scholarly journals Microstructure and properties of two glass-ceramics: a lithium disilicate glass-ceramic nucleated by P2O5 and an apatite glass-ceramic

1999 ◽  
Vol 10 (0) ◽  
pp. 628-633
Author(s):  
W. Hoeland ◽  
M. Schweiger ◽  
M. Frank ◽  
V. Rheinberger
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Microstructure And Properties

scholarly journals Effect of Nd:YAG Laser with/without Graphite Coating on Bonding of Lithium Disilicate Glass-Ceramic to Human Dentin

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Amjad Abu Hasna ◽  
Stephanie Semmelmann ◽  
Fernanda Alves Feitosa ◽  
Danilo De Souza Andrade ◽  
Franklin R Tay ◽  
...  
Keyword(s):  
Bond Strength ◽  
Glass Ceramic ◽  
Nd:Yag Laser ◽  
Testing Machine ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Resin Cement ◽  
Cylindrical Shape ◽  
Universal Testing ◽  
Human Dentin

This study evaluated the effect of different surface treatments on the tensile bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. Fifty truncated cone-shape glass-ceramics were divided into five groups (n = 10): G1, control: 10% hydrofluoric acid (HF); G2, Nd:YAG laser + silane; G3, Sil + Nd:YAG laser; G4, graphite + Nd:YAG laser + Sil; and G5, graphite + Sil + Nd:YAG laser. Fifty human third-molars were cut to cylindrical shape and polished to standardize the bonding surfaces. The glass-ceramic specimens were bonded to dentin with a dual-cured resin cement and stored in distilled water for 24 h at 37ºC. Tensile testing was performed on a universal testing machine (10 Kgf load cell at 1 mm/min) until failure. The bond strength values (mean ± SD) in MPa were G1 (9.4 ± 2.3), G2 (9.7 ± 2.0), G3 (6.7 ± 1.9), G4 (4.6 ± 1.1), and G5 (1.2 ± 0.3). Nd:YAG laser and HF improve the bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. The application of a graphite layer prior to Nd:YAG laser irradiation negatively affects this bonding and presented inferior results.

scholarly journals Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 381 ◽  
Author(s):  
Roxana-Diana Vasiliu ◽  
Sorin Daniel Porojan ◽  
Mihaela Ionela Bîrdeanu ◽  
Liliana Porojan
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Surface Treatments ◽  
Lithium Silicate ◽  
Before And After ◽  
Cad Cam

Dental ceramic restorations are widely spread nowadays due to their aesthetics and biocompatibility. In time, the colour and structure of these ceramic materials can be altered by aging processes. How does artificial aging affect the optical and surface roughness of ceramics? This study aims to assess the effect of thermocycling, surface treatments and microstructure upon translucency, opalescence and surface roughness on CAD-CAM and heat-pressed glass-ceramic. Forty-eight samples (1.5 mm thickness) were fabricated from six types of A2 MT ceramic: heat-pressed and milled glass-ceramic (feldspathic, lithium disilicate and zirconia reinforced lithium silicate). The samples were obtained respecting the manufacturer’s instructions. The resulted surfaces (n = 96) were half glazed and half polished. The samples were subjected to thermocycling (10,000 cycles) and roughness values (Ra and Rz), colour coordinates (L*, a*, b*) and microstructural analyses were assessed before and after thermocycling. Translucency (TP) and opalescence (OP) were calculated. Values were statistically analysed using ANOVA test (one way). TP and OP values were significantly different between heat-pressed and milled ceramics before and also after thermocycling (p < 0.001). Surface treatments (glazing and polishing) had a significant effect on TP and OP and surface roughness (p < 0.05). The heat-pressed and milled zirconia reinforced lithium silicate glass-ceramic experienced a loss in TP and OP. Ra and Rz increased for the glazed samples, TP and OP decreased for all the samples after thermocycling. Microstructural analyse revealed that glazed surfaces were more affected by the thermocycling and especially for the zirconia reinforced lithium silicate ceramic. Optical properties and surface roughness of the chosen ceramic materials were affected by thermocycling, surface treatments and microstructural differences. The least affected of the ceramics was the lithium disilicate ceramic heat-pressed polished and glazed.

