Sung-Hun Kim received a DDS and his dental training in Korea, and PhD in England. He is a professor of Department of Prosthodontics at Seoul National University Dental School. He has published more than 100 papers in reputed journals and has been serving as an editor-in-chief of Journal of Advanced Prosthodontics.

PURPOSE: The purpose of this study was to compare the optical properties of pre-colored dental monolithic zirconia ceramics of various thicknesses sintered in a microwave and a conventional furnace. Materials and Methods: A2-shade of pre-colored monolithic zirconia ceramic specimens (22.0 mm x 22.0 mm) in 3 thickness groups of 0.5, 1.0, and 1.5 mm were divided into 2 subgroups according to the sintering methods (n=9): microwave and conventional sintering. Spectrophotometer was used to obtain CIELab color coordinates, and translucency parameters and CIEDE2000 color differences (〖∆E〗_00) were measured. The relative amount of monoclinic phase (Xm) was estimated with x-ray diffraction. Statistical analyses were conducted with two-way ANOVA (α=.05). Results: There were small interaction effects on CIE L*, a*, and TP between sintering method and thickness (P<.001): L* (partial eta squared ηp2=.115), a* (ηp2=.136), and TP (ηp2=.206), although higher b* values were noted for microwave sintering regardless of thickness. Color differences between two sintering methods ranged from 0.52 to 0.96 〖∆E〗_00 units. The Xm values ranged from 7.03% to 9.89% for conventional sintering, and from 7.31% to 9.17% for microwave sintering. Conclusions: Microwave-sintered pre-colored dental monolithic zirconia ceramics can exhibit similar color perception and translucency to those by conventional sintering with reduced processing time.