The aim of this study was to investigate the assumption that "tooth loss predicts further tooth loss". In this study, percentiles of the number of teeth present were used to perform a 6-year generational cohort analysis, in order to develop a prognostic aid. The percentiles were estimated using the cumulative frequency distribution of present teeth (PT) from two surveys of dental diseases undertaken by the Ministry of Health, Labour and Welfare in Japan. The first was a survey involving 1,122 subjects aged 55-64 in 1999, and the second was a survey of 950 participants aged 61-70 in 2005. The first to 100th percentiles of the number of PT were calculated for both age groups. Using these percentiles and a generational cohort analysis from the two surveys, the projected number of teeth lost over the next six years could be calculated. The resulting distribution of the number of teeth lost was an asymmetrical convex curve. The peak of tooth loss was around 14-16 PT. However, the rate of tooth loss (number of teeth lost per number of PT) increased as the number of PT decreased.

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The purpose of this study was to investigate the oral health status of Japanese university students and evaluate the relationship between periodontal health and related factors using a self-reported questionnaire. Undergraduate students (n=2,422) at Okayama University, aged 18-28 years, received oral examinations in 2008. Periodontal examination was conducted according to the protocol of the United States National Health and Nutrition Examination Survey III. The results showed that the number of teeth present was 28 (22-32) [median (range)]. The percentage of subjects with decayed teeth was 13.6%. Subjects with periodontal disease (at least one tooth with a probing pocket depth ≥4mm) comprised 4.9%. According to the questionnaire survey, the prevalence of temporomandibular joint (TMJ) sounds was 26.5%; TMJ pain, 8.0%; and mouth opening limitation, 8.9%. The percentage of subjects with repeated stomatitis was 18.7%. There were gender differences in the number of decayed teeth, periodontal condition, and complaints of symptoms of temporomandibular disorders. There was a significant association between periodontal health and the following four questions: "Do you visit a dental office regularly?", "Do you notice bloody gums?", "Do you think that you have gingival swelling?", and "Do you think you have periodontal disease?"

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In previous studies, we performed caries risk tests of students who participated in school dental health check-ups, as well as of mothers and infants, and patients receiving orthodontic treatment, and reported the usefulness of the results. In the present study, we aimed to clarify the distribution of caries risk factors in children and young adults, and the relationship between caries and risk factors by age. The subjects were 1,262 people, who were infants, school children, and young adults ranging in age from 0-29 years old. The ratio of each caries risk factor in each age group, as well as the relationship between the number of carious teeth and caries risk factors were compared. Our results showed that the distribution of caries risk factors varied with age. In infants and lower-grade elementary school children, the number of carious teeth was correlated with multiple caries risk factors. In contrast, the number of carious teeth showed no correlation with specific caries risk factors in upper-grade elementary school children or junior and senior high-school students. Furthermore, in subjects aged 20-29, a correlation was observed between the number of carious teeth and presence of cariogenic bacteria. Based on our findings, it is suggested that a caries risk test is an effective measure for caries prevention in infants, school children, and young adults.

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The state of oral hygiene has been evaluated by employing various indices, such as the Oral Hygiene Index, Plaque Index, Patient Hygiene Performance, and Plaque Control Record (O'Leary's PCR). Measuring the scores of these indices is time- and labor-consuming, requiring manual reading and recording by professionals, standardization of examination methods. In contrast, measuring the total number of bacteria in saliva using quantitative real-time PCR (qPCR) allows the straightforward collection and storage of samples, making it possible to measure many samples at the same time. This technique facilitates the quantification of the number of bacteria within a shorter time than the culture method. In the present study, the total number of bacteria measured by qPCR was found to be significantly decreased (p<0.05) in stimulated whole saliva collected from 5 volunteers by chewing paraffin after tooth cleaning. These findings were in agreement with the decreases shown by Greene's Debris Index and O'Leary's PCR values. There was a significant correlation (r=0.55, p<0.01) between the salivary bacterial counts measured by qPCR from 81 subjects before and after a 4-month interval. These findings suggest that it is possible to measure the total number of bacteria in saliva using qPCR. This technique is convenient and is suggested to be applicable for assessing the oral hygiene status in the future.

