In vitro secondary caries inhibition by adhesive systems in enamel around composite restorations

This study compared the ability of adhesive systems to inhibit in vitro caries lesions in enamel under high cariogenic challenge. Bovine enamel blocks with cavity preparations were restored with AP-X resin composite (Kuraray Med) using four adhesives systems: Clearfil SE Bond (Kuraray Med); Clearfil Protect Bond (Kuraray Med); One-Up Bond F (Tokuyama) and Single Bond (3M ESPE). The specimens were submitted to an eight-day pH-cycling regimen. After cariogenic challenge, the enamel was evaluated to detect caries lesions using cross-sectional microhardness, polarized light microscopy and scanning electronic microscopy. Data from cross-sectional microhardness and polarized light microscopy evaluations were statistically analyzed by ANOVA and Tukey's test. The mineral % volume showed no statistical difference among adhesives (p > 0.05); however, polarized light microscopy analysis showed lower caries lesions with Clearfil Protect Bond (p < 0.05). The scanning electron microscopy images showed greater caries lesions and demineralization areas close to restorations for Clearfil SE Bond, One-Up Bond F and Single Bond compared to Clearfil Protect Bond. The pH-cycling regimen promoted subsurface enamel demineralization in all specimens treated. The polarized light microscopy and scanning electronic microscopy analyses showed that Clearfil Protect Bond seems to produce lower enamel demineralization around restorations; however, cross-sectional microhardness did not demonstrate differences among the adhesives.