Contribution of changing diagnostic criteria toward reduction of caries between 1971 and 1997 in children attending the same school in Florianopolis, Brazil

– Aim: To assess the relative impact of changing diagnostic criteria on changes in the prevalence and severity of caries between 1971 and 1997. Material and methods: All 12‐ and 13‐year‐old children attending the same school, “Padre Anchieta Primary School”, in Brazil in 1971 (n=202) and 1997 (n=175) were examined by a single dentist. The criteria for the diagnosis of caries proposed by Radike in 1968 were used in both 1971 and 1997. In 1997, a second clinical examination was conducted and the WHO criteria proposed in 1987 were used. Results: Comparison of caries experience expressed as changes in the mean DMFT scores indicated a 67.7% reduction between 1971 and 1997 from 9.2 to 3.0 when Radike’s criteria were used in 1971 and the WHO criteria were used in 1997. The reduction in caries was independent of the diagnostic criteria adopted in the 1997 dental examination, but the reduction of caries was smaller, from 9.2 to 6.2 (31.8%), when caries experience in 1971 and 1997 was measured using Radike’s criteria. Conclusion: The observed reduction of caries is not a statistical artifact. However, while 47.2% of this reduction is real, 52.8% of it is a statistical artifact due to changes in the criteria for measuring caries used by epidemiologists.