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Recent studies have suggested that periodontal diseases in pregnant women may be a significant risk factor for low-birth-weight deliveries (less than 2,500g). The aim of this study was to investigate the relationships between the oral health condition, health behavior of pregnant women, and low-birth-weight outcome. We performed oral examinations and conducted a survey of pregnant women to investigate their oral health status and behavior in Tokushima Prefecture. Among 739 pregnant women that received oral examinations, 454 (61.4%) reported complaints and inconvenience related to their oral cavities, 380 women (51.4%) reported gingival bleeding on brushing, while 406 women (54.9%) had teeth which needed treatment. Three hundred and one women (40.7%) harbored periodontal pockets with a depth &ge;4mm, and were assigned a Community Periodontal Index (CPI) code of 3 or 4. On the other hand, there were only 136 women (18.4%) who received regular dental checkups. The percentage of pregnant women with a CPI of 3 or 4 was higher than that of women in the same age group based on the Comprehensive Guide to the Survey of Dental Diseases (2005). The percentage of subjects with a CPI of 3 or 4 among pregnant women with a smoking habit was higher than in a group of non-smoking pregnant women (p<0.05). All pregnant women with a smoking habit had a CPI&ge;1. In addition, we examined the relationship between the oral health status of the pregnant women and a low-birth-weight outcome. Stepwise logistic regression analysis of the 227 pregnant women who signed the informed consent document for this study showed that a smoking habit (OR 5.96, 95% CI 1.16-30.53, p=0.03) and periodontal pocket depth &ge;4mm (OR 3.34, 95% CI 1.18-9.42, p=0.02) were significantly associated with low-birth-weight deliveries. In conclusion, efforts should be made to motivate pregnant women to undergo regular dental checkups for periodontal disease prevention and quit smoking.

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Tooth loss is a social health problem in terms of not only leading to insufficient nutrient intake, but also decreasing the QOL in elderly people. The aim of this cohort study was to identify predictors of tooth loss over a five-year period in an elderly population in the community. The subjects were recruited among all 4,542 inhabitants aged 70 years according to a registry of residents, and 600 people were selected randomly from those who agreed to participate in this study. Finally, 378 dentate subjects (201 males and 177 females) who could participate in both the baseline examination (1998) and follow-up examinations (2003) after five years were included in the analysis. The follow-up rate was 68.2%. In order to identify predictors of tooth loss with a different degree of robustness, three multiple logistic regression analyses (model-1, -2, and -3) where the dependent variables were one, two, and three or more lost teeth, respectively, were performed. The following dependent variables were used in model-1, -2, and -3: the Eichner index (class A, B1-B4, C1, C2, dummy) based on existing natural tooth contact between the maxilla and mandible in the bilateral premolar and molar regions; gender (Male, Female); number of teeth with decayed roots (0, 1+); number of crowns (0-4, 5-8, 9+, dummy); lactobacilli level (10^3-10^5, 10^6+ CFU/ml); mean clinical attachment level; serum albumin concentration; ability to chew 15 kinds of food (1-14 foods); regular dental visits (Yes, No); and smoking habit (Yes, No). Overall, 56.3% of the subjects lost one or more teeth over the five-year period. The mean number of missing teeth per year was 1.4±2.0. Logistic regression analysis indicated that Eichner index class B4 (OR: 2.11-3.42) or B2 (OR: 1.88-4.83), 9+ crown restorations (OR: 1.78-2.94), a 10^6+ CFU/ml lactobacilli level (OR: 1.61-2.65), and the mean clinical attachment level (OR: 1.41-1.86) were robust risk predictors. The findings of this cohort study suggest that local oral factors such as periodontal disease and the occlusal condition contribute to tooth loss in elderly people.

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This report provides information on the marketing status of dental floss in three types of business categories within a business area and a residential area. The targeted business and residential areas were chosen from Nagoya. A section measuring approximately 4km^2 was chosen from each area. Business categories were classified into three groups: pharmacy, supermarket and convenience store. The percentages of pharmacies and supermarkets distributing dental floss were higher than that of convenience stores in the residential area, and the percentage of pharmacies was higher than those of supermarkets and convenience stores in the business area. Convenience stores distributing dental floss generally sold only one type of floss, while pharmacies had more than seven different types. Dental floss without floss aid was sold in less than 5% of convenience stores, and in more than 60 percent of pharmacies. In general, dentists and dental hygienists should recommend that their patient shop at pharmacies when they purchase dental floss without floss aid. Patients can go to either a supermarket or a pharmacy for dental floss with floss aid in residential areas. However, it is inappropriate to recommend that patients shop at a convenience store when they purchase dental floss without floss aid in business areas.

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