Comparative Analysis of Translucency in Different Thicknesses of Monolithic Zirconia Crowns

Achieving optimal esthetics in dental restorations remains challenging, particularly with zirconia crowns, which, despite their durability, often exhibit less translucency than natural teeth. This study aimed to evaluate how varying thicknesses of monolithic zirconia crowns affect their translucency.

In this experimental laboratory study, an initial model (a brass die) was scanned, and two dies, one black (9005 RAL), and one white (9010 RAL), were created from Resin according to the scanned file. Next, 30 zirconia crowns (ZrO₂, Arum, High Translucent) were fabricated in three thicknesses: 0.5, 0.8, and 1.5 mm. The color and translucency of the samples were assessed under standard lighting conditions (D65) using a spectroradiometer, and the color parameters L*, b*, and a* were recorded. The translucency of each sample was measured using the CIEDE2000 and CIE-Lab formulae. Data were analyzed using one-way ANOVA and the Tamhane test.

Statistically significant changes in the color and translucency of the samples were observed with varying thicknesses (p < 0.001). Specifically, the translucency parameter (TP), L*, and b* values decreased as the thickness increased, whereas a* values remained relatively stable. The average TP values for CIE-Lab ranged from 11.51 at 0.5 mm to 6.54 at 1.5 mm, and for CIEDE2000, they ranged from 8.19 at 0.5 mm to 4.82 at 1.5 mm.

Within the limitations of this in vitro study, it can be concluded that reducing the thickness of monolithic zirconia restorations increases their translucency. Thinner zirconia restorations demonstrate a higher TP, which may offer improved esthetic integration in clinical applications.