Effects of chlorhexidine on bonding durability of different adhesive systems using a novel thermocycling method.

BACKGROUND: The purpose of this study was to evaluate the influence of chlorhexidine on the bonding durability of etch-and-rinse and self-etch adhesive systems using the polymerase chain reaction (PCR) thermocycling method.

METHODS: Twenty freshly extracted intact human third molars were ground and bonded with either an etch-and-rinse adhesive (Single-Bond) or a self-etch adhesive (G-Bond). Specimens were either left untouched or placed in PCR tubes filled with three thermocycling mediums: water, chlorhexidine or silicone oil. Thermocycling (5000 cycles) was done using the PCR programme at temperatures of 5 °C and 55 °C. The microtensile bond strength (μTBS) was evaluated and interfacial nanoleakage was assessed by scanning electron microscopy before and after thermocycling.

RESULTS: Significant differences were detected among groups kept in different media after thermocycling. For Single-Bond, both the chlorhexidine and silicone oil groups could preserve the μTBS (p < 0.001). For G-Bond, μTBS of the chlorhexidine and water groups were significantly decreased (p < 0.05). No obvious increase in silver deposition was observed in specimens incubated in water after thermocycling, less silver penetration was found in specimens incubated in chlorhexidine.

CONCLUSIONS: In this experimental model, chlorhexidine was found to preserve bonding durability in Single-Bond but have no significant effects on G-Bond.