpose of this study was to analyze the actual condition of eating independence and the oral health status to establish a more effective therapy and support for residents with dysphagia. The subjects were 141 individuals (36 males and 105 females; mean age of 79.4, 9.0 SD), who had eating and swallowing therapy at nursing homes for five years from 1998 to 2002. Cerebrovascular accident (CVA) was the most prevalent disease, and 139 subjects had several underlying diseases. In the proportion of independent activities for daily living, eating was the best, and next was oral self care. The average number of teeth present was 5.9, 7.5 SD. Ninety-six percent of the subjects had lost more than one occlusal support region, and 60.1% of subjects had dentures. Subjects with dementia and mental disorders, showed a significantly lower rate of being able to eat independently (p<0.05). Wearing dentures was necessary not to acquire stabilized occlusion but to improve masticatory function. In the future, we have to examine the acceptance of dental treatment and the wearing of dentures for residents with dysphgia.

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In order to prevent dental caries of the primary teeth, an administrative service combined with professionally applied topical fluoride gels (PATFG) and fluoride toothpaste for home use (FTP) was implemented in Mishima Town of Niigata Prefecture in the fall of 1994. The service targeted children aged 1 to 3 years. The PATFG was practiced every 6 months periodically. Fluoride tooth paste was given to every child at the one-year-old examination and his/her mother was instructed to use it once a day. A trained dentist practicing his clinic in this town examined the dental caries status of subjects at the 3-year-old examination in 1990-1998 and preschool examination in 1997-2001. The purposes of this study were to determine the effectiveness of the service, compare the acceptability between PATFG and FTP, and also to estimate the additive effect of FTP to PATFG. The caries prevalence surveyed in 1990-95 was 42-47% in 3-year-old children who did not receive the PATFG and FTP service. In 1997-98, however, the prevalence rate decreased and showed 17% in 3-year-old children who received this service. The prevalence in preschool children also decreased from 73% in 1997-98 to 51% in 2000-01. The mean dft of preschool children who participated in the service was 1.54. On the other hand, a mean dft of more than 3 was found in other groups who could not participate in the service or participated partially. The acceptability in PATFG was superior to that in FTP, because the rate of children who received PATFG twice a year periodically was 83.6% against 55.2%, which was the rate of children using FTP every day. Out of 97 children receiving PATFG regularly, 61 using FTP every day showed a lower caries prevalence, both at the 3-year-old examination and preschool examination, when compared to the children (n=29) without FTP. However, significance was only found in the results at the preschool examination. It might be considered that the difference in caries status expanded from the age of 3 and reached a level of significance at the preschool age. In the stepwise multiple regression analysis, the dft at the preschool examination was adopted as the dependent variable and 8 independent variables were included. The result showed that only the independent variable of 'no use of FTP during 1-3 years old' was significant. The independent variable of 'the experience of PATFG' was not selected. We considered that this variable could not contribute to the analysis because a high rate of children received PATFG. In conclusion, these results suggested that the PATFG plays an important role and the FTP plays an additional role in administrative service for dental caries prevention in primary teeth.

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The aim of the present study was to investigate the effect of health education programs for the prevention of gingivitis in elementary school children, and its relationship with health education methodology and the psycho-behavioral background. Two kinds of health education program based on the idea of a learning support program were applied to 81 children in Fukuoka City. Children were divided into two groups : One group (TEG) was provided with an educational program which consisted mainly of teaching elements in addition to learning elements; The other group (LEG) was provided with another educational program which consisted mainly of learning elements in addition to teaching elements. Toothbrushing behavior and knowledge, and attitude toward toothbrushing were surveyed with questionnaires before and after the intervention. Self-esteem (SE) and self-management skills (SMS) were also evaluated using standardized questionnaires before intervention. Children with moderate to severe gingivitis decreased in the short term (p<0.001), and 8 months after (p<0.01) intervention in both groups. Significant changes in factors related to toothbrushing were observed for 3 items in children of the TEG and 5 items in children of the LEG. Recognition of the educational elements of the program was significantly different between the two groups. SE and SMS were significantly associated with toothbrushing-related factors in 2 and 8 items before intervention, and 6 and 7 items after intervention, respectively. Since both programs were effective in decreasing gingivitis, either program could be selected and applied to school children. The psycho-behavioral background of the children, especially concerning self-management skills, may be taken into account to develop a more effective program of health education for the prevention of gingivitis.

