scholarly journals MODERN TECHNOLOGIES FOR THE MANUFACTURE OF GLASS-CERAMIC DENTAL PROSTHESES

2021 ◽  
pp. 80-85
Author(s):  
Oksana Savvova ◽  
Oleksii Fesenko ◽  
Hennadii Voronov ◽  
Emin Salekh Ohly Bairamov
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Crystalline Phase ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Short Exposure ◽  
Chemical Compositions ◽  
Dental Prostheses ◽  
Modern Technologies ◽  
Dental Prosthetics

The relevance of the problem of improving the quality of life and protecting human health in the context of the successful development of the modern society was presented. A literary review of well-known modern technologies for the design and manufacture of dental prostheses was carried out, as well as the leading domestic and foreign companies that were engaged in this were given. The history of the development of materials for obtaining clinical restorations (crowns, inlays, onlays, etc.) was considered and the main directions of the development of innovative ceramic materials for dental prosthetics were outlined. Based on the analysis of the properties of various types of materials for dental prosthetics, the prospects of using glass-ceramic materials in the development of dental prostheses have been substantiated. The chemical compositions of lithium silicate glasses for the synthesis of the glass matrix have been developed and the technological parameters for the production of glass-ceramic dental prostheses have been selected (Тgl. melting = 1350–1400 °С, Тheat treatment = 600–650 °С). Preliminary heat treatment before the formation of products ensures the formation of the required number of the nucleus of crystalline phase and the prerequisites for creating a volume crystallized structure under conditions of short-term heat treatment. The glass-ceramic prosthesis with a formed interpenetrating sitallized structure was obtained by the method of hot pressing with a short exposure (18-20 min). It was found that the obtained glass-ceramic material containing lithium disilicate as a crystalline phase in an amount of 40-60 vol. %, had high values of bending strength (σ = 400 MPa) and fracture toughness. The indicated mechanical properties of the developed materials, along with the approximate values of their modulus of elasticity to natural teeth, will significantly extend the service life of products under conditions of significant alternating loads that arise during the chewing cycle. A comparative assessment of the competitiveness of the developed dental prostheses based on lithium disilicate with world analogues was carried out, in particular the products of Ivoclar Vivadent and Vita Zahnfabrik, in terms of the main operational parameters. The positive effect of the introduction of domestic developed glass-ceramic dental prostheses to reduce import dependence has been determined.

scholarly journals Solid Solutions Formation Mechanism in Cordierite-Mullite Glass Materials During Ceramization

2020 ◽  
Vol 14 (4) ◽  
pp. 583-589
Author(s):  
Оksana Savvova ◽  
◽  
Hennadiy Voronov ◽  
Оlena Babich ◽  
Oleksii Fesenko ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Formation Mechanism ◽  
Glass Ceramic ◽  
High Strength ◽  
Ceramic Materials ◽  
Ceramic Coatings ◽  
Resource Saving ◽  
Aluminosilicate Glasses ◽  
Glass Ceramic Materials ◽  
Fine Crystalline Structure

Relevance of the development of high-strength glass-ceramic coatings obtained by resource-saving technology for protective elements has been established. Structure formation mechanism in magnesium aluminosilicate glasses during heat treatment has been analyzed. Selection of the system was substantiated, model glasses and glass-ceramic materials on its base have been developed. Patterns of structure regularity and formation of the phase composition of glass-ceramic materials during their ceramization have been investigated. It was established that the presence of crystalline phase of mullite after melting leads to formation of the primary crystals and allows the formation of the fine crystalline structure under conditions of the low-temperature heat treatment at the nucleation stage. Developed high-strength glass ceramic materials can be used as a base in creating protective elements for special-purpose vehicles by energy-saving technology.

scholarly journals Energy Transfer Study on Tb3+/Eu3+ Co-Activated Sol-Gel Glass-Ceramic Materials Containing MF3 (M = Y, La) Nanocrystals for NUV Optoelectronic Devices

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2522 ◽  
Author(s):  
Natalia Pawlik ◽  
Barbara Szpikowska-Sroka ◽  
Wojciech A. Pisarski
Keyword(s):  
Heat Treatment ◽  
Energy Transfer ◽  
Glass Ceramic ◽  
Sol Gel ◽  
Optoelectronic Devices ◽  
Emission Spectra ◽  
Ceramic Materials ◽  
Near Ultraviolet ◽  
Glass Ceramic Materials ◽  
Significant Prolongation

