Bonding Durability and in-Situ DC of Four Different Self-Etch Adhesives.

Objectives: The objectives of this study were to evaluate the bonding durability of four different self-etching adhesives to dentin after 24 hours and thermocycling (TC) and to measure their degree of conversion (DC) in situ.
Methods: Two two-step self-etching adhesives: 1) CLEARFIL SE BOND 2 (SE2, Kuraray Noritake Dental) 2) G2-BOND Universal (G2B, GC) and two one-step self-etching adhesives: 3) Scotchbond Universal Plus Adhesive (SBU, 3M) 4) CLEARFIL Unversal Bond Quick (UBQ, Kuraray Noritake Dental) were used. The labial surfaces of bovine teeth were ground to create flat dentin surfaces and the adhesives were applied according to the manufacturers' instructions. After resin-composite buildup and 24-hour water storage, the specimens were sectioned into beams and all groups were thermocycled for 0, 10,000 or 20,000 cycles followed by microtensile bond strength (µTBS) test. In situ DC were investigated with a laser Raman microscope. µTBS data were statistically analyzed using Weibull analysis. Two-Way ANOVA used to show the effect of different adhesives and thermocycling on the mean DC% followed by Tukey’s post-hoc test for multiple comparisons.
Results: G2B TC10k exhibited significantly higher µTBS comparing with TC0. SBU TC20k showed significant higher µTBS comparing with TC0. Weibull analysis indicated that 1-step self-etch adhesives tended to show lower β values than 2-step self-etch adhesives after TC. G2B showed significant reduction and UBQ showed significant increase of DC% after TC.
Conclusions: The 2-step self-etching adhesives showed relatively stable bonding performance after TC.