Effect of Thickness Variation on the Translucency of Two Recent High Translucent Monolithic Zirconia Ceramics

Abstract

Objective of the study. The objective of this study was to evaluate the effect of thickness change on the translucency of two recent monolithic zirconia dental ceramics used at different thicknesses. Materials and methods. A total of 60 disk-shaped specimens were prepared from two high-translucent tetragonal zirconia (Zolid ht+) and ultra-translucent cubic zirconia (Zolid fx), and divided equally into two groups according to material, each group with further subdivided into 3 subgroups according to thickness 0.5, 1, and 1.5 mm (n=10). A spectrophotometer was used to assess the CIE L*, a*, and b* for each thickness of the two zirconia ceramics. The Translucency Parameter (TP) was calculated. 1-way ANOVA and 2-way ANOVA statistical analysis of variance were performed (α=.05). Results. A statistically significant higher mean TP value was recorded with the ultra-translucent cubic zirconia group compared to that of high-translucent tetragonal zirconia regardless of thickness (P=0.008*< 0.05). Thickness had a significant effect on the translucency parameter of the two zirconia ceramics. Within group comparisons showed that for each of the two materials, the 0.5mm thickness recorded the statistically significant highest mean TP value, followed by the 1mm subgroup, whereas the statistically significant lowest mean TP value was recorded for the 1.5mm subgroup. Conclusions. Within the limitations of this study, it was found that material type and thickness had a significant effect on the translucency of high translucent monolithic zirconia.