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Sample records for dental ceramic systems

  1. Interfacial adhesion of dental ceramic-resin systems

    Science.gov (United States)

    Della Bona, Alvaro

    The clinical success of resin bonding procedures for indirect ceramic restorations and ceramic repairs depends on the quality and durability of the bond between the ceramic and the resin. The quality of this bond will depend upon the bonding mechanisms that are controlled in part by the surface treatment that promotes micromechanical and/or chemical bonding to the substrate. The objective of this study is to correlate interfacial toughness (K A) with fracture surface morphological parameters of the dental ceramic-resin systems as a function of ceramic surface treatment. The analytical procedures focused on characterizing the microstructure and fracture properties of EmpressRTM ceramics (a leucite-based core ceramic, two lithia disilicate-based core ceramics, and a glass veneer) and determining the ceramic-resin adhesion zone bond strength characteristics. Microstructure and composition are controlling factors in the development of micromechanical retention produced by etching. Silane treated ceramics negated the effect of surface roughening produced by etching, inducing lower surface energy of the ceramic and, reduced bonding effectiveness. There was a positive correlation between WA, tensile bond strength (a), and KA, i.e., higher mean WA value, and higher mean sigma and KA values. This study suggests that (1) the sigma and KA values for ceramic bonded to resin are affected by the ceramic microstructure and the ceramic surface treatments; (2) the definition of the adhesion zone is essential to classify the modes of failure, which should be an integral component of all failure analyses; (3) the microtensile test may be preferable to conventional shear or flexural tests as an indicator of composite-ceramic bond quality; and (4) careful microscopic analysis of fracture surfaces and an x-ray dot map can produce a more consistent and complete description of the fracture process and interpretation of the modes of failure. The mode of failure and fractographic analyses

  2. Degradability of dental ceramics.

    Science.gov (United States)

    Anusavice, K J

    1992-09-01

    The degradation of dental ceramics generally occurs because of mechanical forces or chemical attack. The possible physiological side-effects of ceramics are their tendency to abrade opposing dental structures, the emission of radiation from radioactive components, the roughening of their surfaces by chemical attack with a corresponding increase in plaque retention, and the release of potentially unsafe concentrations of elements as a result of abrasion and dissolution. The chemical durability of dental ceramics is excellent. With the exception of the excessive exposure to acidulated fluoride, ammonium bifluoride, or hydrofluoric acid, there is little risk of surface degradation of virtually all current dental ceramics. Extensive exposure to acidulated fluoride is a possible problem for individuals with head and/or neck cancer who have received large doses of radiation. Such fluoride treatment is necessary to minimize tooth demineralization when saliva flow rates have been reduced because of radiation exposure to salivary glands. Porcelain surface stains are also lost occasionally when abraded by prophylaxis pastes and/or acidulated fluoride. In each case, the solutes are usually not ingested. Further research that uses standardized testing procedures is needed on the chemical durability of dental ceramics. Accelerated durability tests are desirable to minimize the time required for such measurements. The influence of chemical durability on surface roughness and the subsequent effect of roughness on wear of the ceramic restorations as well as of opposing structures should also be explored on a standardized basis.

  3. FATIGUE OF DENTAL CERAMICS

    Science.gov (United States)

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-01-01

    Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

  4. Fatigue of dental ceramics.

    Science.gov (United States)

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-12-01

    Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Characterization of ceramic powders used in the inCeram systems to fixed dental Prosthesis

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    Alexandra Almeida Diego

    2007-03-01

    Full Text Available InCeram (Vita Zahnfabrik- Germany is known as a high strength ceramic being used for core crowns and for fixed partial denture frameworks. InCeram system consists of slip-casting technique which is used for to build the framework, which is then pre-sintered obtaining an open-pore microstructure. The material gains its strength by infiltration of the lanthanum glass into the porous microstructure. In this work, commercial alumina (Al2O3, alumina-zirconia (Al2O3-ZrO2 and glasses lanthanum oxide-rich powders, used in InCeram system, were characterized, using x ray diffraction, dilatometry and scanning electron microscopy. The characteristics of these powders were related aiming to consider their substitution for new ceramic materials.

  6. Viscoelastic analysis of a dental metal-ceramic system

    Science.gov (United States)

    Özüpek, Şebnem; Ünlü, Utku Cemal

    2012-11-01

    Porcelain-fused-to-metal (PFM) restorations used in prosthetic dentistry contain thermal stresses which develop during the cooling phase after firing. These thermal stresses coupled with the stresses produced by mechanical loads may be the dominant reasons for failures in clinical situations. For an accurate calculation of these stresses, viscoelastic behavior of ceramics at high temperatures should not be ignored. In this study, the finite element technique is used to evaluate the effect of viscoelasticity on stress distributions of a three-point flexure test specimen, which is the current international standard, ISO 9693, to characterize the interfacial bond strength of metal-ceramic restorative systems. Results indicate that the probability of interfacial debonding due to normal tensile stress is higher than that due to shear stress. This conclusion suggests modification of ISO 9693 bond strength definition from one in terms of the shear stress only to that accounting for both normal and shear stresses.

  7. Thermal compatibility of dental ceramic systems using cylindrical and spherical geometries.

    Science.gov (United States)

    DeHoff, Paul H; Barrett, Allyson A; Lee, Robert B; Anusavice, Kenneth J

    2008-06-01

    To test the hypothesis that bilayer ceramic cylinders and spheres can provide valid confirmation of thermal incompatibility stresses predicted by finite element analyses. A commercial core ceramic and an experimental core ceramic were used to fabricate open-ended cylinders and core ceramic spheres. The core cylinders and spheres were veneered with one of four commercial dental ceramics representing four thermally compatible groups and four thermally incompatible groups. Axisymmetric thermal and viscoelastic elements in the ANSYS finite element program were used to calculate temperatures and stresses for each geometry and ceramic combination. This process required a transient heat transfer analysis for each combination to determine input temperatures for the structural model. After fabrication, each specimen was examined visually using fiberoptic transillumination for evidence of cracking. There were 100% failures of the thermally incompatible cylinders while none of the thermally compatible combinations failed. Among the spheres, 100% of the thermally incompatible systems failed, 16% of one of the thermally compatible systems failed, and none of the remaining compatible combinations failed. The calculated stress values were in general agreement with the experimental observations, i.e., low residual stresses for the specimens that did not fail and high residual stresses for the specimens that did fail. Simple screening geometries can be used to identify highly incompatible ceramic combinations, but they do not identify marginally incompatible systems.

  8. Dental ceramics: a current review.

    Science.gov (United States)

    Lawson, Nathaniel C; Burgess, John O

    2014-03-01

    Ceramics are used for many dental applications and are characterized in various ways, including by their hardness, brittleness, thermal and electrical insulation, and biocompatibility. The ceramics most commonly used in dentistry are oxides, particularly silicon dioxide (SiO2), or silica; aluminum oxide (Al2O3), or alumina; and zirconium dioxide (ZrO2), or zirconia. This article reviews the microstructure of current dental ceramic materials and how it relates to their mechanical properties, clinical techniques, and optical properties. Typical ceramics currently in use are described, and their clinically relevant properties such as strength, fracture, polishability, and wear are compared. Cementation methods are also discussed.

  9. SHEAR BOND STRENGTHS BETWEEN CERAMIC CORES AND VENEERING CERAMICS OF DENTAL BI-LAYERED CERAMIC SYSTEMS AND THE SENSITIVITY TO THERMOCYCLING

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    SUN TING, BDS, DDS

    2012-09-01

    Full Text Available The purpose of this study was to investigate the bond strength between various commercial ceramic core materials and veneering ceramics of dental bi-layered ceramic combinations and the effect of thermocycling. The shear bond strength of four dental bi-layered ceramic combinations (white Cercon, yellow Cercon, white Lava, yellow Lava, IPS E.max were tested. Metal ceramic combinations were conducted as a control group. Half of each group was subjected to thermocycling. All specimens were thereafter subjected to a shear force. The initial mean shear bond strength values in MPa ± S.D were 28.02 ± 3.04 for White Cercon Base/Cercon Ceram Kiss, 27.54 ± 2.20 for Yellow Cercon Base/Cercon Ceram Kiss, 28.43 ± 2.13for White Lava Frame/Lava Ceram, 27.36 ± 2.25 for Yellow Lava Frame/Lava Ceram, 47.10 ± 3.77 for IPS E.max Press/IPS E.max Ceram and 30.11 ± 2.15 for metal ceramic control. The highest shear strength was recorded for IPS E.max Press/IPS E.max Ceram before and after thermocycling. The mean shear bond strength values of five other combinations were not significantly different (P < 0.05. Lithium-disilicate based combinations produced the highest core-veneer bonds that overwhelmed the metal ceramic combinations. Thermocycling had no effect on the core-veneer bonds. The core-veneer bonds of zirconia based combinations were not weakened by the addition of coloring pigments.

  10. Viscoelastic finite element stress analysis of the thermal compatibility of dental bilayer ceramic systems.

    Science.gov (United States)

    DeHoff, Paul H; Anusavice, Kenneth J

    2009-01-01

    The aim of this study was to test the hypothesis that viscoelastic finite element analyses can reliably predict the effect of geometry on maximum tensile stresses in bilayer screening tests that are used to determine thermal compatibility. Three-dimensional viscoelastic finite element models of a beam, cylinder, disk, sphere, central incisor crown, molar crown, and posterior three-unit fixed partial denture (FPD) were used to calculate residual stresses after simulated bench cooling. Four compatible and four incompatible systems were evaluated. The highest residual tensile stresses for all material combinations were associated with the three-unit FPD. Residual tensile stresses ranged from 5.4 MPa in the disk for a compatible combination to 262 MPa in the three-unit FPD for an incompatible system. Residual tensile stresses in the three-unit FPD ranged from 16.8 MPa to 44.0 MPa for the compatible systems and from 175 MPa to 262 MPa for the incompatible systems. Based on finite element calculations, it is predicted that all-ceramic dental prostheses with an average thermal contraction mismatch (500 degrees C to 25 degrees C) greater than +/- 1.0 ppm/K will likely exhibit a relatively high percentage of failures in clinical use compared with systems having smaller thermal contraction mismatch between core and veneering ceramics.

  11. Novel glass-ceramics for dental restorations.

    Science.gov (United States)

    Pollington, Sarah

    2011-01-01

    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. The aim of this review article is to discuss the types of novel glass-ceramic currently be investigated including composition, microstructure and properties. 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. There is a gap in the market for a machinable resin bonded glass-ceramic with sufficient strength as well as excellent esthetics.

  12. Recent developments in restorative dental ceramics.

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    Anusavice, K J

    1993-02-01

    Since the introduction of porcelain jacket crowns in the early 1900s, dental ceramics have been praised for their esthetic appearance. But there's more to consider: other benefits, longevity, limitations. This review addresses major developments in modern dental ceramics and metal-ceramics.

  13. Preparation and properties of dental zirconia ceramics

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Y2O3-stabilized tetragonal zireonia polyerystalline (Y-TZP) ceramics with high-performance were prepared for dental application by use of the micro-emulsion and two-step sintering method.The crystal phase,morphology,and microstructure of the reaction products were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).XRD results show that the ceramics mainly consist of tetragonal zirconia.Physical and mechanical properties test results show that the bending strength,fracture toughness,and the density of full sintered Y-TZP ceramics are llS0 MPa,5.53 crown machined with this material by CAD/CAM system exhibits a verisimilitude configuration and the material's expansion coefficient well matches that of the glaze.These results further indicate that the product can be used as a promising new ceramic material

  14. Ceramics as biomaterials for dental restoration.

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    Höland, Wolfram; Schweiger, Marcel; Watzke, Ronny; Peschke, Arnd; Kappert, Heinrich

    2008-11-01

    Sintered ceramics and glass-ceramics are widely used as biomaterials for dental restoration, especially as dental inlays, onlays, veneers, crowns or bridges. Biomaterials were developed either to veneer metal frameworks or to produce metal-free dental restorations. Different types of glass-ceramics and ceramics are available and necessary today to fulfill customers' needs (patients, dentists and dental technicians) regarding the properties of the biomaterials and the processing of the products. All of these different types of biomaterials already cover the entire range of indications of dental restorations. Today, patients are increasingly interested in metal-free restoration. Glass-ceramics are particularly suitable for fabricating inlays, crowns and small bridges, as these materials achieve very strong, esthetic results. High-strength ceramics are preferred in situations where the material is exposed to high masticatory forces.

  15. Dental ceramics: a review of new materials and processing methods.

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    Silva, Lucas Hian da; Lima, Erick de; Miranda, Ranulfo Benedito de Paula; Favero, Stéphanie Soares; Lohbauer, Ulrich; Cesar, Paulo Francisco

    2017-08-28

    The evolution of computerized systems for the production of dental restorations associated to the development of novel microstructures for ceramic materials has caused an important change in the clinical workflow for dentists and technicians, as well as in the treatment options offered to patients. New microstructures have also been developed by the industry in order to offer ceramic and composite materials with optimized properties, i.e., good mechanical properties, appropriate wear behavior and acceptable aesthetic characteristics. The objective of this literature review is to discuss the main advantages and disadvantages of the new ceramic systems and processing methods. The manuscript is divided in five parts: I) monolithic zirconia restorations; II) multilayered dental prostheses; III) new glass-ceramics; IV) polymer infiltrated ceramics; and V) novel processing technologies. Dental ceramics and processing technologies have evolved significantly in the past ten years, with most of the evolution being related to new microstructures and CAD-CAM methods. In addition, a trend towards the use of monolithic restorations has changed the way clinicians produce all-ceramic dental prostheses, since the more aesthetic multilayered restorations unfortunately are more prone to chipping or delamination. Composite materials processed via CAD-CAM have become an interesting option, as they have intermediate properties between ceramics and polymers and are more easily milled and polished.

  16. Ceramics for Dental Applications: A Review

    Directory of Open Access Journals (Sweden)

    Julie A. Holloway

    2010-01-01

    Full Text Available Over the past forty years, the technological evolution of ceramics for dental applications has been remarkable, as new materials and processing techniques are steadily being introduced. The improvement in both strength and toughness has made it possible to expand the range of indications to long-span fixed partial prostheses, implant abutments and implants. The present review provides a state of the art of ceramics for dental applications.

  17. Translucency of Dental Ceramic, Post and Bracket

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    Yong-Keun Lee

    2015-10-01

    Full Text Available Translucency of dental ceramics, esthetic posts and orthodontic brackets was reviewed. Translucency parameter (TP and contrast ratio (CR are generally used for translucency evaluation. For the evaluation of translucency, two criteria such as the translucency of human teeth (TP = 15–19, 1 mm thick and the visual perceptibility threshold for the translucency difference (∆CR > 0.07 or ∆TP > 2 were used. In ceramics, translucency differences were in the perceptible range depending on the type of material and the thickness. However, variations caused by the difference in the required thickness for each layer by the material and also by the measurement protocols should be considered. As to the translucency of esthetic posts, a significant difference was found among the post systems. Translucency was influenced by the bracket composition and brand, and the differences by the brand were visually perceptible.

  18. Defective dental restorations: to repair or not to repair? Part 2: All-ceramics and porcelain fused to metal systems.

    Science.gov (United States)

    Blum, Igor R; Jagger, Daryll C; Wilson, Nairn H F

    2011-04-01

    With the increasing use of ceramics in restorative dentistry, and trends to extend restoration longevity through the use of minimal interventive techniques, dental practitioners should be familiar with the factors that may influence the decision either to repair or replace fractured metal-ceramic and all-ceramic restorations and, also, the materials and techniques available to repair these restorations. This second of two papers addresses the possible modes of failure of ceramic restorations and outlines indications and techniques in this developing aspect of restoration repair in clinical practice. The repair of metal-ceramic and all-ceramic restorations is a reliable low-cost, low-risk technique that may be of value for the management of loss or fracture of porcelain from a crown or bridge in clinical practice.

  19. [Dental ceramics: its history and development].

    Science.gov (United States)

    Moureau, Thomas; Vanheusden, Alain

    2006-01-01

    This article presents an historical background of dental ceramics. It synthesises the evolution of such material and its technical improvements from the stone-age to our time. Focusing on the importance of dental aesthetics, it shows the investigations realised to upgrade the prosthetic results.

  20. Translucency of dental ceramics with different thicknesses.

    Science.gov (United States)

    Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

    2013-07-01

    The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (Pceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  1. Relationship between Leucite Content and Compressive Strength of K2O-Al2O3-SiO2 System Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; QIAN Fatang; DUAN Xinglong; WU Bolin

    2009-01-01

    Relationship between leucite content and compressive strength of K2O-Al2O3-SiO2 sys-tem dental glass ceramics were investigated. 10 groups of feedstock powder with different composi-tions were treated according to the same thermal treatment system of leucite micro-crystallization reported in some primary studies. The products of each group were analyzed by X-ray diffractometer,polaring microscope and scanning electronic microscope (SEM), and then the compressive strength was tested by a material testing machine. A direct proportion was found between leucite content and the compressive strength when leucite content was less than 50 vol%, and compressive strength de-creased with the increasing of leucite micro-crystals when leucite content was more than 50vol%, The leucite content has a notable influence on the compressive strength of K2O-Al2O3-SiO2 system dental glass ceramics.

  2. Did we push dental ceramics too far? A brief history of ceramic dental implants.

    Science.gov (United States)

    Haubenreich, James E; Robinson, Fonda G; West, Karen P; Frazer, Robert Q

    2005-01-01

    Humankind has developed and used ceramics throughout history. It currently has widespread industrial applications. Dental ceramics are used for fabricating highly esthetic prosthetic denture teeth, crowns, and inlays. However, ceramic's biocompatibility and compressive strength are offset by its hardness and brittleness. Nonetheless, a single crystal sapphire aluminum oxide endosseous implant was developed in 1972 as an alternative to metal. It was more esthetic than its metallic counterparts and was eventually produced in a variety of shapes and sizes. Clinical studies demonstrated its excellent soft and hard tissue biocompatibility, yet the range of problems included fractures during surgery, fractures after loading, mobility, infection, pain, bone loss, and lack of osseointegration. Ultimately, single crystal sapphire implants fell into irredeemable disfavor because of its poor impact strength, and dentists and surgeons eventually turned to other implant materials. However, bioactive ceramic coatings on metal implants have kept ceramics as a key component in dental implantology.

  3. A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

    Science.gov (United States)

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-01-01

    Objectives A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia–ceramic and metal–ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia–ceramic systems occurred more frequently than those in metal–ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Methods Vinyl-polysiloxane impressions of 12 zirconia–ceramic and 6 metal–ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3 ± 2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Results Among the 12 zirconia–ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal–ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Significance Zirconia–ceramic and metal–ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia–ceramic FDPs relative to their metal–ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia–ceramic FDPs. PMID:26233469

  4. Classifying dental ceramics: numerous materials and formulations available for indirect restorations.

    Science.gov (United States)

    Helvey, Gregg A

    2014-01-01

    Because there are numerous ceramic systems available to clinicians for all types of indirect restorations, deciding which system works best for a given clinical situation can be a challenge. Understanding the different classifications of ceramic restoratives can be helpful not only to the clinician but also the dental technician. Manufacturers are constantly introducing newer ceramic materials and improving their existing systems, which has resulted in an increase in all-ceramic restorations and fewer porcelain-to-metal restorations. The classification of ceramic materials remains mostly constant; however, it is subject to change based on newer materials and formulations. The classifications of ceramics are described using several different methods.

  5. Sensitivity analysis of bi-layered ceramic dental restorations.

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    Zhang, Zhongpu; Zhou, Shiwei; Li, Qing; Li, Wei; Swain, Michael V

    2012-02-01

    The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how "sensitive" the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Transmission of Er:YAG laser through different dental ceramics.

    Science.gov (United States)

    Sari, Tugrul; Tuncel, Ilkin; Usumez, Aslihan; Gutknecht, Norbert

    2014-01-01

    The aim of this study was to determine the erbium-doped yttrium aluminum garnet (Er:YAG) laser transmission ratio through different dental ceramics with different thicknesses. Laser debonding procedure of adhesively luted all-ceramic restorations is based on the transmission of laser energy through the ceramic and the ablation of resin cement, because of the transmitted laser energy. Five different dental ceramics were evaluated in this study: sintered zirconium-oxide core ceramic, monolithic zirconium-oxide ceramic, feldspathic ceramic, leucite-reinforced glass ceramic, and lithium disilicate-reinforced glass ceramic. Two ceramic discs with different thicknesses (0.5 and 1 mm) were fabricated for each group. Ceramic discs were placed between the sensor membrane of the laser power meter and the tip of the contact handpiece of an Er:YAG laser device with the aid of a custom- made acrylic holder. The transmission ratio of Er:YAG laser energy (500 mJ, 2 Hz, 1 W, 1000 μs) through different ceramic discs was measured with the power meter. Ten measurements were made for each group and the results were analyzed with two way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests. The highest transmission ratio was determined for lithium disilicate-reinforced ceramic with 0.5 mm thickness (88%) and the lowest was determined for feldspathic ceramic with 1 mm thickness (44%). The differences among the different ceramics and between the different thicknesses were significant (pCeramic type and thickness should be taken into consideration to adjust the laser irradiation parameters during laser debonding of adhesively luted all-ceramic restorations.

  7. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  8. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  9. Shear stress relaxation of dental ceramics determined from creep behavior.

    Science.gov (United States)

    DeHoff, Paul H; Anusavice, Kenneth J

    2004-10-01

    To test the hypothesis that shear stress relaxation functions of dental ceramics can be determined from creep functions measured in a beam-bending viscometer. Stress relaxation behavior was determined from creep data for the following materials: (1) a veneering ceramic-IPS Empress2 body ceramic (E2V); (2) an experimental veneering ceramic (EXV); (3) a low expansion body porcelain-Vita VMK 68 feldspathic body porcelain (VB); (4) a high expansion body porcelain-Will Ceram feldspathic body porcelain (WCB); (5) a medium expansion opaque porcelain-Vita feldspathic opaque porcelain (VO); and (6) a high expansion opaque porcelain-Will Ceram feldspathic opaque porcelain (WCO). Laplace transform techniques were used to relate shear stress relaxation functions to creep functions for an eight-parameter, discrete viscoelastic model. Nonlinear regression analysis was performed to fit a four-term exponential relaxation function for each material at each temperature. The relaxation functions were utilized in the ANSYS finite element program to simulate creep behavior in three-point bending for each material at each temperature. Shear stress relaxation times at 575 degrees C ranged from 0.03 s for EXV to 195 s for WCO. Knowledge of the shear relaxation functions for dental ceramics at high temperatures is required input for the viscoelastic element in the ANSYS finite element program, which can used to determine transient and residual stresses in dental prostheses during fabrication.

  10. A new classification system for all-ceramic and ceramic-like restorative materials.

    Science.gov (United States)

    Gracis, Stefano; Thompson, Van P; Ferencz, Jonathan L; Silva, Nelson R F A; Bonfante, Estevam A

    2015-01-01

    Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

  11. Randomized clinical trial of implant-supported ceramic-ceramic and metal-ceramic fixed dental prostheses: preliminary results.

    Science.gov (United States)

    Esquivel-Upshaw, Josephine F; Clark, Arthur E; Shuster, Jonathan J; Anusavice, Kenneth J

    2014-02-01

    The aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height. An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52-75 years) were recruited for the study to receive a three-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A. ceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD, and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality. Recall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher's exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure (p = 0.68), and connector height (p = 0

  12. Randomized Clinical Trial of Implant-Supported Ceramic-Ceramic and Metal-Ceramic Fixed Dental Prostheses: Preliminary Results

    Science.gov (United States)

    Esquivel-Upshaw, Josephine F.; Clark, Arthur E.; Shuster, Jonathan J.; Anusavice, Kenneth J.

    2013-01-01

    Purpose The aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52–75 years) were recruited for the study to receive a 3-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A. Material: ceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality. Results Recall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher’s exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure

  13. In Vitro Mechanical Tests for Modern Dental Ceramics

    Directory of Open Access Journals (Sweden)

    L. Sadighpour

    2006-01-01

    Full Text Available The fracture resistance of all-ceramic restorations is one of the major concerns in clinical applications of these materials. Before initiating a time-consuming and costly clinical investigation, an in vitro study can help to estimate the in vivo usability of a new dental material. Mechanical properties of all-ceramic materials are frequently evaluated to predict their clinical performance. Since the test methods have influences on the obtained results and mechanical behavior of ceramic materials, the differences between different methods and techniques should be well recognized.The aim of this review article was to briefly appraise mechanical test methods usually use to evaluate dental ceramic materials, and to discuss their clinical implication and limits in dentistry. The search was limited to PubMed and only available and the mostrelevant sources were included.

  14. An experimental bioactive dental ceramic for metal-ceramic restorations: Textural characteristics and investigation of the mechanical properties.

    Science.gov (United States)

    Goudouri, Ourania-Menti; Kontonasaki, Eleana; Papadopoulou, Lambrini; Manda, Marianthi; Kavouras, Panagiotis; Triantafyllidis, Konstantinos S; Stefanidou, Maria; Koidis, Petros; Paraskevopoulos, Konstantinos M

    2017-02-01

    The aim of this study was the evaluation of the textural characteristics of an experimental sol-gel derived feldspathic dental ceramic, which has already been proven bioactive and the investigation of its flexural strength through Weibull Statistical Analysis. The null hypothesis was that the flexural strength of the experimental and the commercial dental ceramic would be of the same order, resulting in a dental ceramic with apatite forming ability and adequate mechanical integrity. Although the flexural strength of the experimental ceramics was not statistically significant different compared to the commercial one, the amount of blind pores due to processing was greater. The textural characteristics of the experimental ceramic were in accordance with the standard low porosity levels reported for dental ceramics used for fixed prosthetic restorations. Feldspathic dental ceramics with typical textural characteristics and advanced mechanical properties as well as enhanced apatite forming ability can be synthesized through the sol-gel method. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Effects of different concentrations of carbamide peroxide and bleaching periods on the roughness of dental ceramics

    Directory of Open Access Journals (Sweden)

    Sérgio Augusto Morey Ourique

    2011-10-01

    Full Text Available The wide use of dental bleaching treatment has brought concern about the possible effects of hydrogen peroxide on dental tissue and restorative materials. The objective of this study was to evaluate in vitro the effect of nightguard bleaching on the surface roughness of dental ceramics after different periods of bleaching treatment. Fifteen specimens of 5 × 3 × 1 mm were created with three dental ceramics following the manufacturers' instructions: IPS Classic (Ivoclar-Vivadent; IPS d.Sign (Ivoclar-Vivadent; and VMK-95 (Vita. A profilometer was used to evaluate baseline surface roughness (Ra values of all ceramics by five parallel measurements with five 0.25 mm cut off (Λc at 0.1 mm/s. Afterwards, all specimens were submitted to 6-h daily bleaching treatments with 10% or 16% carbamide peroxide (Whiteness- FGM for 21 days, while control groups from each ceramic system were stored in artificial saliva. The surface roughness of all groups was evaluated after 18 h, 42 h, 84 h, and 126 h of bleaching treatment. The surface roughness of each specimen (n = 5 was based on the mean value of five parallel measurements in each time and all data were submitted to two-way repeated measures ANOVA and Tukey's post-hoc test (α = 0.05. No significant differences in ceramic surface roughness were observed between untreated and bleached ceramic surfaces, regardless of bleaching intervals or bleaching treatments. This study provided evidence that at-home bleaching systems do not cause detrimental effects on surface roughness of dental ceramics.

  16. Dental Encounter System (DES)

    Data.gov (United States)

    Department of Veterans Affairs — Dental Encounter System (DES) is an automated health care application designed to capture critical data about the operations of VA Dental Services. Information on...

  17. Y-TZP ceramic processing from coprecipitated powders: a comparative study with three commercial dental ceramics.

    Science.gov (United States)

    Lazar, Dolores R R; Bottino, Marco C; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H A

    2008-12-01

    (1) To synthesize 3mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. A coprecipitation route was used to synthesize a 3mol% yttria-stabilized zirconia ceramic processed by uniaxial compaction and pressureless sintering. Commercially available alumina or alumina/zirconia ceramics, namely Procera AllCeram (PA), In-Ceram Zirconia Block (CAZ) and In-Ceram Zirconia (IZ) were chosen for comparison. All specimens (6mmx5mmx5mm) were polished and ultrasonically cleaned. Qualitative phase analysis was performed by XRD and apparent densities were measured on the basis of Archimedes principle. Ceramics were also characterized using SEM, TEM and EDS. The hardness measurements were made employing Vickers hardness test. Fracture toughness (K(IC)) was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (alpha=0.05). ANOVA revealed that the Vickers hardness (pceramic materials composition. It was confirmed that the PA ceramic was constituted of a rhombohedral alumina matrix, so-called alpha-alumina. Both CAZ and IZ ceramics presented tetragonal zirconia and alpha-alumina mixture of phases. The SEM/EDS analysis confirmed the presence of aluminum in PA ceramic. In the IZ and CAZ ceramics aluminum, zirconium and cerium in grains involved by a second phase containing aluminum, silicon and lanthanum were identified. PA showed significantly higher mean Vickers hardness values (H(V)) (18.4+/-0.5GPa) compared to vitreous CAZ (10.3+/-0.2GPa) and IZ (10.6+/-0.4GPa) ceramics. Experimental Y-TZP showed significantly lower results than that of the other monophased ceramic (PA) (pceramics (pceramic processing conditions led to ceramics with mechanical properties comparable to commercially available reinforced ceramic materials.

  18. Microstructure, composition, and etching topography of dental ceramics.

    Science.gov (United States)

    Della Bona, Alvaro; Anusavice, Kenneth J

    2002-01-01

    Topographic analysis of etched ceramics provides qualitative surface structure information that affects micromechanical retention mechanisms. This study tested the hypothesis that the etching mechanism changes according to the type of etchant and the ceramic microstructure and composition. Quantitative and qualitative analyses of 15 dental ceramics were performed using scanning electron microscopy, back-scattered imaging, X-ray diffraction, optical profilometry, and wavelength dispersive spectroscopy based on Phi-Rho-Z correction. All ceramic specimens were polished to 1 micron with diamond compound, and the following etchants and etching times were used: ammonium bifluoride (ABF) for 1 minute, 9.6% hydrofluoric acid (HF) for 2 minutes, and 4% acidulated phosphate fluoride (APF) for 2 minutes. HF produced an irregular etching pattern in which pores were the characteristic topographic feature. ABF-etched ceramic surfaces showed mostly grooves, and APF etchant caused a buildup of surface precipitate. Core ceramics showed less topographic change after etching because of their high alumina content and low chemical reactivity. The observations suggest that the etching mechanism is different for the three etchants, with HF producing the most prominent etching pattern on all dental ceramics examined.

  19. The influence of silane evaporation procedures on microtensile bond strength between a dental ceramic and a resin cement

    OpenAIRE

    Pereira Carolina; Buono Vicente; Mota Joao Mauricio

    2010-01-01

    Aim: To assess the influence of silane evaporation procedures on bond strength between a dental ceramic and a chemically activated resin cement. Materials and Methods: Eighteen blocks (6 mm Χ 14 mm Χ 14 mm) of ceramic IPS Empress 2 were cemented (C and B) to composite resin (InTen-S) blocks using a chemical adhesive system (Lok). Six groups were analyzed, each with three blocks divided according to ceramic surface treatment: two control groups (no treatment, NT; 10% hydroflu...

