title: Number of teeth and 5-year mortality in an elderly population.
abstract: OBJECTIVE
  Several epidemiological studies have shown the association between tooth loss and mortality. However, the impact of number of teeth on mortality has not yet been fully addressed in an elderly population with many teeth. Thus, the purpose of this cohort study was to assess the possible role of number of teeth as a predictor of mortality in the elderly.
  
  
  METHODS
  The subjects included in this study were generated from a cohort study started in 1998. Oral examinations and the completion of a questionnaire were carried out. A total of 600 subjects aged 70 years were enrolled at baseline. All the subjects were in good general health and did not require any special care for their daily activities. The 5-year mortality data were collected after the baseline survey. After excluding those with incomplete data, 569 subjects were analyzed. The Kaplan-Meier method was used to analyze survival curves and a Cox regression model to clarify the impact of the number of remaining teeth on the 5-year mortality.
  
  
  RESULTS
  During the follow-up period, 25 (4.4%) subjects died. Subjects with 20 teeth or more had a significantly lower mortality rate (2.5%) than those with 19 teeth or fewer (6.1%, log-rank test, P = 0.036). Even after adjusting for confounders including gender, BMI, serum albumin level, current smoking status, education, number of family members living together and a history of chronic diseases, the risk of all-cause mortality was significantly associated with the number of remaining teeth (P = 0.047) with a hazard ratio of 0.96, indicating that there was a 4% point increase in the 5-year survival rate per additional tooth retained at the age of 70.
  
  
  CONCLUSIONS
  The findings of this study suggest that retaining more teeth might be a useful indicator for longevity of older people.
authors.affiliation: Division of Preventive Dentistry, Department of Oral Health Science, Graduate School of Medical and Dental Sciences, Niigata University, Japan.
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Hirotomi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yoshihara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ogawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Miyazaki
mesh_terms: D000368:Aged; D015992:Body Mass Index; D004522:Educational Status; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008297:Male; D009026:Mortality; D016016:Proportional Hazards Models; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D016388:Tooth Loss / Q000401:mortality*
keywords: epidemiology; geriatrics; risk assessment; tooth loss