title: Antecedents and associations of root surface caries experience among 38-year-olds.
abstract: OBJECTIVE
  To determine whether coronal caries experience through to the 30s predicts root surface caries experience by age 38.
  
  
  METHODS
  Prospective study of a complete birth cohort (n = 1,037) born in 1972/73 in Dunedin, New Zealand. Dental examinations were conducted at ages 5, 9, 15, 18, 26, 32 and 38. Root surface caries data were first collected at age 38. Data from ages 5 through 32 were used previously to identify low, medium and high life course trajectories of caries experience and plaque accumulation.
  
  
  RESULTS
  Of the 916 dentate individuals examined at age 38, 23.0% had 1+ root DFS, 17.2% had 1+ root DS and 11.4% had 1+ root FS. The mean root DS, FS and DFS were 0.6 (SD 3.5), 0.3 (SD 1.1) and 0.9 (SD 3.8), respectively. The mean Root Caries Index (RCI) score was 7.2% (SD 18.0). Age 38 coronal DMFS and root surface caries DFS were only weakly correlated (r = 0.32), but root surface caries experience was strongly associated with coronal caries trajectory, with the mean RCI in the low, medium and high caries trajectory groups being 4.4, 8.0 and 13.5%, respectively (p < 0.0001); their prevalence of 1+ root DFS was 14.5, 25.9 and 42.2% (p < 0.0001). Those in the high coronal caries trajectory were more likely to have 1+ root surface DFS (odds ratio = 3.83; 95% CI = 2.33-6.30); for the medium trajectory, the odds ratio was 1.86 (95% CI = 1.25-2.75).
  
  
  CONCLUSIONS
  Lifelong coronal caries experience (represented by discrete longitudinal trajectories of caries experience) is indeed a risk factor for root surface caries experience by age 38.
authors.affiliation: Sir John Walsh Research Institute, School of Dentistry, The University of Otago, Dunedin, New Zealand. murray.thomson@otago.ac.nz
authors.forename: W M
authors.initials: WM
authors.lastname: Thomson
authors.forename: J M
authors.initials: JM
authors.lastname: Broadbent
authors.forename: L A
authors.initials: LA
authors.lastname: Foster Page
authors.forename: R
authors.initials: R
authors.lastname: Poulton
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology*; D003773:Dental Plaque / Q000453:epidemiology; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D008297:Male; D008963:Molar / Q000473:pathology; D009520:New Zealand / Q000453:epidemiology; D011159:Population Surveillance; D011446:Prospective Studies; D012307:Risk Factors; D017213:Root Caries / Q000453:epidemiology*; D012923:Social Class; D016388:Tooth Loss / Q000453:epidemiology; D055815:Young Adult