  20. Interfacial modulus mapping of layered dental ceramics using nanoindentation

    Science.gov (United States)

    Bushby, Andrew J; P'ng, Ken MY; Wilson, Rory M

    2016-01-01

    PURPOSE The aim of this study was to test the modulus of elasticity (E) across the interfaces of yttria stabilized zirconia (YTZP) / veneer multilayers using nanoindentation. MATERIALS AND METHODS YTZP core material (KaVo-Everest, Germany) specimens were either coated with a liner (IPS e.max ZirLiner, Ivoclar-Vivadent) (Type-1) or left as-sintered (Type-2) and subsequently veneered with a pressable glass-ceramic (IPS e.max ZirPress, Ivoclar-Vivadent). A 5 µm (nominal tip diameter) spherical indenter was used with a UMIS CSIRO 2000 (ASI, Canberra, Australia) nanoindenter system to test E across the exposed and polished interfaces of both specimen types. The multiple point load – partial unload method was used for E determination. All materials used were characterized using Scanning Electron Microscopy (SEM) and X – ray powder diffraction (XRD). E mappings of the areas tested were produced from the nanoindentation data. RESULTS A significantly (P<.05) lower E value between Type-1 and Type-2 specimens at a distance of 40 µm in the veneer material was associated with the liner. XRD and SEM characterization of the zirconia sample showed a fine grained bulk tetragonal phase. IPS e-max ZirPress and IPS e-max ZirLiner materials were characterized as amorphous. CONCLUSION The liner between the YTZP core and the heat pressed veneer may act as a weak link in this dental multilayer due to its significantly (P<.05) lower E. The present study has shown nanoindentation using spherical indentation and the multiple point load - partial unload method to be reliable predictors of E and useful evaluation tools for layered dental ceramic interfaces. PMID:28018566

  1. Topological design of all-ceramic dental bridges for enhancing fracture resistance.

    Science.gov (United States)

    Zhang, Zhongpu; Chen, Junning; Li, Eric; Li, Wei; Swain, Michael; Li, Qing

    2016-06-01

    Layered all-ceramic systems have been increasingly adopted in major dental prostheses. However, ceramics are inherently brittle, and they often subject to premature failure under high occlusion forces especially in the posterior region. This study aimed to develop mechanically sound novel topological designs for all-ceramic dental bridges by minimizing the fracture incidence under given loading conditions. A bi-directional evolutionary structural optimization (BESO) technique is implemented within the extended finite element method (XFEM) framework. Extended finite element method allows modeling crack initiation and propagation inside all-ceramic restoration systems. Following this, BESO searches the optimum distribution of two different ceramic materials, namely porcelain and zirconia, for minimizing fracture incidence. A performance index, as per a ratio of peak tensile stress to material strength, is used as a design objective. In this study, the novel XFEM based BESO topology optimization significantly improved structural strength by minimizing performance index for suppressing fracture incidence in the structures. As expected, the fracture resistance and factor of safety of fixed partial dentures structure increased upon redistributing zirconia and porcelain in the optimal topological configuration. Dental CAD/CAM systems and the emerging 3D printing technology were commercially available to facilitate implementation of such a computational design, exhibiting considerable potential for clinical application in the future. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Reliability and strength of all-ceramic dental restorations fabricated by direct ceramic machining (DCM).

    Science.gov (United States)

    Filser, F; Kocher, P; Weibel, F; Lüthy, H; Schärer, P; Gauckler, L J

    2001-04-01

    All-ceramic dental bridges for the molar region are not yet available at reasonable costs. The novel direct ceramic machining (DCM) process allows an easy, reliable and rapid fabrication for all-ceramic dental restorations with high mechanical strength and good biocompatibility. In DCM, an enlarged framework is easily milled out of a pre-fabricated porous ceramic blank made of zirconia. After sintering to full density, no further time-consuming hard machining with diamond tools is needed. For individual esthetical requirements, the framework is coated with a veneer porcelain. Compared to the commercially available In-Ceram Alumina and IPS Empress2 restorations, the mechanical strength of zirconia frameworks is twice as high, allowing the restorations to bear the high mastication forces in the molar region. In terms of reliability, zirconia bridges fabricated by the DCM process are also superior to In-Ceram Alumina and IPS Empress2. A clinical study of three-unit dental bridges in the molar region found no problems after the first year of observation.

  3. Residual stresses in bilayer dental ceramics.

    Science.gov (United States)

    Taskonak, Burak; Mecholsky, John J; Anusavice, Kenneth J

    2005-06-01

    It is clinically observed that lithia-disilicate-based all-ceramic fixed partial dentures (FPD) can fail because of the fragmentation of the veneering material. The hypothesis of this study is that the global residual stresses within the surface of those veneered FPDs may be responsible for partial fragmentation of the veneering ceramic. Bilayer and monolithic ceramic composites were prepared using a lithia disilicate based (Li2OSiO2) glass-ceramic core and a glass veneer. A four-step fracture mechanics approach was used to analyze residual stress in bilayered all-ceramic FPDs. We found a statistically significant increase in the mean flexural strengths of bilayer specimens compared with monolithic glass specimens (p < or = 0.05). There was a statistically significant difference between the mean longitudinal and transverse indentation-induced crack sizes in bilayer specimens (p < or = 0.05), which indicates the existence of residual stress. Global residual stresses in the veneer layer, calculated using a fracture mechanics equation, were determined to be responsible for the increased strength and observed chipping, i.e., spallation in bilayer ceramic composites.

  4. Assessment of measurement techniques to determine the interfacial properties of bilayer dental ceramics

    Science.gov (United States)

    Anunmana, Chuchai

    The clinical success of all-ceramic dental restorations depends on the quality of interfacial bonding between ceramic layers. In addition, the residual stress in the structure that developed during ceramic processing is one of the important factors that contributes to the quality of the bond. Because all-ceramic restorations are usually fabricated as bilayer or trilayer structures and failures of all-ceramic restorations have been frequently reported as chipping or delamination of the veneer layers, the interfacial quality of bilayer dental ceramic restorations was investigated. However, most of the published bond test data reflect strength values that are inversely related to cross-sectional areas and failure locations are frequently disregarded or bond strength values are misinterpreted. In addition, residual tensile stresses that develop in the structures because of thermal expansion/contraction mismatches may also adversely affect interfacial fracture resistance. The first objective of this study was to determine the interfacial toughness of bonded bilayer ceramics using two different approaches. The results indicate that the short-bar chevron-notch test and a controlled-flaw microtensile test can induce interfacial failure that represents true bonding quality. The second objective of this study was to test the hypothesis that residual stresses estimated from an indentation technique are not significantly different from residual stresses that are calculated based on fractography and flexural strength. The indentation technique may be useful as a simplified method to determine residual stresses in bilayer dental ceramics. The results of this study demonstrate that there is no significant difference in mean residual stresses determined from the two techniques. Because of relationship between residual stresses and apparent interfacial toughness, estimates of residual stresses can now be estimated more rapidly by measuring the apparent interfacial toughness of

  5. Dental ceramics and the molar crown testing ground

    Directory of Open Access Journals (Sweden)

    Van P. Thompson

    2004-01-01

    Full Text Available All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior, and flexural cracking. Constitutive equations based upon materials properties have been developed that predict the damage modes operational for a given ceramic and thickness. Ceramic thickness or thickness of the stiff supporting core in layer crowns is critical in flexural cracking as well as the flaw state of the inner aspect of the crown. The elastic module of the supporting structure and of the luting cement and its thickness play a role in flexural fracture. Clinical studies of ceramics extending over 16 years are compared to the above relationships and predictions. Recommendations for clinical practice are made based upon the above.

  6. Properties and Clinical Application of Three Types of Dental Glass-Ceramics and Ceramics for CAD-CAM Technologies

    Science.gov (United States)

    Ritzberger, Christian; Apel, Elke; Höland, Wolfram; Peschke, Arnd; Rheinberger, Volker M.

    2010-01-01

    The main properties (mechanical, thermal and chemical) and clinical application for dental restoration are demonstrated for three types of glass-ceramics and sintered polycrystalline ceramic produced by Ivoclar Vivadent AG. Two types of glass-ceramics are derived from the leucite-type and the lithium disilicate-type. The third type of dental materials represents a ZrO2 ceramic. CAD/CAM technology is a procedure to manufacture dental ceramic restoration. Leucite-type glass-ceramics demonstrate high translucency, preferable optical/mechanical properties and an application as dental inlays, onlays and crowns. Based on an improvement of the mechanical parameters, specially the strength and toughness, the lithium disilicate glass-ceramics are used as crowns; applying a procedure to machine an intermediate product and producing the final glass-ceramic by an additional heat treatment. Small dental bridges of lithium disilicate glass-ceramic were fabricated using a molding technology. ZrO2 ceramics show high toughness and strength and were veneered with fluoroapatite glass-ceramic. Machining is possible with a porous intermediate product.

  7. Dental Implant Systems

    Science.gov (United States)

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  8. Dental Implant Systems

    Directory of Open Access Journals (Sweden)

    Yoshiki Oshida

    2010-04-01

    Full Text Available Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities.

  9. Evolution of Dental Ceramic from the Platinum Foil to CAD-CAM Technologies: Review

    OpenAIRE

    Isgrò G; Sachs A.

    2015-01-01

    New ceramic materials and novel fabrication methods have been developed and introduced in dentistry with the aim to improve the longevity of dental ceramic restorations and to extent their use for more demanding clinical situations like construction of multi units posterior fixed partial dentures (FPDs). Dental ceramics have now reached a stage of development where it is possible to make long-span metal free posterior FPDs. Dentists and dental technicians should have knowledge&...

  10. Novel dental composites reinforced with zirconia-silica ceramic nanofibers.

    Science.gov (United States)

    Guo, Guangqing; Fan, Yuwei; Zhang, Jian-Feng; Hagan, Joseph L; Xu, Xiaoming

    2012-04-01

    To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37°C deionized water for 24h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey's Honestly Significant Differences test used for post hoc analysis. Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Adjusting dental ceramics: An in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface.

    Science.gov (United States)

    Steiner, René; Beier, Ulrike S; Heiss-Kisielewsky, Irene; Engelmeier, Robert; Dumfahrt, Herbert; Dhima, Matilda

    2015-06-01

    During the insertion appointment, the practitioner is often faced with the need to adjust ceramic surfaces to fit a restoration to the adjacent or opposing dentition and soft tissues. The purpose of this study was to assess the ceramic surface smoothness achieved with various commercially available ceramic polishing kits on different commonly used ceramic systems. The reliability of the cost of a polishing kit as an indicator of improved surface smoothness was assessed. A total of 350 ceramic surfaces representing 5 commonly available ceramic systems (IPS Empress Esthetic, IPS e.max Press, Cergo Kiss, Vita PM 9, Imagine PressX) were treated with 5 types of ceramic polishing systems (Cerapreshine, 94006C, Ceramiste, Optrafine, Zenostar) by following the manufacturers' guidelines. The surface roughness was measured with a profilometer (Taylor Hobson; Precision Taylor Hobson Ltd). The effects of ceramic systems and polishing kits of interest on surface roughness were analyzed by 2-way ANOVA, paired t test, and Bonferroni corrected significance level. The ceramic systems and polishing kits statistically affected surface roughness (Pceramic surface. No correlation could be established between the high cost of the polishing kit and low surface roughness. None of the commonly used ceramic polishing kits could create a surface smoother than that of glazed ceramic (Pceramic polishing kits is not recommended as a reliable indicator of better performance of ceramic polishing kits (P>.30). Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  12. Microwave processing of a dental ceramic used in computer-aided design/computer-aided manufacturing.

    Science.gov (United States)

    Pendola, Martin; Saha, Subrata

    2015-01-01

    Because of their favorable mechanical properties and natural esthetics, ceramics are widely used in restorative dentistry. The conventional ceramic sintering process required for their use is usually slow, however, and the equipment has an elevated energy consumption. Sintering processes that use microwaves have several advantages compared to regular sintering: shorter processing times, lower energy consumption, and the capacity for volumetric heating. The objective of this study was to test the mechanical properties of a dental ceramic used in computer-aided design/computer-aided manufacturing (CAD/CAM) after the specimens were processed with microwave hybrid sintering. Density, hardness, and bending strength were measured. When ceramic specimens were sintered with microwaves, the processing times were reduced and protocols were simplified. Hardness was improved almost 20% compared to regular sintering, and flexural strength measurements suggested that specimens were approximately 50% stronger than specimens sintered in a conventional system. Microwave hybrid sintering may preserve or improve the mechanical properties of dental ceramics designed for CAD/CAM processing systems, reducing processing and waiting times.

  13. Biomechanical Analysis of Individual All-Ceramic Abutments Used in Dental Implantology

    Directory of Open Access Journals (Sweden)

    Ziębowicz B.

    2016-09-01

    Full Text Available The paper presents the results of finite element analysis and experimental testing under simulated physiological loading conditions on issues shaping the functional properties of individual all-ceramic abutments manufactured by CAD/CAM technology. The conducted research have cognitive significance showing the all-ceramic abutment behavior, as a key element of the implantological system, under the action of cyclic load. The aim of this study was evaluation the fatigue behavior of yttria-stabilized zirconia abutment submitted to cyclic stresses, conducted in accordance with EN ISO 14801 applies to dynamic fatigue tests of endosseous dental implants.

  14. Effect of ceramic dental waste in thermo-physical properties of materials composed with polyester resins

    Directory of Open Access Journals (Sweden)

    Lorena Martínez-Maldonado

    2014-12-01

    Full Text Available Thermophysical properties at room temperature of a composite material based on polyester resins and powders obtained from dental ceramic residues for mixtures with percentage by weight of 50-50, 60-40, 70- 30, 80-20 and 90-10 are recorded, where the minority phase are dental ceramic powders with particle size through sieve No. 200 (75 um, and the majority of pre-accelerated polyester resin brand P-2000, and as catalyst (Meck-Peroxide. The manufacturing process of the specimens was by casting them into cylindrical molds of diameter 3 cm and 6 cm long. The properties of conductivity (k and thermal diffusivity (α and the specific heat per unit volume (ρc, were found using the KD2 Pro® system which operates on the physical principle of linear transient heat flow. Thermal effusivity (ε was determined using data from k and α, and the expression ε = k/√ α. The results show that as the percentage of the ceramic powder is increased, the density of the samples increases, and thus the thermal conductivity (k, which is directly proportional to both heat diffusion rate (α and the amount of heat that the material can store or release (ρc. These results suggest a new material for technological applications, as well as they help to mitigate the environmental impact due to the recycling process of dental ceramic waste.

  15. CERAMICS FOR DENTAL RESTORATIONS - AN INTRODUCTION

    Directory of Open Access Journals (Sweden)

    SANTIAGO ARANGO SANTANDER

    2010-01-01

    Full Text Available Las cerámicas dentales son el material de elección para restauración oral debido a características como adecuada estética, elevada resistencia a la fractura y gran estabilidad química.En la actualidad, los profesionales de la Odontología tienen a su disposición una gran cantidad de sistemas cerámicos de restauración que presentan pequeñas o grandes diferencias en términos químicos, temperatura de procesamiento, resistencia mecánica y aplicación clínica, lo que lleva a sistemas de clasificación de las cerámicas que son poco útiles para profesionales ajenos a la odontología. El presente trabajo tuvo como objetivo hacer una revisión de los sistemas cerámicos de uso dental y presentarlos desde una perspectiva composicional para favorecer el entendimiento de profesionales ajenos a la Odontología. Se hizo un importante esfuerzo para evadir la clasificación que han impuesto las casas comerciales y tener así una rápida compilación de información disponible en la literatura que permita tener una visión general completa, pero no intensiva, del estado del arte de las cerámicas dentales.

  16. Fabrication of all-ceramic dental restorations with CEREC 3D CAD/CAM system%CEREC 3D系统制作全瓷修复体的临床研究

    Institute of Scientific and Technical Information of China (English)

    赵堂民; 王莹; 夏璐; 关丽娜; 刘戈边

    2013-01-01

    Objective:To observe clinical effect of all - ceramic dental restorations fabricated by CEREC 3D CAD/CAM system. Methods: Forty - one patients with 67 all - ceramic restorations were involved in this study. After one year, the clinical performance of the restoration was evaluated by the same dentist using modified USPHS criteria. Results; 86. 57% of all -ceramic restorations scored grade A by the modified USPHS criteria. The color matching of the restoration was satisfactory in 97. 01% patients with grade A by the criteria. Conclusion: The CEREC 3D CAD/CAM system could offer easy, accurate and quick fabrication of all -ceramic dental restorations with natural color.%目的:观察椅旁CAD/CAM系统CEREC 3D制作的各类全瓷修复体的临床应用效果.方法:选取41名患者,按照CAD/CAM系统CEREC 3D标准程序制作完成各类全瓷修复体67个.修复后追踪观察1年,由同一位医师按照改良的USPHS标准对修复体进行评价.结果:86.57%的全瓷修复体各项检查标准都达到了改良的USPHS标准的A类,颜色匹配方面最令人满意,达到A类标准者为97.01%.结论:CEREC 3D CAD/CAM系统能够便捷、精准、高效地制作具有天然牙色的全瓷修复体,临床效果令人满意.

  17. Systematic approach to preparing ceramic-glass composites with high translucency for dental restorations.

    Science.gov (United States)

    Yoshimura, Humberto N; Chimanski, Afonso; Cesar, Paulo F

    2015-10-01

    Ceramic composites are promising materials for dental restorations. However, it is difficult to prepare highly translucent composites due to the light scattering that occurs in multiphase ceramics. The objective of this work was to verify the effectiveness of a systematic approach in designing specific glass compositions with target properties in order to prepare glass infiltrated ceramic composites with high translucency. First it was necessary to calculate from literature data the viscosity of glass at the infiltration temperature using the SciGlass software. Then, a glass composition was designed for targeted viscosity and refractive index. The glass of the system SiO2-B2O3-Al2O3-La2O3-TiO2 prepared by melting the oxide raw materials was spontaneously infiltrated into porous alumina preforms at 1200°C. The optical properties were evaluated using a refractometer and a spectrophotometer. The absorption and scattering coefficients were calculated using the Kubelka-Munk model. The light transmittance of prepared composite was significantly higher than a commercial ceramic-glass composite, due to the matching of glass and preform refractive indexes which decreased the scattering, and also to the decrease in absorption coefficient. The proposed systematic approach was efficient for development of glass infiltrated ceramic composites with high translucency, which benefits include the better aesthetic performance of the final prosthesis. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Machinability of lithium disilicate glass ceramic in in vitro dental diamond bur adjusting process.

    Science.gov (United States)

    Song, Xiao-Fei; Ren, Hai-Tao; Yin, Ling

    2016-01-01

    Esthetic high-strength lithium disilicate glass ceramics (LDGC) are used for monolithic crowns and bridges produced in dental CAD/CAM and oral adjusting processes, which machinability affects the restorative quality. A machinability study has been made in the simulated oral clinical machining of LDGC with a dental handpiece and diamond burs, regarding the diamond tool wear and chip control, machining forces and energy, surface finish and integrity. Machining forces, speeds and energy in in vitro dental adjusting of LDGC were measured by a high-speed data acquisition and force sensor system. Machined LDGC surfaces were assessed using three-dimensional non-contact chromatic confocal optical profilometry and scanning electron microscopy (SEM). Diamond bur morphology and LDGC chip shapes were also examined using SEM. Minimum tool wear but significant LDGC chip accumulations were found. Machining forces and energy significantly depended on machining conditions (pMachining speeds dropped more rapidly with increased removal rates than other glass ceramics (pmachinability indices associated with the hardness, Young's modulus and fracture toughness were derived based on the normal force-removal rate relations, which ranked LDGC the most difficult to machine among glass ceramics. Surface roughness for machined LDGC was comparable for other glass ceramics. The removal mechanisms of LDGC were dominated by penetration-induced brittle fracture and shear-induced plastic deformation. Unlike most other glass ceramics, distinct intergranular and transgranular fractures of lithium disilicate crystals were found in LDGC. This research provides the fundamental data for dental clinicians on the machinability of LDGC in intraoral adjustments.

  19. Hertzian contact response and damage tolerance of dental ceramics.

    Science.gov (United States)

    Coldea, Andrea; Swain, Michael V; Thiel, Norbert

    2014-06-01

    To determine the contact response and damage tolerance or strength degradation of a range of dental CAD/CAM ceramic materials including novel polymer-infiltrated-ceramic-network (PICN) materials by means of spherical indentations at various loads and indenter radii. The seven tested materials included Mark II, PICN test materials 1 and 2, In-Ceram Alumina, VM 9, In-Ceram YZ (Vita Zahnfabrik, Bad Saeckingen, Germany) and IPS e.max CAD, (Ivoclar Vivadent, Schaan, Liechtenstein). To evaluate the damage tolerance and role of indenter size, indentations with tungsten carbide spheres (0.5mm and 1.25mm radius) were placed on bending bars with varying loads (1.96-1000N). The indented bending bars were subsequently loaded to fracture in three-point bending. The contact induced damage was analyzed by light microscopy (LM) and SEM. The spherical contact response was measured on polished surfaces. The initial strengths for the individual materials were found to reduce above specific indentation loads, which were a function of the indenter radius. Employing a 0.5mm radius sphere resulted in the following strength degrading loads and ordering of materials: VM9 (98N)different damage modes were observed by SEM and LM - brittle cone cracking and plastic deformation. The PICN materials exhibited elastic-plastic behavior with creep. In contrast YTZP showed entirely elastic behavior upon loading with both spheres. This study aims to emulate the likely clinical behavior of contact loading by opposing cusps to dental restorative ceramic materials by utilizing spherical indentations at various loads and sphere diameters. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Synthesis and testing of dental ceramic

    Directory of Open Access Journals (Sweden)

    Dhirendra Mishra*,

    2014-07-01

    Full Text Available Zirconia has been recently introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures, in combination with CAD/CAM techniques. Zirconia stabilized with Y2O3 has the best properties for these applications. This project aims at producing cast Zirconia blocks primarily for dental application that is more cost effective and biocompatible in comparison to the commercially available zirconia. A simple co-precipitation method was used to produce the zirconia powder; simple, inexpensive and indigenous method of uniaxial compression was employed to cast the zirconia pellet. Further studies have to be carried out to study and improve the densification behaviour, biocompatibility, aesthetics and resistance to masticatory force.

  1. Ceramics for dental restorations – an introduction

    OpenAIRE

    SANTIAGO ARANGO SANTANDER; ALEJANDRO PELÁEZ VARGAS; JORGE SALDARRIAGA ESCOBAR; FERNANDO JORGE MONTEIRO; LUIS FELIPE RESTREPO TAMAYO

    2011-01-01

    Las cerámicas dentales son el material de elección para restauración oral debido a características como adecuada estética, elevada resistencia a la fractura y gran estabilidad química.En la actualidad, los profesionales de la Odontología tienen a su disposición una gran cantidad de sistemas cerámicos de restauración que presentan pequeñas o grandes diferencias en términos químicos, temperatura de procesamiento, resistencia mecánica y aplicación clínica, lo que lleva a sistemas de clasificació...

  2. Central Dental Evacuation Systems.

    Science.gov (United States)

    1982-05-01

    20 High-Vacuum Oral Evacuation System (HIVAC) for Oral Surgery, Periodontics, and Endodontics Treatment Rooms..................... 20...handpiece. Inlets to this system are required throughout the dental facility for all disciplines of patient treatment where coolant and irrigation liquids...System (HIVAC) for Oral Surgery, Periodontics, and Endodontics Treatment Rooms The HIVAC system is designed to build and sustain high vacuum pressures

  3. Sliding contact fracture of dental ceramics: Principles and validation.

    Science.gov (United States)

    Ren, Linlin; Zhang, Yu

    2014-07-01

    Ceramic prostheses are subject to sliding contact under normal and tangential loads. Accurate prediction of the onset of fracture at two contacting surfaces holds the key to greater long-term performance of these prostheses. In this study, building on stress analysis of Hertzian contact and considering fracture criteria for linear elastic materials, a constitutive fracture mechanics relation was developed to incorporate the critical fracture load with the contact geometry, coefficient of friction and material fracture toughness. Critical loads necessary to cause fracture under a sliding indenter were calculated from the constitutive equation, and compared with the loads predicted from elastic stress analysis in conjunction with measured critical load for frictionless normal contact-a semi-empirical approach. The major predictions of the models were calibrated with experimentally determined critical loads of current and future dental ceramics after contact with a rigid spherical slider. Experimental results conform with the trends predicted by the models.

  4. Luminescence characterization of dental ceramics for individual retrospective dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Correcher, V.; Gomesdarocha, R. [CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Garcia G, J. [Consejo Superior de Investigaciones Cientificas, Museo Nacional de Ciencias Naturales, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Rivera M, T., E-mail: v.correcher@ciemat.es [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    Full text: Ceramic materials in general and dental crowns in particular exhibit thermoluminescence (Tl) properties and are of interest in the field of individual retrospective dosimetry. This property could be potentially employed to provide a means of determining cumulative exposure to external gamma radiation arising from accidents or large-scale incidents (radiological terrorism) involving population groups where conventional monitoring has not been established. The thermal stability and dose effect of the UV-blue Tl emission of a well characterized Spanish samples (by means of cathodoluminescence and electron-probe microanalysis) are here reported. It displays (i) an excellent linearity in the range of 0.12 - 9.6 Gy, (II) good stability of the Tl signal of 0.6, 1.2 and 2.4 Gy irradiated samples after 6 months of storage showing an initial rapid decay (ca. 30%) maintaining the stability from 30 days onwards. It means that the electron population decreases asymptotically by the X - axis and the involved electrons are located in deeper traps at room temperature. (III) The reusability performed on the dental ceramic, involving successive cycles of irradiation (1.2 Gy) followed by readout (up to 500 degrees C), exhibited a negligible variation in the Tl response, when measured six times. (IV) The tests of thermal stability at different temperatures (in the range of 100-240 degrees C) confirms a continuum in the trap distribution with progressive changes in the glow curve shape, intensity and temperature position of the maximum peak. Therefore, these preliminary results suggest that dental ceramics could be used as suitable dosimeters in retrospective conditions. (Author)

  5. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function

    OpenAIRE

    Øilo, Marit; Hardang, Anne Dybdahl; Ulsund, Amanda Hembre; Gjerdet,Nils Roar

    2014-01-01

    Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based res...

  6. Reliability and properties of core materials for all-ceramic dental restorations

    Directory of Open Access Journals (Sweden)

    Seiji Ban

    2008-07-01

    Full Text Available Various core materials have been used as all-ceramic dental restorations. Since many foreign zirconia product systems were introduced to the Japanese dental market in the past few years, the researches and the papers on zirconia for ceramic biomaterials have immediately drawn considerable attention. Recently, most of the manufactures supply zirconia blocks available to multi-unit posterior bridges using CAD/CAM, because zirconia has excellent mechanical properties comparable to metal, due to its microstructures. The properties of conventional zirconia were further improved by the composite in nano-scale such as zirconia/alumina nanocomposite (NANOZR. There are many interesting behaviors such as long-term stability related to low temperature degradation, effect of sandblasting and heat treatment on the microstructure and the strength, bonding to veneering porcelains, bonding to cement, visible light translucency related to esthetic restoration, X-ray opacity, biocompatibility, fracture load of clinical bridge as well as lifetime and clinical survival rates of the restoratives made with zirconia. From the recent material researches on zirconia not only in Japan but also in the world, this review takes into account these interesting properties of zirconia and reliability as core material for all-ceramic dental restorations.

  7. Influence of polishing procedures on the surface roughness of dental ceramics made by different techniques.

    Science.gov (United States)

    Oliveira-Junior, Osmir Batista; Buso, Leonardo; Fujiy, Fábio Hiroshi; Lombardo, Geraldo Henrique Leao; Campos, Fernanda; Sarmento, Hugo Ramalho; Souza, Rodrigo Othavio Assuncao

    2013-01-01

    The aim of this study was to evaluate the influence of 2 different surface polishing procedures-glazing and manual polishing-on the roughness of ceramics processed by computer-aided design/computer-aided manufacturing (CAD/CAM) and conventional systems (stratification technique). Eighty ceramic discs (diameter: 8 mm, thickness: 1 mm) were prepared and divided among 8 groups (n = 10) according to the type of ceramic disc and polishing method: 4 GZ and 4 MP. Specimens were glazed according to each manufacturer's recommendations. Two silicone polishing points were used on the ceramic surface for manual polishing. Roughness was measured using a surface roughness tester. The roughness measurements were made along a distance of 2 mm on the sample surface and the speed of reading was 0.1 mm/s. Three measurements were taken for each sample. The data (μm) were statistically analyzed using analysis of variance (ANOVA) and Tukey's test (α = 0.05). Qualitative analysis was performed using scanning electron microscopy (SEM). The mean (± SD) roughness values obtained for GZ were: 1.1 ± 0.40 μm; 1.0 ± 0.31 μm; 1.6 ± 0.31 μm; and 2.2 ± 0.73 μm. For MP, the mean values were: 0.66 ± 0.13 μm; 0.43 ± 0.14 μm; 1.6 ± 0.55 μm; and 2.0 ± 0.63 μm. The mean roughness values were significantly affected by the ceramic type (P = 0.0001) and polishing technique (P = 0.0047). The SEM images confirmed the roughness data. The manually polished glass CAD/CAM ceramics promoted lower surface roughness than did the glazed feldspathic dental ceramics.

  8. Long Term Fatigue Behavior of Zirconia Based Dental Ceramics

    Directory of Open Access Journals (Sweden)

    Moustafa N. Aboushelib

    2010-04-01

    Full Text Available This study evaluated the influence of cyclic loading on zirconia bar-shaped specimens after being subjected to three different surface treatments: particle abrasion with either 50 μm or 110 μm alumina and grinding with diamond points, while polished specimens served as a control. Statistical analysis revealed significant reduction (38-67% in flexure strength (P < 0.001 after three million cycles of dynamic loading for all surface treatments. Scanning electron imaging revealed grain boundary thickening, grain pull-out, and micro-cracking as the main structural defects. The results suggest that various surface treatments of zirconia based dental ceramics may significantly influence their long term fatigue resistance in the oral environment.

  9. The teaching of all-ceramic restorations in Scandinavian dental schools: a survey.

    Science.gov (United States)

    Jokstad, A; Mjör, I A; Frazier, K B

    1996-06-01

    The study was designed to survey the curricular requirements, types of clinical experience, and materials/ techniques used in teaching programs for all-ceramic restorations in Scandinavian dental schools. All 13 dental schools responded. Ten offered some clinical experience to pre-doctoral students, but only one required one all-ceramic restoration. The departments of fixed prosthodontics had the main teaching responsibility. All-ceramic crowns were taught at 9, veneers at 7, and inlays/onlays at 10 dental schools. A wide range of different teaching concepts, materials, and views on indications and contraindications was reported. It appears as if all-ceramic restorations are regarded as experimental by the teaching institutions, although the dental industry and some practitioners strongly recommend these types of restorations.

  10. Non-destructive thermo-mechanical behavior assessment of glass-ceramics for dental applications

    Science.gov (United States)

    Kordatos, E. Z.; Abdulkadhim, Z.; Feteira, A. M.

    2017-05-01

    Every year millions of people seek dental treatment to either repair damaged, unaesthetic and dysfunctional teeth or replace missing natural teeth. Several dental materials have been developed to meet the stringent requirements in terms of mechanical properties, aesthetics and chemical durability in the oral environment. Glass-ceramics exhibit a suitable combination of these properties for dental restorations. This research is focused on the assessment of the thermomechanical behavior of bio-ceramics and particularly lithium aluminosilicate glass-ceramics (LAS glass-ceramics). Specifically, methodologies based on Infrared Thermography (IRT) have been applied in order the structure - property relationship to be evaluated. Non-crystallized, partially crystallized and fully crystallized glass-ceramic samples have been non-destructively assessed in order their thermo-mechanical behavior to be associated with their micro-structural features.

