Influence of different enamel substrates on microtensile bond strength of sealants after cariogenic challenge.

Abstract

To evaluate the microtensile bond strength (μTBS) of resin sealer on enamel substrates after cariogenic challenge. Enamel blocks were obtained from human third molars and randomly divided into 6 groups (n = 10) according to enamel substrates (S: sound, CL: caries-like lesion, or CLTF: caries-like lesion + topical fluoride application) and sealant material (F: FluroShield, or H: Helioseal Clear Chroma). Sealants were placed on enamel surfaces, stored in 100% humidity (24 h, 37°C), and longitudinally sectioned into hourglass shapes. According to the groups, pH cycling was applied and the μTBS test was performed. The fracture patterns were assessed by SEM. Regarding substrates, the highest μTBS values in MPa were observed for CLTF enamel (26.0 ± 7.6), followed by S (22.0 ± 7.4) and CL (15.5 ± 4.9). A significant interaction was found between material and pH cycling (p = 0.0395). F (23.9 ± 7.6) showed higher μTBS values than H (18.3 ± 7.5) when submitted to pH cycling. The majority of samples presented mixed failure. Enamel substrate significantly affected μTBS, with the highest values for remineralized caries-like enamel lesions. Furthermore, μTBS values were dependent on both materials and pH cycling.