Effects of accelerated artificial aging on the translucency and color stability of monolithic ceramics with different surface treatments

Statement of problem. Different surface finishing procedures can be applied to monolithic restorations. However, information is limited regarding the long-term performance of these procedures. Purpose. The purpose of this in vitro study was to evaluate the effect of aging on the translucency and color stability of monolithic ceramics with different surface finishing procedures. Material and methods. Disk-shaped (14x1.5 mm) specimens of monolithic zirconia (Zirkonzahn Prettau [ZZ]) and lithium disilicate glass-ceramic (IPS e.max Press [IPS]) were fabricated. The specimens were divided into 3 subgroups according to the surface treatments (n=9, G: glazing, R: rubber polishing system, and P: rubber polishing system followed by polishing paste). Color measurements were made by using a spectrophotometer before and after an ultraviolet aging process. L*, a*, and b* parameters were recorded. Delta E and translucency parameter (TP) values were calculated. One specimen from each subgroup was examined by scanning electron microscopy (x30 000). The data were statistically analyzed using the Mann-Whitney U, Kruskal-Wallis, and post hoc tests (alpha=.05). Results. Delta E values of group ZZ (5.03) exceeded the clinically acceptable level (3.5); however, the color change was not clinically perceptible for IPS (0.41). The Delta E value of the subgroup P was found to be higher than that of the others for ZZ (P<.001). The Delta E value was not affected by the surface treatment for IPS. Group IPS showed significantly higher translucency than the ZZ group (P<.001). TP values were not affected by the surface treatment in either material and decreased after aging. However, changes in the TP values were too slight to be clinically perceptible. Conclusions. Lithium disilicate ceramic was found to be more esthetic than monolithic zirconia ceramic in terms of color stability and translucency.