Ceramics and Glass-Ceramics Dental Materials: Chemical Solubility, Cytotoxicity and Mechanical Properties

2018 ◽  
Vol 912 ◽  
pp. 170-174
Author(s):  
Roberto de Oliveira Magnago ◽  
Carlos Eduardo de Lima Abreu ◽  
Ronaldo Reis Silva ◽  
Manuel Fellipe Rodrigues Pais Alves ◽  
Caio Marcelo Felbinger Azevedo Cossu ◽  
...  

In this work three dental ceramics were characterized according to ISO 6872: yttria-stabilized zirconia (ZrO2-Y2O3), lithium disilicate (Li2Si2O5) and the spinel-zirconia composite (MgAl2O4-ZrO2). The zirconia ceramic and the zirconia-spinel composite were sintered at 1600°C-2h, while the lithium disilicate was thermally treated at 820°C-20min. These materials were characterized by relative density, X-ray diffraction, scanning electron microscopy, hardness, fracture toughness, chemical solubility and cytotoxicity. The XRD results showed for the stabilized zirconia only the tetragonal phase of ZrO2, and to the composite only the phase MgAl2O4, Li2Si2O5 was the only phase to lithium disilicate. Relative density results showed that the zirconia and the lithium disilicate showed high densification (> 99.5%) and the composite had a relative density of 75% (10% composite doped with ZrO2) and 90% (50% doped with ZrO2). Hardness and toughness showed 450HV and 3.2MPa.m1/2 to ZrO2-MgAl2O4 composites, 525HV and 1.8MPam1/2 to lithium disilicate and 1280HV and 8.0MPa.m1/2 to zirconia. The materials evaluated showed chemical solubility <30μg/cm2 and the results of cytotoxicity tests indicated cell viability of the samples near 100% for all the materials, showing good chemical stability and potential for dental applications.

2016 ◽  
Vol 881 ◽  
pp. 323-328
Author(s):  
Claudinei dos Santos ◽  
Roberto de Oliveira Magnago ◽  
Fernando Silva Santos ◽  
Samuel Kascher Moraes ◽  
Frederico Paula Ribeiro ◽  
...  

Spinel is a ceramic material of excellent translucence when sintered in high densification, however, its low sinterability and toughness difficulty limit its use as an interesting material for dental applications. The use of stabilized zirconia ZrO2(Y2O3) as Spinel agent is studied in this work. Zirconia contents between 10% and 50% were mixed to Spinel and samples were uniaxially and isostatically pressed. The specimens were sintered at 1575oC with isothermal holding time of 120 minutes. Samples were characterized by X Ray Diffraction (XRD), SEM, relative density, microhardness and fracture toughness. The samples which showed better mechanical performance were the ones with 50% zirconia and sintered at 1575oC, with 90% relative density, hardness of 400HV and KIC of 2.4MPa.m1/2.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Naruporn Monmaturapoj ◽  
Pornchanok Lawita ◽  
Witoon Thepsuwan

This work proposes four different glass formulas derived from the SiO2-Li2O-K2O-Al2O3system to investigate the effect of glass composition on their crystal formations and properties. Glass LD1 was SiO2-Li2O-K2O-Al2O3system with the addition of P2O5and CaF2as nucleating agents. In Glass LD2, a slight amount of MgO was mixed in order to increase the viscosity of the melting glass. Finally, the important factor of Si : Li ratio was increased in Glasses LD3 and LD4 with compositions otherwise the same as LD1 and LD2. The results found that P2O5and CaF2served as a nucleating site for lithium phosphate and fluorapatite to encourage heterogenous nucleation and produce a fine-grained interlocking microstructure of lithium disilicate glass ceramics. MgO content in this system seemed to increase the viscosity of the melting glass and thermal expansion coefficient including the chemical solubility. Increasing the Si : Li ratio in glass compositions resulted in the change of the microstructure of Li2Si2O5crystals.


2014 ◽  
Vol 936 ◽  
pp. 164-169 ◽  
Author(s):  
Jia Bai ◽  
Duangrudee Chaysuwan

The glass system of SiO2-Al2O3-MgO-MgF2-SrCO3-CaCO3-CaF2-P2O5 was used to prepare machinable glass-ceramics for restorative dental applications. The aim of this study was to apply various heat treatments to produce mica-based glass-ceramics. Differential Thermal Analysis (DTA) was used to determine the optimal heat treatment conditions for nucleation and growth of the crystalline phases in the quenched glass. It was found that the optimum nucleation temperatures for the first and the second crystallization temperatures (Tp1 and Tp2) were 642°C and 635°C, respectively, and the optimum nucleation times were between 2 and 4 hours. X-Ray Diffraction (XRD) showed the phases developed were anorthite, calcium-mica, fluorapatite, strontium apatite, forsterite, fluorite and stishovite phases. The microstructures of glass-ceramics were observed by Scanning electron microscope (SEM), found to exhibit plate-like mica crystals with high interlocking and randomly oriented with a higher soaking temperature and prolongation of the soaking time for crystallization.