  11. Adhesion between dental ceramic and bonding resin: quantitative evaluation by Vickers indenter methodology.

    Science.gov (United States)

    Doucet, Sylvie; Tavernier, Bruno; Colon, Pierre; Picard, Bernard

    2008-01-01

    The purpose of this study was to evaluate the adhesion to dental ceramic by Vickers indenter methodology. This technique allows the creation of adhesive fractures and determines the influence of the surface treatment on adhesive capacities. A single bond adhesive system (One Step Bisco) was applied to ceramic Vitapan 3D Master CE 0124 samples. Ceramic samples were polished with 500 or 4000-grit paper, sandblasted or not (Sa/NSa), treated with fluorhydric acid or not (A/NA) and silane or not (Si/NSi). The experimental groups (Gr) were: (Gr 1) 4000; (Gr 2) 4000+Si; (Gr 3) 4000+Sa+A; (Gr 4) 4000+Sa+A+Si; (Gr 5) 500+Sa+A+Si. Each sample was indented with the diamond Vickers indenter Leitz Durimet 2 (Wetzlar, Germany) using a load of 20N for 30s. The surfaces of the debonded areas were observed in an optical microscope providing a digital image of the debonded surface. The adhesion bond strength was calculated according to the formula of Engel and Roshon [Engel PA, Roshon DD. Indentation-debonding of an adhered surface layer. J Adhesion 1979;10(33): 237-53]. The statistical analysis was conducted using Student's t test (padhesion of an adhesive layer on a feldspathic ceramic.

  12. Updating Classifications of Ceramic Dental Materials: A Guide to Material Selection.

    Science.gov (United States)

    McLaren, Edward A; Figueira, Johan

    2015-06-01

    The indications for and composition of today's dental ceramic materials serve as the basis for determining the appropriate class of ceramics to use for a given case. By understanding the classifications, composition, and characteristics of the latest all-ceramic materials, which are presented in this article in order of most to least conservative, dentists and laboratory technicians can best determine the ideal material for a particular treatment.

  13. Effect of Ceramic Surface Treatments After Machine Grinding on the Biaxial Flexural Strength of Different CAD/CAM Dental Ceramics.

    Science.gov (United States)

    Bagheri, Hossein; Hooshmand, Tabassom; Aghajani, Farzaneh

    2015-09-01

    This study aimed to evaluate the effect of different ceramic surface treatments after machining grinding on the biaxial flexural strength (BFS) of machinable dental ceramics with different crystalline phases. Disk-shape specimens (10mm in diameter and 1.3mm in thickness) of machinable ceramic cores (two silica-based and one zirconia-based ceramics) were prepared. Each type of the ceramic surfaces was then randomly treated (n=15) with different treatments as follows: 1) machined finish as control, 2) machined finish and sandblasting with alumina, and 3) machined finish and hydrofluoric acid etching for the leucite and lithium disilicate-based ceramics, and for the zirconia; 1) machined finish and post-sintered as control, 2) machined finish, post-sintered, and sandblasting, and 3) machined finish, post-sintered, and Nd;YAG laser irradiation. The BFS were measured in a universal testing machine. Data based were analyzed by ANOVA and Tukey's multiple comparisons post-hoc test (α=0.05). The mean BFS of machined finish only surfaces for leucite ceramic was significantly higher than that of sandblasted (P=0.001) and acid etched surfaces (P=0.005). A significantly lower BFS was found after sandblasting for lithium disilicate compared with that of other groups (Pceramics was affected by the type of ceramic material and surface treatment method. Sandblasting with alumina was detrimental to the strength of only silica-based ceramics. Nd:YAG laser irradiation may lead to substantial strength degradation of zirconia.

  14. Strength degradation and lifetime prediction of dental zirconia ceramics under cyclic normal loading.

    Science.gov (United States)

    Li, Wanzhong; Xu, Yingqiang; He, Huiming; Zhao, Haidan; Sun, Jian; Hou, Yue

    2015-01-01

    Clinical cases show that zirconia restoration could happen fracture by accident under overloading after using a period of time. The purpose of this study is to research mechanical behavior and predict lifetime of dental zirconia ceramics under cyclic normal contact loading with experiments. Cyclic normal contact loading test and three point bending test are carried on specimens made of two brands of dental zirconia ceramic to obtain flexure strength and damage degree after different number of loading cycles. By means of damage mechanics model, damage degree under different number of contact loading cycles are calculated according to flexure strength, and verified by SEM photographs of cross section morphology of zirconia ceramics specimen phenomenologically. Relation curve of damage degree and number of cycles is fitted by polynomial fitting, then the number of loading cycles can be concluded when the specimen is complete damage. Strength degradation of two brands dental zirconia ceramics are researched in vitro, and prediction method of contact fatigue lifetime is established.

  15. Fracture and shear bond strength analyses of different dental veneering ceramics to zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, Alexandre C. [School of Dentistry (DOD), Division of Prosthodontics, Universidade Federal do Rio Grande do Norte -UFRN, 59056-000, Natal (Brazil); Nascimento, Rubens M. [Materials Engineering Department, Universidade Federal do Rio Grande do Norte - UFRN, Natal (Brazil); Souza, Julio C.M. [Centre for Mechanics and Materials Technologies - CT2M, Department of Mechanical Engineering (DEM), Universidade do Minho, Campus Azurém, 4800-058, Guimarães (Portugal); Henriques, Bruno B. [Materials Engineering Department, Universidade Federal do Rio Grande do Norte - UFRN, Natal (Brazil); Centre for Mechanics and Materials Technologies - CT2M, Department of Mechanical Engineering (DEM), Universidade do Minho, Campus Azurém, 4800-058, Guimarães (Portugal); Carreiro, Adriana F.P., E-mail: adrianadafonte@hotmail.com [School of Dentistry (DOD), Division of Prosthodontics, Universidade Federal do Rio Grande do Norte -UFRN, 59056-000, Natal (Brazil)

    2014-05-01

    The purpose of this work was to evaluate the interaction of different layering porcelains with zirconia via shear bond strength test and microscopy. Four different groups of dental veneering porcelains (VM9, Zirkonzanh, Ceramco, IPS) were fused onto forty zirconia-based cylindrical substrates (8 mm in diameter and 12 mm in height) (n = 10), according to the manufacturer's recommendations. Additionally, layered dental porcelain (D-sign, Ivoclar) was fired on ten Ni–Cr cylindrical substrates Shear bond strength tests of the veneering porcelain to zirconia or Ni–Cr were carried out at a crosshead speed of 0.5 mm/min. After the shear bond tests, the interfaces were analyzed by scanning electron microscopy (SEM). The fracture type exhibited by the different systems was also assessed. The results were statistically analyzed by ANOVA at a significant level of p < .05. The shear bond strength values of the porcelain-to-NiCr interfaces (25.3 ± 7.1 MPa) were significantly higher than those recorded for the following porcelain-to-zirconia systems: Zirkonzanh (18.8 ± 1 MPa), Ceramco (18.2 ± 4.7 MPa), and IPS (16 ± 4.5 MPa). However, no significant differences were found in the shear bond strength values between the porcelain-to-NiCr and porcelain (VM9)-to-zirconia (23.2 ± 5.1 MPa) groups (p > .05). All-ceramic interfaces revealed mixed failure type, cohesive in the porcelain and adhesive at the interface. This study demonstrated that all-ceramic systems do not attain yet the same bond strength standards equivalent to metal–ceramic systems. Therefore, despite the esthetic appeal of all-ceramic restorations, the adhesion between the porcelain and zirconia framework is still an issue considering the long term success of the restoration. - Highlights: • This study assessed the shear bond strength of different porcelains to zirconia. • The porcelain Vita VM9 showed a high shear bond strength to zirconia. • The fracture surface of all-ceramic systems revealed

  16. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly.

    Science.gov (United States)

    Lu, Xiaoli; Xia, Yang; Liu, Mei; Qian, Yunzhu; Zhou, Xuefeng; Gu, Ning; Zhang, Feimin

    2012-01-01

    To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride)] and anionic [poly(sodium 4-styrenesulfonate)] polymers to improve the dispersion and adsorption of positively charged nano-ZrO(2) (zirconia) as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO(2). To determine the optimum addition levels for nano-ZrO(2), ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO(2) were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO(2) resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P ceramics are good potential candidates for ceramic-based dental materials.

  17. Laser treatment of dental ceramic/cement layers: transmitted energy, temperature effects and surface characterisation.

    Science.gov (United States)

    Pich, Olena; Franzen, René; Gutknecht, Norbert; Wolfart, Stefan

    2015-02-01

    In the present paper, we investigate the behaviour of different dental materials under laser irradiation. We have used e.max Ceram, e.max ZirCAD, and e.max Press dental ceramics and glass ionomer cement Ketac Cem in the present study. The dental ceramics were prepared in the form of samples with thickness of 0.5-2 mm. We used two lasers [solid-state laser (Er:YAG, Fidelis III+, Fotona) and an 810- nm diode laser (FOX, A.R.C)] for the transillumination of ceramic samples. It has been shown that the laser energy transmitted through the ceramic material decreases to 30-40% of the original values along with an increase in the thickness of the irradiated sample. Pigmented ceramic samples show more laser energy loss compared to the samples containing no pigment. We investigated the temperature evolution in composite sandwiched ceramic/cement samples under laser treatment. The increase in the irradiation time and laser power led to a temperature increase of up to 80 °C. The surfaces of irradiated ceramic samples were examined with X-ray photoelectron spectroscopy to evaluate changes in chemical composition, such as a decrease in the C signal, accompanied by a strong increase in the Zr peak for the Er:YAG laser, while the 810-nm diode laser showed no change in the ratio of elements on the surface.

  18. Effects of Number of Firings on the Microstructure and Color Difference of Dental All-ceramic Systems%烧结次数对牙科全瓷微结构和色差的影响

    Institute of Scientific and Technical Information of China (English)

    庞莉苹; 姚江武

    2012-01-01

    Objective: To evaluate the effects of number of firings on the microstructure and color difference of dental all-ceramic systems. Methods: Specimens were made of three kinds of all- ceramics systems i. e. heat pressed all-ceramic (IPS Empress Ⅱ) . alumina all-ceramic (In-Cream alumina) and zirconia all -ceramic (Cer-con CAD/CAM zirconia). Specimens after firings were characterised using X-ray diffractQmer(XRD) and scanning electron microscope (SEM)and color difference (AE * ab) of all-ceramic after firings was measured and calculated by spectrophotometer. Results: XRD and SEM revealed the transformation of core and veneering material of Empress H from an amorphous glass to a crystalline phase and the change of alumina and zirconia in reverse after 5 firings. Significant interactions were present between the number of firings and the brand and △E * ab (P the change of color difference after 5 firings was still within perceptible and acceptable range.%目的:评价烧结次数对牙科全瓷微结构和色差的影响.方法:样本由3种品牌的全瓷材料制作,即:热压全瓷(IPS EmpressⅡ)、氧化铝全瓷(In-Cream alumina)和氧化锆全瓷(Cercon CAD/CAM zirconia).通过X射线衍射仪(x- ray diffractomer,XRD)和扫描电子显微镜(scanning electron microscope,SEM)表征烧结后全瓷样本,分光光谱仪上测量和计算烧结后全瓷样本的色差(△E* ab).结果:XRD和SEM结果显示5次烧结后热压全瓷基底冠和饰面瓷均发生由无定形玻璃相向晶相的转变,而氧化铝全瓷和氧化错全瓷的转变则相反.烧结次数与全瓷品牌和△E* ab之间存在交互作用(P<0.05).氧化铝全瓷5次烧结后的色差最大(1.9),已接近临床可接受色差的域值.结论:烧结次数因玻璃相与晶相之间的相互转变对色差造成影响,5次烧结后热压全瓷发生了玻璃相向晶相的转化,氧化锆全瓷几乎不受影响.但5次烧结后的3种全瓷的色差变化仍在视觉可接受范围内.

  19. Systemic disorders affecting dental pathology

    Directory of Open Access Journals (Sweden)

    Knežević Milan R

    2014-12-01

    Full Text Available A retrospective overview of systemic disorders which might be associated with dental pathology is made. They are grouped as follows: (a congenital dental developmental disorders, (b chromosomal anomalies, (c radiations, (d immune disorders, (e intoxications, (f neurological alterations, (g gastrointestinal diseases, (h osteodystrophy and associated conditions, (i skin diseases, (j metabolic and endocrine disorders, (k craniofacial malformation syndromes and other congenital general malformations. The associated dental pathology is described in each case.

  20. Measuring residual stress in ceramic zirconia-porcelain dental crowns by nanoindentation.

    Science.gov (United States)

    Zhang, Y; Allahkarami, M; Hanan, J C

    2012-02-01

    Residual stress plays a critical role in failure of ceramic dental crowns. The magnitude and distribution of residual stress in the crown system are largely unknown. Determining the residual stress quantitatively is challenging since the crown has such complex contours and shapes. This work explored the feasibility and validity of measuring residual stress of zirconia and porcelain in ceramic crowns by nanoindentation. Nanoindentation tests were performed on the cross-section of a crown for both porcelain and zirconia along four critical locations: the thickest, thinnest and medium porcelain thicknesses. Zirconia and porcelain pieces, chipped off from the crown and annealed at 400 °C, were used as reference samples. The residual stress was determined by comparing the measured hardness of the stressed sample with that of the reference sample. Nanoindentation impression images were acquired through a scanning probe microscope (SPM) equipped with a Hysitron Triboindenter. Zirconia showed large pile-up. Residual stress is determined along the thickness of crowns at the chosen locations for both porcelain and zirconia. The measured results were compared with the results from X-ray diffraction (XRD) and finite element modeling (FEM). Results show there are large amounts of residual stresses in the dental crown and their magnitude differs between locations due to the complex shape of the crown. The average residual stress readings were as high as -637 MPa and 323 MPa for zirconia and porcelain respectively.

  1. [Preliminary study of bonding strength between diatomite-based dental ceramic and veneering porcelains].

    Science.gov (United States)

    Lu, Xiao-li; Gao, Mei-qin; Cheng, Yu-ye; Zhang, Fei-min

    2015-04-01

    In order to choose the best veneering porcelain for diatomite-based dental ceramic substrate, the bonding strength between diatomite-based dental ceramics and veneering porcelains was measured, and the microstructure and elements distribution of interface were analyzed. The coefficient of thermal expansion (CTE) of diatomite-based dental ceramics was detected by dilatometry. Three veneering porcelain materials were selected with the best CTE matching including alumina veneering porcelain (group A), titanium porcelain veneering porcelain (group B), and E-max veneering porcelain (group C). Shear bonding strength was detected. SEM and EDS were used to observe the interface microstructure and element distribution. Statistical analysis was performed using SPSS 17.0 software package. The CTE of diatomite-based dental ceramics at 25-500 degrees centigrade was 8.85×10-6K-1. The diatomite-based substrate ceramics combined best with group C. Shear bonding strength between group A and C and group B and C both showed significant differences(Pdiatomite-based substrate ceramics combines better with E-max porcelain veneer.

  2. Soft tissue adhesion of polished versus glazed lithium disilicate ceramic for dental applications.

    Science.gov (United States)

    Brunot-Gohin, C; Duval, J-L; Azogui, E-E; Jannetta, R; Pezron, I; Laurent-Maquin, D; Gangloff, S C; Egles, C

    2013-09-01

    Ceramics are widely used materials for prosthesis, especially in dental fields. Despite multiple biomedical applications, little is known about ceramic surface modifications and the resulting cell behavior at its contact. The aim of this study is to evaluate the biological response of polished versus glazed surface treatments on lithium disilicate dental ceramic. We studied a lithium disilicate ceramic (IPS e.max(®) Press, Ivoclar Vivadent) with 3 different surface treatments: raw surface treatment, hand polished surface treatment, and glazed surface treatment (control samples are Thermanox(®), Nunc). In order to evaluate the possible modulation of cell response at the surface of ceramic, we compared polished versus glazed ceramics using an organotypic culture model of chicken epithelium. Our results show that the surface roughness is not modified as demonstrated by equivalent Ra measurements. On the contrary, the contact angle θ in water is very different between polished (84°) and glazed (33°) samples. The culture of epithelial tissues allowed a very precise assessment of histocompatibility of these interfaces and showed that polished samples increased cell adhesion and proliferation as compared to glazed samples. Lithium disilicate polished ceramic provided better adhesion and proliferation than lithium disilicate glazed ceramic. Taken together, our results demonstrate for the first time, how it is possible to use simple surface modifications to finely modulate the adhesion of tissues. Our results will help dental surgeons to choose the most appropriate surface treatment for a specific clinical application, in particular for the ceramic implant collar. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. An optical coherence tomography investigation of materials defects in ceramic fixed partial dental prostheses

    Science.gov (United States)

    Sinescu, Cosmin; Negrutiu, Meda; Hughes, Michael; Bradu, Adrian; Todea, Carmen; Rominu, Mihai; Laissue, Philippe L.; Podoleanu, Adrian Gh.

    2008-04-01

    Metal ceramic and integral ceramic fixed partial prostheses are mainly used in the frontal part of the dental arch because for esthetics reasons. The masticatory stress may induce fractures of the bridges. There are several factors that are associated with the stress state created in ceramic restorations, including: thickness of ceramic layers, mechanical properties of the materials, elastic modulus of the supporting substrate material, direction, magnitude and frequency of applied load, size and location of occlusal contact areas, residual stresses induced by processing or pores, restoration-cement interfacial defects and environmental defects. The fractures of these bridges lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of optical coherence tomography (OCT) in detection and analysis of possible material defects in metal-ceramic and integral ceramic fixed partial dentures.

  4. Effect of acidic agents on surface roughness of dental ceramics

    Directory of Open Access Journals (Sweden)

    Boonlert Kukiattrakoon

    2011-01-01

    Conclusion: Acidic agents used in this study negatively affected the surface of ceramic materials. This should be considered when restoring the eroded tooth with ceramic restorations in patients who have a high risk of erosive conditions.

  5. Effect of Ceramic Surface Treatments After Machine Grinding on the Biaxial Flexural Strength of Different CAD/CAM Dental Ceramics

    Science.gov (United States)

    Bagheri, Hossein; Aghajani, Farzaneh

    2015-01-01

    Objectives: This study aimed to evaluate the effect of different ceramic surface treatments after machining grinding on the biaxial flexural strength (BFS) of machinable dental ceramics with different crystalline phases. Materials and Methods: Disk-shape specimens (10mm in diameter and 1.3mm in thickness) of machinable ceramic cores (two silica-based and one zirconia-based ceramics) were prepared. Each type of the ceramic surfaces was then randomly treated (n=15) with different treatments as follows: 1) machined finish as control, 2) machined finish and sandblasting with alumina, and 3) machined finish and hydrofluoric acid etching for the leucite and lithium disilicate-based ceramics, and for the zirconia; 1) machined finish and post-sintered as control, 2) machined finish, post-sintered, and sandblasting, and 3) machined finish, post-sintered, and Nd;YAG laser irradiation. The BFS were measured in a universal testing machine. Data based were analyzed by ANOVA and Tukey’s multiple comparisons post-hoc test (α=0.05). Results: The mean BFS of machined finish only surfaces for leucite ceramic was significantly higher than that of sandblasted (P=0.001) and acid etched surfaces (P=0.005). A significantly lower BFS was found after sandblasting for lithium disilicate compared with that of other groups (P<0.05). Sandblasting significantly increased the BFS for the zirconia (P<0.05), but the BFS was significantly decreased after laser irradiation (P<0.05). Conclusions: The BFS of the machinable ceramics was affected by the type of ceramic material and surface treatment method. Sandblasting with alumina was detrimental to the strength of only silica-based ceramics. Nd:YAG laser irradiation may lead to substantial strength degradation of zirconia. PMID:27148372

  6. SYSTEMIC DISORDERS AFFECTING DENTAL PATHOLOGY

    OpenAIRE

    Knezevic R. Milan; Andjelic S. Gordana; Knezevic M. Milena

    2014-01-01

    A retrospective overview of systemic disorders which might be associated with dental pathology is made. They are grouped as follows: (a) congenital dental developmental disorders, (b) chromosomal anomalies, (c) radiations, (d) immune disorders, (e) intoxications, (f) neurological alterations, (g) gastrointestinal diseases, (h) osteodystrophy and associated conditions, (i) skin diseases, (j) metabolic and endocrine disorders, (k) craniofacial malformation syndromes and other congenital g...

  7. In Vitro Comparison of the Bond Strength between Ceramic Repair Systems and Ceramic Materials and Evaluation of the Wettability.

    Science.gov (United States)

    Kocaağaoğlu, Hasan; Manav, Taha; Albayrak, Haydar

    2017-04-01

    When fracture of an all-ceramic restoration occurs, it can be necessary to repair without removing the restoration. Although there are many studies about the repair of metal-ceramic restorations, there are few about all-ceramic restorations. The aim of this study was to evaluate the shear bond strength between ceramic repair systems and esthetic core materials and to evaluate the wettability of all-ceramic core materials. Disk-like specimens (N = 90) made of three dental ceramic infrastructure materials (zirconia ceramic, alumina ceramic, glass ceramic) were polished with silicon carbide paper, prepared for bonding (abrasion with 30 μm diamond rotary cutting instrument). Thirty specimens of each infrastructure were obtained. Each infrastructure group was divided into three subgroups; they were bonded using 3 repair systems: Bisco Intraoral Repair Kit, Cimara & Cimara Zircon Repair System, and Clearfil Repair System. After 1200 thermocycles, shear bond strength was measured in a universal testing machine at a 0.5 mm/min crosshead speed. In addition, the contact angle values of the infrastructures after surface treatments were examined for wettability. Data were analyzed by using ANOVA and Tukey post hoc tests. Although there were no significant differences among the repair systems (p > 0.05) in the glass ceramic and zirconia groups, a significant difference was found among the repair systems in alumina infrastructure (p 0.05); however, a statistically significant difference was found among the repair systems (p < 0.05). No difference was found among the infrastructures and repair systems in terms of contact angle values. Cimara & Cimara Zircon Repair System had higher bond strength values than the other repair systems. Although no difference was found among the infrastructures and repair systems, contact wettability angle was decreased by surface treatments compared with polished surfaces. © 2015 by the American College of Prosthodontists.

  8. Similar Marginal Precision of Zirconia- and Metal-Ceramic Fixed Dental Prostheses

    DEFF Research Database (Denmark)

    Nicolaisen, Maj Høygaard; Bahrami, Golnosh; Schropp, Lars

    Similar Marginal Precision of Zirconia- and Metal-Ceramic Posterior Fixed Dental Prostheses Objective: An increased gap between restoration and prepared tooth causes more luting material to be exposed to the oral environment resulting in increased deterioration, leading to bacterial accumulation...... which can cause marginal periodontitis and secondary caries. The purpose of this randomized clinical study was to compare the marginal precision of CAD/CAM Zirconia-ceramic (ZC) and cast gold alloy metal-ceramic (MC) posterior fixed dental prostheses. Methods: As part of an ongoing randomized controlled...... clinical trial, 34 patients were randomized into two groups to receive a 3-unit fixed dental prosthesis (FDP) replacing a second premolar or a first molar. 17 ZC FDPs (BeCe CAD Zirkon, BEGO with Vita VM9, VITA ) and 17 MC FDPs (Bio PontoStar, BEGO with Vita VM13, VITA). All FDPs were made in accordance...

  9. Similar Marginal Precision of Zirconia- and Metal-Ceramic Fixed Dental Prostheses

    DEFF Research Database (Denmark)

    Nicolaisen, Maj Høygaard; Bahrami, Golnosh; Schropp, Lars

    clinical trial, 34 patients were randomized into two groups to receive a 3-unit fixed dental prosthesis (FDP) replacing a second premolar or a first molar. 17 ZC FDPs (BeCe CAD Zirkon, BEGO with Vita VM9, VITA ) and 17 MC FDPs (Bio PontoStar, BEGO with Vita VM13, VITA). All FDPs were made in accordance......Similar Marginal Precision of Zirconia- and Metal-Ceramic Posterior Fixed Dental Prostheses Objective: An increased gap between restoration and prepared tooth causes more luting material to be exposed to the oral environment resulting in increased deterioration, leading to bacterial accumulation...... which can cause marginal periodontitis and secondary caries. The purpose of this randomized clinical study was to compare the marginal precision of CAD/CAM Zirconia-ceramic (ZC) and cast gold alloy metal-ceramic (MC) posterior fixed dental prostheses. Methods: As part of an ongoing randomized controlled...

  10. Luminescence characteristics of dental ceramics for retrospective dosimetry: a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Bailiff, I.K.; Correcher, V.; Delgado, A.; Goksu, Y.; Huebner, S

    2002-07-01

    Ceramic materials that are widely employed in dental prosthetics and repairs exhibit luminescent properties. Because of their use in the body, these materials are potentially of interest in situations where retrospective dosimetry for individuals is required but where monitoring was not planned. The luminescent properties of dental ceramics obtained in Germany, Spain and the UK were examined. Linear dose-response characteristics were obtained in the range <100 mGy to 10 Gy using thermoluminescence (TL), optically stimulated luminescence and infrared-stimulated luminescence measurement techniques. Measurements of time-resolved luminescence were also performed to examine the nature of the luminescence recombination under visible (470 nm) and IR (855 nm) stimulation. The results obtained by TL and optically stimulated techniques suggest that there may be deeper traps than previously observed in certain types of dental ceramic. Such traps may be less susceptible to optical and athermal fading than was reported in earlier studies. (author)

  11. A randomized controlled clinical trial of 3-unit posterior zirconia-ceramic fixed dental prostheses (FDP) with layered or pressed veneering ceramics: 3-year results.

    Science.gov (United States)

    Naenni, Nadja; Bindl, Andreas; Sax, Caroline; Hämmerle, Christoph; Sailer, Irena

    2015-11-01

    The aim of the present pilot study was to test whether or not posterior zirconia-ceramic fixed dental prostheses (FDPs) with pressed veneering ceramic exhibit less chipping than FDPs with layered veneering ceramics. Forty patients (13 female, 27 male; mean age 54 years (range 26.1-80.7 years) in need of one maxillary or mandibular three-unit FDP in the second premolar or molar region were recruited and treated at two separate centers at the University of Zurich according to the same study protocol. The frameworks were made out of zirconia using a CAD/CAM system (Cerec Sirona, Bensheim, Germany). The patients were randomly assigned to either the test group (zirconia frameworks veneered with pressed ceramic; IPS e.max ZirPress, Ivoclar Vivadent AG, Schaan, Liechtenstein; n=20) or the control group (layered veneering ceramic; IPS e.max Ceram, Ivoclar Vivadent AG, Schaan, Liechtenstein; n=20). All FDPs were adhesively cemented and evaluated at baseline (i.e., cementation), at 6 months and at 1 and 3 years of clinical service. The survival of the reconstruction was recorded. The technical outcome was assessed using modified United States Public Health Services (USPHS) criteria. The biologic parameters analyzed at abutment teeth and analogous non-restored teeth included probing pocket depth (PPD), plaque control record (PCR), bleeding on probing (BOP), and tooth vitality (CO2). Data was descriptively analyzed and survival was calculated using Kaplan-Meier statistics. 36 patients (25 female, 11 male; mean age 52.3 years) with 18 test and 18 control FDPs were examined after a mean follow-up of 36 months (95% CI: 32.6-39.1 months). Comparison of groups was done by Crosstabulation showing even distribution of the respective restored teeth amidst the groups. Survival rate was 100% for both test and control FDPs. Chipping of the veneering ceramic tended to occur more frequently in test (n=8; 40%) than in control (n=4; 20%) FDPs, albeit not significantly (p=0.3). No further

  12. A rubber-covered ceramic weapon reduces the incidence of dental trauma in recruits during combat basic training.

    Science.gov (United States)

    Becker, Talia; Ashkenazi, Malka

    2011-10-01

    The effect of a rubber-covered ceramic weapon was assessed on the incidence of dental trauma during basic training, since soldiers are more at risk of impact from a personal weapon. Dental files of soldiers (n = 4,542), who completed 8 months of training during 2008, were analyzed for incidence and type of dental trauma from a personal weapon. A rubber-covered ceramic weapon (n = 2,972) or a conventional one (n = 1,570, control) was used. Dental trauma was 0.4% per 8 months (0.6% per year) from the ceramic weapon and 1.5% per 8 months (2.3% per year) from the conventional one (pcontrol group). The ceramic weapon significantly reduced dental trauma by diminishing the impact while in direct contact with the teeth or by absorbing and/or distributing the impact force. In conclusion, when possible a rubber-covered ceramic weapon should be preferred for basic combat training.

  13. Process Development of Porcelain Ceramic Material with Binder Jetting Process for Dental Applications

    Science.gov (United States)

    Miyanaji, Hadi; Zhang, Shanshan; Lassell, Austin; Zandinejad, Amirali; Yang, Li

    2016-03-01

    Custom ceramic structures possess significant potentials in many applications such as dentistry and aerospace where extreme environments are present. Specifically, highly customized geometries with adequate performance are needed for various dental prostheses applications. This paper demonstrates the development of process and post-process parameters for a dental porcelain ceramic material using binder jetting additive manufacturing (AM). Various process parameters such as binder amount, drying power level, drying time and powder spread speed were studied experimentally for their effect on geometrical and mechanical characteristics of green parts. In addition, the effects of sintering and printing parameters on the qualities of the densified ceramic structures were also investigated experimentally. The results provide insights into the process-property relationships for the binder jetting AM process, and some of the challenges of the process that need to be further characterized for the successful adoption of the binder jetting technology in high quality ceramic fabrications are discussed.

  14. Optical properties of CAD-CAM ceramic systems.

    Science.gov (United States)

    Della Bona, Alvaro; Nogueira, Audrea D; Pecho, Oscar E

    2014-09-01

    To evaluate the direct transmittance (T%), translucency, opacity and opalescence of CAD-CAM ceramic systems and the correlation between the translucency parameter (TP) and the contrast ratio (CR). Specimens of shades A1, A2 and A3 (n=5) were fabricated from CAD-CAM ceramic blocks (IPS e.max(®) CAD HT and LT, IPS Empress(®) CAD HT and LT, Paradigm™ C, and VITABLOCS(®) Mark II) and polished to 1.0±0.01mm in thickness. A spectrophotometer (Lambda 20) was used to measure T% on the wavelength range of 400-780nm. Another spectrophotometer (VITA Easyshade(®) Advance) was used to measure the CIE L(*)a(*)b(*) coordinates and the reflectance value (Y) of samples on white and black backgrounds. TP, CR and the opalescence parameter (OP) were calculated. Data were statistically analysed using VAF (variance accounting for) coefficient with Cauchy-Schwarz inequality, one-way ANOVA, Tukey's test, Bonferroni correction and Pearson's correlation. T% of some ceramic systems is dependent on the wavelength. The spectral behaviour showed a slight and constant increase in T% up to approximately 550nm, then some ceramics changed the behaviour as the wavelength gets longer. TP and CR values ranged, respectively, from 16.79 to 21.69 and from 0.52 to 0.64 (r(2)=-0.97). OP values ranged from 3.01 to 7.64. The microstructure of CAD-CAM ceramic systems influenced the optical properties. TP and CR showed a strong correlation for all ceramic systems evaluated. Yet, all ceramics showed some degree of light transmittance. In addition to shade, this study showed that other optical properties influence on the natural appearance of dental ceramics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. The teaching of all-ceramic restorations in North American dental schools: materials and techniques employed.

    Science.gov (United States)

    Frazier, K B; Mjör, I A

    1997-01-01

    North American dental schools were surveyed to determine the types of clinical experiences and the extent of material use that predoctoral students encounter with restorative procedures that employ all-ceramic materials. The results were based on an overall response rate of 80% from the 64 surveyed schools. The majority (96%) of the 51 schools responding to the survey did offer an opportunity to become experienced with all-ceramic restorations. The selection of bases and liners for all-ceramic restorations included dentin adhesive agents, glass ionomer materials, and calcium hydroxide products, by a ratio of 5:4:1, respectively. The most commonly used impression material types were addition silicone and polyether. One or both of these materials were used by every school. Dicor glass ceramic and alumina core ceramic were the most commonly used materials by the responding schools for veneers, onlays, and crowns. Dicor glass ceramic and CAD/CAM ceramic were most commonly used for inlays. Crowns were made of more different all-ceramic material types than the other restoration classes. Fabrication of all-ceramic restorations was primarily by commercial laboratories and school technicians. Students have hands-on experience in the fabrication of all-ceramic restorations in 6% of the responding schools. Luting agents for all-ceramic restorations include dual-cured resin, in 96% of the responding schools, light-cured resin, 43%, and glass ionomer cement, 33%. Zinc phosphate, chemical-cured composite, and polycarboxylate were used by less than one fourth of the respondents. Only resin-based composite materials were used to lute ceramic veneers. Rubber dam was applied primarily during luting procedures involving all-ceramic inlays and onlays. Crowns and veneers were isolated by this method in less than 30% of the responding schools. Finishing procedures with all-ceramic restorations were accomplished with three or more instruments by 89% of the schools.

