The Impact of Surface Roughness and Different Pre-treatments on the Shear Bond Strength of Super-translucent Multi-layered Zirconia to Adhesive Resin Cement: An In Vitro Study.

Purpose The purpose of this in vitro study was to examine the impact of surface pre-treatment on the shear bond strength (SBS) of an adhesive resin cement to super-translucent multi-layered (STML) zirconia. Materials and methods Forty (n = 40) uniformly sized discs of STML zirconia (Katana, Kuraray, Noritake Dental Inc., Okayama, Japan), with dimensions of 3 mm in diameter and 3 mm in thickness, were produced using computer-aided design (CAD)/computer-aided manufacturing (CAM) technology and subsequently sintered following the manufacturer's instructions. The discs were subsequently divided into four equal groups (n = 10 each) based on the surface treatment method applied as follows: group 1 - control group with no treatment (Co); group 2 - sandblasting (SB); group 3 - Zircos Acids Zircos-E etching solution (BIO DEN CO, Seoul, Korea) (Z); group 4 - erbium-doped yttrium aluminum garnet (Er:YAG) laser. Surface roughness (Ra) was evaluated for each group. Round composite discs (Filtek Bulk Fill, 3M ESPE, St. Paul, MN), measuring 3 × 2 mm, were prepared for SBS testing and then bonded to the ceramic sample surface using composite resin cement (RelyX Ultimate Automix, 3M ESPE, Neuss, Germany). After securing the composite disc on the sample, each sample underwent an SBS test at a stress rate of 1 MPa/second with a force of 10 N. To ascertain the fracture type, fractured samples were inspected under a microscope. The ANOVA and post-hoc Tukey tests were employed to analyze differences in bond strength values among groups. All tests were conducted with a significance level of α = 0.05. Results Significant differences were observed in the SBS of cement applied to zirconium dioxide dental ceramics following various preparation methods. Statistically significant differences in the mean shear stress values (in megapascals) were found between the Z group and the Co group, as well as between the Er:YAG group and the other groups. Conclusions The application of Zircos-E for etching super ultra-translucent zirconia presents a promising approach to enhancing resin bonding, particularly in comparison to techniques involving Er:YAG laser and sandblasting.