In vitro comparison of bonding effectiveness of different adhesive strategies

Purpose: To compare the bond strength to human dentin for a variety of adhesive materials, including self-adhesive resin composites, self-etch and etch-and-rinse adhesive systems and glass-ionomer cement by means of micro shear bond strength (μSBS) test and SEM observations.

Seventy-two human molars were sectioned to obtain a 2 mm-thick slab of mid-coronal dentin and were subsequently randomly divided into nine groups (n = 8). Nine conical frustum-shaped build-ups were constructed on the occlusal surface of each dentin slab using bonding agents (Group 1: OptiBond FL; Group 2: OptiBond XTR) combined with a resin composite (Premise Flow), self-adhesive resin composites (Group 3: RelyX Unicem; Group 4: RelyX Unicem 2; Group 5: SmartCem2; Group 6: SpeedCEM; Group 7: Maxcem Elite; Group 8: Vertise Flow) and a glass-ionomer cement (Group 9: Ketac-Fil). Specimens were subjected to μSBS test and observed with SEM. Data were analyzed by a mixed model and chi-square test.

The bond strengths measured in Groups 3-9 were significantly lower than those recorded in Groups 1 and 2. There were no significant differences in bond strengths between Groups 1 and 2 or between Groups 4 through 8. The bond strength measured in Group 9 was significantly lower than those recorded in Groups 4, 5, and 6 but was not significantly different than those recorded in Groups 3, 7, and 8. Failures were mainly adhesive in all groups.