  16. Which mechanical and physical testing methods are relevant for predicting the clinical performance of ceramic-based dental prostheses?

    Science.gov (United States)

    Anusavice, K J; Kakar, Kunjan; Ferree, N

    2007-06-01

    The survival and performance of clinical prostheses with a ceramic component are probabilistic in nature. Only under very rare circumstances will all of the prostheses in a group exhibit either 100% successes or 100% failures over a period of 5 years or more. Prosthesis failure may be defined as any condition that leads to replacement. These conditions include secondary caries, irreversible pulpitis, excessive wear of opposing tooth surfaces, excessive erosion and roughening of the ceramic surface, ditching of the cement margin, unacceptable esthetics, cracking, chipping and fracture. A systematic review of the dental literature was performed to determine the extent to which the mechanical and physical properties of dental alloys and ceramics can predict the 5-year clinical performance of metal-ceramic and all-ceramic fixed dental prostheses (FDP) and to determine the associated quality of reported outcomes associated with these clinical studies. The review was based on clinical research studies of 5 years or greater duration that were published in English dental journals between 1980 and 2006 using the following key words and MeSH terms. Our search strategy was as follows: Search 1: Partial fixed denture OR denture, partial, fixed OR denture, partial fixed OR dental porcelain OR metal ceramic alloys OR dental ceramic Search 2: Prosthesis failure OR dental restoration failure OR time factors OR survival analysis Search 3: Meta-analysis OR evaluation studies OR review OR clinical trial OR comparative study OR follow-up studies OR prospective studies OR clinical follow-up study OR clinical trial OR longitudinal studies Inclusion of searches 1, 2 and 3 and limits placed on the publication date starting on January 1, 1980, English language, and clinical studies involving humans resulted in a total of 684 articles. By restricting the clinical studies to 5 years or more in duration, the number was reduced to 193. By eliminating resin-bonded FDPs, cantilever designs

  17. Wear resistance of a pressable low-fusing ceramic opposed by dental alloys.

    Science.gov (United States)

    Faria, Adriana Cláudia Lapria; de Oliveira, André Almeida; Alves Gomes, Erica; Silveira Rodrigues, Renata Cristina; Faria Ribeiro, Ricardo

    2014-04-01

    Dental alloys have increasingly replaced by dental ceramics in dentistry because of aesthetics. As both dental alloys and ceramics can be present in the oral cavity, the evaluation of the wear resistance of ceramics opposed by dental alloys is important. The aim of the present study was to evaluate wear resistance of a pressable low-fusing ceramic opposed by dental alloys as well as the microhardness of the alloys and the possible correlation of wear and antagonist microhardness. Fifteen stylus tips samples of pressable low-fusing ceramic were obtained, polished and glazed. Samples were divided into three groups according to the disk of alloy/metal to be used as antagonist: Nickel-Chromium (Ni-Cr), Cobalt-Chromium (Co-Cr) and commercially pure titanium (cp Ti). Vickers microhardness of antagonist disks was evaluated before wear tests. Then, antagonist disks were sandblasted until surface roughness was adjusted to 0.75μm. Wear tests were performed at a speed of 60 cycles/min and distance of 10mm, in a total of 300,000 cycles. Before and after wear tests, samples were weighted and had their profile designed in an optical comparator to evaluate weight and height loss, respectively. Ni-Cr and cp Ti caused greater wear than Co-Cr, presenting greater weight (p=.009) and height (p=.002) loss. Cp Ti microhardness was lower than Ni-Cr and Co-Cr (p<.05). There is a positive correlation between weight and height loss (p<.05), but weight (p=.204) and height (p=.05) loss are not correlated to microhardness. The results suggest that pressable low-fusing ceramic presents different wear according to the dental alloy used as antagonist and the wear is not affected by antagonist microhardness.

  18. Comparison of Metal-Ceramic and All-Ceramic Three-Unit Posterior Fixed Dental Prostheses: A 3-Year Randomized Clinical Trial.

    Science.gov (United States)

    Nicolaisen, Maj H; Bahrami, Golnosh; Schropp, Lars; Isidor, Flemming

    2016-01-01

    The aim of this randomized clinical study was to compare the 3-year clinical outcome of metal-ceramic fixed dental prostheses (MC-FDPs) and zirconia all-ceramic fixed dental prostheses (AC-FDPs) replacing a posterior tooth. A sample of 34 patients with a missing posterior tooth were randomly chosen to receive either a MC-FDP (n = 17) or an AC-FDP (n = 17). The FDPs were evaluated at baseline and yearly until 3 years after cementation. They were assessed using the California Dental Association assessment system. Periodontal parameters were measured at the abutment teeth, and the contralateral teeth served as control. The statistical unit was the FDP/patient. The survival rates for MC-FDPs and AC-FDPs were 100%. The success rate was 76% and 71% for MC-FDPs and AC-FDPs, respectively. Three technical complications were observed in the MC-FDP group and five in the AC-FDP group, all chipping fractures of the ceramic veneer. Furthermore, one biologic complication in the MC-FDP group (an apical lesion) was observed. No framework fractures occurred. All patients had optimal oral hygiene and showed no bleeding on periodontal probing at any of the recalls. Only minor changes in the periodontal parameters were observed during the 3 years of observation. Three-unit posterior MC-FDPs and AC-FDPs showed similar high survival rates and acceptable success rates after 3 years of function, and ceramic veneer chipping fracture was the most frequent complication for both types of restorations.

  19. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly

    Directory of Open Access Journals (Sweden)

    Lu X

    2012-04-01

    Full Text Available Xiaoli Lu1,2, Yang Xia1, Mei Liu1, Yunzhu Qian3, Xuefeng Zhou4, Ning Gu4, Feimin Zhang1,41Institute of Stomatology, Nanjing Medical University, Nanjing, 2Nantong Stomatological Hospital, Nantong, 3Center of Stomatology, The Second Affiliated Hospital of Suzhou University, Suzhou, 4Suzhou Institute, Southeast University, Suzhou, People's Republic of ChinaAbstract: To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride] and anionic [poly(sodium 4-styrenesulfonate] polymers to improve the dispersion and adsorption of positively charged nano-ZrO2 (zirconia as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO2. To determine the optimum addition levels for nano-ZrO2, ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO2 were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO2 resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P < 0.05. Our results show that diatomite-based nanocomposite ceramics are good potential candidates for ceramic-based dental materials.Keywords: layer-by-layer, diatomite, nanoceramics, zirconia (ZrO2, dental materials

  20. Creep functions of dental ceramics measured in a beam-bending viscometer.

    Science.gov (United States)

    DeHoff, Paul H; Anusavice, Kenneth J

    2004-03-01

    To characterize the high temperature viscoelastic properties of several dental ceramics by the determination of creep functions based on mid-span deflections measured in a beam-bending viscometer (BBV). Six groups of beam specimens (58 x 5.5 x 2.5 mm) were made from the following materials: (1) IPS Empress2 body--a glass veneer ceramic (E2V); (2) an experimental glass veneer (EXV); (3) Vita VMK 68 feldspathic body porcelain--a low-expansion body porcelain (VB); (4) Will-Ceram feldspathic body porcelain--a high-expansion body porcelain (WCB); (5) Vita feldspathic opaque porcelain--a medium-expansion opaque porcelain (VO); and (6) Will-Ceram feldspathic opaque porcelain--a high-expansion opaque porcelain (WCO). Midpoint deflections for each specimen were measured in a BBV under isothermal conditions at furnace temperatures ranging from 450 to 675 degrees C. Non-linear regression and linear regression analyses were used to determine creep functions and shear viscosities, respectively, for each material at each temperature. The shear viscosities of each group of dental ceramics exhibited bilinear Arrhenius behavior with the slope ratios (x) ranging from 0.19 for WCB to 0.71 for EXV. At the higher temperature ranges, activation energies ranged from 363 kJ/mol for VO to 386 kJ/mol for E2V. The viscoelastic properties of dental ceramics at high temperatures are important factors in understanding how residual stresses develop in all-ceramic and metal-ceramic dental restorations.

  1. Clinical performance - a reflection of damage accumulation in ceramic dental crowns

    Energy Technology Data Exchange (ETDEWEB)

    Rekow, D.E. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). Dept. of Orthodontics; Thompson, V.P. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). New Jersey Dental School

    2001-07-01

    All-ceramic dental crowns have tremendous appeal for patients - their esthetics nearly match those of natural teeth. Unfortunately, the most esthetic materials are brittle and, consequently, are vulnerable to damage relating to shaping which is exacerbated during cyclic loading during normal chewing. Clinical performance of all-ceramic dental prostheses are directly dependent on damage introduced during fabrication and during fatigue loading associated with function. The accumulation of damage results in unacceptably high failure rates (where failure is defined as a complete fracture requiring replacement of the prosthesis). The relation between shaping damage and fatigue damage on clinical performance of all-ceramic dental crowns was investigated. Materials used commercially for all-ceramic crowns and investigated in this study included a series of different microstructures of machinable glass ceramics (Corning), aluminas and porcelains (Vita Zahnfabrik), and zirconia (Norton). As monolithic materials, strong, tough, fatigue-resistant materials are not sufficiently esthetic for crowns. Crowns fabricated from monolithic esthetic materials have high failure rates. Layering ceramics could provide acceptable strength through management of damage accumulation. (orig.)

  2. The effects of residual stress, viscoelastic and thermodynamic parameters on apparent fracture toughness of dental bilayer ceramic composites

    Science.gov (United States)

    Taskonak, Burak

    Bilayer dental ceramic composites used for fixed partial dentures are becoming more widely used in dental practices because of their biocompatibility, aesthetic properties, and chemical durability. However, large statistical variations in the strength of ceramics are associated with the structural flaws as a result of processing and complex stress states within the surfaces of the materials because of thermal properties of each layer. In addition, partial delaminations of the veneer layer and connector fractures of bilayer ceramic fixed partial dentures (FPDs) have been observed in a clinical study which is a part of this dissertation. Analysis of fracture surfaces of failed FPDs reveals that such fractures of the veneering ceramic are most likely caused by lateral crack growth. Global residual stresses associated with the coefficient of thermal expansion differences between core and veneering ceramics can cause lateral crack initiation. Also, rapid cooling of bilayer ceramics from the sintering temperature of the glass veneer may not allow the interfacial stresses in the viscoelastic glass to relax to equilibrium values. This can further contribute to the propagation of lateral cracks. Furthermore, local residual stresses that develop in the plastic deformation zone below sharp contact areas on the occlusal surface are another contributor to lateral crack growth. Superposition of global residual stresses and a Boussinesq stress field can incrementally increase the possibility of lateral crack growth. The long-range goals of this study are to critically analyze the lateral crack growth mechanisms associated with residual stresses, to modify residual tensile stress distributions by controlled heat treatment, and to minimize the probability of veneering ceramic fractures. Four approaches were used to accomplish these goals: (1) clinical evaluation of a bilayer ceramic fixed partial denture system; (2) fracture surface analysis of clinically failed FPDs; (3

  3. Application of Monolithic Zirconia Ceramics in Dental Practice: A Case History Report.

    Science.gov (United States)

    Kim, Hee-Kyung; Kim, Sung-Hun; Lee, Jai-Bong; Han, Jung-Suk; Yeo, In-Sung

    2016-01-01

    Monolithic zirconia restorations increasingly have been used in dental practice in recent years and demonstrate superior mechanical performance compared with porcelain-veneered zirconia restorations. Recent advances in manufacturing technology have made possible the fabrication of translucent monolithic zirconia ceramics. This case report describes three clinical examples of monolithic zirconia fixed dental prostheses being used in the anterior and posterior regions and exhibiting acceptable esthetic results.

  4. Bonding strength of resin cement to silicate glass ceramics for dental CAD/CAM systems is enhanced by combination treatment of the bonding surface.

    Science.gov (United States)

    Shimakura, Yusuke; Hotta, Yasuhiro; Fujishima, Akihiro; Kunii, Jun; Miyazaki, Takashi; Kawawa, Tadaharu

    2007-09-01

    To increase the bond strength of CAD/CAM-fabricated, leucite-reinforced glass ceramics with a resin cement, the effects of the following were investigated: surface modification by tribochemical (TBC) treatment, followed by combined application of a silane coupling agent and a functional monomer as a primer. Bond strength was evaluated by a shear bond test. It was found that a silane coupling agent was useful for all the surfaces, particularly for the TBC-treated surface. This was because of the presence of a silica layer on the modified surface. The combination of a silane coupling agent and a functional monomer on the TBC surface allowed marked improvement in bonding, whereby the bonding endured 20,000 cycles of thermal cycling. Therefore, TBC treatment in combination with a silane coupling agent and a functional monomer as a primer substantially increased the bond strength of CAD/CAM-fabricated glass ceramics with resin cement, if the treatment conditions were appropriate.

  5. Surface characterization of dental ceramics and initial streptococcal adhesion in vitro.

    Science.gov (United States)

    Hahnel, Sebastian; Rosentritt, Martin; Handel, Gerhard; Bürgers, Ralf

    2009-08-01

    The aim of this in vitro study was to investigate the surface properties of dental ceramic materials belonging to different ceramic classes, and to correlate the findings to the initial adherence of three oral streptococcal strains. Rectangular specimens were prepared from different ceramic materials (glass/lithium disilicate glass/glass-infiltrated zirconia/partially sintered zirconia/hipped zirconia ceramic) and polished; surface roughness (Ra) was determined. Glass plates were used as a control. Specimens were incubated with phosphate-buffered saline or an artificial saliva (protein mixture; 2h, 37 degrees C). Surface free energy (gamma(t)) and its polar (gamma(p)) and disperse (gamma(d)) contribution were determined prior to and after artificial saliva exposure. Uncoated and protein-coated specimens were incubated with Streptococcus gordonii DSMZ 6777, Streptococcus oralis DSMZ 20068 or Streptococcus sanguinis DSMZ 20068 suspension for 2.5h at 37 degrees C (n=15 for each treatment and strain). Adherent streptococci were quantified fluorometrically. The lithium disilicate glass ceramic showed the highest values for Ra; the lowest values were found for the glass ceramic, the partially sintered zirconia and the hipped zirconia ceramic. Protein coating caused a significant increase in gamma(t) and gamma(p), but not in the control material. The control material showed higher values for streptococcal adhesion than all ceramic materials. After protein coating, only slight and random differences in streptococcal adhesion were found between the various ceramic materials. Dental ceramic materials show differences in terms of Ra, gamma(t) and initial streptococcal adhesion; however, correlations between surface properties and streptococcal adhesion were poor.

  6. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal-ceramic fixed dental prostheses.

    Science.gov (United States)

    Anusavice, Kenneth J

    2012-01-01

    The recent increase in reports from clinical studies of ceramic chipping has raised the question of which criteria should constitute success or failure of total-ceramic prostheses. Terminologies such as minor chipping [1], partial chipping, technical complications [2,3], and biological complications have crept into the dental terminology and they have complicated our classification of success and failure of these crown and bridge restorations. Some journals have permitted the reporting of fractures as "complications" and they are not necessarily classified as failures in the study. One study has attempted to classify chipping fractures according to their severity and subsequent treatment [4]. This is a promising approach to resolve the challenges to the classification of chipping fracture. The term 'chipping fracture' is more descriptive than 'chipping' since the latter term tends to imply an event of minor consequence. Two types of statistics are reported routinely in these studies, i.e., percent success, which is a measure of restorations that survive without any adverse effects, and percent survival, which is a measure of all restorations that survive even though they may have exhibited chipping fracture or they may have been repaired. Why has this scenario occurred? One possible explanation is that many of these types of fractures are very small and do not affect function or esthetics. Another reason is that corporate sponsors prefer to use the term chipping since it does not connote failure in the sense that the term fracture does. In any event, we need to be more precise in our scientific observations of fracture and classifications of the various types of fracture including details on the location of fracture and the prosthesis design configuration. Because of the lack of standardized methods for describing chipping fractures, materials scientists are unable to properly analyze the effect of material properties and design factors on the time

  7. Characterization of the bioactive and mechanical behavior of dental ceramic/sol-gel derived bioactive glass mixtures.

    Science.gov (United States)

    Abbasi, Zahra; Bahrololoum, Mohammad E; Bagheri, Rafat; Shariat, Mohammad H

    2016-02-01

    Dental ceramics can be modified by bioactive glasses in order to develop apatite layer on their surface. One of the benefits of such modification is to prolong the lifetime of the fixed dental prosthesis by preventing the formation of secondary caries. Dental ceramic/sol-gel derived bioactive glass mixture is one of the options for this modification. In the current study, mixtures of dental ceramic/bioactive glass with different compositions were successfully produced. To evaluate their bioactive behavior, prepared samples were immersed in a simulated body fluid at various time intervals. The prepared and soaked specimens were characterized using Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. Since bioactive glasses have deleterious effects on the mechanical properties of dental ceramics, 3-point bending tests were used to evaluate the flexural strength, flexural strain, tangent modulus of elasticity and Weibull modulus of the specimens in order to find the optimal relationship between mechanical and bioactive properties.

  8. Flexural strength and fracture toughness of dental core ceramics.

    Science.gov (United States)

    Yilmaz, Handan; Aydin, Cemal; Gul, Basak E

    2007-08-01

    Many different strengthened all-ceramic core materials are available. In vitro study of their mechanical properties, such as flexural strength and fracture toughness, is necessary before they are used clinically. The purpose of this study was to evaluate and compare the mechanical properties of 6 commonly used all-ceramic core materials using biaxial flexural strength and indentation fracture toughness tests. Specimens of 6 ceramic core materials (Finesse, Cergo, IPS Empress, In-Ceram Alumina, In-Ceram Zirconia, and Cercon Zirconia) were fabricated (n=25) with a diameter of 15 mm and width of 1.2 +/- 0.2 mm. For each group, the specimens were tested to compare their biaxial flexural strength (piston on 3 balls) (n=15), Weibull modulus, and indentation fracture toughness (n=10) (IF method). The data were analyzed with 1-way ANOVA test (a=.05). The Tamhane multiple comparison test was used for post hoc analysis. Mean (SD) of biaxial flexural strength values (MPa) and Weibull modulus (m) results were: Finesse (F): 88.04 (31.61), m=3.17; Cergo (C): 94.97 (13.62), m=7.94; IPS Empress (E): 101.18 (13.49), m=10.13; In-Ceram Alumina (ICA): 341.80 (61.13), m=6.96; In-Ceram Zirconia (ICZ): 541.80 (61.10), m=10.17; and Cercon Zirconia (CZ): 1140.89 (121.33), m=13.26. The indentation fracture toughness results showed that there were significant differences between the tested ceramics. The highest fracture toughness values (MPa x m(0.5)) were obtained with the zirconia-based ceramic core materials. Significant differences were found in strength and toughness values of the materials evaluated. Cercon Zirconia core material showed high values of biaxial flexural strength and indentation fracture toughness when compared to the other ceramics studied.

  9. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function.

    Science.gov (United States)

    Oilo, Marit; Hardang, Anne D; Ulsund, Amanda H; Gjerdet, Nils R

    2014-06-01

    Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation.

  10. Experimental observation of silver and gold penetration into dental ceramic by means of a radiotracer technique

    Energy Technology Data Exchange (ETDEWEB)

    Moya, F.; Payan, J.; Bernardini, J.; Moya, E.G.

    1987-12-01

    A radiotracer technique was used to study silver and gold diffusion into dental porcelain under experimental conditions close to the real conditions in prosthetic laboratories for porcelain bakes. It was clearly shown that these non-oxidizable elements were able to diffuse into the ceramic as well as oxidizable ones. The penetration depth varied widely according to the element. The ratio DAg/DAu was about 10(3) around 850 degrees C. In contrast to gold, the silver diffusion rate was high enough to allow silver, from the metallic alloy, to be present at the external ceramic surface after diffusion into the ceramic. Hence, the greening of dental porcelains baked on silver-rich alloys could be explained mainly by a solid-state diffusion mechanism.

  11. Effect of test method on flexural strength of recent dental ceramics.

    Science.gov (United States)

    Jin, Jingyue; Takahashi, Hidekazu; Iwasaki, Naohiko

    2004-12-01

    The purpose of the present study was to evaluate the relationships among three flexural strengths of recent dental ceramics using 3-point and 4-point bending tests and biaxial flexural test. Three brands of porcelain for veneering (d.SIGN, Supper porcelain AAA, Vintage Hallo), two injectable ceramics (Empress 2, OPC 3G), and one castable ceramic (Crys-Cera) were used. Twenty bar-shaped and 10 disc-shaped specimens of each ceramic type were prepared according to manufacturers' instructions, polished, and subjected to 3-point and 4-point bending tests and biaxial flexural test, respectively. Three flexural strengths for each ceramics were compared using one-way analysis of variance and Tukey comparison, and also investigated by Weibull analysis. The biaxial flexural strength and 3-point bending strength of all ceramics, except OPC 3G and Crys-Cera, were significantly greater than the corresponding 4-point bending strength. As for OPC 3G and Crys-Cera, their biaxial flexural strengths were significantly greater than their 3-point bending strengths, which is contrary to the other ceramics. The Weibull moduli ranged from 6.6 to 20.8. The Weibull moduli of examined ceramics, except Crys-cera, were statistically insignificant regardless of test methods.

  12. Comparative study of physical properties of zirconia based dental ceramics

    OpenAIRE

    Pittayachawan, P.

    2009-01-01

    The aim of this project was to evaluate and compare the mechanical properties of commercial yttria partially stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics, which have generated interest in restorative dentistry because of their high strength and high resistance to fracture. Mechanical properties of three commercial Y-TZP ceramics (Lava™, Cercon® and Invizion™) were investigated including the biaxial flexural strength, hardness, fatigue, and subcritical crack growth....

  13. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics.

    Science.gov (United States)

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l’Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a shifts (D65 to A switch) or by the CIE b shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  14. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics

    Science.gov (United States)

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l'Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a* shifts (D65 to A switch) or by the CIE b* shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  15. Mechanical fatigue degradation of ceramics versus resin composites for dental restorations.

    Science.gov (United States)

    Belli, Renan; Geinzer, Eva; Muschweck, Anna; Petschelt, Anselm; Lohbauer, Ulrich

    2014-04-01

    For posterior partial restorations an overlap of indication exists where either ceramic or resin-based composite materials can be successfully applied. The aim of this study was to compare the fatigue resistance of modern dental ceramic materials versus dental resin composites in order to address such conflicts. Bar specimens of five ceramic materials and resin composites were produced according to ISO 4049 and stored for 14 days in distilled water at 37°C. The following ceramic materials were selected for testing: a high-strength zirconium dioxide (e.max ZirCAD, Ivoclar), a machinable lithium disilicate (e.max CAD, Ivoclar), a pressable lithium disilicate ceramic (e-max Press, Ivoclar), a fluorapatite-based glass-ceramic (e.max Ceram, Ivoclar), and a machinable color-graded feldspathic porcelain (Trilux Forte, Vita). The composite materials selected were: an indirect machinable composite (Lava Ultimate, 3M ESPE) and four direct composites with varying filler nature (Clearfil Majesty Posterior, Kuraray; GrandioSO, Voco; Tetric EvoCeram, Ivoclar-Vivadent; and CeramX Duo, Dentsply). Fifteen specimens were tested in water for initial strength (σin) in 4-point bending. Using the same test set-up, the residual flexural fatigue strength (σff) was determined using the staircase approach after 10(4) cycles at 0.5 Hz (n=25). Weibull parameters σ0 and m were calculated for the σin specimens, whereas the σff and strength loss in percentage were obtained from the fatigue experiment. The zirconium oxide ceramic showed the highest σin and σff (768 and 440 MPa, respectively). Although both lithium disilicate ceramics were similar in the static test, the pressable version showed a significantly higher fatigue resistance after cyclic loading. Both the fluorapatite-based and the feldspathic porcelain showed equivalent initial and cyclic fatigue properties. From the composites, the highest filled direct material Clearfil Majesty Posterior showed superior fatigue performance

  16. Biocompatibility study of lithium disilicate and zirconium oxide ceramics for esthetic dental abutments

    Science.gov (United States)

    2016-01-01

    Purpose The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate (LS2) and zirconium oxide (ZrO2) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. Methods Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). Results The best cell migration was observed on ZrO2 ceramic. Cell adhesion was also drastically lower on the polished ZrO2 ceramic than on both the raw and polished LS2. Evaluating various surface topographies of LS2 showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. Conclusions Our results demonstrate that a biomaterial, here LS2, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of LS2 and ZrO2 ceramic showed that LS2 was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical

  17. Biocompatibility study of lithium disilicate and zirconium oxide ceramics for esthetic dental abutments.

    Science.gov (United States)

    Brunot-Gohin, Céline; Duval, Jean-Luc; Verbeke, Sandra; Belanger, Kayla; Pezron, Isabelle; Kugel, Gérard; Laurent-Maquin, Dominique; Gangloff, Sophie; Egles, Christophe

    2016-12-01

    The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate (LS2) and zirconium oxide (ZrO2) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). The best cell migration was observed on ZrO2 ceramic. Cell adhesion was also drastically lower on the polished ZrO2 ceramic than on both the raw and polished LS2. Evaluating various surface topographies of LS2 showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. Our results demonstrate that a biomaterial, here LS2, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of LS2 and ZrO2 ceramic showed that LS2 was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.

  18. Towards the synthesis of an experimental bioactive dental ceramic. Part I: Crystallinity characterization and bioactive behavior evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Goudouri, O.-M. [Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Kontonasaki, E. [School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Papadopoulou, L.; Kantiranis, N. [Department of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Lazaridis, N.K. [Chemistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Chrissafis, K.; Chatzistavrou, X. [Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Koidis, P. [School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Paraskevopoulos, K.M., E-mail: kpar@auth.gr [Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2014-05-01

    An attachment between the dental ceramic and the surrounding marginal tissues in fixed prosthetic restorations could eliminate secondary carries prevalence. The development of dental ceramics with apatite forming ability could provide the biological surface required for selective spread and attachment of specific cell types able to promote tissue attachment. Dental ceramics/bioactive glass composites synthesized by the sol gel method have been previously reported to develop carbonated hydroxyapatite (HCAp) in biomimetic solutions, requiring though a high amount of bioactive glass, which resulted in the compromise of their mechanical integrity. Thus, the aim of the present work was the synthesis and characterization of an experimental sol–gel derived dental ceramic with low amount of bioactive glass and the evaluation of its in vitro bioactivity. Differential thermal and thermogravimetric analysis (TG–DTA), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to evaluate the crystal structure and the in vitro apatite forming ability of the synthesized material. The results of this study indicated the successful sol–gel synthesis of an experimental dental ceramic containing low amount of bioactive glass that presented similar structural and morphological characteristics with a commercial feldspathic dental ceramic, while exhibiting in vitro bioactivity. The apatite forming ability of the experimental sol–gel derived feldspathic dental ceramic may trigger the appropriate cellular mechanisms towards the establishment of attachment with the surrounding connective tissue. This attachment could provide a barrier to oral bacteria penetration, prolonging the life expectation of the restorations. - Highlights: • Synthesis of a bioactive sol–gel dental ceramic for fixed prosthetic restorations. • The sol–gel technique promoted the crystallization of

  19. Comparison of marginal and internal fit of press-on-metal and conventional ceramic systems for three- and four-unit implant-supported partial fixed dental prostheses: An in vitro study.

    Science.gov (United States)

    Bayramoğlu, Emre; Özkan, Yasemin Kulak; Yildiz, Coşkun

    2015-07-01

    Adaptation is an important factor in the long-term clinical success of implant supported ceramic restorations. Ceramic firings may affect the adaptation of the restoration. The purpose of this study was to compare the marginal and internal adaptation of 3 different restorative materials and the effect of veneering/pressing on the material used for 3- and 4-unit implant supported fixed dental prostheses. One mandibular epoxy cast was prepared for 3-unit restorations and one for 4-unit restorations. Impressions of the casts were made and 60 stone die casts (30 3-unit, 30 4-unit) produced. The casts were divided into 3 subgroups: group MCR, conventional metal ceramic restorations; group POM, press-on-metal restorations; group ZIR, computer-aided design/computer-aided manufacturing CAD/CAM) zirconia restorations. A replica technique was used to examine the marginal and internal gap values. A total of 2400 measurements were made by making 40 measurements of each restoration. The data were evaluated statistically using analysis of variance and the least significant difference post hoc test (α=.05). The lowest marginal gaps were found in group POM (81.58 μm) and the highest in group MCR (103.82 μm). The differences in marginal adaptation measurements were found to be statistically significant. The highest values for internal adaptation were found at the occlusal surface in all groups. Although veneering metal ceramic restorations increased the misfit of the restoration, the marginal discrepancy of the materials (81 to 120 μm) can be considered clinically acceptable. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  20. A New Technology of Microcrystallizing Leucite to Reinforce Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; PENG Bin; DUAN Xing-long; QIAN Fa-tang; WU Bo-lin

    2004-01-01

    The key technology and the main mechanism of microcrystallizing leucite to reirforce dentalglass ceramics were investigated. The feedstock powders were selected, mixed according to the ratios of the theoreti-cal composition of leucite, ball - milled, melted at 1600℃ and then cooled to room temperature quickly. Thecooled clinkers were ball - milled again to 4 μm. After cold - isostatic pressure molded and air sintered at 1 500℃for 1 h, the dental glass ceramics were fabricated. They have following characteristics: excellent mechanical prop-erties ( mean compressive strength is 206.6 MPa ), low sintering temperature and good reoccurrence to keep steadyquality.

  1. Chemical adhesion rather than mechanical retention enhances resin bond durability of a dental glass-ceramic with leucite crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Meng, X F [Department of Prosthodontics, The Stomatological Hospital Affiliated Medical School, Nanjing University, Nanjing 210008 (China); Yoshida, K [Division of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588 (Japan); Gu, N, E-mail: mengsoar@nju.edu.c [Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)

    2010-08-01

    This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group). The scale of their surface roughness and rough area was measured by a 3D laser scanning microscope. These plates then received one of the following two bond procedures to form four bond test groups: HFA/cement, NoHFA/cement, HFA/silane/cement and NoHFA/silane/cement. The associated micro-shear bond strength and bond failure modes were tested after 0 and 30 000 thermal water bath cycles. Four different silane/cement systems (Monobond S/Variolink II, GC Ceramic Primer/Linkmax HV, Clearfil Ceramic Primer/Clearfil Esthetic Cement and Porcelain Liner M/SuperBond C and B) were used. The data for each silane/cement system were analyzed by three-way ANOVA. HFA treatment significantly increased the surface R{sub a} and R{sub y} values and the rough area of the ceramic plates compared with NoHFA treatment. After 30 000 thermal water bath cycles, the bond strength of all the test groups except the HFA/Linkmax HV group was significantly reduced, while the HFA/Linkmax HV group showed only adhesive interface failure. The other HFA/cement groups and all NoHFA/cement groups lost bond strength completely, and all NoHFA/silane/cement groups with chemical adhesion had significantly higher bond strength and more ceramic cohesive failures than the respective HFA/cement groups with mechanical retention. The result of the HFA/silane/cement groups with both chemical adhesion and mechanical retention revealed that HFA treatment could enhance the bond durability of resin/silanized glass ceramics, which might result from the increase of the chemical adhesion area on the ceramic rough surface and subsequently reduced degradation speed of the silane

  2. Clinical evaluation of fractured metal-ceramic fixed dental prostheses repaired with indirect technique.

    Science.gov (United States)

    Galiatsatos, Aristidis A; Galiatsatos, Panagiotis A

    2015-03-01

    Metal ceramic restorations continue to be widely used in dental practice, as they combine esthetics with superior mechanical properties. However, ceramic materials have the potential to fracture due to their brittle nature. The purpose of this study was to evaluate the clinical survival of fractured metal-ceramic restorations repaired with an indirect technique which uses a new "overlay" metal-ceramic crown that is luted to the existing restoration. The study population consisted of 92 patients. Only patients with one or more fractured retainers of multipleunit metal-ceramic fixed partial dentures were involved in this study. In all cases there were a bulk fracture of the overlaying ceramic material and exposure of the underlying metal substructure. The remaining retainers of the fixed partial dentures were intact. The total number of fractured retainers was 106. All clinical procedures of the indirect repairs were carried out by a single investigator, according the previously published technique. The patients were examined clinically at 1, 2, 4, 6, and 8 years after placement of the new restorations. The repaired restorations were examined for debonding, fracture rate, and esthetics. Patient acceptance was also recorded. Of the 92 patients re-examined, all were satisfied with the function and the esthetic appearance of their restorations. None of the repaired restorations fractured after 8 years of service, and there were no gingival margin problems of significance. Four restorations debonded during the evaluation period. The overall survival rate was 96.2% after 8 years. Repair methodology and materials employed in this study resulted in satisfactory longevity for metal-ceramic dental prostheses. The success rate was 96.2% after 8 years. The retention rate was very good, patient satisfaction was very encouraging, and maintenance of the esthetics was good.

