Effect of water aging on the shear bond strength of different self-adhesive restorative materials to dentin

This study aimed to evaluate the effect of water aging on the shear bond strength of four self-adhesive restorative materials on dentin. Sixty permanent human molars recently extracted for prophylactic purposes were used in this study. The crown of each tooth was cut under water-cooled conditions using a plaster cutting engine to expose the middle dentin surface of the teeth. The prepared teeth were randomly divided into six groups according to the restorative materials [KERR Vertise Flow (VF), GC EQUIA Forte (EQ), PENTRON Fusio Liquid Dentin (PF), IMICRYL Nova Compo SF (NC) Clearfil Majesty ES-2 (CM-control) and Clearfil Majesty ES Flow (CF-control)]. Each restorative material was applied to two different areas of each tooth (n = 120) using cylindrical silicone molds with dimensions of 2 mm × 2 mm. Macro-shear tests were conducted using a Universal Testing Machine (1 mm/min) initially (24 h) and after aging (6 months of water aging), and the failure types were analyzed. For the initial values, a significant difference in the shear bond strength of the self-adhesive and control groups was observed. After aging, the bond strength increased for flowable composite material (CF) and decreased for two different self-adhesive restorative material groups (NC and EQ). There was no significant difference in the bond strength before and aging in the paste-like control composite group (CM) and in the two self-adhesive restorative material groups (VF and PF). Differences in the shear bond strength were observed between the self-adhesive and control materials both before and after aging.