Impact of light-curing time and aging on dentin bond strength of methacrylate- and siloranebased restorative systems

Aim: To evaluate the impact of different light-curing times on dentin microtensile bond strength of two restorative systems after 24 h and 6 months of water storage. Methods: Standardized Class II preparations were performed in 56 freshly-extracted human molars (n = 7), restored with methacrylate- or silorane-based restorative systems, and light-cured using a light-emitting diode at 1390 mW/cm² by the recommended manufacturers’ time or double this time. After storage for 24 h at 37 °C, the teeth were sectioned to yield a series of 0.8-mm thick slices. Each slab was trimmed into an hourglass shape of approximately 0.64 mm² area at the gingival dentin-resin interface. Specimens were tested using universal testing machine at crosshead speed of 0.5 mm/min until failure, after 24 h and 6 months of storage. Data were statistically analyzed by three-way ANOVA and Tukey’s test (α = 0.05). Results: The highest bond strength values were recorded for the groups restored with methacrylate system (p<0.001) as well as for extended light-curing time (p = 0.0034). There was no statistically significant difference between 24 h and 6 months storage on bond strength (p>0.05). Conclusions: Bond strength was influenced by the material and lightcuring time, but the 6-month storage did not affect the bond strength of restorations.

Keywords
dental bonding; composite resins; methacrylates; silorane resins; polymerization