title: Plaque minerals in the prediction of caries activity.
abstract: OBJECTIVE
  Attempts to identify subjects who will develop caries lesions in future years have been only moderately successful, suggesting that one or more important risk factors are being overlooked. The aim of this study was to validate the use of plaque calcium, phosphate and fluoride concentrations as significant risk factors in caries.
  
  
  METHODS
  DMFS and DMFT rates were measured three times over 2 years in a group of rural Chinese schoolchildren initially aged 12 years and not living in a high-fluoride area. At the baseline and year 1 examinations, dental plaque was accumulated for 3 days and, after collection, was analysed for Ca, P and F. Plaque scores, dental health behaviour and parents' occupation data were also recorded.
  
  
  RESULTS
  The mean DMFS increment over 2 years was 1.14 with a range of -2 to +9. Regression analysis taking all factors into account identified only plaque Ca concentration, baseline DMFS score and toothbrushing frequency as significant factors in identifying high-risk individuals. Plaque Ca also showed predictive ability on its own. For example, when high caries was defined as 3+ new DMFS and a Ca cut-off value of 200 nmol/mg dry wt was selected, sensitivity was 0.84 and specificity 0.38. However, with this cut-off value the percentage predicted to have high caries risk was unrealistically high at 66%. As in several other studies, baseline caries score was a useful predictor of future caries.
  
  
  CONCLUSIONS
  Low plaque Ca concentration showed a modest ability to predict future caries, and since it is implicated directly in the chain of events leading to caries, its use in caries prediction should be considered further. Plaque P and F showed no predictive ability in this study.
authors.affiliation: Wellington School of Medicine, Wellington, New Zealand. dentalhp@wnmeds.ac.nz
authors.forename: Euan I F
authors.initials: EI
authors.lastname: Pearce
authors.forename: Yan-Mei
authors.initials: YM
authors.lastname: Dong
authors.forename: Lin
authors.initials: L
authors.lastname: Yue
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Gao
authors.forename: Gordon L
authors.initials: GL
authors.lastname: Purdie
authors.forename: Jia-De
authors.initials: JD
authors.lastname: Wang
mesh_terms: D002118:Calcium / Q000032:analysis; D002648:Child; D002681:China; D004245:DMF Index; D003731:Dental Caries / Q000209:etiology*; D003733:Dental Caries Susceptibility; D003773:Dental Plaque / Q000737:chemistry*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D005260:Female; D005459:Fluorides / Q000032:analysis; D005461:Fluorine / Q000032:analysis; D005500:Follow-Up Studies; D005544:Forecasting; D015438:Health Behavior; D006801:Humans; D016015:Logistic Models; D008297:Male; D016555:Matched-Pair Analysis; D008903:Minerals / Q000032:analysis*; D009910:Oral Hygiene; D010710:Phosphates / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D012307:Risk Factors; D012423:Rural Health; D012680:Sensitivity and Specificity; D012923:Social Class; D018709:Statistics, Nonparametric; D014099:Toothbrushing
chemical_list: D004040:Dietary Carbohydrates; D008903:Minerals; D010710:Phosphates; D010758:Phosphorus; D005461:Fluorine; D005459:Fluorides; D002118:Calcium