title: Individual- and community-level social gradients of edentulousness.
abstract: BACKGROUND
  Community-level factors as well as individual-level factors affect individual health. To date, no studies have examined the association between community-level social gradient and edentulousness. The aim of this study was to investigate individual- and community-level social inequalities in edentulousness and to determine any explanatory factors in this association.
  
  
  METHODS
  We analyzed the data from the Japan Gerontological Evaluation Study (JAGES). In 2010-2012, 112,123 subjects aged 65 or older responded to the questionnaire survey (response rate = 66.3%). Multilevel logistic regression analysis was applied to determine the association between community-level income and edentulousness after accounting for individual-level income and demographic covariates. Then, we estimated the probability of edentulousness by individual- and community-level incomes after adjusted for covariates.
  
  
  RESULTS
  Of 79,563 valid participants, the prevalence of edentulousness among 39,550 men (49.7%) and 40,013 women (50.3%) were both 13.8%. Living in communities with higher mean incomes and having higher individual-level incomes were significantly associated with a lower risk of edentulousness (odds ratios [ORs] by 10,000 USD increments were 0.37 (95% confidence interval [CI] [0.22-0.63]) for community-level and 0.85 (95% CI [0.84-0.86]) for individual-level income). Individual- and community-level social factors, including density of dental clinics, partially explained the social gradients. However, in the fully adjusted model, both community- and individual-level social gradients of edentulousness remained significant (ORs = 0.43 (95% CI [0.27-0.67]) and 0.90 (95% CI [0.88-0.91]), respectively). One standard deviation changes in community- and individual-level incomes were associated with 0.78 and 0.84 times lower odds of edentulousness, respectively. In addition, compared to men, women living in communities with higher average incomes had a significantly lower risk of edentulousness (p-value for interaction < 0.001).
  
  
  CONCLUSIONS
  Individual- and community-level social inequalities in dental health were observed. Public health policies should account for social determinants of oral health when reducing oral health inequalities.
authors.affiliation: Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry, Sendai City, Miyagi, Japan. kanade-i@umin.ac.jp.|Division of Oral Health Sciences, Department of Health Sciences, School of Health and Social Services, Saitama Prefectural University, Koshigaya City, Saitama, Japan. kanade-i@umin.ac.jp.
authors.forename: Kanade
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry, Sendai City, Miyagi, Japan. aidajun@m.tohoku.ac.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Aida
authors.affiliation: Department of Dental Sociology, Graduate School of Dentistry, Kanagawa Dental University, Yokosuka City, Kanagawa, Japan. yamamoto.tatsuo@kdu.ac.jp.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Research Team for Human Care, Tokyo Metropolitan Institute of Gerontology, Itabashi Ward, Tokyo, Japan. rika-o@cam.hi-ho.ne.jp.
authors.forename: Rika
authors.initials: R
authors.lastname: Ohtsuka
authors.affiliation: Department of Nutrition, Faculty of Health and Nutrition, Tokaigakuen University, Nagoya City, Aichi, Japan. nakade-m@tokaigakuen-u.ac.jp.
authors.forename: Miyo
authors.initials: M
authors.lastname: Nakade
authors.affiliation: Center for Well-being and Society, Nihon Fukushi University, Nagoya City, Aichi, Japan. ksuzuki@psis.agu.ac.jp.|Department of Policy Studies, Aichi Gakuin University, Nisshin City, Aichi, Japan. ksuzuki@psis.agu.ac.jp.
authors.forename: Kayo
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Center for Well-being and Society, Nihon Fukushi University, Nagoya City, Aichi, Japan. kkondo@chiba-u.jp.|Center for Preventive Medical Sciences, Chiba University, Chiba City, Chiba, Japan. kkondo@chiba-u.jp.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Kondo
authors.affiliation: Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry, Sendai City, Miyagi, Japan. osaka@m.tohoku.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Osaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003740:Dental Clinics / Q000706:statistics & numerical data; D004522:Educational Status; D005260:Female; D006297:Health Services Accessibility / Q000706:statistics & numerical data; D006304:Health Status; D054624:Health Status Disparities; D006801:Humans; D007182:Income; D007564:Japan / Q000453:epidemiology; D008297:Male; D017533:Marital Status; D009066:Mouth, Edentulous / Q000191:economics / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012737:Sex Factors; D064890:Social Determinants of Health / Q000191:economics / Q000706:statistics & numerical data*