BackgroundAlthough, the influence of cement and background shade on the final color and translucency of zirconia reinforced lithium silicate (ZLS) and lithium disilicate (LDS) ceramics has been ...previously investigated, there is still little data on the translucency of LDS and ZLS ceramics in decreased thickness (0.4 and 0.6 mm). The aim of this study was to investigate ceramic thickness', background and cement shades' effects on the zirconia reinforced lithium silicate (ZLS) and lithium disilicate (LDS) ceramics' translucency.Material and MethodsTotally 160 square-shaped A1 shade LDS and ZLS samples produced in 0.4 and 0.6 mm thicknesses were cemented with light and neutral shade resin cement on A2 and A3 shade composite resin backgrounds. The color notations of specimen were measured and translucency parameter (TP) values were calculated. Factorial ANOVA and Tamhane's T2 multiple comparison statistical analyzes were used.ResultsHighest TP values (11.82±0.97) were obtained in ZLS specimens that were 0.4 mm in thickness, cemented on A2 background with light shade resin cement. While, the lowest TP values (9.60±0.55) were calculated in LDS samples that had 0.6 mm thickness, cemented on A3 background with neutral shade resin cement.ConclusionsMaterial type, thickness, and background shade affected TP values of specimens. The cement and background shade used might change the final translucency of ZLS and LDS ceramics that had 0.4 and 0.6 mm thickness. Key words:Ceramics, lithium disilicate, spectrophotometry, zirconia, dental materials.
The introduction of the new generation of particle-filled and high strength ceramics, hybrid composites and technopolymers in the last decade has offered an extensive palette of dental materials ...broadening the clinical indications in fixed prosthodontics, in the light of minimally invasive dentistry dictates. Moreover, last years have seen a dramatic increase in the patients' demand for non-metallic materials, sometimes induced by metal-phobia or alleged allergies. Therefore, the attention of scientific research has been progressively focusing on such materials, particularly on lithium disilicate and zirconia, in order to shed light on properties, indications and limitations of the new protagonists of the prosthetic scene.
This article is aimed at providing a narrative review regarding the state-of-the-art in the field of these popular ceramic materials, as to their physical-chemical, mechanical and optical properties, as well as to the proper dental applications, by means of scientific literature analysis and with reference to the authors' clinical experience.
A huge amount of data, sometimes conflicting, is available today. Both in vitro and in vivo studies pointed out the outstanding peculiarities of lithium disilicate and zirconia: unparalleled optical and esthetic properties, together with high biocompatibility, high mechanical resistance, reduced thickness and favorable wear behavior have been increasingly orientating the clinicians' choice toward such ceramics.
The noticeable properties and versatility make lithium disilicate and zirconia materials of choice for modern prosthetic dentistry, requiring high esthetic and mechanical performances combined with a minimal invasive approach, so that the utilization of such metal-free ceramics has become more and more widespread over time.
The use of glass‐ceramics in the medical field has grown significantly since the 1980s. With excellent aesthetic properties, semi‐translucency, outstanding mechanical properties, corrosion ...resistance, wear resistance and great biocompatibility and workability glass‐ceramics is one of the most commonly used materials in restorative dentistry and is widely used in veneers, inlays, onlays, all‐ceramic crowns, and implant abutments. This review provides an overview of the research progress of glass‐ceramics in restorative dentistry, focusing on the classification, performance requirements, toughening mechanisms and their association with clinical performance, as well as the manufacturing and fabrication of glass‐ceramics in restorative dentistry. Finally, the developments and prospects of glass‐ceramics in restorative dentistry are summarized and discussed.
The K+-Na+ ion exchange was used to strengthen LAS glass-ceramic materials prepared by hot-pressing sintering. The microstructure, cytocompatibility, and chemical durability of the chemically ...strengthened LAS glass-ceramics were characterized. The XRD results showed that the K+-Na+ ion exchange mainly occurred between the glass phase of the LAS glass-ceramics and molten salt baths. The ion-exchange process was mainly responsible for the improved chemical durability of the LAS glass-ceramics. The dissolution in acetic acid was significantly reduced from 72 to 15 μg·cm−2 after the ion-exchange treatment, which was attributed to residual compressive stress and increased contents of Q3 and Q4 structural units in the surface region of the LAS glass-ceramics. In addition, the chemically strengthened LAS glass-ceramic samples exhibited good biocompatibility determined by the CCK-8 process using the L929 cell line, having a promising potential as dental restorative materials.
•Unique structures of nano-brush Li2Si2O5 coated carbon cloth were prepared using a hydrothermal method.•Adsorption capacities of composites for Mn2+, Cu2+, Ni2+ ions were 325.60, 314.76 and 270.15 ...mg/g, respectively.•Effects of various factors on the adsorption properties of the composite were studied.•Mechanisms of adsorption of heavy metal ions are found as surface complexations and partial ion-exchange.
