scholarly journals Optical and Mechanical Properties of Highly Translucent Dental Zirconia

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3395
Author(s):  
Hee-Kyung Kim
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Fluorescence Emission ◽  
Glass Ceramics ◽  
Secondary Phase ◽  
Lithium Disilicate ◽  
Sintering Behavior ◽  
Chemical Compositions ◽  
Strong Impact ◽  
Dental Ceramics

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

Crystal Phase Formation and Mechanical Properties of Lithium Disilicate Glass-Ceramics for Dental Restoration

2010 ◽  
Vol 177 ◽  
pp. 447-450 ◽  
Author(s):  
Xin Zhang ◽  
Yi Wen Hu ◽  
Yin Wu ◽  
Wen Jie Si
Keyword(s):  
Mechanical Properties ◽  
Phase Formation ◽  
Glass Ceramics ◽  
High Strength ◽  
Lithium Disilicate ◽  
Sem Analysis ◽  
Dental Restoration ◽  
Bending Test ◽  
Crystal Phase ◽  
High Temperature Xrd

The purpose of this study was to evaluate the crystal phase formation behavior and its influence on the mechanical properties of LiO2-SiO2-P2O5 glass-ceramics system. High temperature XRD was used to analyze the crystal phase formation in situ. The crystalline phases in the material both before and after heat-treatment were also analyzed. The flexural strength was measured by three-point bending test according to ISO 6872:2008(E). The SEM analysis showed that the high strength of the glass-ceramics is attributed to the continuous interlocking microstructure with fine lithium disilicate crystallines.

scholarly journals Sintering Behavior and Mechanical Properties of Mullite Fibers/Hydroxyapatite Ceramic

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1859 ◽  
Author(s):  
Xueni Zhao ◽  
Qingyao Liu ◽  
Jianjun Yang ◽  
Weigang Zhang ◽  
Yao Wang
Keyword(s):  
Mechanical Properties ◽  
Hydrothermal Synthesis ◽  
Bending Strength ◽  
Fiber Content ◽  
Silicate Glasses ◽  
Sintering Behavior ◽  
Composite Powders ◽  
Hydroxyapatite Ceramic ◽  
Dense Microstructure ◽  
Mullite Fibers

The effect of fiber content and sintering temperature on sintering behavior and mechanical properties of mullite fibers/hydroxyapatite composites was studied. The composites were fabricated by hydrothermal synthesis and pressureless sintering. The amount of fibers was varied from 5 wt % to 15 wt % through hydrothermal synthesis, mullite fibers and hydroxyapatite composite powders were subsequently sintered at temperatures of 1150, 1250, and 1350 °C. The composites presented a more perturbed structure by increasing fiber content. Moreover, the composites experienced pore coalescence and exhibited a dense microstructure at elevated temperature. X-ray diffraction indicated that the composites underwent various chemical reactions and generated silicate glasses. The generation of silicate glasses increased the driving force of particle rearrangement and decreased the number of pores, which promoted densification of the composites. Densification typically leads to increased hardness and bending strength. The study proposes a densification mechanism and opens new insights into the sintering properties of these materials.

Effect of Processing Parameters on the Properties of Glass–Ceramics from Arc-Melting Slag of Incineration Fly Ash

2011 ◽  
Vol 399-401 ◽  
pp. 864-868
Author(s):  
Han Qiao Liu ◽  
Guo Xia Wei ◽  
Yin Liang ◽  
Jun Lan Yang
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Milling Time ◽  
Bending Strength ◽  
Compaction Pressure ◽  
Glass Ceramics ◽  
Physical And Mechanical Properties ◽  
Processing Parameters ◽  
Arc Melting ◽  
Melting Slag

The glass-ceramics were made of arc-melting slag from incinerator fly ash mixed with glass cullet additive by sintering method. The effects of ball milling time and powder compaction pressure on the microstructure, physical and mechanical properties of the glass–ceramics were respectively investigated. Results showed that with milling time delaying, granularity of the parent glass evidently reduces, the major phases of glass–ceramics have no change but the diffraction peaks present intensive trend, the crystal sizes of glass–ceramics decrease, the properties such as volumetric densities, compressive strength, bending strength and toughness are improved, the appropriate milling time is 6h with fifty percent of the volume (d50 value) of 10.62μm. The physical and mechanical properties first increase and then decrease with compaction pressure increasing, and the optimal compaction pressure is 60MPa.

Effects of crystal refining on wear behaviors and mechanical properties of lithium disilicate glass-ceramics

2018 ◽  
Vol 81 ◽  
pp. 52-60 ◽  
Author(s):  
Zhenzhen Zhang ◽  
Jiawen Guo ◽  
Yali Sun ◽  
Beimin Tian ◽  
Xiaojuan Zheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Ceramics ◽  
Lithium Disilicate

scholarly journals Surface Treatments for Repair of Feldspathic, Leucite - and Lithium Disilicate-Reinforced Glass Ceramics Using Composite Resin

2015 ◽  
Vol 26 (2) ◽  
pp. 152-155 ◽  
Author(s):  
Christian Alencar Neis ◽  
Nadine Luísa Guimarães Albuquerque ◽  
Ivo de Souza Albuquerque ◽  
Erica Alves Gomes ◽  
Celso Bernardo de Souza-Filho ◽  
...  
Keyword(s):  
Bond Strength ◽  
Hydrofluoric Acid ◽  
Composite Resin ◽  
Glass Ceramics ◽  
Silica Coating ◽  
Lithium Disilicate ◽  
Surface Treatments ◽  
Dental Ceramics ◽  
Microtensile Bond Strength ◽  
Diamond Bur

The aim of this study was to evaluate the efficacy of different surface conditioning methods on the microtensile bond strength of a restorative composite repair in three types of dental ceramics: lithium disilicate-reinforced, leucite-reinforced and feldspathic. Twelve blocks were sintered for each type of ceramic (n=3) and stored for 3 months in distilled water at 37 °C. The bonding surface of ceramics was abraded with 600-grit SiC paper. Surface treatments for each ceramic were: GC (control) - none; GDB - diamond bur #30 µm; GHF - hydrofluoric acid (10%); GT- tribochemical silica coating (45-μm size particles). Treatments were followed by cleaning with phosphoric acid 37% for 20 s + silane + adhesive. The composite resin was used as restorative material. After repair, samples were subjected to thermocycled ageing (10,000 cycles between 5 °C and 55 °C for 30 s). Thereafter, the samples were sectioned into 1.0 mm2 sticks and tested for microtensile bond strength with 0.5 mm/min crosshead speed. Data were compared by two-way ANOVA and Tukey's test (α=0.05). The superficial wear with diamond bur proved to be suitable for feldspathic porcelain and for leucite-reinforced glass ceramic while hydrofluoric acid-etching is indicated for repairs in lithium disilicate-reinforced ceramic; tribochemical silica coating is applicable to leucite-reinforced ceramic. Predominance of adhesive failures was observed (>85% in all groups). In conclusion, the success of surface treatments depends on the type of ceramic to be repaired.

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