Influence of Pretreatment Methods on the Adhesion of Composite and Polymer Infiltrated Ceramic CAD-CAM Blocks

Purpose: To assess the effect of different surface pretreatments on the shear bond strength of resin luting material on CAD-CAM composite resins and a polymer-infiltrated ceramic network (PICN). Materials and Methods: CAD-CAM materials (Brilliant Crios, Cerasmart, Lava Ultimate, VITA Enamic) were subjected to the following pretreatments: no pretreatment; grit blasting; grit blasting + silane; HF etching + silane; tribochemical silica coating + silane; manufacturers' specifications; manufacturers' specifications + silane; manufacturers' specifications using only the manufacturers' products including their recommended luting materials (DuoCem, G-Cem LinkForce, RelyX Ultimate, RelyX Unicem 2). Specimens were luted with resin luting material according to the Swiss shear test design. After six months of water storage, shear bond tests were performed. Data were analyzed with multiple linear regression models and nested models (α = 0.05). Results: Low bond strengths were obtained without pretreatment (Brilliant Crios 3.01 ± 0.54 MPa, Cerasmart 2.66 ± 0.47 MPa, Lava Ultimate 1.76 ± 0.26 MPa, VITA Enamic 2.83 ± 0.63 MPa). Grit blasting achieved high bond strengths across all materials (Brilliant Crios 5.17 ± 0.77 MPa, Cerasmart 4.27 ± 0.50 MPa, Lava Ultimate 3.98 ± 0.54 MPa, VITA Enamic 4.97 ± 0.90 MPa). Silane application tended to decrease bond strengths on CAD-CAM composite resins. Following the manufacturers' specifications and using their recommended materials achieved the highest bond strengths for all materials except Cerasmart (Brilliant Crios 5.75 ± 0.91 MPa, Cerasmart 2.82 ± 0.28 MPa, Lava Ultimate 6.63 ± 0.97 MPa, VITA Enamic 7.09 ± 0.77 MPa). Conclusion: Grit blasting and the application of a suitable material primer is a useful pretreatment for the bonding of CAD-CAM composite resins. Silane application on CAD-CAM composite resins may entail drawbacks, possibly owing to the scarcity of silanizable fillers. Keywords: silane primer, hydrofluoric acid etching, silica coating, air abrasion, adhesion