  3. A comparison of the marginal vertical discrepancies of zirconium and metal ceramic posterior fixed dental prostheses before and after cementation.

    Science.gov (United States)

    Gonzalo, Esther; Suárez, Maria J; Serrano, Benjamin; Lozano, Jose F L

    2009-12-01

    Marginal discrepancies of zirconia posterior fixed dental prostheses (FDPs) fabricated using various systems have been assessed to determine the quality of the restorations and facilitate clinical use; however, studies are limited and results are ambiguous because of the sample sizes and measurement methods. The purpose of this in vitro study was to compare changes in marginal fit of posterior fixed dental prostheses of 3 zirconia systems manufactured using CAD/CAM technology and metal ceramic posterior fixed dental protheses fabricated with the conventional lost-wax technique, before and after cementation. Forty standardized master steel dies with 2 abutments simulating first mandibular premolars were fabricated to receive a posterior 3-unit FDP (from first molar to first premolar) and divided into 4 groups (n=10): Lava All-Ceramic System, Procera Bridge Zirconia, VITA In-Ceram 2000 YZ, and metal ceramic (control group). All FDPs were prepared for an internal space of 50 microm. The external marginal gap of the restorations was investigated by measuring 30 points in the middle of the buccal and lingual surfaces; therefore, 60 measurements per abutment were recorded. Measurements were made with an image analysis program on the master steel model before and after conventional cementation with a glass ionomer agent (Ketac Cem Easymix). The data obtained were statistically analyzed using 1-way ANOVA, Duncan's multiple range post hoc test, and Student's paired t test (alpha=.05). No significant differences in the vertical marginal fit before and after cementation were recorded for the analyzed groups. The marginal discrepancy of Procera abutments before and after cementation (9 +/-10 microm and 12 +/-9 microm, respectively) was less than that of the other groups. Significant differences (P=.001) were observed in marginal adaptation between Procera Bridge Zirconia and the other groups. The results of this study showed that cementation did not cause a significant

  4. Combination of ICP-OES, XRF and XRD techniques for analysis of several dental ceramics and their identification using chemometrics

    OpenAIRE

    Safwan M. Obeidat; Al-Momani, Idrees; Haddad, Asma'a; Bani Yasein, Motasem

    2011-01-01

    In this paper dental ceramic samples from seven vendors were studied. The elemental composition for each type was investigated using the ICP-OES and the XRF. Assessment of the seven types of ceramic was also successfully achieved using the XRD spectral data and processed with Principal Component Analysis (PCA). Detecting possible adulteration in different mass percentages of ceramic was also possible by applying the XRD data for the adulterated samples to the original PCA model.

  5. Standardizing Failure, Success, and Survival Decisions in Clinical Studies of Ceramic and Metal-Ceramic Fixed Dental Prostheses

    Science.gov (United States)

    Anusavice, Kenneth J.

    2011-01-01

    “Nothing worthwhile is ever without complications.”– Nora Roberts The recent increase in reports from clinical studies of ceramic chipping has raised the question of which criteria should constitute success or failure of total-ceramic prostheses. Terminology such as minor chipping[1], partial chipping, technical complications[2, 3], and biological complications have crept into the dental terminology and they have complicated our classification of success and failure of these crown and bridge restorations. Some journals have permitted the reporting of fractures as “complications” and they are not necessarily classified as failures in the study. One study has attempted to classify chipping fractures according to their severity and subsequent treatment.[4] This is a promising approach to resolve the challenges to the classification of chipping fracture. The term ‘chipping fracture’ is more descriptive than ‘chipping’ since the latter term tends to imply an event of minor consequence. Two types of statistics are reported routinely in these studies, i.e., percent success, which is a measure of restorations that survive without any adverse effects, and percent survival, which is a measure of all restorations that survive even though they may have exhibited chipping fracture or they may have been repaired. Why has this scenario occurred? One possible explanation is that many of these types of fractures are very small and do not affect function or esthetics. Another reason is that corporate sponsors prefer to use the term chipping since it does not connote failure in the sense that the term fracture does. In any event, we need to be more precise in our scientific observations of fracture and classifications of the various types of fracture including details on the location of fracture and the prosthesis design configuration. Because of the lack of standardized methods for describing chipping fractures, materials scientists are unable to properly analyze

  6. Stress and Reliability Analysis of a Metal-Ceramic Dental Crown

    Science.gov (United States)

    Anusavice, Kenneth J; Sokolowski, Todd M.; Hojjatie, Barry; Nemeth, Noel N.

    1996-01-01

    Interaction of mechanical and thermal stresses with the flaws and microcracks within the ceramic region of metal-ceramic dental crowns can result in catastrophic or delayed failure of these restorations. The objective of this study was to determine the combined influence of induced functional stresses and pre-existing flaws and microcracks on the time-dependent probability of failure of a metal-ceramic molar crown. A three-dimensional finite element model of a porcelain fused-to-metal (PFM) molar crown was developed using the ANSYS finite element program. The crown consisted of a body porcelain, opaque porcelain, and a metal substrate. The model had a 300 Newton load applied perpendicular to one cusp, a load of 30ON applied at 30 degrees from the perpendicular load case, directed toward the center, and a 600 Newton vertical load. Ceramic specimens were subjected to a biaxial flexure test and the load-to-failure of each specimen was measured. The results of the finite element stress analysis and the flexure tests were incorporated in the NASA developed CARES/LIFE program to determine the Weibull and fatigue parameters and time-dependent fracture reliability of the PFM crown. CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/Or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program.

  7. ADVANCED CERAMIC MATERIALS FOR DENTAL APPLICATIONS SINTERED BY MICROWAVE HEATING

    OpenAIRE

    Presenda Barrera, Álvaro

    2016-01-01

    [EN] Zirconia has become a widely utilized structural ceramic material with important applications in dentistry due to its superb mechanical properties, biocompatibility, aesthetic characteristics and durability. Zirconia needs to be stabilized in the t-phase to obtain improved mechanical properties such as hardness and fracture toughness. Fully dense yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) materials are normally consolidated through the energy-intensive processing of po...

  8. Adhesion of oral streptococci to all-ceramics dental restorative materials in vitro.

    Science.gov (United States)

    Meier, R; Hauser-Gerspach, I; Lüthy, H; Meyer, J

    2008-10-01

    In recent years, patients have benefited from the development of better and more esthetic materials, including all-ceramics dental restorative materials. Dental plaque formation on teeth and restorative materials plays an important role in the pathogenesis of oral diseases. This study investigates initial adhesion of stationary phase streptococcal species to different all-ceramics dental restorative materials. The saliva-coated materials were incubated with the bacteria for 1 h in an in vitro flow chamber which mimics environmental conditions in the oral cavity. Number and vitality of adhering bacteria were determined microscopically after staining. Surface roughness and the composition of the materials had no distinctive influence on bacterial adhesion. However, S. mutans and S. sobrinus adhered about tenfold less numerous to all materials than the other streptococcal species. Further, there was a correlation between bacterial vitality and materials' glass content. The results showed that early plaque formation was influenced predominantly by the presence of the salivary pellicle rather than by material dependent parameters whereas the composition of the all-ceramics appeared to have influenced the percentage of viable cells during the adhesion process. This presented in vitro technique may provide a useful model to study the influence of different parameters on adherence of oral streptococcal species.

  9. Deformation of a dental ceramic following adhesive cementation.

    LENUS (Irish Health Repository)

    2010-01-01

    Stress-induced changes imparted in a \\'dentin-bonded-crown\\' material during sintering, annealing, pre-cementation surface modification, and resin coating have been visualized by profilometry. The hypothesis tested was that operative techniques modify the stressing pattern throughout the material thickness. We polished the upper surfaces of 10 ceramic discs to remove surface imperfections before using a contact profilometer (40-nm resolution) to measure the \\'flatness\\'. Discs were re-profiled after annealing and after alumina particle air-abrasion and resin-coating of the \\'fit\\' surface. Polished surfaces were convex, with a mean deflection of 8.4 + or - 1.5 microm. Mean deflection was significantly reduced (P = 0.029) following alumina particle air-abrasion and increased (P < 0.001) on resin-coating. Polishing induced a tensile stress state, resulting in surface convexity. Alumina particle air-abrasion reduced the relative tensile stress state of the contralateral polished surface. Resin-polymerization generated compression within the resin-ceramic \\'hybrid layer\\' and tension in the polished surface and is likely to contribute to the strengthening of ceramics by resin-based cements.

  10. Comparative study of flexural strength test methods on CAD/CAM Y-TZP dental ceramics

    Science.gov (United States)

    Xu, Yongxiang; Han, Jianmin; Lin, Hong; An, Linan

    2015-01-01

    Clinically, fractures are the main cause of computer-aided design and computer-aided manufacturing (CAD/CAM) 3 mol%-yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) all-ceramic dental restorations failure because of repetitive occlusal loading. The goal of this work is to study the effect of test methods and specimen’s size on the flexural strength of five ceramic products. Both bi-axial flexure test (BI) and uni-axial flexure tests (UNI), including three-point flexure test (3PF) and four-point flexure test (4PF), are used in this study. For all five products, the flexural strength is as follows: BI > 3PF > 4PF. Furthermore, specimens with smaller size (3PF-s) have higher values than the bigger ones (3PF). The difference between BI and UNI resulted from the edge flaws in ceramic specimens. The relationship between different UNI (including 3PF-s, 3PF and 4PF) can be explained according to Weibull statistical fracture theory. BI is recommended to evaluate the flexural strength of CAD/CAM Y-TZP dental ceramics. PMID:26816646

  11. Cytotoxicity of dental alloys, metals, and ceramics assessed by millipore filter, agar overlay, and MTT tests.

    Science.gov (United States)

    Sjögren, G; Sletten, G; Dahl, J E

    2000-08-01

    Biocompatibility of dental materials is dependent on the release of elements from the materials. In addition, the composition, pretreatment, and handling of the materials influence the element release. This study evaluated the cytotoxicity of dental alloys, metals, and ceramics, with specific emphasis on the effects of altering the composition and the pretreatment. By using cells from a mouse fibroblast cell line and the agar overlay test, Millipore filter test, and MTT test, cytotoxicity of various metals, metal alloys, and ceramics for dental restoration were studied. Effects of altering the composition of a high noble gold alloy and of pretreatment of a ceramic-bonding alloy were also studied. In addition, the release of elements into the cell culture medium by the materials studied was measured using an inductively coupled plasma optical emission spectrophotometer. The results of the MTT test were analyzed statistically using ANOVA and Scheffé test at a significance level of P dental restorations and handled in accordance with the manufacturers' instructions were ranked from "noncytotoxic" to "mildly cytotoxic" according to the agar overlay and Millipore filter tests. For the MTT test, no significant differences were observed between these materials and controls, with the exception of JS C-gold and unalloyed titanium. The modified materials were ranked from "mildly cytotoxic" to "moderately cytotoxic" in the agar overlay and Millipore filter tests and from "noncytotoxic" to "moderately cytotoxic" in the MTT test. Thus, cytotoxicity was related to the alloy composition and treatment. The release of Cu and Zn seemed to be important for the cytotoxic effect. Alterations in the composition and the pretreatment can greatly influence the cytotoxicity, and the results stress the importance of carefully following the manufacturers' instructions when handling dental materials.

  12. Evaluation of the surface roughness in dental ceramics submitted to different finishing and polishing methods.

    Science.gov (United States)

    Vieira, Alex C; Oliveira, Mario C S; Lima, Emilena M C X; Rambob, Isabel; Leite, Mariana

    2013-09-01

    Ceramic restorations have been widely used in dentistry. These restorations often require intraoral adjustment with diamond burs after their cementation causing increasing roughness of the ceramic surface. Consequently some finishing and polishing methods have been used to minimize this occurrence. The aim of this study is to evaluate the roughness of the ceramic surfaces submitted to different finishing and polishing methods. 144 specimens of VITAVM(®)7, VM(®)9 and VM(®)13 (VITA Zahnfabrik) ceramics were fabricated and submitted to grinding using diamond burs. They were then divided into 15 groups (five of each ceramic type). Groups 1, 6 and 11-positive control (Glaze); Groups 2, 7 and 12-negative control (no polishing); Groups 3, 8 and 13-polished with abrasive rubbers (Edenta), felt disc and diamond polishing past; Groups 4, 9 and 14-polished with abrasive rubbers (Shofu), felt disc and diamond polishing past; Groups 5, 10 and 15-polished with aluminum oxide discs (Sof-Lex, 3M-ESPE), felt disc and diamond polishing paste. The roughness of the samples surfaces were measured using the rugosimeter Surfcorder SE 1700 and the data were submitted to statistical analysis using ANOVA and Tukey test at a level of significance of 5 %. There was statistically significance difference between the positive control groups and the other groups in all the ceramic types. Mechanical finishing and polishing methods were not able to provide a surface as smooth as the glazed surface for the tested ceramics. To assist dental practitioners to select the best finishing and polishing methods for the final adjustment of the ceramic restorations.

  13. Two-body wear of dental porcelain and substructure oxide ceramics.

    Science.gov (United States)

    Rosentritt, Martin; Preis, Verena; Behr, Michael; Hahnel, Sebastian; Handel, Gerhard; Kolbeck, Carola

    2012-06-01

    The aim of this in vitro study was to investigate the two-body wear of different ceramics. Two-body wear tests were performed in a chewing simulator with steatite and enamel antagonists, respectively. Specimens were loaded in a pin-on-block design with a vertical load of 50 N for 1.2 × 10(5) cycles; (f = 1.6 Hz; lateral movement, 1 mm; mouth opening: 2 mm). Human enamel was used as a reference. Three zirconia ceramics, three veneering porcelains, two glass-infiltrated and one lithium disilicate ceramic were investigated. Veneering and lithium disilicate ceramics were glazed before testing. Surface roughness Ra (SP6, Perthen-Feinprüf, G) and wear depth were determined using a 3D scanner (Laserscan 3D, Willytec, G). SEM (Quanta FEG 400, FEI, USA) pictures of the worn specimens and antagonists were made for evaluating wear performance. Veneering porcelain provided wear traces between 71.2 and 124.1 μm (enamel antagonist) and 117.4 and 274.1 μm (steatite). Wear of the steatite antagonists varied between 0.618 and 2.85 mm². No wear was found for zirconia and glass-infiltrated substructure ceramics. Also, no wear was found for the corresponding antagonists. Wear of specimens and antagonists was strongly material dependent. No visible wear was found on zirconia and glass-infiltrated ceramics. Porcelain and lithium disilicate ceramic showed a comparable or lower wear than the enamel reference. Antagonist wear was found to be lower when specimens were made of substructure oxide ceramics instead of veneering porcelain. From the point of wear testing, zirconia may be used for the fabrication of fixed dental prosthesis without veneering.

  14. Rugometric and microtopographic non-invasive inspection in dental-resin composites and zirconia ceramics

    Science.gov (United States)

    Fernández-Oliveras, Alicia; Costa, Manuel F. M.; Pecho, Oscar E.; Rubiño, Manuel; Pérez, María. M.

    2013-11-01

    Surface properties are essential for a complete characterization of biomaterials. In restorative dentistry, the study of the surface properties of materials meant to replace dental tissues in an irreversibly diseased tooth is important to avoid harmful changes in future treatments. We have experimentally analyzed the surface characterization parameters of two different types of dental-resin composites and pre-sintered and sintered zirconia ceramics. We studied two shades of both composite types and two sintered zirconia ceramics: colored and uncolored. Moreover, a surface treatment was applied to one specimen of each dental-resin. All the samples were submitted to rugometric and microtopographic non-invasive inspection with the MICROTOP.06.MFC laser microtopographer in order to gather meaningful statistical parameters such as the average roughness (Ra), the root-mean-square deviation (Rq), the skewness (Rsk), and the kurtosis of the surface height distribution (Rku). For a comparison of the different biomaterials, the uncertainties associated to the surface parameters were also determined. With respect to Ra and Rq, significant differences between the composite shades were found. Among the dental resins, the nanocomposite presented the highest values and, for the zirconia ceramics, the pre-sintered sample registered the lowest ones. The composite performance may have been due to cluster-formation variations. Except for the composites with the surface treatment, the sample surfaces had approximately a normal distribution of heights. The surface treatment applied to the composites increased the average roughness and moved the height distribution farther away from the normal distribution. The zirconia-sintering process resulted in higher average roughness without affecting the height distribution.

  15. Ceramic-like wear behaviour of human dental enamel.

    Science.gov (United States)

    Arsecularatne, J A; Hoffman, M

    2012-04-01

    This paper reports a transmission electron microscopy (TEM) analysis of subsurfaces of enamel specimens following in vitro reciprocating wear tests with an enamel cusp sliding on a flat enamel specimen under hydrated conditions. The obtained results show that crack formation occurred in the wear scar subsurface. The path followed by these cracks seems to be dictated either by the histological structure of enamel or by the contact stress field. Moreover, the analysis of a set of enamel wear results obtained from the literature and application of fracture-based models, originally developed for ceramics, correlate well, confirming the similar wear processes taking place in these materials. This analysis also reveals a marked influence of coefficient of friction on the enamel wear rate: for a higher coefficient of friction value, enamel wear can be severe even under forces generated during normal operation of teeth. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Measurements of scattering anisotropy in dental tissue and zirconia ceramic

    Science.gov (United States)

    Fernández-Oliveras, Alicia; Pecho, Oscar E.; Rubiño, Manuel; Pérez, María M.

    2012-06-01

    Knowledge of the optical properties of biological structures is useful for clinical applications, especially when dealing with incoming biomaterials engineered to improve the benefits for the patient. One ceramic material currently used in restorative dentistry is yttrium cation-doped tetragonal zirconia polycrystal (3Y-TZP) because of its good mechanical properties. However, its optical properties have not been thoroughly studied. Many methods for the determination of optical parameters from biological media make the assumption that scattered light is isotropically distributed over all angles. Nevertheless, real biological materials may have an angular dependence on light scattering, which may affect the optical behaviour of the materials. Therefore, the recovery of the degree of anisotropy in the scattering angular distribution is important. The phase function that represents the scattering angular distribution is usually characterized by the anisotropy coefficient g, which equals the average cosine of the scattering angle. In this work, we measured angularscattering distributions for two zirconia ceramic samples, pre-sintered and sintered, with similar thicknesses (0.48 mm and 0.50 mm, respectively) and also for a human dentine sample (0.41 mm in thickness). The samples were irradiated with a He-Ne laser beam (λ = 632.8 nm) and the angular-scattering distributions were measured using a rotating goniometer. The g values yielded were: -0.7970 +/- 0.0016 for pre-sintered zirconia, -0.2074 +/- 0.0024 for sintered zirconia and 0.0620 +/- 0.0010 for dentine. The results show that zirconia sintering results in optical behaviour more similar to those of dentine tissue, in terms of scattering anisotropy.

  17. The effects of viscoelastic parameters on residual stress development in a zirconia/glass bilayer dental ceramic.

    Science.gov (United States)

    Taskonak, Burak; Borges, Gilberto A; Mecholsky, John J; Anusavice, Kenneth J; Moore, B Keith; Yan, Jiahau

    2008-09-01

    The aim of this study was to test the hypothesis that the residual stresses in a zirconia-based bilayer dental composite system can be tailored through heat treatment above and below the glass transition temperature of glass veneers. Ceramic bilayer disc specimens were prepared from a zirconia core and a glass veneer. Each bilayer ceramic group was heat treated 40 degrees C below, 20 degrees C and 40 degrees C above and at the glass transition temperature of the glass veneer, and cooled using a fast or a slow cooling rate. Specimens were tested for flexure strength using a biaxial bending fixture. Residual stresses were calculated using a fracture mechanics approach. Heat treatments produced significant differences (p 0.05) between the mean flexural strengths of the heat treatment groups when a slow cooling rate was used. Fractures initiated from the veneer surfaces of the specimens. Heat treatment above and below the glass transition temperature of the veneer layer, and the cooling rate have a significant effect on the flexural strength of the bilayer ceramic laminates. The existence of residual compressive stress is the most likely reason for the observed strength increases. Residual stresses can be modified using the elastic-viscoelastic relaxation behavior of a glass veneer.

  18. The preparation of dental glass-ceramic composites with controlled fraction of leucite crystals

    Directory of Open Access Journals (Sweden)

    Martina Mrázová

    2008-06-01

    Full Text Available This work is dealing with synthesis of leucite powder, which can be used for the preparation of dental glassceramic composites by subsequent thermal treatment. Newly developed procedure is based on preparation of dental raw material as a mixture of two separate compounds: the crystalline leucite powder prepared at relatively low temperature and a commercial matrix powder.Hydrothermal synthesis of tetragonal leucite particles (KAlSi2O6 with the average size of about 3 μm was developed in our laboratory. The leucite dental raw material was prepared by mixing of 20 wt.% of synthetic tetragonal leucite with commercial matrix. Dental composites were prepared from the dental raw material by uniaxial pressing and firing up to 960°C. Dilatometric measurements confirmed that the coefficient of thermal expansion increased by 32% when 20 wt.% of the tetragonal leucite was added into the basic matrix. In addition, it was showed that the synthesized leucite powder was suitable for the preparation of leucite composites with controlled coefficient of thermal expansion. High value of the thermal expansion coefficient enables application of prepared composite in metal-ceramics restorations.

  19. Innovation of dental education system for researcher, dentist, dental hygienist and dental technician in Hiroshima University

    OpenAIRE

    Kurihara, Hidemi

    2006-01-01

    Hiroshima University Faculty of Dentistry's goal is to become the worldwide research and education center in Dentistry. It seems to constitute the dental education by two missions: core and characteristic. Hiroshima University Faculty of Dentistry has clarified their characteristic mission and improved dental education system to reinforce the innovative part of the education. We started two programs to cultivate researchers/educators who will be a world-wide leader of dental research and educ...

  20. On the surface elemental composition of non-corroded and corroded dental ceramic materials in vitro.

    Science.gov (United States)

    Milleding, P; Karlsson, S; Nyborg, L

    2003-06-01

    Dental ceramics are traditionally looked upon as inert materials. As many are glass phased, it may be hypothesized that they will be subjected to glass corrosion in aqueous environments. The aim of the study was therefore to analyze the surface elemental composition of glass-phased and all-crystalline ceramics, before and after low- and high-intensity, in vitro corrosion (milli-Q-water at 37+/-2 degrees C for 18 h and 4% acetic acid at 80+/-2 degrees C for 18 h, respectively). The analysis of the surface elemental composition was performed using ESCA. The hypothesis was confirmed. After high-intensity corrosion, the complete wash out of alkali ions, alkaline-earth ions and elemental alumina was found, leaving behind a surface totally dominated by silica. The all-crystalline ceramics, densely sintered alumina and yttria-partially stabilized tetragonal zirconia, displayed only minor surface changes, even after high-intensity corrosion. In comparison to the corrosion testing in acid, the corrosion process in milli-Q-water did not produce different results in principle, except for the lower magnitude of the depletion of alkali ions and the virtually unchanged level of elemental alumina. Unexpectedly, no substantial difference in surface degradation was found between the glass ceramic and the ordinary porcelain-fused-to-metal ceramic or between ceramics of higher sintering temperature and those of low or ultra-low sintering temperature. The composition and microstructure alone did not appear to provide a full explanation for the inter-individual differences in surface corrosion when exposed to comparable environmental conditions.

  1. Interfacial toughness of bilayer dental ceramics based on a short-bar, chevron-notch test.

    Science.gov (United States)

    Anunmana, Chuchai; Anusavice, Kenneth J; Mecholsky, John J

    2010-02-01

    The objective of this study was to test the null hypothesis that the interfacial toughness of each of two types of bonded core-veneer bilayer ceramics is not significantly different from the apparent fracture toughness of the control monolithic glass veneer. T-shaped short-bars of a lithia-disilicate glass-ceramic core (LC) and yttria-stabilized polycrystalline zirconia core ceramic (ZC) were prepared according to the manufacturer's recommendations. V-shaped notches were prepared by using 25-mum-thick palladium foil, leaving the chevron-notch area exposed, and the bars were veneered with a thermally compatible glass veneer (LC/GV and ZC/GV). Additionally, we also bonded the glass veneer to itself as a control group (GV/GV). Specimens were kept in distilled water for 30 days before testing in tension. Eight glass veneer bars were prepared for the analysis of fracture toughness test using the indentation-strength technique. The mean interfacial toughness of the LC/GV group was 0.69 MPam(1/2) (0.11), and did not significantly differ from that of the GV/GV control group, 0.74 MPam(1/2) (0.17) (p>0.05). However, the difference between the mean interfacial toughness of the ZC/GV group, 0.13 MPam(1/2) (0.07), and the LC/GV and the GV/GV groups was statistically significant (p<0.05). For bilayer all-ceramic restorations with high-strength core materials, the veneering ceramics are the weakest link in the design of the structure. Since all-ceramic restorations often fail from chipping of veneer layers or crack initiation at the interface, the protective effects of thermal mismatch stresses oral prosthesis design should be investigated. Copyright 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs).

    Science.gov (United States)

    Sailer, Irena; Makarov, Nikolay Alexandrovich; Thoma, Daniel Stefan; Zwahlen, Marcel; Pjetursson, Bjarni Elvar

    2015-06-01

    To assess the 5-year survival of metal-ceramic and all-ceramic tooth-supported single crowns (SCs) and to describe the incidence of biological, technical and esthetic complications. Medline (PubMed), Embase, Cochrane Central Register of Controlled Trials (CENTRAL) searches (2006-2013) were performed for clinical studies focusing on tooth-supported fixed dental prostheses (FDPs) with a mean follow-up of at least 3 years. This was complimented by an additional hand search and the inclusion of 34 studies from a previous systematic review [1,2]. Survival and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. Sixty-seven studies reporting on 4663 metal-ceramic and 9434 all-ceramic SCs fulfilled the inclusion criteria. Seventeen studies reported on metal-ceramic crowns, and 54 studies reported on all-ceramic crowns. Meta-analysis of the included studies indicated an estimated survival rate of metal-ceramic SCs of 94.7% (95% CI: 94.1-96.9%) after 5 years. This was similar to the estimated 5-year survival rate of leucit or lithium-disilicate reinforced glass ceramic SCs (96.6%; 95% CI: 94.9-96.7%), of glass infiltrated alumina SCs (94.6%; 95% CI: 92.7-96%) and densely sintered alumina and zirconia SCs (96%; 95% CI: 93.8-97.5%; 92.1%; 95% CI: 82.8-95.6%). In contrast, the 5-year survival rates of feldspathic/silica-based ceramic crowns were lower (pceramic and zirconia crowns exhibited significantly lower survival rates in the posterior region (pceramic fractures than metal-ceramic SCs (pceramic SCs than for metal-ceramic SCs. Survival rates of most types of all-ceramic SCs were similar to those reported for metal-ceramic SCs, both in anterior and posterior regions. Weaker feldspathic/silica-based ceramics should be limited to applications in the anterior region. Zirconia-based SCs should not be considered as primary option due to their high incidence of technical problems. Copyright © 2015 Academy

  3. Mechanical Properties of a new Dental all-ceramic Material-zirconia Toughened Nanometer-ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    CHAI Feng; XU Ling; CHAO Yong-lie; LIAO Yun-mao; ZHAO Yi-min

    2003-01-01

    Objectives:All-ceramic dental restorations are attractive to the dental community because of their advantages.But they're also challenged by relatively low flexural strength and intrinsic poor resistance to fracture.This paper aims to investigate mechanical properties of a new dental all-ceramic material, i.e. zirconia toughened nanometer-ceramic composite (α-Al2O3/nZrO2).Methods:α-Al2O3/nZrO2 ceramics powder (W) was processed with combined methods of chemical co-precipitation method and ball milling. Scanning electron microscopy (SEM)was used to determine the particle size distribution and to characterize the particle morphology of the powders. Four kinds of powders with different ZrO2 content (5wt%, 10wt%, 15wt% and 20wt%) were prepared by using α-Al2O3 powder to dilute the higher ZrO2 content powder (W). The ceramic matrix compacts were made by slip-casting technique and sintering to 1 200~1 600 ℃. The flexural strength and the fracture toughness of the matrix materials were measured via three-point bending test and single-edge notch beam methods, respectively.Results:1) The particle distribution of the Al2O3/nZrO2 powder ranged from 0.02~3.0 μm, with the superfine particles almost accounting for 20%;2) There is a significant difference of flexural strength (P<0.05) between the groups with 1 450 ℃ and 1 600 ℃ sintering temperature and 1 200 ℃;3) There is a significant difference of flexural strength (P<0.05) between different zirconia volume fraction groups with the same sintering temperature, the ceramic matrix samples with higher nZrO2 (W) content had much better mechanical properties than those of pure α-Al2O3 ceramics.Conclusions:The studied nanometer α-Al2O3/nZrO2 powder was homogeously distributed within the matrix and had reasonable powder-size gradation to improve mechanical properties of ceramics.%目的:口腔全瓷修复体以其独特优越性受到医患青睐,但脆性问题一直限制其应用范围及使用可靠性.本研

  4. [The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

    Science.gov (United States)

    Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

    2015-06-01

    To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

  5. Mechanochemically synthesized kalsilite based bioactive glass-ceramic composite for dental vaneering

    Science.gov (United States)

    Kumar, Pattem Hemanth; Singh, Vinay Kumar; Kumar, Pradeep

    2017-08-01

    Kalsilite glass-ceramic composites have been prepared by a mechanochemical synthesis process for dental veneering application. The aim of the present study is to prepare bioactive kalsilite composite material for application in tissue attachment and sealing of the marginal gap between fixed prosthesis and tooth. Mechanochemical synthesis is used for the preparation of microfine kalsilite glass-ceramic. Low temperature frit and bioglass have been prepared using the traditional quench method. Thermal, microstructural and bioactive properties of the composite material have been examined. The feasibility of the kalsilite to be coated on the base commercial opaque as well as the bioactive behavior of the coated specimen has been confirmed. This study indicates that the prepared kalsilite-based composites show similar structural, morphological and bioactive behavior to that of commercial VITA VMK95 Dentin 1M2.

  6. Mechanochemically synthesized kalsilite based bioactive glass-ceramic composite for dental vaneering

    Science.gov (United States)

    Kumar, Pattem Hemanth; Singh, Vinay Kumar; Kumar, Pradeep

    2015-08-01

    Kalsilite glass-ceramic composites have been prepared by a mechanochemical synthesis process for dental veneering application. The aim of the present study is to prepare bioactive kalsilite composite material for application in tissue attachment and sealing of the marginal gap between fixed prosthesis and tooth. Mechanochemical synthesis is used for the preparation of microfine kalsilite glass-ceramic. Low temperature frit and bioglass have been prepared using the traditional quench method. Thermal, microstructural and bioactive properties of the composite material have been examined. The feasibility of the kalsilite to be coated on the base commercial opaque as well as the bioactive behavior of the coated specimen has been confirmed. This study indicates that the prepared kalsilite-based composites show similar structural, morphological and bioactive behavior to that of commercial VITA VMK95 Dentin 1M2.

