Abstract Objective A deeper understanding of the mechanical behavior of dental restorative materials requires an insight into the materials elastic constants and microstructure. Here we aim to use complementary methodologies to thoroughly characterize chairside CAD/CAM materials and discuss the benefits and limitations of different analytical strategies. Methods Eight commercial CAM/CAM materials, ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e.max CAD, Ivoclar-Vivadent; Suprinity, VITA; Celtra Duo, Dentsply) to hybrid materials (Enamic, VITA; Lava Ultimate, 3M ESPE) have been selected. Elastic constants were evaluated using three methods: Resonant Ultrasound Spectroscopy (RUS), Resonant Beam Technique (RBT) and Ultrasonic Pulse-Echo (PE). The microstructures were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Raman Spectroscopy and X-ray Diffraction (XRD). Results Young’s modulus (E), Shear modulus (G), Bulk modulus (B) and Poisson’s ratio ( ν ) were obtained for each material. E and ν reached values ranging from 10.9 (Lava Ultimate) to 201.4 (e.max ZirCAD) and 0.173 (Empress CAD) to 0.47 (Lava Ultimate), respectively. RUS showed to be the most complex and reliable method, while the PE method the easiest to perform but most unreliable. All dynamic methods have shown limitations in measuring the elastic constants of materials showing high damping behavior (hybrid materials). SEM images, Raman spectra and XRD patterns were made available for each material, showing to be complementary tools in the characterization of their crystal phases. Significance Here different methodologies are compared for the measurement of elastic constants and microstructural characterization of CAD/CAM restorative materials. The elastic properties and crystal phases of eight materials are herein fully characterized.
A method for fracture toughness measurement of ceramics using small disks and plates is presented. Similar to the surface-crack-in-flexure (SCF) method a semielliptical surface crack is introduced centrally into one plane side of the specimen which is fractured in a ball-on-three-balls test. Finite element simulations are used to evaluate the stress intensity factor (SIF) for this loading geometry for a range of crack sizes and crack geometries. Empirical formulae for the geometric function are ...
Last. Tien-Min G. Chu(IUPUI: Indiana University – Purdue University Indianapolis)H-Index: 17
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Abstract Background Elucidating the microstructural responses of the lithium disilicate system like the popular IPS e.max® CAD (LS 2 ), made specifically for computer-aided design and computer-aided manufacturing (CAD-CAM), as a temperature-dependent system unravels new ways to enhance material properties and performance. Objective To study the effect of various thermal processing on the crystallization kinetics, crystallite microstructure, and strength of LS 2 . Methods The control group of the...
Last. Shaochun Xu(Xi'an Jiaotong University)H-Index: 6
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Abstract In this work, transformation of crystalline phases and development of microstructure of two kinds of glass-ceramics, SiO 2 –Li 2 O–P 2 O 5 and SiO 2 –Li 2 O–K 2 O–Al 2 O 3 –ZrO 2 –P 2 O 5 , have been studied by X-ray diffraction and scanning electron microscopy analysis. In the former glass, a small amount of spherical Li 2 Si 2 O 5 crystals precipitated at the usual nucleation temperature, which changed little in size and packing density with the increase of the temperature. These sphe...
Abstract A new fracture toughness test for discs and plates is presented, which can be applied to small specimens (>5 mm diameter). A semi-elliptical surface crack is made into the centre of the top plane using a Knoop intender. Then the layer containing the plastically deformed zone is ground off and the crack is loaded in tension using the Ball-on-3-Balls test. Applied to five different ceramic materials the results gained with the new method agree well with those of standardised methods.
In this study, the high-temperature phase transformation of a multicomponent lithium disilicate glass was investigated by in situ and real-time synchrotron X-ray diffraction in the SiO2–Li2O–P2O5–Al2O3–ZrO2 glass system. Quantitative phase analysis via the Rietveld method was performed on the high-resolution data aiming to reveal the crystallization sequence, crystallization kinetics, and the role of P2O5 on nucleation. It is found that the nucleation of lithium metasilicate (LS) and lithium dis...
Abstract Objectives To determine and identify correlations between flexural strength, strain at failure, elastic modulus and hardness versus ceramic network densities of a range of novel polymer-infiltrated-ceramic-network (PICN) materials. Methods Four ceramic network densities ranging from 59% to 72% of theoretical density, resin infiltrated PICN as well as pure polymer and dense ceramic cross-sections were subjected to Vickers Indentations (HV 5) for hardness evaluation. The flexural strength...
Last. Pascal Laugier('ENS Paris': École Normale Supérieure)H-Index: 67
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Abstract Resonant ultrasound spectroscopy (RUS) allows to accurately characterize the complete set of elastic constants of an anisotropic material from a set of measured mechanical resonant frequencies of a specimen. This method does not suffer from the drawbacks and limitations of the conventional sound velocity approach, but has been reported to fail to measure bone because of its strong viscoelastic damping. In this study, we take advantage of recent developments of RUS to overcome this limit...
Abstract The Newman and Raju formula for the stress intensity factor of a semi-elliptical surface crack loaded in uniaxial tension or in bending has been developed about 30 years ago using an FE-analysis for several geometric parameters and fitting an empirical equation to the data points. The Poisson's ratio analyzed was 0.3. In this paper a reassessment of the Newman and Raju formula is made, where all relevant geometric parameters of crack and specimen and the Poisson's ratio are considered. ...
