Translucency of 3D-Printed 3Y- and 5Y-Doped Zirconia
Sebastian Hetzler1, Clemens Schmitt1, Peter Rammelsberg1
1Department of Prosthodontics, Medical Faculty, Heidelberg University, Heidelberg, Germany.
Objectives:
To evaluate and compare the translucency of 3D-printed zirconia materials: 3Y tetragonal zirconia polycrystal (3Y-TZP) and 5Y partially stabilized zirconia (5Y-PSZ).
Material And Methods:
3D-printed 5Y-PSZ and 3Y-TZP materials fabricated using digital light processing (DLP) were investigated. In addition, three zirconia materials made for the milling approach were examined: one 3Y-TZP and two 5Y-PSZ variants. For translucency measurements, samples with a square base of 100 mm2 and five different thicknesses ranging from 0.25 to 1.25 mm (±50 μm tolerance) were produced (n ≥ 5/subgroup). The L*a*b* color coordinates were measured using an experimental setup consisting of a spectroradiometer, an integrating sphere, and a 35-W tungsten lamp. The translucency parameter was calculated using the color difference between white and black backgrounds. The microstructure and grain size were analyzed using scanning electron microscopy.
Results:
Translucency increased with a decrease in thickness, across all materials. Milled materials exhibited higher translucency than 3D-printed counterparts with equivalent yttria content. The 3D-printed 5Y-PSZ and milled 3Y-TZP materials displayed comparable translucencies. Microstructural analysis revealed discrete microporosities in the 3D-printed materials.
Conclusions:
Despite microstructural differences and defects reducing the translucency of 3D-printed zirconia compared to their milled counterparts, 3D-printed 5Y-PSZ demonstrates sufficient optical properties for monolithic restorations in posterior regions.
