To assess the moisturizing effect of a thickener, the water retainability of a thickener and oral moisturizers was compared in vitro. Using a commercial thickener TsururinkoQ^®, xanthan gum and dextrin and commercial moisturizers, WetCare^® and Oralrefre Gel^®, the viscosities were measured with a SV-10 or ViSmart viscometer and the water retainability was assessed with a filter-paper method. In the concentration range of 1.5～3.0% (w/v), the viscosities of TsururinkoQ^®, xanthan gum and dextrin were 60.8～210, 526～1,307, 0.76～0.82 mPa・s, respectively. Those of WetCare^® and Oralrefre Gel^® were 1.19 and 1.37 mPa・s, respectively. From the changing curve pattern of residual water content, distilled water, WetCare^®, 0.3% (w/v) dextrin, 3.0% (w/v)dextrin and 1.5% (w/v)hyaluronic acid showed pattern Ⅰ. 0.3% (w/v) TsururinkoQ^®, 0.3% (w/v) xanthan gum and Oralrefre Gel^® pattern Ⅱ. 3.0% (w/v) TsururinkoQ^® pattern Ⅲ, and 3.0% (w/v) xanthan gum pattern Ⅳ. In the order of pattern Ⅰ, Ⅱ, Ⅲ and Ⅳ, the water retainability increased. Further, the rate of residual weight of 3.0% (w/v) TsururinkoQ^® was 1.3%. From these results, it was suggested that in the concentration range of 1.5～3.0% (w/v), the viscosity of TsururinkoQ^® might be 51.1～176 times that of WetCare^® and 44.4～153 times that of Oralrefre Gel^®, respectively and also TsururinkoQ^® might possibly have both greater water retainability than oral moisturizers and little dry residues.

　In recent years, the number of remaining teeth in the elderly population has shown an increase. The study of periodontal disease in this case becomes important, because an increase in the number of teeth leads to greater suffering. However, there are only a few reports about periodontal disease among the community-dwelling elderly. The aim of this study was to investigate the actual conditions of periodontal disease among the urban community-dwelling elderly and examine what factors determine the code of Community Periodontal Index（CPI）as a high score. The subjects comprised 206 people aged ≧65 years who visited the medical examination at Tokyo I-ward.

　We surveyed dental parameters such as the number of remaining teeth, CPI, and test results for periodontal microbial screening, and also dental-related items such as tooth brushing and frequency/absence of dental clinic visits, smoking, Mini Mental State Examination scores, medication status, and current medical history.

　We observed that 26.7% of the subjects had a CPI of 4 and 48.1% had a CPI of 3. We divided the subjects into two groups based on presence of ＜20 or ≧20 teeth and examined the factors that determined a CPI of 4.

　In the ＜20 teeth group, relevant independent factors were history of diabetes and tongue-coating adhesiveness. In the ≧20 teeth group, hypertension was the relevant independent factor.

　As a result of the present study, we suggest that oral health professionals should take the presence of dental plaque, as well as tongue coat into consideration, in order to establish the hygiene habit of older periodontal patients with ＜20 teeth. Furthermore, it is necessary to consider to the history of systemic diseases such as hypertension when oral health providers managed periodontal disease for those with more than 20 teeth.

　We analyzed the time spent by nursing staff and dental hygienists on mouth cleaning at a special nursing home and compared the cleaning effects.

　Five nursing staff working at A facility in Tokyo（4 professional caregivers and 1 nurse）and 6 dental hygienists were asked to provide mouth cleaning to 18 residents（aged 68-101）. The nursing care levels of the residents were either 4 or 5. We asked the cleaning practitioners to answer a questionnaire concerning mouth cleaning. Further, we recorded mouth cleaning sessions to analyze the time spent on the cleaning process. For the resident participants, we examined their oral condition to evaluate the oral cleanness before and after cleaning with the ammonia level, using a multi-item saliva test system（Lion, AL-55）. t-test was used for statistical analysis（significance level at 5%）. For the correlation analysis, we used Pearsonʼs simple correlation coefficient.

