Radiopacity and Cytotoxicity of Portland Cement Containing Zirconia Doped Bismuth Oxide Radiopacifiers

Introduction: This study evaluates the radiopacity and cytotoxicity of Portland cements containing a radiopacifier of bismuth oxide (Bi2O3) with yttria-stabilized zirconia (YSZ) dopant. Methods: Various radiopacifier powders of Bi2O3 with 0%, 15%, and 100% YSZ dopant were prepared by solid-state reaction at 700 degrees C for 12 hours and characterized by x-ray diffraction. Portland cement/radiopacifier/calcium sulfate (75/20/5) were mixed and set by deionized water. Changes in radiopacity and in vitro cell viability of the hydrated cements were assessed. An average of 6 measured equivalent thickness of aluminum (N = 6) capable of producing similar radiographic density was recorded. The cytotoxicity of each material was determined in MC3T3 El cell-based methyl-thiazol-tetrazolium assay. Results: The x-ray diffraction patterns of YSZ doped Bi2O3 are different from those of pure Bi2O3 and YSZ. The cement-containing radiopacifier of Bi2O3/YSZ (85/15) presented significantly greater radiopacity (P < .05) compared with pure Bi2O3. The mouse oste-oblastic cell (MC3T3-E1) viabilities of these 2 groups were statistically similar (P < .05). Conclusions: The radiopacifier of Bi2O3/YSZ (85/15) reveals higher radiopacity but similar cell viability when compared with pure Bi2O3. It shows potential use a an alternative radiopacifier in root-end filling materials.