<qa>  What was the population of the study population?The study population comprised 121 schoolchildren aged 8 to 10 years in a high-caries community in Valparaiso, Chile. They were examined clinically and radiographically, divided into 3 groups, and treated accordingly: children in Group A had no carious lesions on the approximal surfaces of 05d-6m and received no sealants; those in group B had active caries on 05d and received a preventive sealant on the caries-free 6m; and those in group C had active caries on 05d with an initial active lesion on 6m and received a therapeutic sealant on 6m. After 3.5 years, standardized follow-up radiographs were obtained for the children that remained. 