Li2Si2O5 nano-brush coated carbon cloth was synthesized using a hydrothermal method with lithium hydroxide and tetraethyl orthosilicate as the resource chemicals. Its adsorption capabilities for Mn2+, Cu2+ and Ni2+ ions were demonstrated for wastewater treatments, and their corresponding maximum adsorption capacities were 325.60, 314.76 and 270.15 mg/g at 298 K, respectively. Brush-like and highly uniformly Li2Si2O5 nanorods with an average diameter of ∼ 60 nm were uniformly synthesized onto the carbon cloth. Adsorption experiments showed that the adsorption behaviors for selected heavy metal ions followed both a pseudo-second-order model and a Langmuir isothermal model, indicating that the adsorption process was a monolayer and chemical adsorption one. The key adsorption mechanisms were identified as surface complexation between heavy metal ions and hydroxyl groups and ion-exchanges between heavy metal ions and lithium ions. These brush-like nanorods have advantages of effective adsorption of heavy metal ions in wastewater due to their widely exposed active sites and effective ion diffusion and transport.
Recycling high-density micronized (HDM) heat-press glass ceramic ingots to press several restorations would be economical and reduce waste. However, to achieve this, the effects of re-pressing on the ...optical properties and long-term durability of HDM glass ceramics must be completely understood. The aim of this study was to assess the effects of re-pressing and glazing on the optical properties of HDM heat-press glass ceramic. Twenty-one HDM glass ceramic (Initial LiSi Press) discs were prepared and randomly divided into three groups (n = 7 per group): single heat pressing, double heat pressing, and triple heat pressing. Optical properties, surface roughness, and crystalline structure were measured for each group at three time points: before glazing and thermocycling, after glazing, and after thermocycling. The effect of these independent variables on optical properties were assessed by two-way ANOVA, and Tukey's post hoc test assessed the differences between groups. Heat re-pressing HDM glass ceramic significantly altered its color, reduced translucency, and reduced surface roughness (P < 0.001). After the second heat-press, the color (ΔΕ00) and translucency parameter changes (ΔTP00) exceeded perceptible thresholds but not clinically acceptable thresholds, but these were exceeded after the third press for ΔΕ00. Additionally, glazing lightened the shade of the ceramic, reduced translucency, and reduced surface roughness (P < 0.001), with ΔΕ00 and ΔTP00 changes exceeding the perceptible but not the clinically acceptable threshold. Thermocycling produced ΔTP00 changes that exceeded the clinically acceptable threshold. Further studies of the effects of heat re-pressing on HDM glass ceramic are now needed to progress toward clinical translation.
The nucleation and crystallization of glass-ceramics are typically influenced by early phase separation, which can impact glass properties. However, it has been challenging to characterize the ...nanoscale phase separation and understand the nucleation mechanism of lithium disilicate (L2S) glass-ceramics, which has resulted in some controversy. Here, we raised the direct evidence of nanoscale clustering in the glassy phase prior to formal nucleation and crystallization by element distribution. Firstly, the amorphous Li3PO4 phase formed on the boundary between the phase separation area and residual glass matrix, and then nucleation tended to start on this phase boundary. Furthermore, the effect of phase-separation on nucleation and final crystallize products was illustrated. By sufficient phase-separation, the formation of desired Li2Si2O5 and LiAlSi4O10 microcrystals was effectively motivated, which is prerequisite for high mechanical properties and transparency. We hope this work provides guidance to rationally understand the early phase separation in glass for subsequent controlling crystallization.
Abstract Objective The aim of this study was to assess the mechanical properties of recently introduced zirconia reinforced lithium silicate glass-ceramic. Methods Two types of CAD/CAM glass-ceramics ...(Vita Suprinity (VS); zirconia reinforced lithium silicate and IPS e.max CAD (IC); lithium disilicate) were used. Fracture toughness, flexural strength, elastic modulus, hardness, brittleness index, and microstructures were evaluated. Data were analyzed using independent t tests. Weibull analysis of flexural strength data was also performed. Results VS had significantly higher fracture toughness (2.31 ± 0.17 MPa m0.5 ), flexural strength (443.63 ± 38.90 MPa), elastic modulus (70.44 ± 1.97 GPa), and hardness (6.53 ± 0.49 GPa) than IC ( P < 0.001). On the other hand, VS glass-ceramic revealed significantly a higher brittleness index (2.84 ± 0.26 μm−1/2 ) (lower machinability) than IC glass-ceramic ( P < 0.05). VS demonstrated a homogeneous fine crystalline structure while, IC revealed a structure with needle-shaped fine-grained crystals embedded in a glassy matrix. The VS glass-ceramic revealed a lower probability of failure and a higher strength than IC glass-ceramic according to Weibull analysis. Significance The VS zirconia reinforced lithium silicate glass-ceramic revealed higher mechanical properties compared with IC lithium disilicate glass-ceramic.
The mechanical properties of lithium disilicate glass-ceramics depend on various factors, a prominent one being their microstructure. The aim of this review article is to elucidate the effect of ...processing parameters such as annealing temperature, holding time, number of heating stages and chemical composition and additives on the microstructure and physical properties of these glass-ceramics.
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