An intraoral study of caries induced on enamel in contact with fluoride-releasing restorative materials

The aim was to study the effect of three fluoride-releasing restorative materials on sound enamel of approximal teeth under cariogenic conditions intraorally. Bovine enamel slabs were paired with four hemispherical samples from each of three test materials (Ketac Molar, ESPE; Vitremer, F-2000, both from 3M) and one control material (Pertac II, ESPE). Their curved surface touched enamel at a contact point allowing space for plaque accumulation. Pairs were inserted in the buccal flanges of 2 lower dentures for 70 days. Initially and upon dismantling, enamel surface microhardness was measured and the increase in length of indentation in micrometers was recorded at a distance of 0, 0.4, 0.8 and 1.2 mm from the contact point. Respective values were: Pertac II: 16.0+/-7.5, 27.6+/-15.4, 38.6+/-23.3, 47.8+/-25.2; F-2000: 11.89+/-9.6, 15.8+/-14.2, 21.0+/-15.0, 25.1+/-15.2; Ketac Molar: 6.6+/-6.8, 9.4+/-7.0, 9.5+/-8.0), 13.4+/-9.4; Vitremer: 2.7+/-4.1, 3.5+/-3.5, 3.6+/-4.5), 7.4+/-5.2. Caries protection was Vitremer 82% > Ketac Molar 69% >F-2000 42% in relation to Pertac II (p<0.001). Sections of the slabs examined with polarized light showed typical subsurface lesions only in the Pertac II group, areas of pseudoisotropy in the F-2000 and Ketac Molar groups and no signs of lesion in the Vitremer group.