Early bond strength to low pressure sandblasted zirconia : evaluation of a self-adhesive cement

The debonding of a densely sintered zirconia prosthesis is a clinically reported, and undesirable event. A standardized, affordable adhesive cementation protocol for zirconia-based restorations is not yet available. The aim of this investigation was to assess the influence of several surface treatments on the initial shear bond strength of self-adhesive resin cement to densely sintered zirconia ceramic. Thirty densely sintered zirconia cylinders were divided into three groups (n = 10). Each of them received a different surface treatment: control (No_T), with the zirconia surface unconditioned; low pressure air abrasion (Sand_S) (50 µm, 1 bar); and standardized air abrasion (Sand_H) (50 µm, 2.8 bar). Three more surface-treated only specimens were addressed to scanning electron microscope (SEM) for qualitative observations. After specimen fabrication, self-adhesive cementceramic interface was analyzed using SBS (shear bond strength) test. Mean shear bond strengths (MPa) obtained for Sand_H and Sand_S were 16.24 ± 2.95 and 16.01 ± 2.68, respectively; no statistically significant difference (P = 0.8580) was found between sandblasted groups. Low-pressure air abrasion positively affected the initial self-adhesive cement adhesion to zirconia with respect to the No_T control group; however it did not prevent scratches and the formation of microcracks on the ceramic surfaces