Caries trends in Brazilian non-privileged preschool children in 1996 and 2006.

The aims were to analyse caries trends in Brazilian non- privileged preschool children from 1996 to 2006 and to test the hypothesis that a decline in caries prevalence would manifest itself as a reduction in the rate of caries progression. Subjects were 1- to 5-year-old children born in and life time residents of the Federal District of Brazil (cohort 1996=1,465) and (cohort 2006=2,511). The clinical examination determined whether the tooth surfaces were sound, presented active lesions (non cavitated and cavitated), inactive lesions (non-cavitated and cavitated), fillings, were indicated for extraction or had been extracted. Intra- and inter-examiner reliability of caries scores showed kappa values ranging from 0.71-0.93. A significant increase in the percentage of children who were free from any form of untreated or treated caries was observed (p<0.05; chi(2) test). Caries prevalence decreased by almost a half from 1996 to 2006. Differences in the mean caries scores at surface level, which included non-cavitated lesions, were observed for all age groups (p<0.002; Mann-Whitney test) indicating a reduction in the rate of caries progression. In conclusion, since this population has access to fluoride and presents moderate caries prevalence, other measures to reduce the rate of caries progression are required to further improve oral health in non-privileged children.