Shear Bond Strength of Resin Cement to Feldspathic CAD/CAM Ceramic Blocks; Conventional vs Self-etching Ceramic Primer

Purpose: The purpose of this study was to evaluate the effectiveness of using conventional vs self-etching ceramic primer on the shear bond strength (SBS) of luting resin cement to feldspathic CAD/CAM ceramic blocks. Methods: A total of 20 feldspathic porcelain disc specimens were sectioned from prefabricated ceramic blocks (Cerec blocks). They were divided into 2 groups (n=10) according to surface treatment. Group A (Conventional technique) included the application of 9.6% Hydrofluoric acid etching and then a Monobond-N silane agent; Group B included the application of Monobond etch & prime only. Resin cement cylinders (4.25 mm in diameter, 2 mm in height) were directly bonded on the pre-treated ceramic discs and light cured for 40 seconds. Shear bond strength was measured using a universal testing machine at a cross-head speed of 1 mm/min. The data were analyzed using a Student t-test with a significance level of 0.05. Mode of failure was observed and registered. Results: The mean ± standard deviation of shear bond strength of Group A was 7.64 ± 2.9 MPa and Group B was measured at 9.2 ± 2.68 MPa. There was no statistically significant difference between the two groups. Most of the specimens (8/10 in group A and 9/10 in group B) cohesively failed within the ceramic layer. Conclusion: Within the limitation of this study, self-etching ceramic primer provided equivalent results to the conventional technique in terms of shear bond strength to feldspathic ceramic material while simplifying the technique. Cohesive failure within ceramic material indicates good bond strength between the resin cement and pre-treated ceramic surfaces.