Evaluation of leaching components and color stability for colored dental zirconia with various coloring liquids

Abstract

The objective of this study was to evaluate the leaching components from the zirconia colored with various coloring liquids and color stability of the colored zirconia after accelerating aging. Commercially avaliable six coloring agents (AQU, BRU, DMA, LAV, RAI and INC) were tested. 3Y-TZP powder were used to prepare the disk-typed pre-sintered zirconia block. After application of coloring agents to pre-sintered zirconia block according to manufacturer’s instruction, final sintering was performed. XRD analysis was done to detect formation of secondary phases and phase transition of zirconia due to the addition of coloring agents. For the chemical stability test, ISO 6872:2008 was adopted and analytical equipments were used. ISO 7491:2000 was adopted for the color stability test. After accelerated aging treatments, color coordinates (CIE L<SUP>*</SUP>a<SUP>*</SUP>b<SUP>*</SUP>) were measured using spectrophotometer.BR Effects of coloring liquid on the microstructure of zirconia were not observed using XRD analysis, however, small peak of yittrium (Y) was observed in INC. In CTL and all experimental groups, Fe, Y, Mn and Ni ions were leached. Small amounts of Er, Co, and Cr ions were released from some experimental groups. The test of chemical stability in acetic acid solution did not affect the color stability of the colored zirconia (ΔE=0.06-0.69). After the accelerated aging treatment for 24 hrs, lightness (L<SUP>*</SUP>) and a<SUP>*</SUP> values showed the increasing behavior, but b<SUP>*</SUP> values did not show consistent changes. Color difference (ΔE) of CTL was 0.56, 1.61 for BRU, 1.26 for RAI, 1.16 for INC, 1.01 for DMA, 0.60 for AQU and 0.52 for LAV.