Aims: This study aimed to assess changes in caries prevalence and severity in preschool children in Diadema, Brazil.
Methods: Three cross-sectional surveys were conducted, using the same protocol, in 1995, 1997 and 1999. The first survey included children aged 5-35 months, and the second and third, children aged 5-59 months. Participants were selected from all children attending a National Day of Children's Vaccination; 548, 992 and 690 in 1995, 1997 and 1999, respectively. This approach was sound as uptake rates for all years studied were above 90% for children aged between 1 and 59 months in all three surveys. Caries experience was measured using the World Health Organization (WHO) def index. Time-lag and quasi-longitudinal analysis were carried out.
Results: Time-lag analysis showed a marked and statistically significant decline in the prevalence and severity of coronal and rampant caries between 1995 and 1999. There were reductions of 36.5% in the prevalence of caries in 2-year-olds between 1995 and 1997 (P < 0.002) and 36.0% between 1997 and 1999 (P = 0.041). The mean def-s at the same age decreased from 2.0 in 1995 to 1.1 in 1997 (P < 0.001) and to 1.0 in 1999 (P > 0.05). The quasi-longitudinal analysis showed a statistically significantly increase in the percentage of children with caries between 1995 and 1997 and 1997 and 1999 (P < 0.001), but not for 2-year-old children between 1995 and 1997 (P > 0.05). The same pattern was observed for severity of dental caries.
Conclusion: Oral health in preschool children in Diadema improved markedly during 1995-99.