Effects of simplified ethanol–wet bonding and hydrophobic coating on resin–dentin bonding properties

Abstract

The purpose of the present study is to evaluate the impact of simplified ethanol-wet bonding (EWB) and hydrophobic coating (HC) on the three adhesives. We collected 105 fresh human molars and randomly divided them into three groups according to the three types of adhesives: Single Bond (SB), Gluma Comfort Bond (GB), and Tetric N-Bond (TB). Then, each group was further divided into five subgroups based on different bonding schemes: (1) Water wetting bonding (WWB); (2) EWB for 1 min (EWB 1); (3) EWB for 2 min (EWB 2); (4) EWB for 1 min combined with HC (EWB 1 + HC); and (5) HC. We evaluated the micro-tensile bonding strength (MTBS), fracture types, hybrid layer and resin tags of the specimens. At 24 h, SB (EWB 2), GB (EWB 2), TB (EWB 2), GB (HC), TB (HC), TB (EWB 1) and TB (EWB 1 + HC) groups revealed significant improvement in MTBS (p＜0.05); After 6 months, SB (EWB 1 + HC), GB (EWB 2), and TB (HC) groups showed no significant reduction in MTBS (p＜0.05). Besides, EWB 2 has the most noticeable effect on both hybrid layer and resin tags in all adhesives; EWB 1 + HC or HC alone scheme increase the number and length of resin tags in partly adhesives. Simplified ethanol wetting technology can increase the bond strength, durability, and quality of the three adhesives, and its effect depends on the wetting time. In this study, ethanol wetting for 2 min improved the adhesion properties significantly.