  7. Synthesis and ceramic processing of alumina and zirconia based composites infiltrated with glass phase for dental applications; Sintese e processamento de compositos a base de alumina e zirconia com infiltracao de fase vitrea para aplicacoes odontologicas

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Daniel Gomes

    2009-07-01

    The interest for the use of ceramic materials for dental applications started due to the good aesthetic appearance promoted by the similarity to natural teeth. However, the fragility of traditional ceramics was a limitation for their use in stress conditions. The development of alumina and zirconia based materials, that associate aesthetic results, biocompatibility and good mechanical behaviour, makes possible the employment of ceramics for fabrication of dental restorations. The incorporation of vitreous phase in these ceramics is an alternative to minimize the ceramic retraction and to improve the adhesion to resin-based cements, necessary for the union of ceramic frameworks to the remaining dental structure. In the dentistry field, alumina and zirconia ceramic infiltrated with glassy phase are represented commercially by the In-Ceram systems. Considering that the improvement of powder's synthesis routes and of techniques of ceramic processing contributes for good performance of these materials, the goal of the present work is the study of processing conditions of alumina and/or 3 mol% yttria-stabilized zirconia ceramics infiltrated with aluminum borosilicate lanthanum glass. The powders, synthesized by hydroxide coprecipitation route, were pressed by uniaxial compaction and pre-sintered at temperature range between 950 and 1650 degree C in order to obtain porous ceramics bodies. Vitreous phase incorporation was performed by impregnation of aluminum borosilicate lanthanum powder, also prepared in this work, followed by heat treatment between 1200 and 1400 degree C .Ceramic powders were characterized by thermogravimetry, X-ray diffraction, scanning and transmission electron microscopy, gaseous adsorption (BET) and laser diffraction. Sinterability of alumina and /or stabilized zirconia green pellets was evaluated by dilatometry. Pre-sintered ceramics were characterized by apparent density measurements (Archimedes method), X-ray diffraction and scanning

  8. Dental ceramics coated with bioactive glass: Surface changes after exposure in a simulated body fluid under static and dynamic conditions

    Science.gov (United States)

    Papadopoulou, L.; Kontonasaki, E.; Zorba, T.; Chatzistavrou, X.; Pavlidou, E.; Paraskevopoulos, K.; Sklavounos, S.; Koidis, P.

    2003-07-01

    Bioactive materials develop a strong bond with living tissues through a carbonate-containing hydroxyapatite layer, similar to that of bone. The fabrication of a thin bioactive glass coating on dental ceramics used in metal-ceramic restorations, could provide a bioactive surface, which in combination with a tissue regenerative technique could lead to periodontal tissues attachment. The aim of this study was the in vitro investigation of the surface structure changes of dental ceramics used in metal-ceramic restorations, coated with a bioactive glass heat-treated at 950 °C, after exposure in a simulated body fluid (SBF) under two different soaking conditions. Coating of dental ceramics with a bioactive glass resulted in the formation of a stable and well bonded with the ceramic substrate thin layer. The growth of a well-attached carbonate apatite layer on their surface after immersion in a simulated body fluid is well evidenced under both experimental conditions, although in static environment the rate of apatite growth is constant and the grown layers seem to be more dense and compact compared with the respective layers observed on specimens under dynamic conditions.

  9. Influence of metal-ceramic fixed dental restorations on the occurrence of discoloration of gingiva

    Directory of Open Access Journals (Sweden)

    Ristić Ljubiša

    2006-01-01

    Full Text Available Background. Adverse effects of dental cast alloys on the health of patients are the problem in clinical practice. The aim of this paper was to describe the case of a patient with discolorated gingivae in the presence of fixed dental restorations and used diagnostic and therapeutic procedures. Case report. A 30-year old patient, presented with the complaints about unsatisfactory esthetic of his fixed dental restorations. He complained about the greyish discoloration of gingivae, inappropriate color of the crowns, and a larger space between the central incisors. Both discolorated and normal gingivae around the fixed dental restorations were taken by excision and the samples of gingivae were examined histopathologically, and by using the Atomic Absorption Spectrophotometry test (AAS. Histopathological examination of the discolorated gingivae showed the presence of non-specific inflammation with a foreign body. AAS revealed the presence of various metals in the samples and the higher metal contents in the samples of discolorated gingivae as compared with the samples of normal gingivae. New metal-ceramic crowns were made for the patient. Conclusion. A main cause of greyish discoloration of gingivae was presence of a metal in gingival tissue. After the excision of discolorated gingivae old metalceramic crowns should be replaced with new crowns.

  10. Novel, Ceramic Membrane System For Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, S.

    2012-12-31

    Separation of hydrogen from coal gas represents one of the most promising ways to produce alternative sources of fuel. Ceramatec, teamed with CoorsTek and Sandia National Laboratories has developed materials technology for a pressure driven, high temperature proton-electron mixed conducting membrane system to remove hydrogen from the syngas. This system separates high purity hydrogen and isolates high pressure CO{sub 2} as the retentate, which is amenable to low cost capture and transport to storage sites. The team demonstrated a highly efficient, pressure-driven hydrogen separation membrane to generate high purity hydrogen from syngas using a novel ceramic-ceramic composite membrane. Recognizing the benefits and limitations of present membrane systems, the all-ceramic system has been developed to address the key technical challenges related to materials performance under actual operating conditions, while retaining the advantages of thermal and process compatibility offered by the ceramic membranes. The feasibility of the concept has already been demonstrated at Ceramatec. This project developed advanced materials composition for potential integration with water gas shift rectors to maximize the hydrogenproduction.

  11. Ceramic and polymeric dental onlays evaluated by photo-elasticity, optical coherence tomography, and micro-computed tomography

    Science.gov (United States)

    Sinescu, Cosmin; Negrutiu, Meda; Topala, Florin; Ionita, Ciprian; Negru, Radu; Fabriky, Mihai; Marcauteanu, Corina; Bradu, Adrian; Dobre, George; Marsavina, Liviu; Rominu, Mihai; Podoleanu, Adrian

    2011-10-01

    Dental onlays are restorations used to repair rear teeth that have a mild to moderate amount of decay. They can also be used to restore teeth that are cracked or fractured if the damage is not severe enough to require a dental crown. The use of onlays requires less tooth reduction than does the use of metal fillings. This allows dentists to conserve more of a patient's natural tooth structure in the treatment process. The aims of this study are to evaluate the biomechanical comportment of the dental onlays, by using the 3D photo elasticity method and to investigate the integrity of the structures and their fitting to the dental support. For this optical coherence tomography and micro-computed tomography were employed. Both methods were used to investigate 37 dental onlays, 17 integral polymeric and 20 integral ceramic. The results permit to observe materials defects inside the ceramic or polymeric onlays situate in the biomechanically tensioned areas that could lead to fracture of the prosthetic structure. Marginal fitting problems of the onlays related to the teeth preparations were presented in order to observe the possibility of secondary cavities. The resulted images from the optical coherence tomography were verified by the micro-computed tomography. In conclusion, the optical coherence tomography can be used as a clinical method in order to evaluate the integrity of the dental ceramic and polymeric onlays and to investigate the quality of the marginal fitting to the teeth preparations.

  12. Study of TSL and OSL properties of dental ceramics for accidental dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Veronese, Ivan, E-mail: ivan.veronese@unimi.i [Dipartimento di Fisica, Universita degli Studi di Milano and INFN Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Galli, Anna [CNR-INFM, via Cozzi 53, 20125 Milano (Italy); Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca, via Cozzi 53, 20125 Milano (Italy); Cantone, Marie Claire [Dipartimento di Fisica, Universita degli Studi di Milano and INFN Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Martini, Marco [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca, via Cozzi 53, 20125 Milano (Italy); Vernizzi, Fabrizio; Guzzi, Gianpaolo [Italian Association for Metals and Biocompatibility Research - A.I.R.M.E.B., Milan (Italy)

    2010-01-15

    Interest is increasing in the development of new methodologies for accidental dose assessment, exploiting the luminescence and dosimetric properties of objects and materials which can be usually found directly on exposed subjects and/or in the contaminated area. In this work, several types of ceramics employed for dental prosthetics restoration, including both innovative materials used as sub-frames for the construction of the inner part of dental crowns (core), and conventional porcelains used for the fabrication of the external layer (veneer), were investigated with regard to their thermally and optically stimulated luminescence (TSL and OSL respectively) properties, in view of their potential application in accidental dosimetry. The sensitivity to ionizing radiation proved to strongly depend on the type and brand of ceramic, with minimum detectable dose ranging from few mGy up to several tens of mGy. A linear dose-response was observed for most of the samples. However, the luminescence signals were characterised by a significant fading, which has to be taken into account for a reliable accidental dose assessment after a radiation exposure event.

  13. Glass and glass-ceramic photonic systems

    Science.gov (United States)

    Zur, Lidia; Thi Ngoc Tran, Lam; Meneghetti, Marcello; Varas, Stefano; Armellini, Cristina; Ristic, Davor; Chiasera, Alessandro; Scotognella, Francesco; Pelli, Stefano; Nunzi Conti, Gualtiero; Boulard, Brigitte; Zonta, Daniele; Dorosz, Dominik; Lukowiak, Anna; Righini, Giancarlo C.; Ramponi, Roberta; Ferrari, Maurizio

    2017-02-01

    The development of optically confined structure is a major topic in both basic and applied physics not solely ICT oriented but also concerning lighting, laser, sensing, energy, environment, biological and medical sciences, and quantum optics. Glasses and glass-ceramics activated by rare earth ions are the bricks of such structures. Glass-ceramics are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing developing new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. The dependence of the final product on the specific parent glass and on the fabrication protocol still remain an important task of the research in material science. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including optical amplifiers, monolithic waveguide laser, novel sensors, coating of spherical microresonators, and up and down converters. This paper presents some results obtained by our consortium regarding glass-based photonics systems. We will comment the energy transfer mechanism in transparent glass ceramics taking as examples the up and down conversion systems and the role of SnO2 nanocrystals as sensitizers. Coating of spherical resonators by glass ceramics, 1D-Photonic Crystals for luminescence enhancement, laser action and disordered 1-D photonic structures will be also discussed. Finally, RF-Sputtered rare earth doped P2O5- SiO2-Al2O3-Na2O-Er2O3 planar waveguides, will be presented.

  14. Suppression effects of dental glass-ceramics with polarization-induced highly dense surface charges against bacterial adhesion.

    Science.gov (United States)

    Nozaki, Kosuke; Koizumi, Hiroki; Horiuchi, Naohiro; Nakamura, Miho; Okura, Toshinori; Yamashita, Kimihiro; Nagai, Akiko

    2015-01-01

    This study investigated the surface characteristics and antibacterial ability capacity of surface-improved dental glass-ceramics by an electrical polarization process. Commercially available dental glass-ceramic materials were electrically polarized to induce surface charges in a direct current field by heating. The surface morphology, chemical composition, crystal structure, and surface free energy (SFE) were evaluated using scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and water droplet methods, respectively. The antibacterial capacity was assessed by a bacterial adhesion test using Streptococcus mutans. Although the surface morphology, chemical composition, and crystal structure were not affected by electrical polarization, the polar component and total SFE were enhanced. After 24 h incubation at 37ºC, bacterial adhesion to the polarized samples was inhibited. The electrical polarization method may confer antibacterial properties on prosthetic devices, such as porcelain fused to metal crowns or all ceramic restorations, without any additional bactericidal agents.

  15. Haptic rendering for dental training system

    Institute of Scientific and Technical Information of China (English)

    WANG DangXiao; ZHANG YuRu; WANG Yong; L(U) PeiJun; ZHOU RenGe; ZHOU WanLin

    2009-01-01

    Immersion and Interaction are two key features of virtual reality systems,which are especially important for medical applications.Based on the requirement of motor skill training in dental surgery,haptic rendering method based on triangle model is investigated in this paper.Multi-rate haptic rendering architecture is proposed to solve the contradiction between fidelity and efficiency requirements.Realtime collision detection algorithm based on spatial partition and time coherence is utilized to enable fast contact determination.Proxy-based collision response algorithm is proposed to compute surface contact point.Cutting force model based on piecewise contact transition model is proposed for dental drilling simulation during tooth preparation.Velocity-driven levels of detail hapUc rendering algorithm is proposed to maintain high update rate for complex scenes with a large number of triangles.Hapticvisual collocated dental training prototype is established using half-mirror solution.Typical dental operations have been realized Including dental caries exploration,detection of boundary within dental crose-section plane,and dental drilling during tooth preparation.The haptic rendering method is a fundamental technology to improve Immersion and interaction of virtual reality training systems,which is useful not only in dental training,but also in other surgical training systems.

  16. Effect of the applied power of atmospheric pressure plasma on the adhesion of composite resin to dental ceramic.

    Science.gov (United States)

    Han, Geum-Jun; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Oh, Kyu-Hwan; Cho, Byeong-Hoon

    2012-08-01

    To evaluate the effect of applied power on dental ceramic bonding of composite resin using nonthermal atmospheric pressure plasma (APP). A pencil-type APP torch was used to modify the surface chemical composition and hydrophilicity of dental ceramic and to improve the adhesion of composite resin to the surface. The effect of the applied power on chemical changes of the plasma polymer on a ceramic surface and the adhesive strength between the composite resin and feldspathic porcelain were examined. Adhesion was evaluated by comparing shear bond strengths (SBS) using the iris method. The chemical composition of the plasma polymer deposited on the ceramic surface was evaluated using x-ray photoelectron spectroscopy (XPS). Hydrophilicity was evaluated by contact angle measurements. The fracture mode at the interface was also evaluated. The APP treatment was effective and the SBS of the experimental groups were significantly higher than those of the negative control group (p adhesion by producing carboxyl groups on the ceramic surface and as a result by improving surface hydrophilicity. The carboxyl group contents in the plasma polymer on the ceramic surface increased as the applied power increased.

  17. The influence of silane evaporation procedures on microtensile bond strength between a dental ceramic and a resin cement

    Directory of Open Access Journals (Sweden)

    Pereira Carolina

    2010-01-01

    Full Text Available Aim: To assess the influence of silane evaporation procedures on bond strength between a dental ceramic and a chemically activated resin cement. Materials and Methods: Eighteen blocks (6 mm Χ 14 mm Χ 14 mm of ceramic IPS Empress 2 were cemented (C and B to composite resin (InTen-S blocks using a chemical adhesive system (Lok. Six groups were analyzed, each with three blocks divided according to ceramic surface treatment: two control groups (no treatment, NT; 10% hydrofluoric acid plus silane Monobond-S dried at room temperature, HFS; the other four groups comprised different evaporation patterns (silane rinsed and dried at room temperature, SRT; silane rinsed in boiling water and dried as before, SBRT; silane rinsed with boiling water and heat dried at 50°C, SBH; silane dried at 50 ± 5°C, rinsed in boiling water and dried at room temperature, SHBRT. The cemented blocks were sectioned to obtain specimens for microtensile test 7 days after cementation and were stored in water for 30 days prior to testing. Fracture patterns were analyzed by optical and scanning electron microscopy. Statistics and Results: All blocks of NT debonded during sectioning. One way ANOVA tests showed higher bond strengths for HFS than for the other groups. SBRT and SBH were statistically similar, with higher bond strengths than SRT and SHBRT. Failures were 100% adhesive in SRT and SHBRT. Cohesive failures within the "adhesive zone" were detected in HFS (30%, SBRT (24% and SBH (40%. Conclusion: Silane treatment enhanced bond strength in all conditions evaluated, showing best results with HF etching.

  18. Adhesion of Streptococcus mutans to various dental materials in a laminar flow chamber system.

    Science.gov (United States)

    Rosentritt, Martin; Hahnel, Sebastian; Gröger, Gerhard; Mühlfriedel, Bastian; Bürgers, Ralf; Handel, Gerhard

    2008-07-01

    Newly developed dental materials have to be tested for their susceptibility to adhere bacteria causing caries and periodontitis. The objective of this study was to establish an in vitro laminar flow chamber assay for dental material evaluation with regard to the adhesion of oral bacteria. Test specimens of commonly used dental materials (ceramic (five brands of ceramics, n = 15/brand), composite (eight brands of composites, n = 15/brand), and alloy (two brands of alloys, n = 15/brand) specimens) were inserted in a laminar flow chamber system and rinsed with artificial saliva (2 h) and Streptococcus mutans NCTC 10,449 suspension (4 h) successively. The amount of adhered bacteria was quantified using a Resazurin reduction assay (Alamar Blue). Statistical analysis was performed using the Mann-Whitney U-test (alpha = 0.05). Regarding adhesion of Streptococcus mutans, significant differences between the various material classes were found. Highest fluorescence values (ranging from 973 to 3145), correlating with high bacterial adhesion, were found on composite samples, and lowest values (173-272) were found on the alloys. Ceramic specimens showed an intermediate adhesion of Streptococcus mutans (fluorescence values from 532 to 1326). Streptococcus mutans NCTC 10449 adhered differently to the various classes of dental materials. The established laminar flow chamber device provides a suitable method for evaluating the adhesion of oral bacteria to dental material surfaces. 2007 Wiley Periodicals, Inc.

  19. Processing and properties of ceramic matrix-polymer composites for dental applications

    Science.gov (United States)

    Huang, Hsuan Yao

    The basic composite structure of natural hard tissue was used to guide the design and processing of dental restorative materials. The design incorporates the methodology of using inorganic minerals as the main structural phase reinforced with a more ductile but tougher organic phase. Ceramic-polymer composites were prepared by slip casting a porous ceramic structure, heating and chemical treating the porous preform, infiltrating with monomer and then curing. The three factors that determined the mechanical properties of alumina-polymer composites were the type of polymer used, the method of silane treatments, and the type of bond between particles in the porous preforms. Without the use of silane coupling agents, the composites were measured to have a lower strength. The composite with a more "flexible" porous alumina network had a greater ability to plastically dissipate the energy of propagating cracks. However, the aggressive nature of the alumina particles on opposing enamel requires that these alumina-polymer composites have a wear compatible coating for practical application. A route to dense bioactive apatite wollastonite glass ceramics (AWGC)-polymer composites was developed. The problems associated with glass dissolution into the aqueous medium for slip casting were overcome with the use of silane. The role of heating rate and development of ceramic compact microstructure on composite properties was explored. In general, if isothermal heating was not applied, decreasing heating rate increased glass crystallinity and particle-particle fusion, but decreased pore volume. Also composite strength and fracture toughness decreased while modulus and hardness increased with decreasing heating rate. If isothermal heating was applied, glass crystallinity, pore content, and composite mechanical properties showed relatively little change regardless of the initial heating rate. The potential of AWGC-polymer composites for dental and implant applications was explored

  20. The effects of firing numbers on the opening total pore volume, translucency parameter and color of dental all-ceramic systems%烧结次数对牙科全瓷开放性总孔体积、透明度和色度的影响

    Institute of Scientific and Technical Information of China (English)

    李水根; 庞莉苹; 姚江武

    2012-01-01

    目的 评价烧结次数对牙科全瓷开放性总孔体积(TPV)、透明度(TP)和色度的影响.方法 采用热压全瓷(IPS Empress Ⅱ)、氧化铝全瓷(In-Cream alumina blanks)和氧化锆全瓷(Cercon CAD/CAM zirconia)3种材料制作试样,使用分光光谱仪与表面积和孔隙率仪测量计算试样经过1、3、5次烧结后的TP、明度(ΔL)、彩度(ΔC)和TPV变化.应用SAS 8.0软件对数据进行统计分析.结果 相同烧结次数下,3种全瓷试件的TPV、TP、ΔL和ΔC间均存在统计学差异(P<0.05),其中TPV为热压全瓷大于氧化铝全瓷和氧化锆全瓷(P<0.05);TP和ΔL均为热压全瓷最高,氧化锆全瓷其次,氧化铝全瓷最低(P<0.05);ΔC为热压全瓷和氧化铝全瓷大于氧化锆全瓷(P<0.05).不同烧结次数下,同一全瓷试件TPV、TP、ΔL和ΔC间也存在统计学差异(P<0.05).随着烧结次数的增加,TPV逐渐减小,TP、ΔL和△C逐渐增加.烧结次数与TPV、TPV与TP和ΔL均呈负相关(P<0.05).结论 重复烧结可通过TPV变化影响全瓷修复体的TP和ΔL的稳定性.%Objective To evaluate the effects of firing numbers on the total opening pore volume (TPV), translucency parameter (TP) and color of dental all-ceramic systems. Methods Specimens of three kinds of all-ceramics systems were made, i.e. heat pressed all-ceramic (IPS Empress E), alumina all-ceramic (In-Cream alumina blanks) and zirconia all-ceramic (Cercon CAD/CAM zirconia). The specimens' TP, lightness (AL), chroma (AC) and TPY after 1, 3 and 5 firings were measured and calculated by spectrophotometer and surface area/porosity system. The data were analyzed statistically using SAS 8.0 software. Results There were significant differences in TPV, TP, AL and AC for all-ceramic specimens at same number of firings (Palumina and zirconia for TPV(Pzirconia>alumina for TP and AL(Pzirconia for AC(P<0.05). The significant differences also presented in TPV, TP, AL and AC for a same specimen at different

  1. Electronic Dental Records System Adoption.

    Science.gov (United States)

    Abramovicz-Finkelsztain, Renata; Barsottini, Claudia G N; Marin, Heimar Fatima

    2015-01-01

    The use of Electronic Dental Records (EDRs) and management software has become more frequent, following the increase in prevelance of new technologies and computers in dental offices. The purpose of this study is to identify and evaluate the use of EDRs by the dental community in the São Paulo city area. A quantitative case study was performed using a survey on the phone. A total of 54 offices were contacted and only one declinedparticipation in this study. Only one office did not have a computer. EDRs were used in 28 offices and only four were paperless. The lack of studies in this area suggests the need for more usability and implementation studies on EDRs so that we can improve EDR adoption by the dental community.

  2. Ceramic-ceramic shell tile thermal protection system and method thereof

    Science.gov (United States)

    Riccitiello, Salvatore R. (Inventor); Smith, Marnell (Inventor); Goldstein, Howard E. (Inventor); Zimmerman, Norman B. (Inventor)

    1986-01-01

    A ceramic reusable, externally applied composite thermal protection system (TPS) is proposed. The system functions by utilizing a ceramic/ceramic upper shell structure which effectively separates its primary functions as a thermal insulator and as a load carrier to transmit loads to the cold structure. The composite tile system also prevents impact damage to the atmospheric entry vehicle thermal protection system. The composite tile comprises a structurally strong upper ceramic/ceramic shell manufactured from ceramic fibers and ceramic matrix meeting the thermal and structural requirements of a tile used on a re-entry aerospace vehicle. In addition, a lightweight high temperature ceramic lower temperature base tile is used. The upper shell and lower tile are attached by means effective to withstand the extreme temperatures (3000 to 3200F) and stress conditions. The composite tile may include one or more layers of variable density rigid or flexible thermal insulation. The assembly of the overall tile is facilitated by two or more locking mechanisms on opposing sides of the overall tile assembly. The assembly may occur subsequent to the installation of the lower shell tile on the spacecraft structural skin.

  3. Three-unit posterior zirconia-ceramic fixed dental prostheses (FDPs) veneered with layered and milled (CAD-on) veneering ceramics: 1-year follow-up of a randomized controlled clinical trial.

    Science.gov (United States)

    Grohmann, Philipp; Bindl, Andreas; Hämmerle, Christoph; Mehl, Albert; Sailer, Irena

    2015-01-01

    The aim of this multicenter randomized controlled clinical trial was to test posterior zirconia-ceramic fixed dental prostheses (FDPs) veneered with a computer-aided design/computer- assisted manufacture (CAD/CAM) lithium disilicate veneering ceramic (CAD-on) and manually layered zirconia veneering ceramic with respect to survival of the FDPs, and technical and biologic outcomes. Sixty patients in need of one posterior three-unit FDP were included. The zirconia frameworks were produced with a CAD/CAM system (Cerec inLab 3D/Cerec inEOS inLab). Thirty FDPs were veneered with a CAD/CAM lithium disilicate veneering ceramic (Cad-on) (test) and 30 were veneered with a layered zirconia veneering ceramic (control). For the clinical evaluation at baseline, 6, and 12 months, the United States Public Health Service (USPHS) criteria were used. The biologic outcome was judged by comparing the plaque control record (PCR), bleeding on probing (BOP), and probing pocket depth (PPD). Data were statistically analyzed. Fifty-six patients were examined at a mean follow-up of 13.9 months. At the 1-year follow-up the survival rate was 100% in the test and in the control group. No significant differences of the technical outcomes occurred. Major chipping occurred in the control group (n = 3) and predominantly minor chipping in the test group (minor n = 2, major n = 1). No biologic problems or differences were found. Both types of zirconia-ceramic FDPs exhibited very good clinical outcomes without differences between groups. Chipping occurred in both types of FDPs at small amounts, yet the extension of the chippings differed. The test FDPs predominantly exhibited minor chipping, the control FDPs major chipping.

  4. Utilization of dental health services by Danish adolescents attending private or public dental health care systems

    DEFF Research Database (Denmark)

    Christensen, Lisa Bøge; Petersen, Poul Erik; Bastholm, Annelise

    2002-01-01

    The objectives of the study were: 1) to describe the choice of dental care system among 16-year-olds, 2) to describe the utilization of dental services among 16-17-year-olds enrolled in either public or private dental care systems, and to compare the dental services provided by the alternative...... systems. The study comprised 1,245 adolescents from 3 municipalities; the historical cohort study design was applied; and data were collected from dental records (public dental service) and dental claims (private practice). At age 16, 12% preferred being enrolled in the private practice system, while 88......% remained in the public dental care system. During the 2-year study period the attendance rate was 99% for the public system, while 90% attended the private practice system (Pdental services were provided more frequently by the public than the private system (P

  5. Optical properties of zirconia ceramics for esthetic dental restorations: A systematic review.

    Science.gov (United States)

    Shahmiri, Reza; Standard, Owen Christopher; Hart, Judy N; Sorrell, Charles Christopher

    2017-09-16

    Yttria-stabilized tetragonal zirconia polycrystal has been used as a dental biomaterial for several decades because the fracture toughness and bend strength are increased by a stress-induced transformation-toughening mechanism. However, its esthetics are compromised by its poor translucency and grayish-white appearance. The purpose of the present systematic review was to assess information on the mechanical, chemical, and optical requirements of monolithic zirconia dental restorations. The following databases (2010 to 2015) were electronically searched: ProQuest, EMBASE, SciFinder, MRS Online Proceedings Library, Medline, Compendex, and Journal of the American Ceramic Society. The search was limited to English-language publications, in vitro studies, experimental reports, and modeling studies. The data from 57 studies were considered in order to review the intrinsic and extrinsic characteristics of zirconia and their effects on the optical properties. The materials and microstructural issues relevant to the esthetics and long-term stability of zirconia have been considered in terms of monolithic restorations, while there also are restorations specifically for esthetic applications. Although zirconia-toughened lithium silicate offers the best esthetic outcomes, transformation-toughened zirconia offers the best mechanical properties and long-term stability; cubic stabilized zirconia offers a potential compromise. The properties of these materials can be altered to some extent through the appropriate application of intrinsic (such as, annealing) and extrinsic (such as, shade-matching) parameters. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  6. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Moradabadi, Ashkan [Department of Electrochemistry, Universität Ulm, Ulm (Germany); Roudsari, Sareh Esmaeily Sabet [Department of Optoelectonics, Universität Ulm, Ulm (Germany); Yekta, Bijan Eftekhari [School of Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Rahbar, Nima, E-mail: nrahbar@wpi.edu [Department of Civil and Environmental Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 (United States)

    2014-01-01

    This paper presents the results of an experimental study to understand the dominant mechanism in bond strength between dental resin agent and zirconia ceramic by investigating the effects of different surface treatments. Effects of two major mechanisms of chemical and micromechanical adhesion were evaluated on bond strength of zirconia to luting agent. Specimens of yttrium-oxide-partially-stabilized zirconia blocks were fabricated. Seven groups of specimens with different surface treatment were prepared. 1) zirconia specimens after airborne particle abrasion (SZ), 2) zirconia specimens after etching (ZH), 3) zirconia specimens after airborne particle abrasion and simultaneous etching (HSZ), 4) zirconia specimens coated with a layer of a Fluorapatite-Leucite glaze (GZ), 5) GZ specimens with additional acid etching (HGZ), 6) zirconia specimens coated with a layer of salt glaze (SGZ) and 7) SGZ specimens after etching with 2% HCl (HSGZ). Composite cylinders were bonded to airborne-particle-abraded surfaces of ZirkonZahn specimens with Panavia F2 resin luting agent. Failure modes were examined under 30 × magnification and the effect of surface treatments was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SZ and HSZ groups had the highest and GZ and SGZ groups had the lowest mean shear bond strengths among all groups. Mean shear bond strengths were significantly decreased by applying a glaze layer on zirconia surfaces in GZ and SGZ groups. However, bond strengths were improved after etching process. Airborne particle abrasion resulted in higher shear bond strengths compared to etching treatment. Modes of failure varied among different groups. Finally, it is concluded that micromechanical adhesion was a more effective mechanism than chemical adhesion and airborne particle abrasion significantly increased mean shear bond strengths compared with another surface treatments. - Highlights: • Understanding the dominant mechanism of bonding

  7. Three-Point Bending Tests of Zirconia Core/Veneer Ceramics for Dental Restorations

    Directory of Open Access Journals (Sweden)

    Massimo Marrelli

    2013-01-01

    Full Text Available Introduction. The mechanical strength and the surface hardness of commercially available yttrium-doped zirconia were investigated. Furthermore, a comparative study of eight different ceramic veneers, to be used for the production of two-layered all-ceramic restorative systems, was carried out. Materials and Methods. Four types of zirconia specimens were analyzed, according to a standard ISO procedure (ISO 6872. Besides, two-layered zirconia-veneer specimens were prepared for three-point bending tests. Results. A strong effect of the surface roughness on the mechanical strength of zirconia specimens was observed. Finally, a comparative study of eight commercially available veneering ceramics shows different modes of failure between the selected veneers. Conclusion. The results indicate that close attention should be paid to the preparation of zirconia-based crowns and bridges by CAD/CAM process, because surface roughness has an important effect on the mechanical strength of the material. Finally, the results of the mechanical tests on two-layered specimens represent an important support to the choice of the veneering ceramic.

  8. Crack tip fracture toughness of base glasses for dental restoration glass-ceramics using crack opening displacements.

    Science.gov (United States)

    Deubener, J; Höland, M; Höland, W; Janakiraman, N; Rheinberger, V M

    2011-10-01

    The critical stress intensity factor, also known as the crack tip toughness K(tip), was determined for three base glasses, which are used in the manufacture of glass-ceramics. The glasses included the base glass for a lithium disilicate glass-ceramic, the base glass for a fluoroapatite glass-ceramic and the base glass for a leucite glass-ceramic. These glass-ceramic are extensively used in the form of biomaterials in restorative dental medicine. The crack tip toughness was established by using crack opening displacement profiles under experimental conditions. The crack was produced by Vickers indentation. The crack tip toughness parameters determined for the three glass-ceramics differed quite significantly. The crack tip parameters of the lithium disilicate base glass and the leucite base glass were higher than that of the fluoroapatite base glass. This last material showed glass-in-glass phase separation. The discussion of the results clearly shows that the droplet glass phase is softer than the glass matrix. Therefore, the authors conclude that a direct relationship exists between the chemical nature of the glasses and the crack tip parameter.

  9. Hard tissue formation in a porous HA/TCP ceramic scaffold loaded with stromal cells derived from dental pulp and bone marrow.

