The purpose of this study was to evaluate the effect of different etching times on microtensile bond strength(μTBS) to dentin both initial and after thermocycling with 3 different types of total-etching adhesives. Fifty four teeth were divided into 18 groups according to 3 etching times(5, 15, 25sec), 3 types of adhesives(Scotchbond Multipurpose(SM), Single Bond(SB), One-Step(OS)), and thermocycling(0, 2,000cycles). Following the bonding procedure, the specimens were bonded using Z250 composite. Half of them were not thermocycled (control group) and the others were subjected to 2,000 thermocycle (experimental group) and processed for microtensile bond strength testing. The microtensile bond strength(MPa) by different etching time(5, 15, 25s) was 37.7±9.1, 34.3±10.9 and 30.5±7.5 using Scotchbond Multipurpose(SM), 34.6±10.1, 33.8±7.6, 35.3±9.9 using single bond(SB) and 34.3±7.6, 31.3±8.5, 35.8±11.0 using one step(OS). After 2000 thermocycling the specimens, the microtensile bond strength(MPa) was decreased for all dentin bonding systems tested. But when specimens were bonded with OS, there is no significant difference between microtensile bond strength of the groups with the different etching times(5, 15, 25s) (28.2±7.8a , 29.1±8.6a and 28.2±9.4a). And the microtensile bond strength of the groups using SM, SB was decreased significantly when the etchant was applied for 25 sec(p<0.05). After all, the adhesive durability for dentin could be affected by type of solvents in adhesive and etching time. Especially, extended etching time may deteriorate dentin bond strength when ethanol-based adhesive was used
Effect of Saliva Contamination on the Bond Strength of Dentin Adhesives to Central and Peripheral Primary Dentin in vitro