Bond strength of resin cements to noble and base metal alloys after two surface treatments

The reported bond strengths of resin cements to metal alloys depend on the metal used, the conditioning methods and the adhesive resins. The aim of this study was to evaluate the bond strength of resin cements to two alloys (Degubond 4 and Verabond) after sandblasting or using Silano-Pen. Eighty disk shaped specimens (6mm diameter and 2mm thickness) of Verabond or Degubond 4 were cast according to the manufacturer's instructions. After mounting in auto polymerizing acryl, all samples were polished with a 600 grit silicon carbide paper under water. Half of each alloy’s samples were randomly sandblasted with 50 µ Al2O3 and the other half were flamed with Silano-Pen device after sandblasting with 110 µ Al2O3. Cylinders of composite resin (Z250) were cured and then cemented to the prepared substrates by either Panavia F2 or RelyX Unicem. All specimens were stored in distilled water at 37oC for 24 hours and were subjected to 2000 thermal cycles (5-55oC), then submitted to shear bond strength (SBS) test using Universal Testing Machine at 0.5mm/min speed, until failure. SBS was analyzed by three way ANOVA (α=0.05). Failure patterns were determined using stereomicroscope with 40X magnification. Both cements provided stronger bond to Verabond compared to Degubond 4 (p<0.001). Comparing the surface treatments, Silano-Pen provided higher SBS of RelyX Unicem to both alloys. Panavia cement resulted in higher bond strengths to sandblasted Verabond alloy (p=0.003), but after treatment with Silano-Pen device RelyX Unicem showed higher bond (p=0.011). When cementing Verabond or Degubond 4 by RelyX Unicem, Silano-Pen provided a stronger bond, but in case of using Panavia F2, treatment with Silano-Pen or sandblast resulted no difference in bond strength.