Microtensile bond strengths of one-step and self-etching adhesive systems

The microtensile bond strength of resin composite bonded to human enamel was evaluated utilizing four light-cure bonding agents. Human third molars were embedded in auto-cure acrylic and the buccal surfaces were sequentially abraded to 400 grit. Resin composite cylinders were then bonded using the four bonding systems according to the manufacturer's specifications. Each bonded tooth produced three to four longitudinal sections which were then laterally notched to give a square bond area (approximately 2.25 mm2). Specimens (n=10) were assigned to two groups: Group I was stored in distilled water at 37 degrees +/- 2 degrees C for seven days. Group II was stored in distilled water at 37 degrees +/- 2 degrees C for seven days, during which time it was thermocycled in hot and cold water baths for 1,000 cycles. In addition, a water sorption test was performed on three of the four adhesive systems. The microtensile bond strength of the conventional adhesive Optibond Solo Plus was significantly greater than that of the self-etching adhesives Tyrian SPE and Prompt L-Pop. Adhesive systems that were more hydrophilic tended to show lower bond strengths, especially after thermocycling.