Effect of two surface treatments on the micro-shear bond strength of different machined esthetic restorative materials with two types of resin cement

Abstract

This study was designed to evaluate the effect of two surface treatments on the micro-shear bond strengths of four different indirect esthetic restorative materials to adhesive and self-adhesive resin cements. The materials tested were VITA Mark II, IPS e.max CAD, Lava-Ultimate and VITA Enamic. They were cut into slices of the same dimensions. After finishing, four slices of each material were surface treated by etching and silanization. The other four slices were sandblasted and silanized. After surface treatment, templates made of starch-based plastic, each with five cylinder-like openings (diameter: 0.9mm, height: 1mm) acting as molds for the resin cements, was adapted tightly on each slice to receive the two types of resin cement. Two slices of the etched slices received adhesive resin cement, while the other two slices received self-adhesive resin cement. Also, two slices of the sandblasted slices received adhesive resin cement, while the other two slices received self-adhesive resin cement. All substrates, slices with starch-based template and resin cement micro-cylinders, were stored in distilled water for 24 hours. After this period, the template was carefully removed under a gentle water stream exposing the micro-cylinders of resin cement. A total of one hundred and sixty micro-cylinders were loaded under shear at a crosshead speed of 1 mm/min until failure in a Universal Testing Machine. The micro-shear bond strength data was collected and tabulated. Three-way ANOVA was used to statistically analyze the effect of type of material, surface treatment and resin cement on the micro-shear bond strength between restorative material and resin cement. The results revealed significantly lower bond strength values for VITA Mark II compared to the other three materials. Etching showed significantly higher bond strength values than sandblasting. And the difference between them was statistically significant. Adhesive resin cement showed better results than self-adhesive resin cement, but of no statistical significance. In general, the interaction between the three variables was statistically non-significant. However, the interaction between IPS e.max CAD, etching and adhesive resin cement was highly significant and their combination showed the highest mean value for micro-shear bond strength.