Evaluation of different aging times on flexural strength of zirconia ceramics

Objective: The purpose of this study was to investigate the effect of 1 hour and 5 hours artificial aging process on flexural strength of Y-TZP ceramics with different thickness and different amount of yttria content. Materials and Methods: A total of 300 disc-shaped specimens; DD Bio ZX2 Color, DD Cube One ML, DD Cube X2 ML, IPS e. max ZirCAD Prime and IPS e. max ZirCAD MT Multi were produced as final dimentions 12 mm diameter, 0.8 and 1.5 mm thickness. According to ISO 13356 standards, experimental groups were artificially aged at 134 °C, under 2 bar pressure, for 1 hour and 5 hours at autoclave. Control groups were not subjected to any treatment. SEM and XRD analysis were performed. The effect of aging on flexural strength was investigated by biaxial bending test. Datas were analyzed using the Shapiro-Wilk, Levene test, Analysis of Variance and Bonferroni test. Results: The mean flexural strength (FS) values of the materials are DD Bio ZX2 Color, IPS e. max ZirCAD Prime and DD Cube One ML, IPS e. max ZirCAD MT Multi and DD Cube X2 ML respectively. The flexural strengths of IPS e. max ZirCAD Prime and IPS e. max ZirCAD MT Multi materials increased with a increase in the thickness. Flexural strength of DD Bio ZX2 Color was increased with aging time, no significant difference was observed in the FS values of other materials. SEM investigation revealed that with increasing aging time, the surface degradation increased. Conclusions: Significant differences were observed in the flexural strengths of materials with different amounts of yttria content. Aging times and material thickness have an effect on the flexural strength of Y-TZP ceramics.