title: Relationship between survival rates and numbers of natural teeth in an elderly Japanese population.
abstract: OBJECTIVE
  The objective of this study was to assess whether elderly people with 20 or more natural teeth were more likely to live longer than a cohort with less than 20 teeth.
  
  
  METHODS
  Groups of elderly people over 80 years of age (24 males and 35 females) with 20 or more teeth (>or=20 group) were compared with elderly people (24 males and 35 females) with less than 20 teeth (<20 group). Follow-up studies were conducted at regular intervals for 10 years from July 1992 to July 2002. The cumulative survival rate of the >or=20 group (average +/- SE tooth number of teeth - males, 23.9 +/- 0.6; females, 23.8 +/- 0.4) was compared with the <20 group (average number of teeth - males, 3.8 +/- 1.1; females, 2.6 +/- 0.8). The multivariate Cox proportional hazard models with the number of teeth in a group (>or=20 group or <20 group). Smoking status and alcohol intake as covariates were used to adjust the cumulative survival rate.
  
  
  RESULTS
  The male participants in the >or=20 group had a significantly higher cumulative survival rates (p < 0.05) than the <20 group at 18 and 21 months from baseline. There were no significant differences in survival rates between the female groups. Adjusted cumulative survival rate was significantly different at 72, 75 and 78 months between the >or=20 group and <20 group for males but not for females.
  
  
  CONCLUSIONS
  Having 20 or more natural teeth was associated with increased survival rate in elderly males, but not among the elderly females.
authors.affiliation: Department of Preventive Dentistry and Dental Public Health, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan. i.morita@ucl.ac.uk
authors.forename: Ichizo
authors.initials: I
authors.lastname: Morita
authors.forename: Haruo
authors.initials: H
authors.lastname: Nakagaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kato
authors.forename: Taeko
authors.initials: T
authors.lastname: Murakami
authors.forename: Shinji
authors.initials: S
authors.lastname: Tsuboi
authors.forename: Junko
authors.initials: J
authors.lastname: Hayashizaki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyama
authors.forename: Masanori
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Simozato
authors.forename: Norikazu
authors.initials: N
authors.lastname: Morishita
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Kawanaga
authors.forename: Junko
authors.initials: J
authors.lastname: Igo
authors.forename: Aubrey
authors.initials: A
authors.lastname: Sheiham
mesh_terms: D017677:Age Distribution; D000369:Aged, 80 and over; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007564:Japan; D008297:Male; D016016:Proportional Hazards Models; D017678:Sex Distribution; D012737:Sex Factors; D016019:Survival Analysis; D015996:Survival Rate; D016388:Tooth Loss