Influence of long-term water storage and thermocycling on shear bond strength of glass-ionomer cement to Er:YAG laser-prepared dentin.

PURPOSE

To evaluate the influence of long-term water storage and thermocycling on the shear bond strength of a glass-ionomer cement to Er:YAG-irradiated and bur-prepared dentin.

MATERIALS AND METHODS

Fifteen bovine incisors were selected and the roots removed. Crowns were sectioned into four pieces, resulting in 60 samples that were individually embedded in polyester resin (n = 15) and ground to plane the enamel and expose the dentin. The bonding site was delimited and samples were randomly assigned according to the method of cavity preparation: Er:YAG laser (250 mJ/4 Hz) or high-speed handpiece (diamond bur #2096). Samples were fixed to a metallic device, where glass-ionomer cement (GIC) cylinders were prepared. Subsequently, they were subdivided according to the duration of water storage (WS) and number of thermocycles (TCs) - 24 h WS/no TCs and 6 months WS/12,000 TCs - and subjected to a shear bond strength test (500 N at 0.5 mm/min).

RESULTS

The duration of water storage and number of thermocycles tested had no statistically significant effect on the shear bond strength to laser-irradiated dentin (p > 0.05). For bur-prepared substrate, the long-term degradation process promoted a decrease in shear bond strength values (p < 0.05).

CONCLUSION

Long-term water storage and thermocycling did not affect shear bond strength of glass-ionomer cement bonded to Er:YAG laser-prepared dentin.