title: Monitoring time-related trends in dental caries in permanent teeth in Japanese national surveys.
abstract: OBJECTIVE
  According to dental examinations of 3- and 12-year-old children conducted throughout Japan, the prevalence of dental caries in children is decreasing. However, little is known about changes in the prevalence of dental caries in adults. This study analysed past and present prevalences of dental caries in permanent teeth and predicted future trends in dental caries in adults.
  
  
  METHODS
  Data were sourced from nine national dental surveys conducted in Japan at 6-year intervals from 1957 to 2005. Data from oral examinations were recorded as indices of decayed, missing and filled teeth.
  
  
  RESULTS
  The mean number of filled teeth increased markedly, whereas mean numbers of decayed teeth and missing teeth decreased substantially in people aged ≥ 40 years. By contrast, the mean number of filled teeth first increased and then decreased in groups aged 5-39 years.
  
  
  CONCLUSIONS
  Among Japanese respondents sampled in a series of cross-sectional studies between 1957 and 2005, the incidence of dental caries in young adults decreased, suggesting a decrease in prevalences of dental caries in future generations. However, this tendency was not observed in respondents aged ≥ 40 years. The results suggest adults will experience less dental caries in the near future.
authors.affiliation: Department of Oral Health, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto, Nagasaki, Japan. yumiko-t@nagasaki-u.ac.jp
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kawashita
authors.forename: Masayasu
authors.initials: M
authors.lastname: Kitamura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Saito
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology*; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D016388:Tooth Loss / Q000453:epidemiology; D055815:Young Adult