Assessment of final shade and translucency of two monolithic zirconia versus veneered zirconia on a dark substrate. An Invitro study

Abstract

Abstract Objectives: The aim of this study was to assess the final shade and translucency of two monolithic zirconia versus veneered zirconia on a dark substrate. Materials and methods: 15 square shaped A2 zirconia specimens were cut using cutting machine (Isomet; Buehler Ltda.). Specimens were divided into 3 groups according to the type of zirconia (5 mol %, 3 mol% Y-TZP zirconia and veneered zirconia) their CIE L*, a* and b* values were measured using a spectrophotometer to determine the translucency parameter (TP). Then 15 composite discs (C3) (ArtisteTM, Pentron, USA) were fabricated. Zirconia specimens were placed on the composite background then CIE L*, a* and b* values were measured and color difference ∆E value was calculated. To determine the masking ability, perceptibility threshold was assumed as ∆E = 3.7. Results: There was a statistically significant difference between mean TP values and mean ΔE values in the three groups where Cubic Zirconia showed statistically significant highest mean TP (10.97) and ΔE (9.04), Tetragonal Zirconia showed statistically significant lower mean TP (8.7) and ΔE (7.06) and Veneered Zirconia showed statistically significant lowest mean TP (7.72) and ΔE (6.26). Conclusions: Masking ability and translucency was affected by the type of the zirconia used due to difference in their composition. Neither the two monolithic zirconia nor the veneered one were able to mask the color of the underlying substrate. Increasing the yttria content to 5mol% increased the content of nonbirefringent cubic phase which was found to increase the translucency parameter of the zirconia.