Microtensile bond strength evaluation of self-adhesive resin cement to zirconia ceramic after different pre-treatments.

PURPOSE: To evaluate the influence of different surface treatments and metal primer application on bond strength of zirconia ceramic to a self-adhesive resin cement. METHODS: 40 cylinder-shaped (O 12 x 5.25 mm high) of zirconia ceramic (Aadva Zirconia) were randomly divided into four groups (n= 10), based on the surface treatment to be performed: (1) Sandblasting with 125 microm Al2O3 particles (S) (positive control); (2) Selective infiltration etching (SIE); (3) Experimental heated etching solution applied for 30 minutes (ST); (4) No treatment (C). Half of the zirconia specimens of each group received the application of Metal Primer II. Eight disks for each group were luted using a self-adhesive resin cement (G-Cem Automix) to composite overlays (Paradigm MZ100). After 24-hour storage (37 degrees C, 100% RH) bonded specimens were cut into microtensile sticks and loaded in tension until failure. Data were analyzed with two-way ANOVA and Games-Howell (P < 0.05). Failure mode distribution was recorded and scanning electron microscopy (SEM) was used to examine the fractured microbars. The remaining cylinders of each group (n = 2) were used for SEM surface analysis. RESULTS: Both surface treatments and Metal Primer II application improved bond strength values (P < 0.05). When Metal Primer II was not applied ST treatment achieved highest bond strength values (22.17 +/- 10.37 MPa). Sandblasting in combination with Metal Primer II enhanced bond strength values compared to the other groups (23.46 +/- 11.19 MPa).