title: Caries experience in the primary dentition and presence of plaque in 7-year-old Chinese children: A 4-year time-lag study.
abstract: OBJECTIVE
  The aim of the present study was to test the hypothesis that dental caries prevalence and caries experience in primary dentitions has increased over 4 years and to compare the presence of plaque on permanent teeth in child cohorts over 4 years.
  
  
  METHODS
  A time-lag study design was used comprising two cohorts of children aged 7 years from the same five primary schools in Wuhan examined in 2007 and 2011. Two calibrated examiners visually assessed plaque accumulation according to the Greene and Vermillion Index and the dentitions according to the Atraumatic Restorative Treatment (ART) caries criteria. Analysis of variance (ANOVA), logistic regression, and Chi-square test were used to test for differences between dependent and independent variables.
  
  
  RESULTS
  The 2007 sample consisted of 817 children and the 2011 sample consisted of 1010 children. The prevalence of dental caries (d3mft) was 68.2% in 2007 and 67.7% in 2011, while that of d2mft was 78.5% in 2007 and 71.4% in 2011 (P < 0.0006). The mean d3mft score was 2.8 in 2007 and 3.1 in 2011 (P = 0.046), while the mean d3mfs score was 4.9 in 2007 and 7.3 in 2011 (P < 0.0001). The d3-component of the d3mft index was 73% in 2007 and 69% in 2011, while the f-component was 22% in 2007 and 26% in 2011. The hypothesis was not accepted. The proportion of children with plaque code 3 (extensive coverage) was higher in 2011 (21.8%) than in age mates in 2007 (5.7%).
  
  
  CONCLUSIONS
  There were no obvious signs that dental caries prevalence had been increased in primary dentitions of this child population between 2007 and 2011. But as the mean caries experience scores at the surface level were higher in 2011 than in 2007, monitoring caries prevalence remains essential, but should start at an earlier age than that covered by this study. Health and educational authorities should collaborate in setting up programs aimed at ensuring good oral health for school children.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST), and Key Laboratory for Oral Biomedical Engineering of the Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Hu
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST), and Key Laboratory for Oral Biomedical Engineering of the Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Mingwen
authors.initials: M
authors.lastname: Fan
authors.affiliation: Department of Global Oral Health, College of Dental Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Mulder
authors.affiliation: Department of Global Oral Health, College of Dental Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: J E
authors.initials: JE
authors.lastname: Frencken
keywords: Caries epidemiology; China; cohort effects; primary dentition; time trends; time-lag design