Shear bond strength of four dentine bonding systems to dry and moist dentine

Recent studies demonstrated that dentine wetness may be an important factor influencing the bond strength of dentine bonding systems. The purpose of this in vitro study was to evaluate the ability of four different dentine bonding systems to bond to dry (Group 1) and moist (Group 2) dentine. The four systems tested were Scotchbond Multi-Purpose (SMP, 3M), Imperva Bond (IB, Shofu), All-Bond 2 (AB2, Bisco) and OptiBond (OB, Kerr). In Group 1 the products were applied to dentine surfaces which had been dried with compressed air, after the etchant was rinsed off. In Group 2, however, the dentine was wiped with a damp facial tissue to remove excess water from the surface after rinsing off the etchant. The bond strengths (MPa) for the different products to dry (D) and moist (M) dentine were as follows: SMP: D: 24.9 +/- 4.5; M: 18.9 +/- 4.4; IB: D: 19.2 +/- 3.6; M; 15.6 +/- 2.8; OB: D: 25.9 +/- 2.9; M: 24.5 +/- 4.5 and AB2: D: 16.3 +/- 2.6; M: 27.2 +/- 2.3. Data were statistically analysed using the Wilcoxon Sum of Rank as well as Kruskal-Wallis tests. SMP and IB showed statistically significant higher bond strengths to dry dentine than to moist dentine. OB demonstrated no significant difference in bond strength between dry and moist dentine. AB2, however, demonstrated significantly higher bond strengths to moist than to dry dentine.