Microtensile Bond Strengths of One-Step and Conventional Bonding Agents

Objective:  The microtensile bond strength of composite resin bonded to human enamel was evaluated utilizing four light-cure bonding agents (Prime & Bond NT [NT], Optibond Solo [OP], and two self-etching adhesive systems Prompt L-pop [LP] and Tyrian SPE [TS].  Method:  Freshly extracted non-carious human third molars were embedded in epoxy and the buccal surfaces sequentially abraded to 400 grit with silicon paper and water.  Teeth were distributed at random and composite resin cylinders were then bonded using the four bonding agents according to manufacturer’s specifications.  Each bonded tooth produced three to four longitudinal sections, which were then laterally notched to give a square bond area (~2.25 mm²).  Specimens (n=10) were assigned to two groups:  Group I was stored in distilled water at 37°±2°C for 7 days.  Group II was stored in distilled water at 37°C for 7 days during which time they were thermocycled in water baths at 5°C and 55°C for a 30 second dwell time per bath and 1000 cycles.  Results:  Mean microtensile bond values (MPa) with standard deviations (SD) are listed below:

Conclusion: The microtensile bond strength of the conventional adhesive OP was significantly greater than that of the self-etching adhesives TS and LP.  Thermocycling resulted in significantly lower bond strengths for all four adhesive brands.