#1Márcia Borba(UPF: Universidade de Passo Fundo)H-Index: 15
#2M.D. Araujo(USP: University of São Paulo)H-Index: 4
Last. Alvaro Della Bona(UPF: Universidade de Passo Fundo)H-Index: 46
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Abstract Objective To evaluate the effect of the specimen design on the flexural strength ( σ f ) and failure mode of ceramic structures, testing the hypothesis that the ceramic material under tension controls the mechanical performance of the structure. Methods Three ceramics used as framework materials for fixed partial dentures (YZ – Vita In-Ceram YZ; IZ – Vita In-Ceram Zirconia; AL – Vita In-Ceram AL) and two veneering porcelains (VM7 and VM9) were studied. Bar-shaped specimens were produced...
Last. Tanguy Rouxel(CNRS: Centre national de la recherche scientifique)H-Index: 38
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Poisson's ratio describes the resistance of a material to distort under mechanical load rather than to alter in volume. On the bicentenary of the publication of Poisson's Traite de Mecanique, the continuing relevance of Poisson's ratio in the understanding of modern materials is reviewed.
Abstract The microstructural development during crystallization firing of a commercially-available dental-grade nanostructured lithia-zirconia glass-ceramic (Vita Suprinity® PC) was unraveled using a wide battery of ex-situ and in-situ characterization techniques. It was found that the milling blocks are slightly crystallized glass-ceramics, with a complex chemical composition and consisting of partially de-polymerized glass plus Li2SiO3 nanocrystals. It was also found that during crystallizatio...
#1Renan Belli(FAU: University of Erlangen-Nuremberg)H-Index: 23
#2Katrin Hurle(FAU: University of Erlangen-Nuremberg)H-Index: 7
Last. Ulrich Lohbauer(FAU: University of Erlangen-Nuremberg)H-Index: 57
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Abstract null null The relationship between fracture toughness and Yttria content in modern zirconia ceramics was revised. For that purpose, we evaluated here 10 modern Y2O3-stabilized zirconia (YSZ) materials currently used in biomedical applications, namely prosthetic and implant dentistry. The most relevant range between 2-5 mol% Y2O3 was addressed by selecting from conventional opaque 3 mol% YSZ up to more translucent compositions (4-5 mol% YSZs). A technical 2YSZ was used to extend the rang...
Abstract null null The fatigue behavior and survival rates of different ceramic materials cemented over different substrates for implant-supported crowns were evaluated in this study. Discs of 10 mm in diameter of both restorative and substrate materials were made and randomly allocated into pairs (n = 15) considering the two study factors: ‘restorative ceramic material’ (1 mm thickness) – polymer-infiltrated ceramic network (PICN), lithium disilicate (LD), zirconia-reinforced lithium silicate (...
Last. Liliana Gressler May(UFSM: Universidade Federal de Santa Maria)H-Index: 17
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This study evaluated if using an MDP-containing ceramic primer combined with acid etching or without improves the microshear bond strength of resin cement to a zirconia-reinforced lithium silicate ...
PURPOSE This study investigated the in-vitro performance of anterior implant-supported fixed dental prostheses (FDP). The effect of ceramics, fabrication, finalization and the presence of a screw-channel wa s investigated. METHODS Identical anterior ceramic FDPs (tooth 11-13; n=80) were milled (Lithiumdisilicate (LiSiCAD, emaxCAD, Ivoclar-Vivadent), Lithiumaluminiumsilicate (LiAlSi, experimental material) or pressed (Lithiumdisilicate (LiSiPress, emaxPress, Ivoclar-Vivadent), Lithiumsilicate (ZL...
OBJECTIVES The present narrative review was focused on the optical properties, surface treatment, adhesion, and clinical indications of zirconia-reinforced lithium silicate ceramics (ZLS) for Computer-aided design / Computer-aided manufacturing (CAD/CAM) technologies. DATA/SOURCES A literature search was performed by 3 calibrated independent researchers on PubMed, Scopus, Embase, Google Scholar, Dynamed, and Open Grey. The criteria for inclusion were: 1) papers addressing at least one of the fol...
The aim of this in vitro study was to investigate the fracture resistance, fracture failure pattern, and fractography of four types of chairside computer-aided design/computer-aided manufacturing (CAD/CAM) restoration materials in teeth and titanium abutments fabricated using a standardization method. An artificial mandibular left first premolar prepared for all-ceramic crown restoration was scanned. Forty extracted mandibular molars and cylindrical titanium specimens were milled into a standard...
PURPOSE To test the hypothesis that surface roughening and polishing of ceramics have no effect on their surface roughness and biofilm adhesion. MATERIALS AND METHODS Feldspathic ceramic Vitablocks™ TriLuxe forte (VTF), lithium disilicate glass IPS e.max Press™ (IPS) and zirconia reinforced lithium silicate Vita Suprinity™ (VS) ceramic blocks (n = 27 per group) were prepared from sintered CAD blocks using a water-cooled saw. They were further subdivided into 3 subgroups according to the surface ...
Abstract Objectives Compare failure modes and fracture origins using fractography on recovered clinically fractured parts of indirect resin composite endocrowns and overlay restorations on endodontically treated teeth (ETT). Methods Four endocrowns (3 molars, 1 premolar) and one overlay (molar) adhesively luted on ETT were recovered after fracturing during function. The time in service ranged between 4 and 48 months. The composite materials were (i) CAD/CAM LAVA Ultimate (N = 1), (ii) Premise In...