Effect of aging on Y-Zr on phase stability and surface characteristics – An in vitro study

Objective: The purpose of this study was to evaluate the phase stability and surface characteristics of Yttrium stabilised zirconia ceramics after various low temperature aging using X-ray diffraction analysis and Scanning Electron Microscopy respectively. Materials and Methods: Our study included discs of Yttrium stabilized tetragonal zirconia from two manufacturers (n=15) Sample A AIDITE (Qinhuangdao Technology Co., Ltd, Hebei, China) and Sample B UPCERA (Shenzhen Upcera Dental Technology Co., Ltd, Guangdong, China), for each brand which were machined and sintered and glazed according to manufacturer’s specifications to mimic a final polished crown that is ready for cementation. Specimens were artificially aged in distilled water by heat treatment at temperatures of 100, 150 and 200°C for 10 hours each in order to induce phase transformation. These specimens after aging were individually evaluated for the phase transformation using X- ray diffraction (JDX 8P, JEOL machine)and surface characteristics using scanning electron microscopy (6380 LA, JEOL machine). Results: The results from x-ray diffraction analysis of both the specimens with and without low temperature aging revealed only the tetragonal phase. On scanning electron microscopy, the surface of the specimens in as received condition appeared to be smooth with a few blebs here and there. As aging was carried out, the surface irregularities became more pronounced. Conclusion: The invitro tests conducted reveal that the two materials Aidite and Upcera did not show significant results on x-ray diffraction analysis and scanning electron microscopy.