SPECTROPHOTOMETRIC ANALYSIS AND FRACTURE RESISTANCE OF SUPER AND ULTRA TRANSLUCENCY ZIRCONIA VERSUS LITHIUM DISILICAET GLASS CERAMICS

2017 ◽  
Vol 63 (2) ◽  
pp. 1647-1652
Author(s):  
Sara Telyani ◽  
Esam Osman ◽  
Mohammad Rayyan ◽  
Ehab Farghaly ◽  
Ghada Hamza
Keyword(s):  
Fracture Resistance ◽  
Glass Ceramics ◽  
Spectrophotometric Analysis

scholarly journals SPECTROPHOTOMETRIC ANALYSIS AND FRACTURE RESISTANCE OF SUPER AND ULTRA TRANSLUCENCY ZIRCONIA VERSUS LITHIUM DISILICAET GLASS CERAMICS

2018 ◽  
Vol 64 (2) ◽  
pp. 1647-1652
Author(s):  
Sara Telyani ◽  
Esam Osman ◽  
Mohammad Rayyan ◽  
Ehab Farghaly ◽  
Ghada Hamza
Keyword(s):  
Fracture Resistance ◽  
Glass Ceramics ◽  
Spectrophotometric Analysis

scholarly journals Effect of Thermo-Mechanical Aging and Repressing on Fracture Resistance of Lithium Disilicate Crowns

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Amr El-Etreby ◽  
Mahmoud Metwally ◽  
Gihan EL-Nagar
Keyword(s):  
Glass Ceramic ◽  
Fracture Resistance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Mean Value ◽  
Resistance Testing ◽  
Novel Approach ◽  
Significant Difference ◽  
Keywords Fracture ◽  
Mechanical Aging

Objective: The recycling of heat pressed lithium disilicate glass-ceramic leftover material has been reported to be done by dental laboratories. The effect of this procedure on the fracture resistance of single crowns is unknown, especially when it is functioning inside the oral cavity with subsequent exposure to temperature changes and cycles of mastication. Material and Methods: A total of 28 lithium disilicate glass-ceramic crowns (IPS emax Press) were constructed and randomly assigned into two groups (n = 14); Group (P): Included crowns fabricated from new e.max ingots. Group (R): Included crowns fabricated from repressed e.max buttons. Specimens of each group were divided into two equal subgroups (n = 7) according to whether the aging of specimens will be performed or not before fracture resistance testing. Subgroup (N), samples were subjected to fracture resistance without thermo-mechanical aging, while subgroup (A), samples were subjected to thermo-cycling and cyclic loading before being subjected to fracture strength testing. Different methods; SEM, XRD, EDAX were used to characterize the properties of lithium disilicate glass-ceramics before and after repressing. Results: The highest statistically significant fracture resistance value was recorded for the subgroup (RN) repressed/non-aged, followed by the subgroup repressed/aged (RA), while the lowest statistically significant mean value was recorded for the subgroup pressed/aged (PA). There was no significant difference between pressed/non-aged (PN) and repressed/aged (RA) subgroups. Conclusion: Repressing of leftover buttons may increase the fracture resistance of IPS emax Press crowns. Thermo-mechanical aging may negatively affect the fracture resistance of IPS emax Press crowns, yet Repressing may decrease this effect. Clinical implications: This is a novel approach that targets a point of research that has not been investigated before. It elaborates how repressing may decrease the effect of aging and increase the fracture resistance of lithium disilicate crowns. Thus, recycling of lithium disilicate glass ceramics might decrease its failure and prolong their serviceability.   Keywords Fracture resistance; Heat pressed; Lithium disilicate; Recycling; Repressing; Thermo-mechanical aging.

scholarly journals Fracture behaviors of monolithic lithium disilicate ceramic crowns with different thicknesses

RSC Advances ◽  
2017 ◽  
Vol 7 (41) ◽  
pp. 25542-25548 ◽  
Author(s):  
Tao Yu ◽  
Fu Wang ◽  
Yan Liu ◽  
Tao Wu ◽  
Zaixi Deng ◽  
...  
Keyword(s):  
Fracture Resistance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Fracture Behaviors ◽  
Ceramic Crowns

The present in vitro study assessed the fracture resistance of monolithic ceramic crowns, made from two lithium disilicate glass ceramics with different thicknesses.

scholarly journals Trade-off between fracture resistance and translucency of zirconia and lithium-disilicate glass ceramics for monolithic restorations

2019 ◽  
Vol 91 ◽  
pp. 24-34 ◽  
Author(s):  
Fei Zhang ◽  
Helen Reveron ◽  
Benedikt C. Spies ◽  
Bart Van Meerbeek ◽  
Jérôme Chevalier
Keyword(s):  
Fracture Resistance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Trade Off

scholarly journals UV-Vis spectrophotometric analysis and light irradiance through hot-pressed and hot-pressed-veneered glass ceramics

2008 ◽  
Vol 19 (3) ◽  
pp. 197-203 ◽  
Author(s):  
Myrna Carvalho Dias ◽  
Evandro Piva ◽  
Rafael Ratto de Moraes ◽  
Gláucia Maria Bovi Ambrosano ◽  
Mário Alexandre Coelho Sinhoreti ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Glass Ceramics ◽  
Spectrophotometric Analysis ◽  
Significance Level ◽  
Light Emitting ◽  
The Core ◽  
Quartz Tungsten Halogen ◽  
Intermittent Exposure ◽  
Dunnett's Test ◽  
Intermittent Mode

This study evaluated the irradiance of curing units through core and veneered hot-pressed ceramics as well as the transmittance of these materials. Discs of 0.7, 1.4 and 2 mm in thickness of Empress (EMP) and Empress Esthetic (EST), and 0.8 (n=5) and 1.1 mm (n=5) thickness of Empress 2 (E2) were obtained. For E2, two of the 0.8-mm-thick discs were covered with dentin (1.2- and 1.4-mm-thick) and two with dentin + enamel (1.5-mm-thick). The 1.1-mm-thick specimens were submitted to the same veneering procedures. Specimens were evaluated by UV-Vis transmittance analysis and the percentage of transmittance was recorded. Irradiance through each specimen was evaluated with a quartz-tungsten-halogen (QTH), used in continuous or intermittent exposure modes, or a blue light-emitting diode (LED). Data were analyzed by Dunnett's test, ANOVA and Tukey's test at 5% significance level. Exposure through ceramic decreased the irradiance for all ceramics. Irradiance through EST was significantly higher than through EMP. For E2, reduction in irradiance depended on the core and/or veneer thickness. The QTH intermittent mode showed higher irradiance than the continuous mode, and both showed higher irradiance than LED. The ceramic significantly influenced irradiance and transmittance, which were found to decrease with the increase in thickness.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

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