[Effect of hot chemical etching on bond strength of zirconia to resin].

OBJECTIVE

This study aims to evaluate the influence of hot chemical etching on short- and long-term shear bond strength (SBS) of zirconia to resin.

METHODS

Eighty zirconia ceramic slices were obtained and randomly divided into five groups based on the surface treatment to be applied--group A: H2SO4/(NH4)2SO4 hot solution etching + application of Clearfil; group B: HF/HNO3 hot solution etching + application of Clearfil; group C: H2SO4/HF/HNO3 hot solution etching + Clearfil; group D: alumina sandblasting + application of Clearfil; group E: tribochemical silica coating + application of silane coupling agent. Eighty composite cylinders were bonded to pretreated ceramic slices using a bis-GMA-based resin cement. Specimens in each group were divided into two fractions: the first half received 24 h water storage, and the second half received 40 d water storage. Then, SBS tests were conducted. Morphological analysis of sandblasted alumina and hot chemical-etched zirconia surfaces were performed by scanning electron microscopy(SEM).

RESULTS

Group E displayed the highest SBS before artificial aging, and no statistical difference was found among the other groups. After 40 d water storage, groups A, B, and E showed significantly higher SBS than groups C and D. SBS increased significantly after artificial aging in groups A and B. No significant variations were found before and after artificial aging in the other groups.

CONCLUSION

The experimental hot chemical etching solution provides enhanced bonding for zirconia than sandblasting, and the bond strengths remain stable after artificial aging.