Evaluation of micro shear bond strength of ormocer after various ceramic materials surface treatments

Purpose: The purpose of this study was to assess the impact of various surface treatments on the ormocer's microshear bond strength bonded to different CAD/CAM materials.
Materials and Methods: Zirconia Reinforced Lithium Silicate Glass-ceramic and Flexible Nanoceramic materials CAD-CAM blocks were used. Different surface treatments were performed on sliced specimens where in Group1, no surface treatments; Group 2, Sandblasting was done using 50 aluminum oxide powder and silane, Group 3; 8% hydrofluoric acid etching and silane, and Group 4; dry grinding using a green coded diamond stone and silane. The repair material underwent thermocycling for 5000 cycles between 5o C and 55o C. A universal testing device was used to assess the micro shear bond strength at a crosshead speed of 0.5 mm/min until failure occurs. A stereomicroscope was used to test the failure modes. In addition to the Kruskal-Wallis and Mann-Whitney tests, 2-way ANOVA was used to statistically examine the data (= 0.05).
Results: The hydrofluoric acid etching had the highest (mean SD) value in the zirconia reinforced lithium silicate ceramic and there was no significant difference between all other groups. For the Flexible Nanoceramic, grinding had the highest (mean SD) value and the three surface treatments did not differ significantly from one another.
Conclusion: The best surface treatment protocol for the repair of Zirconia Reinforced Lithium Silicate Glass-ceramic is the hydrofluoric acid etching followed by silane. The flexible nanoceramic repair could be done using either sandblasting, hydrofluoric acid etchant or dry grinding, followed by silane.