Can universal adhesive systems bond to zirconia?

OBJECTIVE: To measure the bond strength to zirconia subjected to different surface treatments of universal bonding agents. MATERIALS AND METHODS: Eighty blocks of zirconia were obtained by CAD/CAM milling. The blocks were embedded into PVC tubes, polished sequentially with increasing granulation sandpapers and divided into two groups according to surface treatment: polished or grit-blasted with alumina particles. Each group was then subdivided by bonding agent employed: Z-Prime Plus (control); Scotchbond Universal; All Bond Universal; and Z-Prime Plus + All Bond Universal. Cylindrical composite resin build-ups were constructed atop the blocks using a two-part metal die. Specimens were stored for 24 hours and subjected to microshear bond strength testing. Statistical analyses were performed by means of the F-test (ANOVA), Student's t and Tukey's test. After sputter coating, zirconia surfaces and adhesive interfaces were analyzed by scanning electron microscopy (SEM). RESULTS: Bond strength was superior for grit-blasted zirconia. In specimens with this surface treatment, there were no significant differences between experimental groups. On SEM, blasted surfaces exhibited areas of micromechanical retention and adhesive interfaces exhibited areas of zirconia-adhesive interlocking. CONCLUSION: Universal adhesive systems were able to bond to zirconia. The interlocking promoted by grit-blasting enhanced bond strength. CLINICAL SIGNIFICANCE: Universal adhesive systems simplify bonding to zirconia and enable intraoral repair of fractures.