IADR Abstract Archives
Color Stability of Zirconia-based All-ceramics After Accelerated Artificial Aging
Objectives: The aim of this study was to investigate the color stability of zirconia-based ceramics that fabricated with different veneering techniques after accelerated artificial aging (AAA).
Methods: Sixty-four zirconia discs (10mm diameter, 0.5mm thickness) were prepared and divided into 4 groups (n=16) according to veneering techniques: Layering (LA), heat-pressing (HP), cut-back (CB), CAD-on (CO). Sixteen zirconia discs (10mm diameter, 1.5mm thickness) also prepared from translucent zirconia for full-contour zirconia group (FC) without veneer ceramic. Liner layer (0.1mm thickness) was applied to LA, HP and CB groups. LA group veneered by nano-fluorapatite glass-ceramic (0.9mm thickness), HP group veneered by heat-pressing fluorapatite glass-ceramic (0.9mm thickness), CB group veneered by partially pressed ingots (0.6mm thickness) after layered by nano-fluorapatite glass-ceramic (0.3mm thickness). For the CO group, lithium disilicate veneer ceramic (0.9mm thickness) designed and milled by CAD-CAM and fused to zirconia by glass-fusion ceramic. All the specimens attributed to AAA for 300 hours. The color was measured before and after the AAA according to CIELAB system and color parameters (ΔE, ΔC, ΔL, Δa, Δb) were calculated. Data were statistically evaluated by Kruskal-Wallis and Dunn’s Tests (α=0.05).
Results: Significant differences were found for all of the color parameters (ΔE, ΔC, ΔL, Δa, Δb) among the groups (P<0.05). The highest ΔE was observed in the LA (2.22) and the lowest ΔE was observed in the HP group (0.65). Chroma of the all groups was significantly increased. LA and CO groups became lighter; HP, CB and FC groups became darker. All the groups became greenish except the LA group. HP and CO groups became yellowish; however LA, CB and FC groups became bluish in appearance.
Conclusions: All the color parameters of the veneered-zirconia ceramics were affected from AAA. Color changes of heat-pressing and cut-back groups not appreciable by the human eye (ΔE<1). Color changes of the layering, CAD-on and full-contour zirconia groups were appreciable by skilled operators, but in clinically acceptable range (1<ΔE<3.3).
Methods: Sixty-four zirconia discs (10mm diameter, 0.5mm thickness) were prepared and divided into 4 groups (n=16) according to veneering techniques: Layering (LA), heat-pressing (HP), cut-back (CB), CAD-on (CO). Sixteen zirconia discs (10mm diameter, 1.5mm thickness) also prepared from translucent zirconia for full-contour zirconia group (FC) without veneer ceramic. Liner layer (0.1mm thickness) was applied to LA, HP and CB groups. LA group veneered by nano-fluorapatite glass-ceramic (0.9mm thickness), HP group veneered by heat-pressing fluorapatite glass-ceramic (0.9mm thickness), CB group veneered by partially pressed ingots (0.6mm thickness) after layered by nano-fluorapatite glass-ceramic (0.3mm thickness). For the CO group, lithium disilicate veneer ceramic (0.9mm thickness) designed and milled by CAD-CAM and fused to zirconia by glass-fusion ceramic. All the specimens attributed to AAA for 300 hours. The color was measured before and after the AAA according to CIELAB system and color parameters (ΔE, ΔC, ΔL, Δa, Δb) were calculated. Data were statistically evaluated by Kruskal-Wallis and Dunn’s Tests (α=0.05).
Results: Significant differences were found for all of the color parameters (ΔE, ΔC, ΔL, Δa, Δb) among the groups (P<0.05). The highest ΔE was observed in the LA (2.22) and the lowest ΔE was observed in the HP group (0.65). Chroma of the all groups was significantly increased. LA and CO groups became lighter; HP, CB and FC groups became darker. All the groups became greenish except the LA group. HP and CO groups became yellowish; however LA, CB and FC groups became bluish in appearance.
Conclusions: All the color parameters of the veneered-zirconia ceramics were affected from AAA. Color changes of heat-pressing and cut-back groups not appreciable by the human eye (ΔE<1). Color changes of the layering, CAD-on and full-contour zirconia groups were appreciable by skilled operators, but in clinically acceptable range (1<ΔE<3.3).