　In the questionnaire, all respondents answered that the purpose of mouth cleaning is to prevent aspiration pneumonia. The self-assessed time spent on mouth cleaning was longer among dental hygienists, and caregivers self-rated their evaluation score lower. Actual measurement of cleaning time showed that nursing staff spent 1 minute 33 seconds to 3 minutes 59 seconds, while dental hygienists spent 3 minutes 57 seconds to 15 minutes 52 seconds. Also, all dental hygienists conducted intraoral observation. The level of ammonia after a single cleaning session by all practitioners decreased significantly, and there were no differences based on the practitionersʼ professions.

　Dental hygienists spent longer on mouth cleaning than other professionals. Mouth cleaning by different professions were equally effective, and no differences were observed among different professionals.

　Using data from The Surveys of Dental Diseases, conducted by the Ministry of Health, Labour, and Welfare from 1957 to 2011, variations in the number of permanent teeth in the Japanese population were descriptively and epidemiologically observed by performing a cohort analysis using a Bayesian age-period-cohort model.

　Between 1957 and 1975, the number of teeth among 65-year-old Japanese males and females ranged from 13 to 15 and 9 to 10, respectively. In 2011, the number of teeth exceeded 20 for both sexes. Similarly, in other groups over the age of 40, until 1987, the number of teeth was 3 to 5 higher among males than among females；however, such differences between the sexes were rarely observed in 2011.

　In the cohort analysis, the age effect, when compared with the two other effects, ranged more markedly indicating a close association between the number of teeth and age. The period effect, which was the smallest between 1975 and 1987, subsequently increased. This tendency of the period to increase was more marked among females. The cohort effect was small among those born before 1900, and generally, large among those born between 1930 and 1975. Females also showed a higher level of improvement than males in this respect.

　To summarize, while decrease in the number of teeth was associated with aging in most cases, there was a tendency for it to improve in all age groups from 1993, with the pace of such improvement being higher among females. Sex differences in the number of teeth in adults were not observed in 2011. If this tendency continues, the situation will probably reverse, and the number of teeth will be higher among females than among males. In order to promote dental health on a nationwide basis under these circumstances, it may be necessary to provide population-based approaches, particularly the ones to enhance the interest of males in dental health and to guide them to take measures to maintain a sufficient number of teeth.

　To increase of the number of teeth of the elderly, we should start quantitative changes as well as qualitative ones for their oral health care and dental treatment.

　To clarify the characteristics of temporomandibular joint dislocation in the elderly, we clinically studied 51 patients with temporomandibular joint dislocation, who had been treated at the Department of Oral and Maxillofacial Surgery, Hirosaki University, from April 2004 to March 2014（the past 10 years）. We investigated two groups of patients：a younger group （aged less than 65 years）and an elderly group（aged over 65 years）. The average age of the younger group（26 patients；11 men［42.3%］and 15 women［57.7%］）was 32.0 years. The average age of the elderly group（25 patients；5 men［20.0%］and 20 women［80.0%］）was 78.1 years. More patients in both groups were referred by medical clinics than by dental clinics（14 patients［53.8%］and 17 patients［68.0%］, respectively）. In the younger group, acute dislocation occurred in eight patients（30.8%）and onset triggered by yawning occurred in 10（38.5%）. In the elderly group, habitual dislocation occurred in 23 patients（92.0%）and the onset trigger was unclear in 17 cases（68.0%）. General complications were found in 13 patients（50.0%）in the younger group and 23（92.0%）in the elderly group. In the elderly group, mental nervous system disease was found in 13 patients（52.0%）, while cerebral infarction or cerebral hemorrhage was found in 7（28.0%）. In the younger group, manual reduction and follow-up were conducted in 25 patients（96.2%）. Chin cup therapy was used in 12 patients（48.0%）in the elderly group to prevent dislocation. Patients in both groups obtained good treatment results.