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Since the current national health insurance in Japan only covers treatments for existing diseases and injuries, there is little incentive for regular preventive dental visits or preventive interventions in dental practice. In order to provide basic data to evaluate these preventive activities for future dental practices, the trends in dental utilization and dental practice were investigated using some national surveys. 1. In adults, the prevalence of dental caries was more than 40 percent, and from 20 to 30 percent of people consulted a dentist for dental caries in the past year. As for periodontal diseases, the prevalence was more than 80 percent, and the dental visit rate was just a few percent. The number of outpatients was comparatively close to that for people with oral symptoms. It seems that people mainly consult a dentist only after they realize the symptoms. 2. During the past 15 years, the dental visit rate for people aged 54 and under decreased, but increased among those aged 70 and over. Visits for dental caries or pulpitis decreased and those for periodontal diseases increased. However, most dental visits were for treatments of dental caries or prosthodontics. Visits for dental check-ups were less than 1% of total visits. 3. The transition of fees per dental claim from 1985 through 2002, excluding the influence of the revision on dental treatment fee points, revealed that the "Restoration and Prosthodontics fee" had plateaued and the "Treatment and Surgery fee" and the "Diagnostic Test and Radiology fee" had decreased since the second half of the 1990's. On the contrary, the "Instruction fee", mostly consisring of fees for oral health instructions and disease preventions, has increased remarkably. 4. According to a regression model analysis using panel data by age groups from 1994 to 2002, I estimated that 1% of the "Total fee" and the "Instruction fee" change in the previous year affected the "Instruction fee" in the following year by 0.04% and 0.98%, respectively. Therefore the "Instruction fee" has been promoted by the increase of the "Instruction fee" in the previous year, rather than by the change of the "Total fee" in the previous year. This implies that receiving and giving preventive instruction has been established and become accustomed to over the same period. I also found that the raise of the co-payment rate of the employed in September 1997 caused a 27.5% reduction of the "Instruction fee". These findings show that the instructions for prevention, mainly for periodontal diseases, have been provided for more in dental practice. This means that the recent remuneration policy has induced more preventive interventions, even under the current health insurance system. Meanwhile, there is a disparity between the number of people with oral diseases and that of people who realize their symptoms. I conclude that dental practitioners should encourage their patients to have routine dental check-ups, and consultations at an early stage should be recommended for those who have not yet realized their symptoms.

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The prevalence of dental caries in 3-year-old infants in Okayama prefecture was 32.3% in 2002. This prevalence was about 10 fold higher than that of 1.5-year-olds in 2001. Effective intervention is required to control the incidence of caries. In Japan, municipalities (cities, towns and villages) have conducted many oral health care programs. However, there are few reports evaluating these programs. Ensuring the effectiveness of these programs is an integral part of the planning and executing community-based interventions. The purpose of this study was to evaluate the effectiveness of community-based oral health programs on reducing the incidence of dental caries in 3-year-old infants. A total of 78 municipalities in Okayama prefecture were included in this study. The municipalities were categorized into two groups according to the execution or absence of each intervention, and the dental caries incidences were compared between these groups. Odds ratios of dental caries prevalence were estimated for each intervention. All data were obtained from the year reports of nursing mothers and infants of Okayama prefecture. Caries prevalence was calculated from 30,514 infants who had had a periodical health check at age 3 (15,379 infants in the fiscal year of 2001 and 15,135 in 2002). In regions with the topical fluoride application program conducted by municipalities, the prevalence of dental caries was statistically lower than those without the program (odds ratio; 0.75-0.84). The regions with a dental caries risk assessing program showed a statistically higher prevalence than those without the program (odds ratio; 1.07-1.14). The execution of oral health education or a commendation for no decay infants at 3 years old had no clear effect on controlling a high caries prevalence. In the regions with an action policy on oral health (inquired in 1999), the incidences of dental caries in 2002 and 2003 were higher than in regions without an action policy. The results showed that the topical fluoride application program could be the best measure for reducing the incidence of dental caries among 3-year-old infants. But the caries risk assessing programs had no effect on caries prevalence. Topical fluoride application programs should have priority over other community-based intervention programs for infants' dental caries.

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The purpose of this investigation was to clarify the spread conditions of the school-based fluoride mouthrinsing program throughout Japan. Data were collected by questionnaire surveys regarding the schools and children participating in the program, frequency of rinsing, mouthrinsing agent used, fluoride concentration of the rinsing solution and financial support for the program. Questionnaires were sent to the key persons and dentists of the non-profit Japanese Conference on the Promotion of the Use of Fluoride in Caries Prevention (NPO-JPUF) by mail or e-mail every two years. In 2004, the total numbers of schools and individuals participating in the program were 3,923 and 396,702, respectively (in schools : nursery schools and kindergartens 60.6%, primary schools 33.6%, and secondary schools 5.3%; for children : nursery schools and kindergartens 27.5%, primary schools 63.5%, and secondary schools 8.8%). In nursery schools and kindergartens, 65.8% of the participating children adopted the daily rinsing-method using mainly 0.05% NaF solution. In primary and secondary schools, respectively, 85.9% and 90.2% adopted the weekly rinsing-method using mainly 0.2% NaF solution. The programs are supported by public funds of the prefectural and municipal governments in 80.0% of nursery schools and kindergartens, 87.0% of primary schools and 92.4% of secondary schools. Although the number of schools and children involved in the program is increasing, it is still modest and shows regional differences. These results suggest that cooperation between dental organizations, dental schools and municipal corporations plays an important role in order to reduce regional differences and increase the schools and children participating in school-based fluoride mouthrinsing programs in Japan.

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