Evaluation of the bond strength and characteristics of zirconia after different surface treatments

Nonthermal plasma treatment could increase the bond strength of resin cements to zirconia, but studies are lacking. The purpose of this in vitro study was to evaluate zirconia bond strength, surface roughness, and contact angle and to measure the infrared spectrum after different surface treatments. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP; n=9) blocks were sectioned into 36 slices (12×11×3 mm) and divided (n=4) into surface treatment groups as follows: 2 control groups, consisting of airborne-particle abrasion plus primer (APP) and 10% hydrofluoric acid etching plus primer (HFP), and 3 experimental groups consisting of a nonthermal plasma (NP) application; a nonthermal plasma plus primer application (NPP); and a 10% hydrofluoric acid etching plus nonthermal plasma plus primer (HFNPP) application. Each zirconia disk was cemented to a prepolymerized resin block. After cementation, the specimens were sectioned for microtensile strength testing and for surface roughness analysis and contact angle analysis. Results were submitted to analysis of variance and Tukey tests (α=.05). Results showed no statistically significant differences between the APP and HFNPP groups, but these 2 groups showed statistically better bonding than those of HFP, NP, and NPP. Airborne-particle abrasion resulted in a significant increase in surface roughness compared with the other groups. After nonthermal plasma treatment, the contact angle of the zirconia surface decreased within 48 hours. Nonthermal plasma application for surface treatment of zirconia showed no significant difference in bond strength when compared with airborne-particle abrasion.