Optical properties of currently used zirconia-based esthetic restorations fabricated with different techniques.

Objective: The aim was to evaluate the effects of different types of monolithic zirconia (MZ) and fabrication techniques on the optical properties of newly generated zirconia-based materials after aging.

Material And Methods: Sixty specimens (n = 10) were prepared. For the groups layering-veneering (LV), overpressing (OP), porcelain fused to zirconia (PFZ), and cutback (CB), 3Y-TZP, IPS e.max ZirCAD was prepared as the core material (0.5 ± 0.01 mm). For full-contour (FC) technique, 3Y-TZP was used for MZ-LT (low translucency) and 4Y-TZP was used for MZ-MT (medium translucency). L*, a*, b*, chroma (C), and relative translucency (RTP) were measured before (L *, a *, b *, C , RTP ) and after (L *, a *, b *, C , RTP ) UV aging. Statistical analyses were performed by one-way ANOVA with Tukey's test and paired sample t tests (P = .05).

Results: Fabrication techniques significantly affected the L*, a*, b*, C, RTP, and ΔE values (P ˂ .01). The highest L * value was found in MZ-LT; followed, in order, by OP, PFZ, LV, CB, and MZ-MT. The highest b * and C values were found in OP, while MZ-MT had the lowest values (P ˂ .05). FC had the highest RTP values for MZ-MT (13 ± 0.9 RTP 11.2 ± 0.9 RTP ), and the lowest RTP values were found for MZ-LT (8.5 ± 0.9 RTP 8.3 ± 1.2 RTP ) (P ˂ .01). Aging caused significant differences in the L*, a*, b*, C, and RTP values (P < .05). The color changes were between 0.9 and 2.1 ΔE .

Conclusions: The fabrication technique significantly affected the optical properties. UV aging caused zirconia-based restorations to become darker and more yellow, red, saturated, and opaque.

Clinical Implications: Fabrication techniques with different zirconia structures affected the optical properties of the restoration, even when the same shades were chosen. If more translucent restorations are needed, choosing 4-YTZP with the FC technique is better than veneering with 3-YTZP. Choosing 3-YTZP with the FC technique produces more esthetic results if brighter and more opaque restorations are needed.