    NARCIS (Netherlands)

    Zhang, W.; Walboomers, X.F.; Osch, G.J.V.M. van; Dolder, J. van den; Jansen, J.A.

    2008-01-01

    The aim of this study was to compare the ability of hard tissue regeneration of four types of stem cells or precursors under both in vitro and in vivo situations. Primary cultures of rat bone marrow, rat dental pulp, human bone marrow, and human dental pulp cells were seeded onto a porous ceramic sc

  10. Effect of elasticity on stress distribution in CAD/CAM dental crowns: Glass ceramic vs. polymer-matrix composite.

    Science.gov (United States)

    Duan, Yuanyuan; Griggs, Jason A

    2015-06-01

    Further investigations are required to evaluate the mechanical behaviour of newly developed polymer-matrix composite (PMC) blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The purpose of this study was to investigate the effect of elasticity on the stress distribution in dental crowns made of glass-ceramic and PMC materials using finite element (FE) analysis. Elastic constants of two materials were determined by ultrasonic pulse velocity using an acoustic thickness gauge. Three-dimensional solid models of a full-coverage dental crown on a first mandibular molar were generated based on X-ray micro-CT scanning images. A variety of load case-material property combinations were simulated and conducted using FE analysis. The first principal stress distribution in the crown and luting agent was plotted and analyzed. The glass-ceramic crown had stress concentrations on the occlusal surface surrounding the area of loading and the cemented surface underneath the area of loading, while the PMC crown had only stress concentration on the occlusal surface. The PMC crown had lower maximum stress than the glass-ceramic crown in all load cases, but this difference was not substantial when the loading had a lateral component. Eccentric loading did not substantially increase the maximum stress in the prosthesis. Both materials are resistant to fracture with physiological occlusal load. The PMC crown had lower maximum stress than the glass-ceramic crown, but the effect of a lateral loading component was more pronounced for a PMC crown than for a glass-ceramic crown. Knowledge of the stress distribution in dental crowns with low modulus of elasticity will aid clinicians in planning treatments that include such restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Electrochemical behavior of 45S5 bioactive ceramic coating on Ti6Al4V alloy for dental applications

    Science.gov (United States)

    Machado López, M. M.; Espitia Cabrera, M. I.; Faure, J.; Contreras García, M. E.

    2016-04-01

    Titanium and its alloys are widely used as implant materials because of their mechanical properties and non-toxic behavior. Unfortunately, they are not bioinert, which means that they can release ions and can only fix the bone by mechanical anchorage, this can lead to the encapsulation of dense fibrous tissue in the body. The bone fixation is required in clinical conditions treated by orthopedic and dental medicine. The proposal is to coat metallic implants with bioactive materials to establish good interfacial bonds between the metal substrate and bone by increasing bioactivity. Bioactive glasses, ceramics specifically 45 S5 Bioglass, have drawn attention as a serious functional biomaterial because osseointegration capacity. The EPD method of bioglass gel precursor was proposed in the present work as a new method to obtain 45S5/Ti6A14V for dental applications. The coatings, were thermally treated at 700 and 800°C and presented the 45 S5 bioglass characteristic phases showing morphology and uniformity with no defects, quantification percentages by EDS of Si, Ca, Na, P and O elements in the coating scratched powders, showed a good proportional relationship demonstrating the obtention of the 45S5 bioglass. The corrosion tests were carried out in Hank's solution. By Tafel extrapolation, Ti6Al4V alloy showed good corrosion resistance in Hank's solution media, by the formation of a passivation layer on the metal surface, however, in the system 45S5/Ti6Al4V there was an increase in the corrosion resistance; icon-, Ecorr and corrosion rate decreased, the mass loss and the rate of release of ions, were lower in this system than in the titanium alloy without coating.

  12. Choice of a dental implant system.

    Science.gov (United States)

    Hunt, Peter R; Gartner, Judith L; Norkin, Frederic J

    2005-04-01

    Many dentists are bewildered by the intricacies and complexities of dental implants. They are constantly besieged by product advertisements and can find it difficult to choose which systems to work with. Some dentists are so intimidated by the subject that they choose to avoid getting involved with implants and instead stick to traditional tooth replacement systems. By breaking implants down into 4 main components, the body, collar, connection, and restorative post, it is easier to understand the structure and function of dental implants. Each portion should be designed to achieve certain objectives. Once these structural components are understood, it is easier to compare and contrast differing implant systems.

  13. Optimizing the design of bio-inspired functionally graded material (FGM) layer in all-ceramic dental restorations.

    Science.gov (United States)

    Cui, Chang; Sun, Jian

    2014-01-01

    Due to elastic modulus mismatch between the different layers in all-ceramic dental restorations, high tensile stress concentrates at the interface between the ceramic core and cement. In natural tooth structure, stress concentration is reduced by the functionally graded structure of dentin-enamel junction (DEJ) which interconnects enamel and dentin. Inspired by DEJ, the aim of this study was to explore the optimum design of a bio-inspired functionally graded material (FGM) layer in all-ceramic dental restorations to achieve excellent stress reduction and distribution. Three-dimensional finite element model of a multi-layer structure was developed, which comprised bilayered ceramic, bio-inspired FGM layer, cement, and dentin. Finite element method and first-order optimization technique were used to realize the optimal bio-inspired FGM layer design. The bio-inspired FGM layer significantly reduced stress concentration at the interface between the crown and cement, and stresses were evenly distributed in FGM layer. With the optimal design, an elastic modulus distribution similar to that in DEJ occurred in the FGM layer.

  14. Microleakage of Four Dental Cements in Metal Ceramic Restorations With Open Margins.

    Science.gov (United States)

    Eftekhar Ashtiani, Reza; Farzaneh, Babak; Azarsina, Mohadese; Aghdashi, Farzad; Dehghani, Nima; Afshari, Aisooda; Mahshid, Minu

    2015-11-01

    Fixed prosthodontics is a routine dental treatment and microleakage is a major cause of its failure. The aim of this study was to assess the marginal microleakage of four cements in metal ceramic restorations with adapted and open margins. Sixty sound human premolars were selected for this experimental study performed in Tehran, Iran and prepared for full-crown restorations. Wax patterns were formed leaving a 300 µm gap on one of the proximal margins. The crowns were cast and the samples were randomly divided into four groups based on the cement used. Copings were cemented using zinc phosphate cement (Fleck), Fuji Plus resin-modified glass ionomer, Panavia F2.0 resin cement, or G-Cem resin cement, according to the manufacturers' instructions. Samples were immersed in 2% methylene blue solution. After 24 hours, dye penetration was assessed under a stereomicroscope and analyzed using the respective software. Data were analyzed using ANOVA, paired t-tests, and Kruskal-Wallis, Wilcoxon, and Mann-Whitney tests. The least microleakage occurred in the Panavia F2.0 group (closed margin, 0.18 mm; open margin, 0.64 mm) and the maximum was observed in the Fleck group (closed margin, 1.92 mm; open margin, 3.32 mm). The Fleck group displayed significantly more microleakage compared to the Fuji Plus and Panavia F2.0 groups (P ceramic restorations, clinicians should try to minimize marginal gaps in order to reduce restoration failure. In situations where there are doubts about perfect marginal adaptation, the use of Fuji Plus cement may be helpful.

  15. Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

    Science.gov (United States)

    Richardson, G Mark; Clemow, Scott R; Peters, Rachel E; James, Kyle J; Siciliano, Steven D

    2016-01-01

    Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins.

  16. Dental implant customization using numerical optimization design and 3-dimensional printing fabrication of zirconia ceramic.

    Science.gov (United States)

    Cheng, Yung-Chang; Lin, Deng-Huei; Jiang, Cho-Pei; Lin, Yuan-Min

    2017-05-01

    This study proposes a new methodology for dental implant customization consisting of numerical geometric optimization and 3-dimensional printing fabrication of zirconia ceramic. In the numerical modeling, exogenous factors for implant shape include the thread pitch, thread depth, maximal diameter of implant neck, and body size. Endogenous factors are bone density, cortical bone thickness, and non-osseointegration. An integration procedure, including uniform design method, Kriging interpolation and genetic algorithm, is applied to optimize the geometry of dental implants. The threshold of minimal micromotion for optimization evaluation was 100 μm. The optimized model is imported to the 3-dimensional slurry printer to fabricate the zirconia green body (powder is bonded by polymer weakly) of the implant. The sintered implant is obtained using a 2-stage sintering process. Twelve models are constructed according to uniform design method and simulated the micromotion behavior using finite element modeling. The result of uniform design models yields a set of exogenous factors that can provide the minimal micromotion (30.61 μm), as a suitable model. Kriging interpolation and genetic algorithm modified the exogenous factor of the suitable model, resulting in 27.11 μm as an optimization model. Experimental results show that the 3-dimensional slurry printer successfully fabricated the green body of the optimization model, but the accuracy of sintered part still needs to be improved. In addition, the scanning electron microscopy morphology is a stabilized t-phase microstructure, and the average compressive strength of the sintered part is 632.1 MPa. Copyright © 2016 John Wiley & Sons, Ltd.

  17. AFM and SEM study of the effects of etching on IPS-Empress 2 TM dental ceramic

    Science.gov (United States)

    Luo, X.-P.; Silikas, N.; Allaf, M.; Wilson, N. H. F.; Watts, D. C.

    2001-10-01

    The aim of this study was to investigate the effects of increasing etching time on the surface of the new dental material, IPS-Empress 2 TM glass ceramic. Twenty one IPS-Empress 2 TM glass ceramic samples were made from IPS-Empress 2 TM ingots through lost-wax, hot-pressed ceramic fabrication technology. All samples were highly polished and cleaned ultrasonically for 5 min in acetone before and after etching with 9.6% hydrofluoric acid gel. The etching times were 0, 10, 20, 30, 60, 90 and 120 s respectively. Microstructure was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to evaluate the surface roughness and topography. Observations with SEM showed that etching with hydrofluoric acid resulted in preferential dissolution of glass matrix, and that partially supported crystals within the glass matrix were lost with increasing etching time. AFM measurements indicated that etching increased the surface roughness of the glass-ceramic. A simple least-squares linear regression was used to establish a relationship between surface roughness parameters ( Ra, RMS), and etching time, for which r2>0.94. This study demonstrates the benefits of combining two microscopic methods for a better understanding of the surface. SEM showed the mode of action of hydrofluoric acid on the ceramic and AFM provided valuable data regarding the extent of surface degradation relative to etching time.

  18. Highly-translucent, strong and aging-resistant 3Y-TZP ceramics for dental restoration by grain boundary segregation.

    Science.gov (United States)

    Zhang, Fei; Vanmeensel, Kim; Batuk, Maria; Hadermann, Joke; Inokoshi, Masanao; Van Meerbeek, Bart; Naert, Ignace; Vleugels, Jef

    2015-04-01

    Latest trends in dental restorative ceramics involve the development of full-contour 3Y-TZP ceramics which can avoid chipping of veneering porcelains. Among the challenges are the low translucency and the hydrothermal stability of 3Y-TZP ceramics. In this work, different trivalent oxides (Al2O3, Sc2O3, Nd2O3 and La2O3) were selected to dope 3Y-TZP ceramics. Results show that dopant segregation was a key factor to design hydrothermally stable and high-translucent 3Y-TZP ceramics and the cation dopant radius could be used as a controlling parameter. A large trivalent dopant, oversized as compared to Zr(4+), exhibiting strong segregation at the ZrO2 grain boundary was preferred. The introduction of 0.2 mol% La2O3 in conventional 0.1-0.25 wt.% Al2O3-doped 3Y-TZP resulted in an excellent combination of high translucency and superior hydrothermal stability, while retaining excellent mechanical properties.

  19. Advancements in all-ceramics for dental restorations and their effect on the wear of opposing dentition

    Science.gov (United States)

    Rashid, Haroon; Sheikh, Zeeshan; Misbahuddin, Syed; Kazmi, Murtaza Raza; Qureshi, Sameer; Uddin, Muhammad Zuhaib

    2016-01-01

    Tooth wear is a process that is usually a result of tooth to tooth and/or tooth and restoration contact. The process of wear essentially becomes accelerated by the introduction of restorations inside the oral cavity, especially in case of opposing ceramic restorations. The newest materials have vastly contributed toward the interest in esthetic dental restorations and have been extensively studied in laboratories. However, despite the recent technological advancements, there has not been a valid in vivo method of evaluation involving clinical wear caused due to ceramics upon restored teeth and natural dentition. The aim of this paper is to review the latest advancements in all-ceramic materials, and their effect on the wear of opposing dentition. The descriptive review has been written after a thorough MEDLINE/PubMed search by the authors. It is imperative that clinicians are aware of recent advancements and that they should always consider the type of ceramic restorative materials used to maintain a stable occlusal relation. The ceramic restorations should be adequately finished and polished after the chair-side adjustment process of occlusal surfaces. PMID:28042280

  20. Effect of pH and fluoride on behavior of dental ZrO{sub 2} ceramics in artificial saliva

    Energy Technology Data Exchange (ETDEWEB)

    Mukaeda, L.E.; Robin, A.; Santos, C.; Taguchi, S.P.; Borges Junior, L.A., E-mail: luizamukaeda@gmail.com, E-mail: alain@demar.eel.usp.br, E-mail: claudinei@demar.eel.usp.br, E-mail: simone@demar.eel.usp.br, E-mail: borges.jr@itelefonica.com.br [Universidade de Sao Paulo (EEL/DEMAR/USP), Lorena, SP (Brazil). Escola de Engenharia; Machado, J.P.B., E-mail: joaopaulo@las.inpe.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    2009-07-01

    A considerable increase in the ceramic products demand occurred due to the evolution of dental restoration techniques and these materials must resist to the complex mouth environment. The pH of saliva can decrease significantly due to the ingestion of acidic foods and beverages and mainly due to reactions occurring during bacteria metabolism that lead to the formation of organic acids. Fluorides are also present in the mouth since fluorides are usually added in drinking water, mouth washes, tooth pastes and gels for the prevention of plaque and caries formation. The combination of low pH and presence of fluorides can lead to the formation of HF and HF{sub 2}{sup -} which are detrimental to metallic and probably to ceramic devices. In this work, commercial blocks of ZrO{sub 2} ceramics (ProtMat Materiais Avancados® and Ivoclar®) were immersed in Fusayama artificial saliva of different pHs and fluoride concentrations. The properties of the as-produced ceramics (crystalline phases (XRD), microstructure (SEM), roughness (3D surface topography AFM) and mechanical resistance - Vickers hardness (Hv) and fracture toughness (KIC) were evaluated. Some of these properties were also determined after the immersion tests as well as the mass variation of the samples in order to evaluate the resistance of these ZrO{sub 2} ceramics to degradation under these conditions. (author)

  1. Advancements in all-ceramics for dental restorations and their effect on the wear of opposing dentition.

    Science.gov (United States)

    Rashid, Haroon; Sheikh, Zeeshan; Misbahuddin, Syed; Kazmi, Murtaza Raza; Qureshi, Sameer; Uddin, Muhammad Zuhaib

    2016-01-01

    Tooth wear is a process that is usually a result of tooth to tooth and/or tooth and restoration contact. The process of wear essentially becomes accelerated by the introduction of restorations inside the oral cavity, especially in case of opposing ceramic restorations. The newest materials have vastly contributed toward the interest in esthetic dental restorations and have been extensively studied in laboratories. However, despite the recent technological advancements, there has not been a valid in vivo method of evaluation involving clinical wear caused due to ceramics upon restored teeth and natural dentition. The aim of this paper is to review the latest advancements in all-ceramic materials, and their effect on the wear of opposing dentition. The descriptive review has been written after a thorough MEDLINE/PubMed search by the authors. It is imperative that clinicians are aware of recent advancements and that they should always consider the type of ceramic restorative materials used to maintain a stable occlusal relation. The ceramic restorations should be adequately finished and polished after the chair-side adjustment process of occlusal surfaces.

  2. Integrated Ceramic Membrane System for Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Joseph; Lim, Hankwon; Drnevich, Raymond

    2010-08-05

    Phase I was a technoeconomic feasibility study that defined the process scheme for the integrated ceramic membrane system for hydrogen production and determined the plan for Phase II. The hydrogen production system is comprised of an oxygen transport membrane (OTM) and a hydrogen transport membrane (HTM). Two process options were evaluated: 1) Integrated OTM-HTM reactor – in this configuration, the HTM was a ceramic proton conductor operating at temperatures up to 900°C, and 2) Sequential OTM and HTM reactors – in this configuration, the HTM was assumed to be a Pd alloy operating at less than 600°C. The analysis suggested that there are no technical issues related to either system that cannot be managed. The process with the sequential reactors was found to be more efficient, less expensive, and more likely to be commercialized in a shorter time than the single reactor. Therefore, Phase II focused on the sequential reactor system, specifically, the second stage, or the HTM portion. Work on the OTM portion was conducted in a separate program. Phase IIA began in February 2003. Candidate substrate materials and alloys were identified and porous ceramic tubes were produced and coated with Pd. Much effort was made to develop porous substrates with reasonable pore sizes suitable for Pd alloy coating. The second generation of tubes showed some improvement in pore size control, but this was not enough to get a viable membrane. Further improvements were made to the porous ceramic tube manufacturing process. When a support tube was successfully coated, the membrane was tested to determine the hydrogen flux. The results from all these tests were used to update the technoeconomic analysis from Phase I to confirm that the sequential membrane reactor system can potentially be a low-cost hydrogen supply option when using an existing membrane on a larger scale. Phase IIB began in October 2004 and focused on demonstrating an integrated HTM/water gas shift (WGS) reactor to

  3. Uses of Advanced Ceramic Composites in the Thermal Protection Systems of Future Space Vehicles

    Science.gov (United States)

    Rasky, Daniel J.

    1994-01-01

    Current ceramic composites being developed and characterized for use in the thermal protection systems (TPS) of future space vehicles are reviewed. The composites discussed include new tough, low density ceramic insulation's, both rigid and flexible; ultra-high temperature ceramic composites; nano-ceramics; as well as new hybrid ceramic/metallic and ceramic/organic systems. Application and advantage of these new composites to the thermal protection systems of future reusable access to space vehicles and small spacecraft is reviewed.

  4. Ceramic dental biomaterials and CAD/CAM technology: state of the art.

    Science.gov (United States)

    Li, Raymond Wai Kim; Chow, Tak Wah; Matinlinna, Jukka Pekka

    2014-10-01

    Ceramics are widely used as indirect restorative materials in dentistry because of their high biocompatibility and pleasing aesthetics. The objective is to review the state of the arts of CAD/CAM all-ceramic biomaterials. CAD/CAM all-ceramic biomaterials are highlighted and a subsequent literature search was conducted for the relevant subjects using PubMed followed by manual search. Developments in CAD/CAM technology have catalyzed researches in all-ceramic biomaterials and their applications. Feldspathic glass ceramic and glass infiltrated ceramic can be fabricated by traditional laboratory methods or CAD/CAM. The advent of polycrystalline ceramics is a direct result of CAD/CAM technology without which the fabrication would not have been possible. The clinical uses of these ceramics have met with variable clinical success. Multiple options are now available to the clinicians for the fabrication of aesthetic all ceramic restorations. Copyright © 2014 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  5. RECENT TRENDS IN DENTAL DRUG DELIVERY SYSTEMS

    Directory of Open Access Journals (Sweden)

    Sharma Nishu

    2013-07-01

    Full Text Available Controlled release local drug delivery systems offer advantages compared to systemic dosage forms for many dental diseases like gingivitis, periodontitis. The objective of this literature survey was to gain knowledge about various dental drug delivery systems for targeted delivery of the drug. The polymer ethyl cellulose was used in the formulation of dental films. The dental film was then evaluated for various parameters like thickness, folding endurance and weight variation and content uniformity, in vitro and in vivo study. There has been a great attention in using iontophoretic technique for the transdermal drug delivery of medications, both ionic and non ionic. This technique of facilitated movement of ions across a membrane under the influence of an externally applied electric potential difference is one of the most promising physical skin penetrations enhancing method. Another novel approach is the use of lasers in dentistry. Lasers can be used in both hard and soft tissue applications including laser bleaching, frenectomy, gingivectomy, caries removal etc. Drugs delivery via the buccal routs using bio adhesive dosage forms offers such a novel route of drugs administration. This route has been used successfully for the systematic delivery of number of drugs candidates. Problems such as high first pass metabolisms and drugs degradation in the gastrointestinal tract can be circumvented by administrating the drug buccal routes.

  6. Aesthetic comparison between crowns made with Cubo and metal-ceramic systems

    Directory of Open Access Journals (Sweden)

    Lis Regina Carneiro HOPPEN

    2010-06-01

    Full Text Available Introduction and objective: The objective of this study was to verify the influence of different materials used in the construction of infrastructures on the aesthetic result of restorations with ceramic coating. Material and methods: A patient that needed a single prosthetic crown on the maxillary central incisors was selected for treatment, one in the right maxillary central incisor (11 and another in the dental implant (21.Metal-free (Cubo system and metal-ceramic (MC crowns were made for each tooth and submitted to blind review by 11 dentists, who answered a questionnaire about ratios of opacity and translucency of the crowns in the oral cavity of the patient, where each answer corresponded to one score.Data was submitted to Wilcoxon test (α = 0.05. Results: Therewas no significant statistical difference between the metal-ceramic and Cubo system crowns (11: p = 0.107; 21: p = 0.739. The analysis of the scores also showed that for the same type of infrastructure there was no significant statistical difference between 11 and 21 (Cubo: p = 0.206; MC: p = 0.102. Conclusion: Within the limits of this study, it was concluded that, according to the visual perception of the evaluators,prosthetic crowns made with metal infrastructure and with ceramic infrastructure showed to be aesthetically similar and satisfactory.

  7. Effect of brushing with conventional versus whitening dentifrices on surface roughness and biofilm formation of dental ceramics.

    Science.gov (United States)

    Azevedo, Sarina Maciel Braga; Kantorski, Karla Zanini; Valandro, Luiz Felipe; Bottino, Marco Antonio; Pavanelli, Carlos Augusto

    2012-01-01

    The aim of this study was to evaluate the effect of conventional and whitening dentifrices on the weight loss, surface roughness, and early in situ biofilm formation on the surface of dental ceramics. Standardized feldspar ceramic specimens (Vita VM7 and Vita VM13) were submitted to the following experimental conditions: no brushing; brushing without a dentifrice; brushing with a conventional dentifrice; and brushing with a whitening dentifrice. A brushing machine was used to simulate brushing. The mass and surface roughness of all specimens from the test groups were evaluated prior to and after brushing. Ten participants used an oral device for eight hours to evaluate the biofilm formed in situ on the specimens. Scanning electron microscopy was used for qualitative and quantitative analysis of the biofilm. ANOVA and Tukey tests were used to analyze the results of weight loss, surface roughness, and presence of bacteria. A one-way Kruskal-Wallis test was used for bacterial colonization results. For both ceramics, brushing with a whitening dentifrice resulted in weight loss that was significantly greater when compared to brushing without a dentifrice or with a conventional dentifrice. Increased surface roughness was noticed on VM13 ceramic samples with both dentifrices, whereas only conventional dentifrice had a significant effect on the surface roughness of VM7 samples. For both VM7 and VM13, no difference was found between the experimental conditions with regard to the presence or number of bacteria. Cocci and short rods were the predominant microbial morphotypes. Granular or fibrillar acellular material partially covered the specimens. Brushing with a whitening dentifrice resulted in significant weight loss of ceramic restorations, while brushing with both conventional and whitening dentifrices can roughen ceramic surfaces. The increase in roughness was not clinically significant to contribute to increased biofilm formation.

  8. Control of dental prosthesis system with microcontroller.

    Science.gov (United States)

    Kapidere, M; Müldür, S; Güler, I

    2000-04-01

    In this study, a microcontroller-based electronic circuit was designed and implemented for dental prosthesis curing system. Heater, compressor and valve were controlled by 8-bit PIC16C64 microcontroller which is programmed using MPASM package. The temperature and time were controlled automatically by preset values which were inputted from keyboard while the pressure was kept constant. Calibration was controlled and the working range was tested. The test results showed that the system provided a good performance.

  9. Colour parameters and shade correspondence of CAD-CAM ceramic systems.

    Science.gov (United States)

    Della Bona, Alvaro; Pecho, Oscar E; Ghinea, Razvan; Cardona, Juan C; Pérez, María M

    2015-06-01

    To evaluate colour differences between (1) CAD-CAM ceramic systems considering shades A1, A2 and A3 and the corresponding nominal shade of VC (Vita Classical shade guide) and (2) shades A1-A2, A2-A3 and A1, A2 and A3 within the same ceramic system. Samples of shades A1, A2 and A3 were fabricated (n=5) from CAD-CAM ceramic blocks (IPS e.max(®) CAD LT and HT, IPS Empress(®) CAD LT and HT, Paradigm™ C, and VITABLOCS(®) Mark II) and polished to 1.0±0.01mm in thickness. Spectral reflectance and colour coordinates were measured using a spectroradiometer inside a viewing booth using the CIE D65 illuminant and the d/0° geometry. Spectral reflectance curves were compared using VAF coefficient and were statistically analyzed using Kruskal-Wallis and the Mann-Whitney U test (α=0.05). Colour coordinates were statistically analyzed using one-way ANOVA, Tukey's test with Bonferroni correction (α=0.001). All colour differences (ΔEab(*) and ΔE00) were analyzed through comparisons with the PT - perceptibility and AT - acceptability thresholds for dental ceramics. ΔE between ceramic systems and its corresponding shade ranged from 6.32 to 13.42 (ΔEab(*)) and 4.48 to 9.30 (ΔE00). ΔE between shades A1-A2, A2-A3 and A1, A2 and A3 ranged, respectively, 1.93-4.82, 1.22-5.59 and 3.63-8.84 (ΔEab(*)); 1.54-3.87, 1.03-3.90 and 2.95-6.51 (ΔE00). Considering the corresponding nominal shade from VC, none of the ceramic systems showed colour differences below the AT. In addition, some ceramic systems showed colour differences below AT (shades A1-A2 and A2-A3) and below PT (shades A2-A3). Careful adjustments should be made to the final shade of CAD-CAM ceramic restorations to reach a clinically acceptable shade match. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. A dose monitoring system for dental radiography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chena; Lee, Sam Sun; Kim, Jo Eun; Huh, Kyung Hoe; Yi, Woo Jin; Heo, Min Suk; Choi, Soon Chul [Dept. of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul (Korea, Republic of); Symkhampha, Khanthaly [Dept. of Oral and Maxillofacial Radiology, Department of Basic Science, Faculty of Dentistry, University of Health Sciences, Vientiane (Lao People' s Democratic Republic); Lee, Woo Jin [Dept. of Interdisciplinary Program in Radiation, Applied Life Sciences Major, College of Medicine, BK21, and Dental Research Institute, Seoul National University, Seoul (Korea, Republic of); Yeom, Heon Young [School of Computer Science Engineering, Seoul National University, Seoul (Korea, Republic of)

    2016-06-15

    The current study investigates the feasibility of a platform for a nationwide dose monitoring system for dental radiography. The essential elements for an unerring system are also assessed. An intraoral radiographic machine with 14 X-ray generators and five sensors, 45 panoramic radiographic machines, and 23 cone-beam computed tomography (CBCT) models used in Korean dental clinics were surveyed to investigate the type of dose report. A main server for storing the dose data from each radiographic machine was prepared. The dose report transfer pathways from the radiographic machine to the main sever were constructed. An effective dose calculation method was created based on the machine specifications and the exposure parameters of three intraoral radiographic machines, five panoramic radiographic machines, and four CBCTs. A viewing system was developed for both dentists and patients to view the calculated effective dose. Each procedure and the main server were integrated into one system. The dose data from each type of radiographic machine was successfully transferred to the main server and converted into an effective dose. The effective dose stored in the main server is automatically connected to a viewing program for dentist and patient access. A patient radiation dose monitoring system is feasible for dental clinics. Future research in cooperation with clinicians, industry, and radiologists is needed to ensure format convertibility for an efficient dose monitoring system to monitor unexpected radiation dose.

  11. Ceramic Oxygen Generator for Carbon Dioxide Electrolysis Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this SBIR Phase I proposal (Topic X9.01), NexTech Materials, Ltd. proposes to develop a high efficiency ceramic oxygen generation system which will separate O2...

  12. KROME Ceramics: color management system for the ceramics industry; KROME: Ceramics Sistema de gestion del color para la industra ceramica

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.; Luque, J.; Pla, O.; Selvi, S.

    2013-05-01

    Digital Decoration Systems, SL (DIGIT-S) with Unicer, SL, has implemented a system to improve and optimize the process of decorating by inkjet printing for ceramic industry. It provides a comprehensive solution, KROME Ceramics, to improve the cost effectiveness of product and process through the implementation of a working system based on the control of digital decoration process and the synchronization of all elements that make up the decorative modules, including the creation of a work flow, management of files that are generated during the process, a correct color management system, and of course, optimizing and evaluating ink jet inks integrating all elements involved: Lighting, Computer, Software, Monitor, Plotter, Paper, Ink, Ink jet, Body's, Enamels and Oven. (Author)

  13. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic.

    Science.gov (United States)

    Moradabadi, Ashkan; Roudsari, Sareh Esmaeily Sabet; Yekta, Bijan Eftekhari; Rahbar, Nima

    2014-01-01

    This paper presents the results of an experimental study to understand the dominant mechanism in bond strength between dental resin agent and zirconia ceramic by investigating the effects of different surface treatments. Effects of two major mechanisms of chemical and micromechanical adhesion were evaluated on bond strength of zirconia to luting agent. Specimens of yttrium-oxide-partially-stabilized zirconia blocks were fabricated. Seven groups of specimens with different surface treatment were prepared. 1) zirconia specimens after airborne particle abrasion (SZ), 2) zirconia specimens after etching (ZH), 3) zirconia specimens after airborne particle abrasion and simultaneous etching (HSZ), 4) zirconia specimens coated with a layer of a Fluorapatite-Leucite glaze (GZ), 5) GZ specimens with additional acid etching (HGZ), 6) zirconia specimens coated with a layer of salt glaze (SGZ) and 7) SGZ specimens after etching with 2% HCl (HSGZ). Composite cylinders were bonded to airborne-particle-abraded surfaces of ZirkonZahn specimens with Panavia F2 resin luting agent. Failure modes were examined under 30× magnification and the effect of surface treatments was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SZ and HSZ groups had the highest and GZ and SGZ groups had the lowest mean shear bond strengths among all groups. Mean shear bond strengths were significantly decreased by applying a glaze layer on zirconia surfaces in GZ and SGZ groups. However, bond strengths were improved after etching process. Airborne particle abrasion resulted in higher shear bond strengths compared to etching treatment. Modes of failure varied among different groups. Finally, it is concluded that micromechanical adhesion was a more effective mechanism than chemical adhesion and airborne particle abrasion significantly increased mean shear bond strengths compared with another surface treatments.

  14. Practical implications of incentive systems are utilized by dental franchises.

    Science.gov (United States)

    Yavner, S B

    1989-01-01

    The success of any dental practice depends, among other factors, on the critical role of staff employees. In order to encourage desired staff behaviors, incentive systems can be designed for employee dentists, assistants/hygienists and managers. A survey of dental franchises was conducted in 1987 for the purpose of examining their incentive control systems. The specific incentives employed by these dental franchises for their employees are analyzed. The implications of these incentive systems used by dental franchise organizations for all dental practices are then discussed.

  15. Adhesion of adhesive resin cements to dental zirconia ceramic and human dentin

    OpenAIRE

    YANG Bin

    2008-01-01

    In this work, the long-term bond strengths of adhesive resin cements to zirconia ceramic and human dentin were evaluated, and resin-ceramic and resin-dentin bonding mechanisms were investigated. In chapter 3, the influence of surface pre-treatment on the bonding durability of three resin cements (Super-Bond C&B resin cement : SB, Clearfil™ Esthetic cement: CEC, Chemiace II: CH) to zirconia ceramic was studied. Most importantly, the influence of chemical reactions of functional monomers in...

