Marginal adaptation of an etch-and-rinse adhesive with a new type of solvent in class II cavities after artificial aging.

This in vitro study evaluated the marginal adaptation of etch-and-rinse adhesives. Standardized class II cavities were cut in 40 human molars with one proximal box limited within enamel and one proximal box extending into dentin. Teeth were assigned randomly to five groups (n = 8) and restored with incrementally placed composite restorations. Five combinations were tested: G1, XP Bond + Ceram-X Mono; G2, P&B NT + Ceram-X Mono; G3, Optibond Solo Plus + Ceram-X Mono; R1, Syntac Classic + Tetric EvoCeram; R2, Scotchbond 1 XT + Z250. After finishing and polishing, teeth were stored for 48 h in water at 37°C before subjected to artificial aging by thermal stress (5/55°C; ×2,000; 30 s) and mechanical loading (50 N; ×50,000). Marginal adaptation of the restorations was evaluated in a SEM (×200) using a replica technique. Statistical analysis was performed with nonparametric test methods (p < 0.05). The percentages of "perfect margin" after aging ranged from 95.9% to 99.6% in enamel and 85.9% to 96.0% in dentin. "Marginal opening" was observed between 0.1% to 2.6% in enamel and 2.6% to 11.8% in dentin. In enamel and dentin, both, G3 showed significantly more gap formation than G1 and G2. Comparing marginal adaptation to enamel and dentin within each group yielded only for G1 no significant differences. Tert-butanol-based XP Bond showed excellent marginal adaptation in both enamel and dentin.