Influence of different surface treatments on the fracture toughness of a commercial ZTA dental ceramic

The objective of this study was to investigate how mechanical surface treatments performed for removal of excess of molten glass, influence the fracture toughness of a dental zirconia toughened alumina (In-Ceram® Zirconia). Infiltrated ZTA disks were submitted to three different surface treatments (grinding, sandblasting and grinding + sandblasting + annealing). Fracture toughness was accessed through indentation strength test (IS). Xray diffraction was used to investigate the metastability of tetragonal zirconia particles under all treatments proposed. Kruskall-Wallis non-parametrical test and Weibull statistics were used to analyze the results. Grinding (group 1) introduced defects which decreased the fracture toughness and reliability, presenting the lowest KIC. On the other hand, grinding followed by sandblasting and annealing (group 3) presented the highest KIC. Sandblasting (group 2) presented the highest reliability but lower KIC compared to group 3.