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Evaluation of microtensile bond strength of glass ionomer cements to dentin after conditioning with the Er,Cr:YSGG laser.

OBJECTIVE
The purpose of this study was to evaluate the hypothesis that conditioning with Er,Cr:YSGG laser energy would affect bond strength of glass ionomers to dentin.


METHODS
Forty extracted caries-free human premolars were selected and ground to expose occlusal dentin. Then the teeth were randomly divided into eight groups of five each and were conditioned in two ways: with and without laser conditioning, and were then restored using Fuji II, Vitremer, and Fuji II LC (with and without polyacrylic acid conditioning) glass ionomers. After immersion in water for 24 h, the teeth were vertically sectioned into 1 x 1-mm beams for microtensile bond strength (microTBS) evaluation. The beams were then subjected to tensile forces in a microtensile tester at a cross-head speed of 0.5 mm/min. Failure patterns were analyzed using a stereomicroscope and unbonded dentin surfaces were evaluated using scanning electron microscopy (SEM) as well. Data were analyzed using one-way ANOVA, Dunnet C, and t-test at the 95% level of confidence.


RESULTS
In unlased dentin, bond strength of Fuji II LC after conditioning with polyacrylic acid (PAA) was significantly higher than that of Vitremer and Fuji II. In the laser-irradiated group, bond strength of Fuji II LC after PAA conditioning and Fuji II were significantly less than those of Vitremer and Fuji II LC without PAA conditioning. With laser irradiation, bond strength of Fuji II and Fuji II LC after PAA conditioning were significantly reduced, while bond strength of Vitremer and Fuji II LC without PAA conditioning were not affected.


CONCLUSION
Laser irradiation with Er,Cr:YSGG energy at 1 W for conditioning does not improve bond strength of Fuji II LC and Vitremer to dentin, and even reduced bond strength of Fuji II and Fuji II LC after PAA conditioning.