Dental caries and gingivitis in schoolchildren from the municipality of Porto Alegre, Brazil in 1975 and 1996.

Abstract

This study assesses changes in the prevalence of dental caries and gingivitis in a population of Brazilian schoolchildren in 1975 and 1996. The study was carried out in the municipality of Porto Alegre, Brazil, and included all 8- to 10-year-old children attending the second, third, and fourth grades at the same public school. Data were recorded from 233 children in cohort 1975 and from 185 children in cohort 1996. Only the children from cohort 1996 benefited from fluoridated water and regular use of fluoridated toothpaste. Caries experience was registered clinically and radiographically and summarised in DMFT and DMFS indices. The gingival status was described according to the GBI-index. Over a period of 21 years, the percentage of caries-free children increased significantly in all age groups; sevenfold at the age of 8, ninefold at the age of 9 and fourfold at the age of 10. Dental caries has almost disappeared from front teeth and premolars and was mainly located at the groove-fossa-system of permanent first molars. A seventy percent reduction in DMFS scores was observed. A significantly higher percentage of filled surfaces was registered in cohort 1975 than in cohort 1996 (P=0.001). The gingival bleeding index did not diminish during the study period, indicating that children's oral hygiene did not improve. Since the children had neither better access to dental care nor improved oral hygiene, it is tempting to believe that their access to fluorides contributed most to the marked decline in caries prevalence.