title: Caries incidence in a cohort of primary school students in Lagos State, Nigeria followed up over a 3 years period.
abstract: OBJECTIVE
  To describe the progression of dental caries in pupils who had access to an education intervention programme over a three years period.
  
  
  METHODS
  This was a prospective cohort study.
  
  
  METHODS
  A school-based study consisting of 251 children aged 2-10 years old attending three primary schools in Lagos State, Nigeria. Baseline and exit dental examinations were conducted. Study exit examination was conducted 3 years after the baseline. The deft and DMFT index was used to assess caries severity. The key outcome measure recorded in the study was the development of new cavities in any of the previously caries-free teeth. The presence or absence of caries was represented by the change in deft and or DMFT status.
  
  
  METHODS
  In the analyses, the incidence of new cavities was recorded at both the subject and tooth levels. Incidence rates for the development of new caries were calculated for all children who: were caries-free at recruitment had caries at recruitment were caries-free at recruitment but developed caries during follow up. Relative risk (RR) analysis was also computed for caries-risk estimation.
  
  
  RESULTS
  The caries incidence for the study cohort was 9.9%. About 11.0% of children who were caries free at inception of the study developed caries three years later. The cumulative incidence of caries for the cohort of children who were caries-free at the commencement of the study was 105 new cases per 1,000 persons. Of the 40 children who had caries at the inception of the study, 21 (52.5%) developed new caries lesions. The cumulative incidence of caries for the cohort of children who had caries at the commencement of the study was 525 new cases per 1,000 persons. The relative risk of developing caries over a three year period was significantly higher (RR=4.99; 95% CI = 2.88 - 8.64; p< 0.001) in those who had caries at baseline than those who were caries-free at baseline. Caries severity remained stable over the 3 years period.
  
  
  CONCLUSIONS
  Caries incidence and severity was low for the study cohort. The relative risk of developing new caries lesion was significantly higher in those with caries when compared with those without caries.
authors.affiliation: Department of Child Dental Health, Obafemi Awolowo University, Ile-Ife, Nigeria. toyinukpong@yahoo.co.uk
authors.forename: M O
authors.initials: MO
authors.lastname: Folayan
authors.forename: O O
authors.initials: OO
authors.lastname: Sofola
authors.forename: A B
authors.initials: AB
authors.lastname: Oginni
mesh_terms: D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology*; D005260:Female; D006267:Health Education, Dental; D006801:Humans; D015994:Incidence; D008297:Male; D009549:Nigeria / Q000453:epidemiology; D011446:Prospective Studies; D012306:Risk