Optical and Mechanical Properties of Highly Translucent Dental Zirconia

Abstract

The aim was to evaluate the translucency, opalescence, and fluorescence of highly translucent zirconia, lithium disilicate, and bovine teeth. One mm-thick specimens of five monolithic zirconia systems, two glass-ceramics, and bovine enamel/dentin were investigated. A spectrophotometer (Ci7600) was used to measure the CIELab color coordinates, and the translucency and opalescence values were obtained. For evaluating the fluorescence emission, the differences in spectral reflectance by the UV component of illumination were calculated. The microstructures of ceramic specimens were examined with a scanning electron microscope and the chemical compositions were determined with an X-ray fluorescence spectrometer. Mechanical properties were appraised with three-point bending strength, indentation fracture toughness, and Vickers hardness. Data were analyzed using a one-way ANOVA, followed by Tukey’s multiple comparison test (α = 0.05). A higher yttria content (5 mol%) significantly improved the translucency of zirconia ceramics, while they were less translucent than lithium disilicate (p < 0.05). Lowering the alumina content below 0.05 wt.% enhanced the translucency (p < 0.05), but a small amount of alumina was still required to obtain full densification. 0.05 wt.% Fe was used to increase the chroma of zirconia specimens without compromising their mechanical properties. The Er-containing zirconia specimen showed a maximal fluorescence emission at 430 nm. The degree of opalescence was affected by the microstructures of ceramic materials. The microstructure, incorporation of a secondary phase, and sintering behavior can have a strong impact on the final mechanical and optical properties of dental ceramics. Addition of small amounts of metal oxides can affect the translucency, opalescence or fluorescence qualities of zirconia

Comparison of Marginal and Internal Adaptation in Endocrowns Milled from Translucent Zirconia and Zirconium Lithium Silicate

“…The sintering shrinkage of Zr has been reported between 20% and 30%, while ZLS has 0.5% firing shrinkage [ 24 , 37 ]. Also, difference in hardness can affect the machinability in the milling system [ 14 , 15 , 18 , 19 ]. El Ghoul et al indicated that there is an inverse relation between hardness and machinability of a material [ 43 ].…”

“…Zirconia, a nonglass containing polycrystalline ceramic, has drawn lots of attention to itself due to the superb mechanical properties and development of digital dentistry [16][17][18][19]. Special characteristics of zirconia and manufacturing translucent types have made it one of the prime choices for lots of restorations [16].…”

Effect of Al2O3 Sandblasting Particle Size on the Surface Topography and Residual Compressive Stresses of Three Different Dental Zirconia Grades

“…Although zirconia has been considered a promising biomaterial in dentistry, it has some drawbacks for the clinical application of this material. For example, 3Y-TZP has certain optical disadvantages due to its relatively high refractive index, which causes a high grade of light reflection [ 5 ]. The high reflectability leads to a further deterioration in translucency and therefore esthetics.…”

The Effect of Brilliant Blue-Based Plaque-Staining Agents on Aesthetic Orthodontic Appliances

“…Since 2001, for materials with small differences in L*, a* and b*, it is recommended to calculate the ∆E 00 parameter rather than the ∆E* ab parameter, since the former takes into account the corrections regarding a*. However, both ∆E* ab and ∆E 00 parameters have been used to report on the discolouration processes in dental and orthodontic materials [31][32][33][34]. Therefore, the ∆E* ab parameter was determined using the formula [34] ∆E * ab = [(∆L * ) 2 + (∆a * ) 2 + (∆b * ) 2 ] 1/2 (5) where ∆L* indicates changes in value, ∆a* indicates changes in the red-green parameter, and ∆b* indicates changes in the yellow-blue parameter between the materials for which ∆E* ab is calculated.…”