This implies that hydrolysis of the bond may have occurred, decreasing the tensile bond strength. Another fact to be considered is the dimensional shrinkage of the cement due to aging, which may have modified the area of stress concentration, consequently weakening the bond in the composite-glass ionomer cement interface. However, for acid-etched Vidrion F glass ionomer cement, the bond strength values did not strongly decrease. According to Fuss et al. The surface acid treatment with variable degradation of the ionomer matrix was also influenced by the moist environment.
Satisfactory adhesion is achieved when there is no hydrolysis of the interface bond.
The best tensile bond strength was obtained without acid etching. Acid etching causes severe surface degradation for this type of cement resulting in poor tensile bond strength. Results obtained for Vidrion F were higher than those for Ketac Bond, which may be due to the cement conditions prior to acid etching, cohesive strength and particle size, all of which may affect bond strength. We suggest that acid etching not be used when glass ionomer cement is used as a lining base for composite resins. The present study indicated that both etched and unetched Vidrion F showed better tensile bond strength than Ketac Bond, and that acid etching did not improve the tensile bond strength of the two products.