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 The Effect of Different Surface Treatment Protocols on the Shear Bond Strength to Repressed Lithium Disilicate Glass Ceramics

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Amr El-Etreby ◽  
Osama AlShanti ◽  
Gihan El-Nagar
Keyword(s):  
Bond Strength ◽  
Surface Treatment ◽  
Glass Ceramic ◽  
Hydrofluoric Acid ◽  
Shear Bond Strength ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Resin Cement ◽  
Treatment Protocols ◽  
X Ray

Objective: The present study aimed to evaluate the effect of repressing and different surface treatment protocols on the shear bond strength of lithium disilicate glass-ceramics. Material and Methods: A total of 52 lithium disilicate glass-ceramic discs (IPS emax Press, Ivoclar Vivadent) were fabricated using the heat-press technique. The discs were divided into two groups; group (P): discs fabricated from new e.max ingots (n=26), group (R): discs fabricated from reused e.max buttons (n=26). Each group was subdivided into subgroup (E): discs were etched with hydrofluoric acid (9.5%) (n=13), subgroup (S): discs were air-abraded with 110 µm alumina particles. All specimens were subjected to X-ray Diffraction analysis, Scanning Electron Microscope, Energy Dispersive X-Ray, Thermo-Cycling, and Shear Bond Strength Testing. Results: Repressed Etched subgroup (RE) recorded the statistically highest shear bond strength value, followed by the Pressed Etched subgroup (PE), while the statistically lowest shear bond strength value was recorded for the Pressed Air-Abraded subgroup (PS) and Repressed Air-Abraded subgroup (RS). Conclusion: Repressing the leftover buttons for the construction of new lithium disilicate glass-ceramic restorations has no adverse effect on the bond strength of the resin cement to the ceramic. Hydrofluoric acid surface treatment improves the shear bond strength and durability of resin cement bond to both pressed and repressed lithium disilicate glass-ceramic. Air-abrasion cannot be considered as a reliable surface treatment when bonding to lithium disilicate glass-ceramics. Keywords Heat pressed; Lithium disilicate glass-ceramics; Repressing; Shear bond strength; Surface treatment.

scholarly journals Novel Glass-Ceramics for Dental Restorations

2011 ◽  
Vol 12 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Sarah Pollington
Keyword(s):  
Clinical Significance ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Review Article ◽  
Conservative Approach ◽  
Tooth Structure ◽  
Microstructure And Properties ◽  
Dental Restorations ◽  
Sufficient Strength

ABSTRACT Background There are many different ceramic systems available on the market for dental restorations. Glass-ceramics are a popular choice due to their excellent esthetics and ability to bond to tooth structure allowing a more conservative approach. However, at present, these materials have insufficient strength to be used reliably in posterior regions of the mouth. Purpose The aim of this review article is to discuss the types of novel glass-ceramic currently be investigated including composition, microstructure and properties. Conclusion Current research in glass-ceramics focuses on the quest for a highly esthetic material along with sufficient strength to enable crowns and bridgework to be reliably placed in these areas. Clinical significance There is a gap in the market for a machinable resin bonded glass-ceramic with sufficient strength as well as excellent esthetics. How to cite this article Pollington S. Novel Glass-Ceramics for Dental Restorations. J Contemp Dent Pract 2011;12(1): 60-67.

scholarly journals Innovative directions of development of ceramic materials for dentistry

2021 ◽  
pp. 19-25
Author(s):  
O.V. Savvova ◽  
G.K. Voronov ◽  
O.I. Fesenko ◽  
Yu.O. Smirnova ◽  
E. Bairamov
Keyword(s):  
High Temperature ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Oxide Glass ◽  
Lithium Silicate ◽  
Silicate System ◽  
Advantages And Disadvantages ◽  
Glass Ceramic Materials

The need to improve the level of dental health of the population of Ukraine was identified. The prospects for the use of ceramic prostheses to provide quality medical care in dentistry have been established. An analytical review of various types of ceramic and glass-ceramic materials used as dental prostheses for tooth replacement: porcelain, alumina, zirconium oxide, glass-ceramics based on leucite and lithium disilicate and mica with the addition of fluorides. Peculiarities of the structure and operational properties of ceramic and glass-ceramic materials for dentistry have been identified, their advantages and disadvantages have been established. The effectiveness of the use of glass-ceramic materials based on lithium disilicate for dental prosthetics is substantiated. The basic lithium silicate system was selected and glasses for obtaining glass-ceramic crowns based on lithium disilicate by the method of high-temperature pressing and calcium phosphate-silicate system for obtaining glass-ceramic coatings were synthesized. The methodological approach to the development of glass-ceramic prostheses based on lithium disilicate is determined. The limits of the compositions of oxide components are determined and raw materials for the synthesis of the glass matrix are selected. The technological parameters of melting (T = 1350 – 1400ºС) and heat treatment with simultaneous formation of products (stage of nucleation T = 600 – 650ºС, τ = 30 – 60 min; stages of formation T = 900ºС, τ ≈ 20 min) are selected. The composition of fluoroapatite glass-ceramic coating for glazing of glass-ceramics and the mode of its firing (T = 800 – 850ºС, τ ≈ 1,0 – 1,5 min) were determined. The serviceability of the developed glass-ceramic samples DL st.glass, which were obtained by the technology of high-temperature pressing, are determined. The comparative analysis of glass-ceramic prostheses for dentistry allowed to establish that the operational properties of the developed glass-ceramic prostheses according to ISO 6872:2015 are at the level of world analogues. This will allow them to successfully compete in the Ukrainian market with well-known foreign counterparts and help ensure the social priorities of the state in the field of health care.

