Purpose: To compare the shear bond strengths (SBS) of two cements to two Y-TZP ceramics subjected to different surface treatments.
Materials and methods: Zirconia specimens were made from Lava (n = 36) and IPS e.max ZirCAD (n = 36), and their surfaces were treated as follows: no treatment (control), silica coating with 30-µm silica-modified alumina (Al2O3) particles (CoJet Sand), or coating with liners Lava Ceram for Lava and Intensive ZirLiner for IPS e.max ZirCAD. Composite resin cylinders were bonded to zirconia with Panavia F or RelyX Unicem resin cements. All specimens were thermocycled (6000 cycles at 5°C/55°C) and subjected to SBS testing. Data were analyzed by three-way ANOVA and Tukey's (HSD) post-hoc test (α = 0.05). Failure mode was analyzed by stereomicroscope and SEM.
Results: CoJet Sand and liners promoted significantly higher SBS than their control groups, but had similar results to one another. Panavia F provided significantly higher SBS values than RelyX Unicem (p < 0.01) for nontreated zirconia specimens of both brands. When Lava and IPS e.max ZirCAD were abraded with CoJet Sand, RelyX Unicem promoted significantly higher SBS values than Panavia F (p < 0.001). There was no significant difference between the two cements when the zirconia specimens were treated with their respective liners. The nontreated specimens and those treated with CoJet Sand exhibited a high percentage of adhesive and mixed A failures, while the specimens treated with liners presented an increase in mixed A and mixed C failures as well as some cohesive failure in the bulk of Lava Ceram for both cements.
Conclusion: CoJet Sand and liners provided the best surface treatment for Lava and IPS e.max ZirCAD. The best surface treatment/cement combinations were CoJet Sand/RelyX Unicem and liner/Panavia F. SBS of Panavia F and RelyX Unicem was not influenced by the zirconia brand.