Effect of Veneering Dental Zirconia on Bond Strength. A pilot study

The objective of the study was to evaluate the effect of veneering zirconia surfaces with feldspar-based ceramics or glass ceramics on bond strength when using a resin composite cement. Forty-eight ytteria tetragonal zirconia polycrystal (Y-TZP) specimens were randomly divided into four groups. Six pairs were created in each group by bonding two of the specimens to each other after having the bonded surfaces treated differently as the following: I) polished and heat-treated (served as control), II) veneered with Vita VM9, III) veneered with e.max CAD Glaze and, IV) polished and heat-treated. The luting agent used in Group I III was RelyX Unicem and in Group IV Charisma. Using a universal testing machine, the load at debonding (Newton) was recorded and the bond strength (MPa) was then calculated. Group I exhibited statistical significantly superior bond strength compared to all other groups. A statistical significantly superior bond strength was seen for the specimens in Group II compared to Group III and IV. Group IV presented the lowest bond strength but there was no significant difference to Group III. The present paper show no promotion in bond strength when zirconia was veneered with feldspar-based ceramic or glass ceramic.