Effect of Heat-Pressing on the Microstructure and Properties of a Novel Lithium Disilicate Glass-Ceramic

2010 ◽  
Vol 177 ◽  
pp. 441-446 ◽  
Author(s):  
Jing Gao ◽  
Ji Hua Chen ◽  
Fu Wang ◽  
Zai Xi Deng ◽  
Feng Li ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Lithium Disilicate ◽  
The Novel ◽  
X Ray Diffraction ◽  
Promising Candidate ◽  
Microstructure And Properties ◽  
Heat Treated ◽  
All Ceramic ◽  
Before And After ◽  
P2o5 System

The purpose of this study was to investigate the effects of heat pressing on the microstructure and properties of a novel lithium disilicate glass-ceramic located in Li2O-SiO2-K2O-Al2O3-ZrO2-P2O5 system. Before and after respective heat pressing, the crystalline phase composition and microstructures were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Three-point flexural strength of glass-ceramic specimens was measured following the instruction of ISO 6872. The results showed that the bonding strength of the heat-pressed specimens was higher than that of the heat- treated controls. XRD examination showed the main crystallization in specimens after heat pressing was lithium disilicate as controls. SEM examination indicated crysta1s were aligned along the direction of pressing, and while in control groups crystals randomly interlocked. Dental heat pressing procedure leads to an anisotropic structure in lithium disilicate glass-ceramic, which is a useful method to improve the mechanical property. With the results under the present conditions, the novel lithium disilicate glass-ceramic may be considered as a promising candidate material for dental all-ceramic application.

Factors Affecting the Wear Behavior of Monolithic Zirconia and the Antagonists: Literature Review

2020 ◽  
Vol 2 (1) ◽  
pp. 4-11
Author(s):  
Marcia Borba ◽  
Paula Benetti ◽  
Giordana P. Furini ◽  
Kátia R. Weber ◽  
Tábata M. da Silva
Keyword(s):  
Literature Review ◽  
Glass Ceramic ◽  
Wear Behavior ◽  
Glass Ceramics ◽  
Surface Treatments ◽  
Human Tooth ◽  
Initial Surface ◽  
Monolithic Zirconia ◽  
Feldspathic Porcelain

Background: The use of zirconia-based ceramics to produce monolithic restorations has increased due to improvements in the optical properties of the materials. Traditionally, zirconiabased ceramics were veneered with porcelain or glass-ceramic and were not directly exposed to the oral environment. Therefore, there are several doubts regarding the wear of the monolithic zirconia restoration and their antagonists. Additionally, different surface treatments are recommended to promote a smooth surface, including glaze and several polishing protocols. To support the correct clinical application, it is important to understand the advantages and limitations of each surface treatment. Objective: The aim of this short literature review is to investigate the factors that may affect the wear of monolithic zirconia restorations in service and their antagonists. Methods: Pubmed/Medline database was accessed to review the literature from a 10-year period using the keywords: zirconia, monolithic, prosthesis, wear. Both clinical and in vitro studies were included in the review. Results: Studies investigated the effect of several surface treatments, including grinding with diamond- burs, polishing and glazing, on the surface roughness, phase transformation and wear capacity of monolithic zirconia. The wear behavior of monolithic zirconia was frequently compared to the wear behavior of other ceramics, such as feldspathic porcelain, lithium disilicate-based glassceramic and leucite-reinforced glass-ceramic. Human tooth, ceramics and resin composites were used as antagonist in the investigations. Only short-term clinical studies are available (up to 2 years). Conclusion: Literature findings suggest that zirconia monolithic restorations are wear resistant and unlikely to cause excessive wear to the antagonist, especially when compared to feldspathic porcelain and glass-ceramics. Monolithic zirconia should be polished rather than glazed. Yet, none of the polishing systems studied was able to completely restore the initial surface conditions of zirconia after being adjusted with burs. More clinical evidence of the antagonist tooth wear potential of monolithic zirconia is needed.

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