Effect of the Dentin Chelating Agents Phytic Acid and EDTA on Degree of Conversion, Microhardness, and Bond Strength of Chemical-curing Self-adhesive Cements

Purpose: To evaluate the effect of the chelating agents phytic acid and EDTA on the degree of conversion (DC), microhardness, and tensile bond strength (TBS) of two chemical-curing self-adhesive cements. Materials and Methods: A total of 110 samples were prepared, with n = 6 in the control group to measure microhardness, n = 6 for DC measurement, and n = 10 for TBS measurement. The bovine dentin specimens were divided into five groups according to treatment: group A (control group): no treatment; group B, 1% phytic acid with ultrasonic rinsing (UR); group C: 1% phytic acid without UR; group D: 18% EDTA with UR; group E: 18% EDTA without UR. A 1-mm-thick coat of self-adhesive cement, G-CEM LinkAce (GC) or RelyX Unicem 2 (3M) was placed on control and treated dentin surfaces and stored in a dark box at 37 degrees C, 93% +/- 1% ambient humidity. DC and microhardness of cement surfaces were measured after 1 hour, 1 day, 3 days, and 1 week using Fourier transform infrared spectroscopy and a Vickers microhardness tester, respectively. TBS on treated and control dentin was evaluated after 1 week of storage in the dark box. Data were analyzed using two-way ANOVA, followed by Tukey's post-hoc test, at the 0.05 level of significance. Results: DC and microhardness of both types of cement without UR were significantly lower than that of groups in which UR was performed. Neither chelating agent had a significant effect on the TBS of G-CEM. For Rely X, the phytic acid treatment with UR showed a significantly higher TBS than the control and the EDTA groups. Conclusion: The chelating agents had a negative effect on DC and microhardness of the resin cements when UR was not used. Phytic acid increased the TBS of RelyX, while EDTA groups did not with either cement.