Y-TZP Ceramic Nano-modification: Topographic and Shear Bond Strength Evaluations

Objectives: The aim of this in vitro study was to evaluate the behavior of yttria-stabilized tetragonal zirconia (Y-TZP) pre-sintered surfaces after sonochemical treatment.
Methods: Forty Y-TZP discs (11mm Ø and 2.7mm thickness) were divided in four groups (n=10): LC: application only of the proprietary liner; S40: pre-sintered sonication with 40% nominal power for 15 minutes; S70: pre-sintered sonication with 70% nominal power for 15 minutes; JAT: sandblasting with 50µm aluminum particles. After sintering, the samples were subjected to Confocal Laser Scanning Microscopy (CLSM) and Atomic Force Microscopy (AFM) analyses, to evaluate the topography and surface roughness. The phases of the crystalline structures were identified through Micro Raman Spectroscopy (MRS). After that, a feldspathic veneering ceramic was applied in all Y-TZP surfaces and subjected to shear bond strength (SBS) test until fracture. Failure modes were classified as Adhesive, Cohesive or Mixed.
Results: Shear bond strength results were subjected to one-way ANOVA (p≤0.05) followed by Tukey’s test (α= 0.05). No differences were shown between groups regarding surface roughness, although AFM images showed topographic differences. The LC group showed the highest SBS mean values, which was significantly different than S70 and JAT, which were not different. S40 showed the lowest SBS mean values. All samples exhibited typical Y-TZP tetragonal bands and monoclinic phases. Most specimens of all groups exhibited mixed failures and the remaining specimens adhesive failures.
Conclusions: Additional surface treatments for Y-TZP, ie, sandblasting and 70% power sonochemical treatment, showed similar results, but did not increase shear bond strengths to a feldspathic ceramic.