Durability of Enamel Bonding Using Two-step Self-etch Systems on Ground and Unground Enamel

OBJECTIVE: To examine the morphological, early and long-term microtensile bond strengths (microTBS) of one-step self-etch systems to unground and ground enamel. MATERIALS AND METHODS: Resin composite (Filtek Z250) buildups were bonded to the buccal and lingual enamel surfaces (unground, bur-cut or SiC-roughened enamel) of third molars after adhesive application using the following adhesives: Clearfil S3 Bond (CS3); Adper Prompt L-Pop (ADP); iBond (iB) and, as the control, Clearfil SE Bond (CSE). Six tooth halves were assigned for each condition. After storage in water (24 hours/37 degrees C), the bonded specimens were sectioned into beams (0.8 mm2) and subjected to microTBS (0.5 mm/min) either immediately (IM) or after six (6 M) or 12 months (12 M) of water storage. The data were analyzed by three-way repeated measures ANOVA and Tukey's test (alpha = 0.05). Surface conditioning was observed under scanning electron microscopy (SEM). RESULTS: The microTBS in the Si-C paper and diamond bur groups were similar and higher than the unground group. No significant difference was observed among the different storage periods, except for CS3, which showed an increase in the microTBS after 12 M. The etching pattern was more retentive on ground enamel. CONCLUSIONS: One-step self-etch adhesives showed higher bond strengths on ground enamel and no reductions in resin-enamel bonds were observed after 12 M of water storage.