Bond Strength of Zirconia Ceramics to Dentin Using Two Resin Cements: Influence of Dentin Conditioning

Abstract

Background Dentin adhesion has difficult challenge compared to enamel adhesion. The purpose of the current study was to assess the impact of different dentin conditioning methods and two different resin cements on bond strength of zirconia ceramics to dentin. Methods A total of 64 zirconia discs were fabricated using CAD/CAM technology according to the desired dimensions (8mm diameter ×3mm thickness). A total of 64molars mounted in plastic rings with acrylic resin were prepared by exposing flat coronal dentin surfaces by removing the occlusal enamel and superficial dentin. The prepared molars were divided into 4 main groups (n = 16) according to dentin surface treatment; Dentin left as cutted, treated with EDTA, treated with Polyacrylic Acid (PAA), treated with self-etch adhesive. Each main group was subdivided into 2 subgroups (n = 8) according to luting cement used. One of the subgroups, zirconia discs were bonded to conditioned dentin surface using adhesive resin cement (VITA ADIVA® F-CEM). The other subgroup was bonded using self-adhesive resin cement (Calibra®Universal). After bonding, all specimens were stored in water bath at 37⁰C for 6 months followed by 10.000 thermal cycles. After artificial aging, all bonded specimens underwent shear bond strength testing using universal testing machine. The data was parametric and normally distributed. Two-way ANOVA was used to test significant difference in shear stress between cements and between surface treatments followed by post hoc Tukey test for correction of p value resulted from multiple comparisons. P is significant if < 0.05 at confidence interval 95%. Results There was a significant difference in shear bond strength between surface treatments. The highest shear bond strength was reported with Self-etch adhesive, followed by PAA, then EDTA surface treatments, and the lowest shear bond strength was reported with as cutted dentin. Also,There was a significant difference between each two surface treatments except between PAA and EDTA for adhesive resin cement group. Conclusion Define dentin surface treatment with self etch adhesive is recommended before bonding zirconia restoration overall the conditioning materials, followed by PAA and EDTA. Specially with self-adhesive resin cement (Calibra universal cement).