['The purpose of the present study was to report on caries status and to explore possible reasons for changes in caries experience among 5- and 12-year-old Norwegian children.', 'National cross-sectional and time trend study.', 'Aggregated data from the Public Dental Services and from official statistics were used. Information was available on the total number of children, the proportion receiving treatment, sale of fluoride tablets, socio-economic background, caries prevalence and dmft/DMFT scores.', 'The prevalence of caries among 5-year-olds reached a low of 30.4% in 1997 and increased to 38.9% in 2000. The mean dmft scores increased from 1.1 to 1.5. Conversely, the prevalence of caries among 12-year-olds decreased from 55.4% in 1997 to 52.2% in 2000 and the mean DMFT score from 1.7 to 1.5. Bivariate analyses at county level revealed significant associations, which for the most part disappeared in multivariate analyses. The sale of fluoride tablets had a significant effect on caries prevalence among 5-year-olds in 1998, in 1999 and in 2000. Infant mortality was associated with the dmft score in 1999. The only consistently significant predictor of caries experience at 12 years of age was caries prevalence at age 5.'] Do evidence for reversal of the caries decline among Norwegian children?