title: Association between maximum occlusal force and 3-year all-cause mortality in community-dwelling elderly people.
abstract: BACKGROUND
  Among the very elderly, poor oral health reduces life expectancy. In this study, differences in the magnitude of the maximum occlusal force (MOF) in the very elderly were examined in terms of effects on all-cause mortality in a 3-year follow-up.
  
  
  METHODS
  We evaluated 489 community-living elderly individuals aged 85 years or older. MOF was measured using an occlusal force measuring device, and participants were classified into three groups according to gender- and dental status-sensitive tertiles. Demographic variables, cognitive, physical function, psychological status, oral health, comorbidity, and blood chemistry factors were assessed. One-way analyses of variance, χ (2) tests, and the Kruskal-Wallis test were used for statistical analyses. The relationship between MOF tertiles and 3-year all-cause mortality was examined using a multivariate Cox model analysis after adjusting for confounding factors.
  
  
  RESULTS
  MOF tertiles were significantly associated with cognitive impairment, number of teeth, limitations on chewable foods, handgrip strength, timed up-and-go test, and diabetes mellitus. During the follow-up period, 74 subjects died. Subjects with the highest MOF had a significantly lower mortality rate than other groups (log rank P  =  0.031). In the univariate Cox model, MOF tertiles were independently associated with a lower risk of death (HR = 0.69, 95 % CI = 0.51-0.91). Even after adjusting for various confounders in the multivariate Cox model (Model 1), MOF was independently associated with a lower risk of death (HR = 0.67, 95 % CI = 0.50-0.91). In model 2, we added handgrip strength as a confounder and found that the HR for MOF was attenuated (HR = 0.73, 95 % CI = 0.54-0.99), but still statistically significant.
  
  
  CONCLUSIONS
  In a cohort of the very elderly, MOF was independently associated with all-cause mortality after adjusting for various health issues. Moreover, this independent association remained after a further adjustment for handgrip strength; however, the HR was attenuated. This suggests that MOF and handgrip strength may share a common mechanism of a general decrease in muscle strength, possibly sarcopenia, which is a significant cause of mortality in the very old.
authors: Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan. iinuma.toshimitsu@nihon-u.ac.jp.
authors: Toshimitsu
authors: http://orcid.org/0000-0001-7705-5550
authors: T
authors: Iinuma
authors: Center for Supercentenarian Medical Research, Keio University School of Medicine, Tokyo, Japan.
authors: Yasumichi
authors: Y
authors: Arai
authors: Center for Preventive Medicine, Keio University School of Medicine, Tokyo, Japan.
authors: Michiyo
authors: M
authors: Takayama
authors: Center for Supercentenarian Medical Research, Keio University School of Medicine, Tokyo, Japan.
authors: Yukiko
authors: Y
authors: Abe
authors: Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan.
authors: Tomoka
authors: T
authors: Ito
authors: Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan.
authors: Yugaku
authors: Y
authors: Kondo
authors: Center for Supercentenarian Medical Research, Keio University School of Medicine, Tokyo, Japan.
authors: Nobuyoshi
authors: N
authors: Hirose
authors: Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan.
authors: Nobuhito
authors: N
authors: Gionhaku
mesh_terms: D000369:Aged, 80 and over; D001732:Bite Force; D015897:Comorbidity; D005260:Female; D018737:Hand Strength; D006801:Humans; D057187:Independent Living; D008297:Male; D009026:Mortality; D011446:Prospective Studies
keywords: All-cause mortality; Bite force; Healthy life expectancy; Very elderly people