2008 ◽  
Vol 368-372 ◽  
pp. 1261-1263
Author(s):  
Hua Wei He ◽  
Bo Li ◽  
Guang Da Li ◽  
Zhi Xiu He ◽  
Zhi Qing Chen

This study sought to compare the biocompatibility of four dental ceramics so as to provide indications useful for the further development of dental materials. Osteoblasts were obtained by culturing the cranial explant of SD rat and cultured in vitro when they were seeded onto four different materials: hydroxyapatite, bioactive glass ceramics, tricalciumphosphate-hydroxyapatite and nano-hydroxyapatite (nHA). The phase contrast microscope and scanning electron microscope were used to evaluate the cell morphology and attachment. The content of alkaline phosphatase was calculated by molecular biological methods. MTT method was performed to find the alteration of proliferation. Then by use of wash way method, the adhesion ability was tested. The results showed that all of the four bioceramics had good cytocompatibility. There were significant differences among them on the levels of cell growth, differation and adhesion in vitro. The biocompatibility of nHA is the best and of conventional HA is the worst.


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 ◽  
...  

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.


2016 ◽  
Vol 702 ◽  
pp. 23-27 ◽  
Author(s):  
Thapanee Srichumpong ◽  
Kallaya Suputtamongkol ◽  
Warat Chinpanuwat ◽  
Pronbadin Nampachoke ◽  
Jia Bai ◽  
...  

The objective of this research is to focus improving the properties of machinable mica-based glass-ceramics in order for restorative dental materials. The glass-ceramics derived from the SiO2- Al2O3-MgO-MgF2-SrCO3-CaCO3-CaF2-P2O5 system were produced by a two-stage heat treatment. It was elucidated that the optimum nucleation and the crystallization temperatures were at 643°C and 892°C. The various heat treatment times in the first stage were applied as 3, 6, 12, 24, 48 and 72 h, respectively, on the optimum nucleation temperature to produce mica-based glass-ceramics. XRD results showed that specimens of variety of nucleation time had similar crystalline structures such as calcium-mica, fluorapatite, stishovite, anorthite, strontiumapatite and forsterite phases. The microstructures of glass-ceramics were observed by SEM basically as interlocked plate-like and needle-like microstructures of mica and fluorapatite, respectively, in all specimens. Furthermore, different heat treatment times influenced on the revealed crystal size of the glass-ceramics; the longer heat treatment, the smaller crystals. The resultant glass-ceramics gave the results of biaxial flexural strength (178-224 MPa) and Vickers hardness (295-393 HV) increasing with the formation of the interconnected mica phases which contributed to improve the machinability. The values of the properties were comparable to those of human enamel and suitable for some restorative dental applications.


2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
C. H. Leong ◽  
A. Muchtar ◽  
C. Y. Tan ◽  
M. Razali ◽  
Noor Faeizah Amat

This study aims to determine the effect of adding 3 mol% yttria stabilized zirconia (3YSZ) in hydroxyapatite (HA) and sintering HA/3YSZ nanocomposites under nitrogen gas on HA decomposition. This paper presents the relationship between microstructure and mechanical properties of HA/3YSZ nanocomposites. Gas pressure and conventional sintering were performed on HA/3YSZ nanocomposites containing different amounts of 3YSZ (i.e., 0, 0.5, 1, and 7 wt%) at 1250°C. The phase stability, morphology, relative density, and microhardness of the HA/3YSZ nanocomposites were investigated. The phase stability of the HA/3YSZ nanocomposites was affected by adding different amounts of 3YSZ. Overall, gas pressure sintering leads to the formation of greater grain size compared with the conventional sintering method. The severe HA decomposition and the presence of the porosity in HA/7 wt% 3YSZ have led to deterioration in relative density and microhardness. In this study, HA/0.5 wt% 3YSZ with gas pressure sintering exhibited the optimum microstructure with the highest relative density (97%) and microhardness (3.93 GPa).


Author(s):  
Larissa Natiele Miotto ◽  
Mariana de Oliveira Carlos Villas-Bôas ◽  
Edgar Dutra Zanotto ◽  
Eduardo Bellini Ferreira ◽  
Laiza Maria Grassi Fais ◽  
...  

AbstractThis study aimed to evaluate the effect of grinding on some surface properties of two lithium disilicate-based glass-ceramics, one experimental new product denominated LaMaV Press (UFSCar-Brazil) and another commercial known as IPS e-max Press (Ivoclar), in the context of simulated clinical adjustment. Discs (N = 24, 12 mm in diameter) were separated into four groups: LaMaV Press with no grinding (E), LaMaV Press after grinding (EG), IPS e-max Press with no grinding (C), and IPS e-max Press after grinding (CG). A 0.1-mm deep grinding was carried out on EG and CG samples (final thickness of 1.4 mm) using a diamond stone in a low-speed device. The E and C samples had the same thickness. The effect of grinding on the sample surfaces was evaluated by X-ray diffraction, mechanical and optical profilometry, scanning electron microscopy, goniometry, and Vickers hardness. The mean roughness (Ra) was evaluated by Kruskal–Wallis and Student–Newman–Keuls statistics. The surface energy (SE) by the sessile drop method and Vickers hardness (VH) were analyzed using two-way ANOVA. The Ra medians were E = 1.69 µm, EG = 1.57 µm, C = 1.45 µm, and CG = 1.13 µm with p = 0.0284. The SE and VH were similar for all materials and treatments. Grinding smoothed the surfaces and did not significantly alter the hardness and surface energy of both LaMaV Press and IPS e-max Press. These glass-ceramics presented similar surface properties, and clinical adjustments can be implemented without loss of performance of both materials.


