Dental zirconia generations: a comparative study of translucency parameters and light transmittance across varying thicknesses

Abstract

Objective: This in vitro study evaluated the translucency and polymerization light transmission of zirconia discs, produced from different generations of dental zirconia materials and with a consideration of varying thicknesses. Material and Methods: Disc-shaped specimens (0.5mm, 1.0mm, 1.5mm, 2.0mm, and 3.0mm) were produced from three A1 pre-shaded monochrome zirconia generations: conventional (3Y-TZP (inCoris TZI C); high translucency 4Y-PSZ (Cercon HT) and super translucent 5Y- PSZ (Cercon XT). A total of 90 discs were prepared. Translucency measurements were conducted using an intraoral spectrophotometer on each specimen against white and black backgrounds. Polymerization light transmission was assessed by measuring the transmitted light through each specimen emitted from confirmed emission spectra light-polymerizing units using a digital optical power meter. Two-way ANOVA tests (alpha = 0.05) were utilized to evaluate the differences between the influences of the zirconia generation and thickness parameters. Results: Different zirconia generations and thicknesses displayed distinct TP and transmittance values, with 5Y-PSZ exhibiting the highest values, which decreased as thickness increased. A significant interaction was found between zirconia generation and thickness on TP and transmittance (p - < 0.001), with more pronounced differences at lower thicknesses and non-significant differences at 3mm thickness. Conclusion: The study demonstrates that the generations and thickness of zirconia, and their interactions, significantly impact light transmission and TP values. Extra translucent cubic zirconia (5Y-PSZ) exhibits the highest TP, making it a more preferable choice for achieving predictable aesthetic outcomes that mimic teeth translucency and high polymerization light transmittance, ensuring adequate photopolymerization of the underlying resin luting cement.

KEYWORDS

Ceramics; Polymerization; Translucency; Transmittance; Zirconia.