INFLUENCE OF SURFACE TREATMENT PROTOCOLS ON SHEAR BOND STRENGTH OF VENEERING COMPOSITE TO ZIRCONIA

Statement of problem: the formation of reliable bond to zirconia-based materials has proven to be difficult which is the major limitation against fabricating adhesive zirconia restorations. Materials and Methods: a total of 35 fully sintered zirconia 5 mm diameter discs (Z1) (Ceramill zi, Amann Girrbach AG) were constructed using MAD MAM technique (Ceramill Multi-x, Amann Girrbach AG). Another 35 composite resin discs (Filtek P60, 3M, U.S.A) (C1) of 5 mm diameter were constructed. The prepared zirconia discs (Z1) were divided into five groups- according to surface treatment applied- each of 7 specimens. (Gr I; control, Gr II; 50 μm Al 2 O 3 Air abrasion, Gr III; 100 μm Al 2 O 3 Air abrasion, Gr IV; 9% hydrofluoric acid etched, Gr V; 50 μm Al 2 O 3 Air abrasion then 9% hydrofluoric acid etched). C1 discs were bonded to the Z1 discs using Resin cement (Multilink, Ivoclar Vivadent Schaan, Liechtenstein) under 500 gm. fixed load. Results: shear bond strengths of the luting cement to the treated zirconia surface were in Gr I:(16 MPa), Gr II:(16 MPa), Gr III:(6.59 MPa ), Gr IV:(11.46 MPa) and Gr V: (5.38 MPa). Conclusions: the air borne particle abrasion surfacetreatment applied to the zirconia surface and the non-treated group had approximately similar results, while hydrofluoric acid decreased the bond strength with resin cement.