2019 ◽  
Vol 56 (1) ◽  
pp. 271-276 ◽  
Author(s):  
Roxana-Diana Vasiliu ◽  
Sorin Porojan ◽  
Liliana Porojan

The interest in aesthetics of dental materials is becoming greater with time and dental ceramics have proven excellent aesthetic properties. The study investigated how does the oral environment and the different surface finishing affect the optical properties and roughness of two types of ceramic, obtained using the heat- pressed method. Results showed that immersion has some influence on the optical and roughness of the two types of ceramics, but the major influence is made by the surface finishing and the type of ceramic. Lithium disilicate ceramic proved to have better optical properties compared to feldspathic ceramic. Roughness values showed that the parameters(Ra and Rz) were influenced by the surface finishing for both type of ceramics.


2021 ◽  
Vol 23 (2) ◽  
pp. 99-105
Author(s):  
Andréa Gallina Menta ◽  
Raísse Da Oliveira Bueno Soares ◽  
Bruno Emmanuelli ◽  
Camila Rodrigues ◽  
Liliana Gressler May

AbstractA wide variety of dental ceramics is launched every year. Therefore, clinicians should constantly study and update themselves to correctly indicate these materials. This cross-sectional study aimed to assess the association of dentists’ academic aspects with their knowledge and the indication of dental ceramics for metal-free restorations. All the dentists from private clinics who affirmed to perform prosthetic treatments on their patients in a Southern Brazilian city were personally invited to this research to avoid dropouts. Participants answered questions related to their knowledge of different dental materials, their information sources and usage frequency of ceramic materials, and related to their academic training/education. Chi-square tests were performed to evaluate the association among the outcomes (knowledge of different materials, information sources considered for material selection and their frequencies of use) and exposure variables (time since graduation and post-graduation degree). Significant associations were also submitted to Chi-square residual analysis. A response rate of 73.3% was reached. The most known and used materials were Y-TZP and porcelain veneered zirconia, respectively, whereas the least known was leucite-based ceramic. The majority of the professionals with at least 25 years since graduation claimed not to know lithium disilicate or leucite-based ceramics, and a significant number of these professionals allow the laboratory prostheses technician to choose the restorative material. In addition, most of dentists with no post-graduation said they did not have knowledge about leucite and lithium disilicate. It was evidenced that continuing education plays an important role in the dentists’ attitudes regarding ceramic materials. Keywords: Surveys and Questionnaires. Ceramics. Prosthodontics. ResumoUma grande variedade de cerâmicas é lançada no mercado a cada ano. Portanto, os clínicos devem se manter em constante estudo e atualização para indicar corretamente o uso desses materiais. Assim, este estudo transversal teve por objetivo avaliar a associação entre aspectos acadêmicos de dentistas com seus conhecimentos e as indicações de cerâmicas dentárias para uso em restaurações livres de metal. Para isso, todos os dentistas de clínicas privadas que afirmaram realizar tratamentos protéticos em seus pacientes em uma cidade do sul do Brasil foram pessoalmente convidados a participar desta pesquisa para evitar desistências. Os participantes responderam a questões relacionadas ao seu conhecimento sobre diferentes materiais dentários, suas fontes de informação, a frequência de uso de materiais cerâmicos, e, também, sobre sua formação acadêmica. Testes qui-quadrado foram realizados para avaliar a associação entre os desfechos (conhecimento de diferentes materiais, fontes de informação consideradas para a seleção do material e sua frequência de uso) e as variáveis de exposição (tempo desde a graduação e grau de pós-graduação). As associações significativas foram submetidas à análise de resíduos do qui-quadrado. A taxa de resposta obtida foi de 73,3%. O material mais conhecido e usado foi a Y-TZP e zircônia recoberta por porcelana, respectivamente, enquanto que o material menos conhecido foi a cerâmica a base de leucita. A maioria dos profissionais com pelo menos 25 desde a graduação afirmaram não conhecer as cerâmicas a base de dissilicato de lítio ou leucita, e um significativo número desses profissionais permitem que o técnico em prótese dentária escolha o material restaurador. Ainda, a maioria dos dentistas sem pós-graduação disseram não conhecer as cerâmicas a base de dissilicato de lítio ou leucita. Concluiu-se que a educação continuada é um fator determinante nas atitudes de dentistas em relação aos materiais cerâmicos. Palavras-chave: Pesquisas e Questionários. Cerâmicas, Prótese Dentária


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