Five-Year Water Degradation of Eight Self-Etching Adhesives Bonded to Dentin

Objectives: To evaluate effect of long term direct water storage on the microtensile dentin bond strength (MTBS) of eight self-etching adhesives. Methods: Two-step (AdheSE Bond, Clearfil Protect Bond, Clearfil SE Bond, Optibond Self-Etch) and one-step (Clearfil Tri-S Bond, Hybrid Bond, G Bond, and Adper Prompt L-Pop) self-etching adhesives were tested. Eighty freshly extracted human third molar teeth were used. Crowns of teeth were sectioned to expose dentin then ground with #400 SiC paper. Adhesive resins were applied according to each manufacturer's instructions and then built up with a hybrid resin composite (Clearfil AP-X; Kuraray, Japan). Ten specimens prepared for each adhesive divided into two experimental groups (n=5): Group 1: the specimens were stored in water for 24 h, then sectioned perpendicular to the adhesive interface to produce beam-shaped specimens (1×1). After 24h, the beams were subjected to a MTBS test. Group 2: the teeth were also sectioned; however, the beams were stored in water for 5 years before MTBS test. The data were statistically analyzed by independent samples t-test. Results: After 5 years of water storage, the dentin bond strengths of Clearfil Protect Bond, Clearfil SE Bond, Optibond Self-Etch and Hybrid Bond were significantly reduced compared to their 24 h results. However, the bond strengths of AdheSE Bond, G Bond, Clearfil Tri-S Bond, and Adper Prompt L-Pop decreased but the reduction was not significantly different from those of 24 h. Conclusion: The resistance of resin-dentin bonds to degradation was material dependent. After 5 years of water storage, the bond created by four self-etching adhesives was able to resist degradation.