The Influence of Nanostructured Alumina Coating on Bonding and Optical Properties of Translucent Zirconia Ceramics: In Vitro Evaluation

Thin, non-retentive, monolithic restorations fabricated from novel translucent zirconia ceramics are widely used in contemporary dentistry. Because of the chemical inertness of zirconia, debonding of such restorations remains the main clinical complication. Limited evidence on the bonding performance of novel translucent zirconia exists; therefore, the present study aimed to evaluate, in vitro, the shear-bond strength (SBS) of translucent zirconia modified with a nanostructured alumina coating (NAC). The SBS of resin cement to translucent zirconia, materials containing 3, 4 or 5 mol.% of yttria modified with NAC, was measured and related to airborne-particle abraded (APA) zirconia surfaces. Half of each of the specimen groups (n = 20) were subjected to 37,500 thermocycles in water. In addition, to evaluate the effect of NAC on thin translucent zirconia discs (n = 10), the translucency parameter (TP) was measured and compared with APA. The results were statistically analyzed using a t-test and one-way ANOVA. NAC provided higher resin-zirconia SBS compared to APA, not affecting the zirconia optical properties. APA, on the other hand, lowered TP for all types of zirconia. NAC did not impair the mechanical or optical properties of translucent zirconia materials and should be regarded as a zirconia pretreatment alternative to APA.