Objectives: The purpose of this study was to evaluate the effect of two zirconia surface treatments; Air borne particle abrasion and Silica coating(Cojet) and three veneering techniques; Layering, Press-on and CAD - onveneering technique on the shear bond strength of the veneering ceramic.Materials and methods: Forty five zirconia based disc samples withstandardized dimensions (7mm diameter × 3mm thickness) werefabricated and randomly assigned into three groups each of 15 samplesaccording to the zirconia surface treatments; group I: control group(untreated Zirconia discs), group II: Zirconia discs subjected toMechanical surface treatment (Airborne particle abrasion), group III:Zirconia discs subjected to Mechanical chemical surface treatment(cojet). Each group was further subdivided into three subgroups of fivesamples each according to ceramic veneering techniques; Subgroup A:zirconia discs veneered by conventional layering technique. Subgroup B:zirconia discs veneered by Press-on technique and subgroup C: zirconiadiscs veneered by CAD-on technique. Shear bond strength was tested.Debonded samples were examined with SEM microscope. Data werecollected, tabulated and statistically analyzed with two-way ANOVAfollowed by Tukey’s post-hoc test for pair-wise comparison between themeans when ANOVA test was significant.Result; Regarding the effect different surface treatments regardless ofveneering techniques, it was found that there was no statisticallysignificant difference between Airborne-particle abrasion (29.6 ± 2.1Mpa) and Cojet surface treatment (29.3 ± 3.2 Mpa) both showed thestatistically significant highest mean shear bond strength values.Concerning the effect of different veneering techniques on shear bondstrength regardless of surface treatment, it was found that the CAD-ontechnique showed the statistically significant highest mean shear bondstrength (31.6 ± 2.6 Mpa), followed by the Press-on technique (26.2 ± 2.5Mpa). Layering technique showed the statistically significantly lowestmean shear bond strength ( 24 ± 1.8 Mpa) at P ≤ 0.05. Regarding theeffect of different interactions on shear bond strength; CAD-on veneeringtechnique with Cojet surface treatment showed the statistically significanthighest mean shear bond strength. Layering veneering technique withcontrol (no surface treatment) showed the statistically significant lowestmean shear bond strengthConclusion: This study concluded that surface treatments (Air borneparticle abrasion and cojet) of zirconia core enhanced the bond strengthwith the veneering ceramic. CAD-on veneering technique had anadvantageous effect on the veneering ceramic bond strength and is apromising way to reduce delamination of the veneer ceramic.Cojet isreliable surface treatment method for zirconia core when veneered withCAD-on veneering technique.Air-borne particle abrasion is suitablesurface treatment for zirconia core when veneered with Press-on orLayering techniques.