After 48 months 162 teeth in the F sealant group and 162 in the conventional sealant group were evaluated. Regarding sealant retention, 124 teeth (77%) in the first group and 144 (89%) in the second were fully sealed, and 23 (14%) compared to 9 (6%) were partly sealed (P = 0.01). Regarding caries development, 14 teeth (9%) had developed caries in the first group and 19 (10%) in the second (P > 0.1).