In the present work, the Tb3+/Eu3+ co-activated sol-gel glass-ceramic materials (GCs) containing MF3 (M = Y, La) nanocrystals were fabricated during controlled heat-treatment of silicate xerogels at 350 °C. The studies of Tb3+ → Eu3+ energy transfer process (ET) were performed by excitation and emission spectra along with luminescence decay analysis. The co-activated xerogels and GCs exhibit multicolor emission originated from 4fn–4fn optical transitions of Tb3+ (5D4 → 7FJ, J = 6–3) as well as Eu3+ ions (5D0 → 7FJ, J = 0–4). Based on recorded decay curves, it was found that there is a significant prolongation in luminescence lifetimes of the 5D4 (Tb3+) and the 5D0 (Eu3+) levels after the controlled heat-treatment of xerogels. Moreover, for both types of prepared GCs, an increase in ET efficiency was also observed (from ηET ≈ 16% for xerogels up to ηET = 37.3% for SiO2-YF3 GCs and ηET = 60.8% for SiO2-LaF3 GCs). The changes in photoluminescence behavior of rare-earth (RE3+) dopants clearly evidenced their partial segregation inside low-phonon energy fluoride environment. The obtained results suggest that prepared SiO2-MF3:Tb3+, Eu3+ GC materials could be considered for use as optical elements in RGB-lighting optoelectronic devices operating under near-ultraviolet (NUV) excitation.

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 Microstructural development during heat treatment of a commercially available dental-grade lithium disilicate glass-ceramic

2019 ◽  
Vol 35 (5) ◽  
pp. 697-708 ◽  
Author(s):  
Angel L. Ortiz ◽  
Oscar Borrero-López ◽  
Fernando Guiberteau ◽  
Yu Zhang
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Lithium Disilicate ◽  
Microstructural Development

scholarly journals Glass-Ceramic Materials on the Lithium Disilicate Basis: Achievements and Development Prospects

2018 ◽  
Vol 12 (3) ◽  
pp. 391-399 ◽  
Author(s):  
Оksana Savvova ◽  
◽  
Gennadii Voronov ◽  
Vitalii Topchyi ◽  
Yuliya Smyrnova ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Glass Ceramic Materials ◽  
Development Prospects

scholarly journals Investigation of the thermal properties of mullite-cordierite materials

2018 ◽  
Vol 118 ◽  
pp. 111-118
Author(s):  
О. V. Savvova ◽  
O. I. Fesenko ◽  
V. D. Timofeеv ◽  
Ya. V. Poviderna
Keyword(s):  
Heat Treatment ◽  
Thermal Properties ◽  
Fire Resistance ◽  
Glass Ceramic ◽  
Linear Expansion ◽  
High Strength ◽  
Ceramic Materials ◽  
Glass Ceramic Materials ◽  
Cordierite Glass ◽  
Coefficient Of Linear Expansion

Based on the analysis of existing mullite-cordierite sitalls, the need to create high-strength materials of this type for individual and local protection against high-speed loads has been determined. They should be characterized by lower cost, due to low-temperature short-term heat treatment using domestic raw materials. An important aspect of ensuring the effective protective effect of an armor-element, in addition to its armor resistance and survivability, is the ability to withstand the effects of open flame and combustible mixtures, which is determined by the thermal properties of the sitalls. The aim of this work is to study the thermal properties, namely thermal expansion coefficient and fire resistance, high strength mullite-cordierite glass-ceramics that they are developed by us earlier. The temperature coefficient of linear expansion was determined using a quartz vertical dilatometer QVD-5A (ASTM C 372-94 (2007)), fire resistance according to GOST 33000—2014. According to X-ray diffraction and differential thermal analyzes, the experimental samples were divided into two groups according to the formation mechanism of structure and phase composition of glass materials during heat treatment. For each of the materials groups, the influence of the chemical and phase compositions on the thermal coefficient of linear expansion of the original mullite-cordierite glass materials and glass-ceramic materials (sitalls) thermally treated using two-stage heat treatment was determined. The study of the fire resistance of the developed glass-ceramic materials made it possible to establish that they withstand the thermal load in a certain mode for 360 minutes. It has been established that providing high thermal- and fire resistance (RE 360 (h)) is a determining factor in the production of hardened glass crystalline materials that are able to resist to thermal destroying at sharp temperature change.

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