  16. Impact of Bruxism on Ceramic Defects in Implant-Borne Fixed Dental Prostheses: A Retrospective Study.

    Science.gov (United States)

    Mikeli, Aikaterini; Walter, Michael H

    2016-01-01

    Ceramic veneer fracture is a frequent complication in implant-borne fixed restorations. The retrospective clinical study assesses the effect of bruxism on this complication. A sample of 507 implant-borne fixed units inserted between 1995 and 2011 in 144 patients were examined. Any detected veneer fractures were assigned to one of four groups according to extent and position. A hypothetical correlation between bruxism and ceramic veneer fractures was examined. Of 34 patients (23.6%) with at least one ceramic veneer fracture, 24 were bruxers (70%) and 10 were nonbruxers (30%) (P = .002). Bruxism may pose a risk for ceramic fractures.

  17. A Survey of Civilian Dental Computer Systems.

    Science.gov (United States)

    1988-01-01

    r.arketplace, the orthodontic community continued to pioneer clinical automation through diagnosis, treat- (1) patient registration, identification...profession." New York State Dental Journal 34:76, 1968. 17. Ehrlich, A., The Role of Computers in Dental Practice Management. Champaign, IL: Colwell...Council on Dental military dental clinic. Medical Bulletin of the US Army Practice. Report: Dental Computer Vendors. 1984 Europe 39:14-16, 1982. 19

  18. Ceramic dentures manufactured with ultrashort laser pulses

    Science.gov (United States)

    Werelius, Kristian; Weigl, Paul

    2004-06-01

    Conventional manufacturing of individual ceramic dental prosthesis implies a handmade metallic framework, which is then veneered with ceramic layers. In order to manufacture all-ceramic dental prosthesis a CAD/CAM system is necessary due to the three dimensional shaping of high strength ceramics. Most CAD/CAM systems presently grind blocks of ceramic after the construction process in order to create the prosthesis. Using high-strength ceramics, such as Hot Isostatic Pressed (HIP)-zirconia, this is limited to copings. Anatomically shaped fixed dentures have a sculptured surface with small details, which can't be created by existing grinding tools. This procedure is also time consuming and subject to significant loss in mechanical strength and thus reduced survival rate once inserted. Ultra-short laser pulses offer a possibility in machining highly complex sculptured surfaces out of high-strength ceramic with negligible damage to the surface and bulk of the ceramic. In order to determine efficiency, quality and damage, several laser ablation parameters such as pulse duration, pulse energy and ablation strategies were studied. The maximum ablation rate was found using 400 fs at high pulse energies. High pulse energies such as 200μJ were used with low damage in mechanical strength compared to grinding. Due to the limitation of available laser systems in pulse repetition rates and power, the use of special ablation strategies provide a possibility to manufacture fully ceramic dental prosthesis efficiently.

  19. The development and testing of glaze materials for application to the fit surface of dental ceramic restorations.

    Science.gov (United States)

    Cattell, Michael J; Chadwick, Thomas C; Knowles, Jonathan C; Clarke, Richard L

    2009-04-01

    The aims of the study were to develop and test overglaze materials for application to the fit surface of dental ceramic restorations, which could be etched and adhesively bonded and increase the flexural strength of the ceramic substrate. Three glaze materials were developed using commercial glass powders (P25 and P54, Pemco, Canada). P25 (90 wt%) was mixed with P54 (10 wt%) to produce (P25/P54). P54 (90 wt%) was mixed with P25 (10 wt%) to produce (P54/P25). P25 (90 wt%) was mixed with 10 wt% of an experimental glass powder (P25/frit). Eighty-two disc specimens (14 mm x 2 mm) were produced by heat pressing a leucite glass-ceramic and were sandblasted with 50 microm glass beads. Group 1 control specimens (10) were sandblasted. Groups 2-4 (10 per group) were coated using P25/frit (Group 2), P25/P54 (Group 3) and P54/P25 (Group 4) overglazes before sintering. Groups 1-4 were etched for 2 min using 9.5% HF (Gresco, USA). Composite cylinders (Marathon v, Den-Mat) were light cured and bonded to the glazed and prepared disc surfaces and groups water stored for 8 days. Groups were tested using shear bond strength (SBS) testing at 0.5mm/min. Disc specimens (42) were tested using the biaxial flexural strength (BFS) test at a crosshead speed of 0.15 mm/min. Group 1 was tested as sandblasted (21) and Group 2 (21) after coating the tensile surface with P25/frit. Xrd, Eds and Sem analyzes were carried out. Mean SBS (MPa+/-S.D.) were: Group 1: 10.7+/-2.1; Group 2: 9.8+/-1.9; Group 3: 1.8+/-1.0 and Group 4: 2.6+/-1.7. Groups 1 and 2 were statistically different to Groups 3 and 4 (p0.05). The mean BFS (MPa+/-S.D.) of the overglazed Group 2 (200.2+/-22.9) was statistically different (pceramic substrate and produced comparable shear bond strengths to an etched and bonded control. The application of etched overglaze materials to dental glass-ceramic and ceramic substrates may be useful in adhesive dentistry.

  20. Seating load parameters impact on dental ceramic reinforcement conferred by cementation with resin-cements.

    LENUS (Irish Health Repository)

    Addison, Owen

    2010-09-01

    Cementation of all-ceramic restorations with resin-cements has been demonstrated to reduce the incidence of fracture in service. The aim was to investigate the influence of loading force and loading duration applied during cementation on the reinforcement conferred by a resin-cement on a leucite reinforced glass-ceramic.

  1. Parametric Weight Comparison of Advanced Metallic, Ceramic Tile, and Ceramic Blanket Thermal Protection Systems

    Science.gov (United States)

    Myers, David E.; Martin, Carl J.; Blosser, Max L.

    2000-01-01

    A parametric weight assessment of advanced metallic panel, ceramic blanket, and ceramic tile thermal protection systems (TPS) was conducted using an implicit, one-dimensional (I-D) finite element sizing code. This sizing code contained models to account for coatings fasteners, adhesives, and strain isolation pads. Atmospheric entry heating profiles for two vehicles, the Access to Space (ATS) vehicle and a proposed Reusable Launch Vehicle (RLV), were used to ensure that the trends were not unique to a certain trajectory. Ten TPS concepts were compared for a range of applied heat loads and substructural heat capacities to identify general trends. This study found the blanket TPS concepts have the lightest weights over the majority of their applicable ranges, and current technology ceramic tiles and metallic TPS concepts have similar weights. A proposed, state-of-the-art metallic system which uses a higher temperature alloy and efficient multilayer insulation was predicted to be significantly lighter than the ceramic tile stems and approaches blanket TPS weights for higher integrated heat loads.

  2. Information system analysis of an e-learning system used for dental restorations simulation.

    Science.gov (United States)

    Bogdan, Crenguţa M; Popovici, Dorin M

    2012-09-01

    The goal of using virtual and augmented reality technologies in therapeutic interventions simulation, in the fixed prosthodontics (VirDenT) project, is to increase the quality of the educational process in dental faculties, by assisting students in learning how to prepare teeth for all-ceramic restorations. Its main component is an e-learning virtual reality-based software system that will be used for the developing skills in grinding teeth, needed in all-ceramic restorations. The complexity of the domain problem that the software system dealt with made the analysis of the information system supported by VirDenT necessary. The analysis contains the following activities: identification and classification of the system stakeholders, description of the business processes, formulation of the business rules, and modelling of business objects. During this stage, we constructed the context diagram, the business use case diagram, the activity diagrams and the class diagram of the domain model. These models are useful for the further development of the software system that implements the VirDenT information system. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  3. Current dental adhesives systems. A narrative review.

    Science.gov (United States)

    Milia, Egle; Cumbo, Enzo; Cardoso, Rielson Jose A; Gallina, Giuseppe

    2012-01-01

    Adhesive dentistry is based on the development of materials which establish an effective bond with the tooth tissues. In this context, adhesive systems have attracted considerable research interest in recent years. Successful adhesive bonding depends on the chemistry of the adhesive, on appropriate clinical handling of the material as well as on the knowledge of the morphological changes caused on dental tissue by different bonding procedures. This paper outlines the status of contemporary adhesive systems, with particular emphasis on chemical characteristics and mode of interaction of the adhesives with enamel and dentinal tissues. Dental adhesives are used for several clinical applications and they can be classified based on the clinical regimen in "etch-and-rinse adhesives" and "self-etch adhesives". Other important considerations concern the different anatomical characteristics of enamel and dentine which are involved in the bonding procedures that have also implications for the technique used as well as for the quality of the bond. Etch-and-rinse adhesive systems generally perform better on enamel than self-etching systems which may be more suitable for bonding to dentine. In order to avoid a possible loss of the restoration, secondary caries or pulp damage due to bacteria penetration or due to cytotoxicity effects of eluted adhesive components, careful consideration of several factors is essential in selecting the suitable bonding procedure and adhesive system for the individual patient situation.

  4. System of acute medical support to emergency during dental treatment.

    Science.gov (United States)

    Kawahara, M; Takeshita, T; Akita, S

    1986-01-01

    The Resuscitation Committee of Hiroshima City Dental Association was established in 1983 in order to provide acute medical support in case of emergency during dental treatment at private dental clinics. This Committee is composed of representatives from the Hiroshima City Dental Association, Hiroshima University School of Dentistry, Hiroshima University School of Medicine, Hiroshima City Health Bureau, and Hiroshima City Fire and Ambulance Department. A portable ECG monitor with defibrillator and a resuscitation kit are held in readiness at the Hiroshima University Hospital. In case of emergency during dental treatment at a private dental clinic, we hurry to the clinic with the resuscitation set and give emergency treatment. We have been involved in two cases of emergency since this system started. Both of them recovered without any sequelae. Besides these activities, we give lectures annually to dentists and dental hygienists on the treatment of medical emergencies.

  5. [Influence of background color on chromatic value of four all-ceramic system core materials].

    Science.gov (United States)

    Ma, Yong-gang; Zhang, Nian; Deng, Xu-liang

    2010-06-01

    To investigate the influence of post-core background color on chromatic value of four all-ceramic system core materials at clinically appropriate thicknesses. Disc specimens of 15 mm in diameter and 0.80 mm in thickness (Empress II: Group A), and 0.50 mm in thickness (In-Ceram Zirconia core: Group B; Cercon base color zirconia core: Group C; Cercon base zirconia core: Group D) were fabricated, five in each group. Au-Pt alloy, Ni-Cr alloy and visible light cured dental composite resin (A2 color) background were prepared. Samples were put on different background and their chromatic values were measured with colorimeter (CIE-1976-L(*)a(*)b(*)). Color differences of each specimen on different background material were calculated. The color differences among specimens of Group A on different background material were more than 1.5 (2.83 ± 0.70) which meant it could be noticeable to eyes. Those of zirconia were less than 1.5 [Group B: (0.14 ± 0.08); Group C: (0.90 ± 0.20); Group D: (0.99 ± 0.09)]. The influence of background color on Group A was noticeable to human eyes, and as a result, tooth-colored post should be used for this all-ceramic system. For the other three kinds of zirconia core materia1 system, the color differences among specimens on different background material were unnoticeable. Therefore the three all-ceramic systems have excellent color masking ability and can be used on all color background.

  6. Dental orthopantomogram biometrics system for human identification.

    Science.gov (United States)

    Singh, Sandeep; Bhargava, Darpan; Deshpande, Ashwini

    2013-07-01

    Fingerprinting is the most widely accepted method of identification of people. But in cases of disfigured, decomposed, burnt or fragmented bodies, it is of limited value. Teeth and dental restorations on the other hand are extremely resistant to destruction by fire. They retain a number of their original characteristics, which are often unique and hence offer a possibility of rather accurate and legally acceptable identification of such remains. This study was undertaken to evaluate the utility of orthopantomography for human identification and propose a coding system for orthopantomogram (OPG), which can be utilized as an identification tool in forensic sciences.

  7. Ceramic Integration Technologies for Advanced Energy Systems: Critical Needs, Technical Challenges, and Opportunities

    Science.gov (United States)

    Singh, Mrityunjay

    2010-01-01

    Advanced ceramic integration technologies dramatically impact the energy landscape due to wide scale application of ceramics in all aspects of alternative energy production, storage, distribution, conservation, and efficiency. Examples include fuel cells, thermoelectrics, photovoltaics, gas turbine propulsion systems, distribution and transmission systems based on superconductors, nuclear power generation and waste disposal. Ceramic integration technologies play a key role in fabrication and manufacturing of large and complex shaped parts with multifunctional properties. However, the development of robust and reliable integrated systems with optimum performance requires the understanding of many thermochemical and thermomechanical factors, particularly for high temperature applications. In this presentation, various needs, challenges, and opportunities in design, fabrication, and testing of integrated similar (ceramic ceramic) and dissimilar (ceramic metal) material www.nasa.gov 45 ceramic-ceramic-systems have been discussed. Experimental results for bonding and integration of SiC based Micro-Electro-Mechanical-Systems (MEMS) LDI fuel injector and advanced ceramics and composites for gas turbine applications are presented.

  8. Influence of Alumina Addition on the Optical Property of Zirconia/Alumina Composite Dental Ceramics

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; LIAO Yunmao; LI Wei; WAN Qianbing; ZHAO Yongqi

    2011-01-01

    The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated.The relative sintered densities,transmittances,color and the microstructure of the composite ceramics were studied.The experimental results showed that the relative sintered densities and transmittances decreased with alumina addition.The lightness increased obviously but the chroma change was small.Pure zirconia nanopowders sintered densely could obtain the relatively high transmittance,while the transmittance and the lightness of slight addition changed significantly.The zirconia/alumina composite ceramics with alumina addition less than 7.5wt% could achieve the relatively stable and reliable optical properties.

  9. Design of Web Content Management System for Dental Laboratories

    OpenAIRE

    Reham Alabduljabbar; Samir El-Masri

    2013-01-01

    Web Content Management system is a management tool for creating a dynamic website. It ensures logical structure of data organization and ease of content accessing and presenting. Dental laboratories need Web Content Management system (WCMS) to control their business. Maintaining a long-term relationship between dental laboratories and their customers (dental clinics and dentists) urges an active communication process between the two sides. The main contribution of this paper is to design a si...

  10. Influence of hot isostatic pressing on ZrO2-CaO dental ceramics properties.

    Science.gov (United States)

    Gionea, Alin; Andronescu, Ecaterina; Voicu, Georgeta; Bleotu, Coralia; Surdu, Vasile-Adrian

    2016-08-30

    Different hot isostatic pressing conditions were used to obtain zirconia ceramics, in order to assess the influence of HIP on phase transformation, compressive strength, Young's modulus and density. First, CaO stabilized zirconia powder was synthesized through sol-gel method, using zirconium propoxide, calcium isopropoxide and 2-metoxiethanol as precursors, then HIP treatment was applied to obtain final dense ceramics. Ceramics were morphologically and structurally characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Density measurements, compressive strength and Young's modulus tests were also performed in order to evaluate the effect of HIP treatment. The zirconia powders heat treated at 500°C for 2h showed a pure cubic phase with average particle dimension about 70nm. The samples that were hot isostatic pressed presented a mixture of monoclinic-tetragonal or monoclinic-cubic phases, while for pre-sintered samples, cubic zirconia was the single crystalline form. Final dense ceramics were obtained after HIP treatment, with relative density values higher than 94%. ZrO2-CaO ceramics presented high compressive strength, with values in the range of 500-708.9MPa and elastic behavior with Young's modulus between 1739MPa and 4372MPa. Finally zirconia ceramics were tested for biocompatibility allowing the normal development of MG63 cells in vitro.

  11. Prevalence of Systemic Diseases in Patients with Dental Infections

    Directory of Open Access Journals (Sweden)

    Seyed Mohsen Khoshniat Nikoo

    2013-02-01

    Full Text Available Background and Aims: The aim of this study was to investigate the prevalence of diabetes and other risk factors in patients with dental infections.Materials and Methods: A cross-sectional study was conducted among 50 patients who preferred in maxillofacial word of shariaty hospital with acute dental infections in 9 months. A self-administered questionnaire was administered during a dental appointment in order to gather demographic information and recorded past history of systemic disease, OPG radiography, gingival examination, and the result of lab tests such as CBC , FBS, PT, Bilirubin , Creat, T3, T4, TSH, HIVAb and HBSAg.Results: 28% of the subjects and diabetes, 28% Anemia, 4% Hepatitis and 4% suffered from thyroid deficiency.28% were smokers and 18% declared using alcohol. 6% of this population was addicted to narcotic substances.There was a significant correlation between age, education, diabetes and dental infections (P<0.05. DMFT forpeople with dental infections without any systemic disease were 8, for diabetic patients, smokers and alcohol users were respectively 17.16, 17 and 14.Conclusion: Diabetes found highly prevalent in patients with dental infection and high DMFT.It indicates a need to establish a comprehensive oral health promotion program based on whole examination and blood glucose control in diabetic patients who have acute dental infection by collaboration between dental and general health care professionals. Moreover, it is recommended that all patients should be educated in dental and oral health forprevention of dental infections.

  12. Prevalence of Systemic Diseases in Patients with Dental Infections

    OpenAIRE

    Seyed Mohsen Khoshniat Nikoo; Mohammad Bayat; Fatemeh Afshar Hezarkhani

    2013-01-01

    Background and Aims: The aim of this study was to investigate the prevalence of diabetes and other risk factors in patients with dental infections.Materials and Methods: A cross-sectional study was conducted among 50 patients who preferred in maxillofacial word of shariaty hospital with acute dental infections in 9 months. A self-administered questionnaire was administered during a dental appointment in order to gather demographic information and recorded past history of systemic disease, OPG...

  13. Interfacial characterization of ceramic core materials with veneering porcelain for all-ceramic bi-layered restorative systems.

    Science.gov (United States)

    Tagmatarchis, Alexander; Tripodakis, Aris-Petros; Filippatos, Gerasimos; Zinelis, Spiros; Eliades, George

    2014-01-01

    The aim of the study was to characterize the elemental distribution at the interface between all-ceramic core and veneering porcelain materials. Three groups of all-ceramic cores were selected: A) Glass-ceramics (Cergo, IPS Empress, IPS Empress 2, e-max Press, Finesse); B) Glass-infiltrated ceramics (Celay Alumina, Celay Zirconia) and C) Densely sintered ceramics (Cercon, Procera Alumina, ZirCAD, Noritake Zirconia). The cores were combined with compatible veneering porcelains and three flat square test specimens were produced for each system. The core-veneer interfaces were examined by scanning electron microscopy and energy dispersive x-ray microanalysis. The glass-ceramic systems showed interfacial zones reach in Si and O, with the presence of K, Ca, Al in core and Ca, Ce, Na, Mg or Al in veneer material, depending on the system tested. IPS Empress and IPS Empress 2 demonstrated distinct transitional phases at the core-veneer interface. In the glassinfiltrated systems, intermixing of core (Ce, La) with veneer (Na, Si) elements occurred, whereas an abrupt drop of the core-veneer elemental concentration was documented at the interfaces of all densely sintered ceramics. The results of the study provided no evidence of elemental interdiffusion at the core-veneer interfaces in densely sintered ceramics, which implies lack of primary chemical bonding. For the glass-containing systems (glassceramics and glass-infiltrated ceramics) interdiffusion of the glass-phase seems to play a critical role in establishing a primary bonding condition between ceramic core and veneering porcelain.

  14. Effect of CNC-milling on the marginal and internal fit of dental ceramics: a pilot study.

    Science.gov (United States)

    Schaefer, Oliver; Kuepper, Harald; Thompson, Geoffrey A; Cachovan, Georg; Hefti, Arthur F; Guentsch, Arndt

    2013-08-01

    Machined restorations have been investigated for their preciseness before, while detailed information on the milling-step itself are lacking. Therefore, the aim of this laboratory study was to quantify the effect of a novel milling-procedure on the marginal and internal fit of ceramic restorations. An acrylic model of a lower left first molar was prepared to receive a ceramic partial crown and was duplicated by one step dual viscosity impressions. Gypsum casts were formed and laser-scanned to realize virtual datasets, before restorations were designed, exported (PRE) and machined from lithium disilicate blanks. Crowns were digitized by a structure-light-scanner to obtain post-milling-data (POST). PRE and POST were virtually superimposed on the reference tooth and subjected to computer-aided-inspection. Visual fit-discrepancies were displayed with colors, while root mean square deviations (RMSD) and degrees of similarity (DS) were computed and analysed by t-tests for paired samples (n=5, α=0.05). The milling procedure resulted in a small increase of the marginal and internal fit discrepancies (RMSD mean: 3μm and 6μm, respectively). RMSD differences were not statistically significant (p=0.495 and p=0.160 for marginal and internal fit, respectively). These results were supported by the DS data. The products of digital dental workflows are prone to imprecisions. However, the present findings suggest that differences between computer-aided designed and actually milled restorations are small, especially when compared to typical fit discrepancies observed clinically. Imprecisions introduced by digital design or production processes are small. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Viscoelastic stress analysis of thermally compatible and incompatible metal-ceramic systems.

    Science.gov (United States)

    DeHoff, P H; Anusavice, K J

    1998-07-01

    the maximum difference in thermal contraction coefficients that can exist between a metal and its ceramic veneer without causing transient failures of ceramic during cooling or delayed failures in ceramic because of high residual tensile stresses. The present research represents a major step in understanding the various factors that influence the development of transient and residual stresses. A knowledge of the effects of process variables on stress development is necessary for selection of potentially successful metal-ceramic systems and for optimizing the design of dental prostheses.

  16. Design of Web Content Management System for Dental Laboratories

    Directory of Open Access Journals (Sweden)

    Reham Alabduljabbar

    2013-01-01

    Full Text Available Web Content Management system is a management tool for creating a dynamic website. It ensures logical structure of data organization and ease of content accessing and presenting. Dental laboratories need Web Content Management system (WCMS to control their business. Maintaining a long-term relationship between dental laboratories and their customers (dental clinics and dentists urges an active communication process between the two sides. The main contribution of this paper is to design a simple Web Content Management System for Dental Laboratories. The system adopts three layers of technical architecture. The paper will also discuss why there is a need to develop a standalone WCMS for Dental Laboratories whilst other open source WCMSs can be utilized such as Joomla, Drupal and WordPress.

  17. Constructing of cure monitoring system with piezoelectric ceramics for composite laminate

    Science.gov (United States)

    Oshima, Nobuo; Inoue, Kouichi; Motogi, Shinya; Fukuda, Takehito

    2003-08-01

    The cure monitoring system with piezoelectric ceramics is constructed. An embedded type piezoelectric ceramics sensor with flat lead wires is developed. And the piezoelectric ceramics is embedded into composite laminate. A dummy piezoelectric ceramics is set in the autoclave oven. The impedance of the piezoelectric ceramics which is embedded in the composite laminate and that of the dummy piezoelectric ceramics are measured by a LCR meter. The piezoelectric ceramics have strong temperature dependency. The temperature dependency of the impedance of piezoelectric ceramics is corrected by the information from the dummy piezoelectric ceramics. A dielectric sensor is also embedded in the composite laminate as a reference sensor for the degree of cure. The change in calculated cure index shows good correspondence with change in the log ion viscosity which is measured by the dielectric cure monitoring sensor.

  18. Teaching Dental Materials Using the Personalized System of Instruction.

    Science.gov (United States)

    Schweitzer, Kathie L.; Cohen, Peter A.

    1987-01-01

    A study of the effectiveness of the personalized system of instruction (PSI) for teaching dental materials to dental hygienists compared the technique's effects to those of conventional instruction on end-of-course achievement, aptitude-achievement relationships, long-term retention, and course attitudes. (MSE)

  19. Ceramics.

    Science.gov (United States)

    Helvey, Gregg

    2010-05-01

    For more than 30 years, Compendium has provided its readers with university-based continuing education and editorial, demonstrating the latest advances in clinical procedures and techniques. Using the same peer-reviewed format and influence/direction from Compendium's distinguished editorial board, Special Report provides insight on the latest advances in product technologies and the resulting benefits to both you and your patients. A discussion by the author on new clinical/laboratory research and product development strategies, as well as what the results could mean for dental treatment, also is included. Focusing on one product category per issue provides a detailed review of the category and a comprehensive resource to help guide your treatment planning process.

  20. 3D Finite element analysis of functionally graded multilayered dental ceramic cores.

    Science.gov (United States)

    Al-Maqtari, Ali Abdullah; Razak, Abdul Aziz Abdul; Hamdi, Mohd

    2014-01-01

    This study aimed at investigating and establishing stress distributions in graded multilayered zirconia/alumina ceramic cores and at veneer-core-cement-dentin interfaces, using finite element analysis (FEA), to facilitate the structural design of ceramic cores through computer modeling. An intact maxillary premolar was digitized using CT scanning. An imaging software, Mimics, was used to reconstruct 3D models based on computed tomography (CT) data saved in DICOM format. Eight different 3D models were created for FEA, where each 3D model was meshed and its bottom boundaries constrained. A static load was applied in the oblique direction. The materials were assumed to be isotropic and homogeneous. Highest von Mises stress values were found in areas directly below the load application point, and stress gradually decreased in occlusal loading direction from the external surface toward the dentin. Stress levels occurring at veneer-ceramic core-cement-dentin interfaces were shown to be lower in multilayered ceramic cores than in single-layer models.

  1. Evaluation of a high fracture toughness composite ceramic for dental applications

    NARCIS (Netherlands)

    Aboushelib, M.N.; Kleverlaan, C.J.; Feilzer, A.J.

    2008-01-01

    Purpose: The introduction of yttrium partially stabilized zirconia polycrystals (Y-TZP) has pushed the application limits of all-ceramic restorations. The mechanical properties of these materials can be further improved by the addition of a secondary dopant phase. The aim of this work was to

  2. Evaluation of a high fracture toughness composite ceramic for dental applications

    NARCIS (Netherlands)

    Aboushelib, M.N.; Kleverlaan, C.J.; Feilzer, A.J.

    2008-01-01

    Purpose: The introduction of yttrium partially stabilized zirconia polycrystals (Y-TZP) has pushed the application limits of all-ceramic restorations. The mechanical properties of these materials can be further improved by the addition of a secondary dopant phase. The aim of this work was to evaluat

  3. Clinical decision support system in dental implantology

    Directory of Open Access Journals (Sweden)

    Alexandra Polášková

    2013-06-01

    Full Text Available Implantology is rapidly developing interdisciplinary field providing enormous amounts of data to be classified, evaluated and interpreted. The analysis of clinical data remains a big challenge, because each new system has specific requirements. The aim of study was prepare specific tool for treatment planning. Decision support system is built on Expert system. It is interactive software which provides clinical recommendations and treatment planning. Expert systems are knowledge-based computer programs designed to provide assistance in diagnosis and treatment planning. These systems are used for health care (dentistry, medicine, pharmacy etc.. The application contained the medical history analysis to obtaining information useful in formulating a diagnosis and providing implant insertion and prosthetic reconstruction to the patient; the diagnostic examination of dental implant procedure; implant positioning diagnosis – 3-D measurement; diagnostic information for treatment planning; treatment plan in the form of objective measurement of implant placement that helps surgeon and prosthodontics. The decision algorithm implemented by programming language is used. Core of program is an expert knowledge programming like a decision tree. The analysis of the decision-making process for implant treatment in general practice is prepared and analyzed.

  4. Apparent interfacial fracture toughness of resin/ceramic systems.

    Science.gov (United States)

    Della Bona, A; Anusavice, K J; Mecholsky, J J

    2006-11-01

    We suggest that the apparent interfacial fracture toughness (K(A)) may be estimated by fracture mechanics and fractography. This study tested the hypothesis that the K(A) of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure. Lithia disilicate-based (Empress2-E2) and leucite-based (Empress-E1) ceramics were surface-treated with hydrofluoric acid (HF) and/or silane (S), followed by an adhesive resin. Microtensile test specimens (n = 30; area of 1 +/- 0.01 mm(2)) were indented (9.8 N) at the interface and loaded to failure in tension. We used tensile strength (sigma) and the critical crack size (c) to calculate K(A) (K(A) = Ysigmac(1/2)) (Y = 1.65). ANOVA and Weibull analyses were used for statistical analyses. Mean K(A) (MPa.m(1/2)) values were: (E1HF) 0.26 +/- 0.06; (E1S) 0.23 +/- 0.06; (E1HFS) 0.30 +/- 0.06; (E2HF) 0.31 +/- 0.06; (E2S) 0.13 +/- 0.05; and (E2HFS) 0.41 +/- 0.07. All fractures originated from indentation sites. Estimation of interfacial toughness was feasible by fracture mechanics and fractography. The K(A) for the systems tested was affected by the ceramic microstructure and surface treatment.

  5. Impact of rehabilitation with metal-ceramic restorations on oral health-related quality of life

    OpenAIRE

    da Silva G.R.; Roscoe M.G.; Ribeiro C.P.; da Mota A.S.; Martins L.R.M.; Soares C.J.

    2012-01-01

    Dental ceramics present excellent ability to reproduce the natural teeth regarding esthetic and biomechanics. Recently, due to the advancement of ceramic technology, metal-free restorations were developed. However, the traditional metal-ceramic restorations still present the requirements of high strength, long survival in the oral environment and favorable aesthetics. In this context, it is essential to know the specificity of each ceramic system available in order to apply it properly to var...

  6. Application of Zirconium Dioxide Ceramics in Dental Rehabilitation%氧化锆陶瓷在口腔修复中的应用

    Institute of Scientific and Technical Information of China (English)

    王晓静

    2015-01-01

    目的:研究氧化锆陶瓷在口腔修复中的作用,从而得出氧化锆陶瓷在口腔修复中的正确应用方法。方法在口腔医院中抽取60名患者分别分为常规口腔修复组和氧化锆陶瓷口腔修复组,各30例,对两组患者的口腔修复效果进行对比。结果常规修复组23例患者满意,7例患者出现不良反应(其中5例轻微,2例较为严重);氧化锆陶瓷修复组28例患者满意,2例患者出现了轻微的不良反应。结论氧化锆陶瓷在口腔修复中比传统治疗材料更见成效,能够更好地为口腔病患者服务。%Objective To study the effects of zirconium dioxide ceramics in dental restorations, calculated the zirconium dioxide ceramics correct application in oral cavity repair. Methods 60 patients were divided into conventional dental restorations and zirconium dioxide ceramics dental restorations,each group of 30, contrast effect of oral cavity repair. Results Routine repair group 23 patients satisfaction, 7 patients appear harmful response, 5 cases of adverse reactions to mild, 2 cases of serious adverse reactions. Zirconium dioxide ceramics repair group 28 cases people are satisfied. Among them 2 patients appeared slight adverse reactions.Conclusion Zirconium dioxide ceramics in oral cavity repair more excellent than conventional treatment.

  7. Effect of heat treatment and in vitro aging on the microstructure and mechanical properties of cold isostatic-pressed zirconia ceramics for dental restorations.

    Science.gov (United States)

    Vatali, Anna; Kontonasaki, Eleana; Kavouras, Panagiotis; Kantiranis, Nikolaos; Papadopoulou, Lambrini; Paraskevopoulos, Konstantinos K M; Koidis, Petros

    2014-10-01

    The temperature variations during the veneering firing cycles of a zirconia dental ceramic can negatively affect its mechanical properties. A possible synergistic effect of both heat-treatment and aging while exposed to the oral environment could result to catastrophic failure. The aim of the present study was to investigate the effect of heat treatment followed during veneering and in vitro aging on the mechanical and microstructural properties of zirconia dental ceramics. Three specimens from each of two zirconia blocks (Ivoclar IPS e.max ZirCAD (IV) and Wieland ZENO Zr (WI)) were cut by CAD/CAM technology, fully sintered and polished. Each one was cut in four equal parts. One part was used as control (C), one was heat-treated (H), one was aged (A) (134°C, 2bar, 10h) and one was heat-treated and subsequently aged (HA). The mechanical properties (nano-hardness (H) and elastic modulus (E*)) were investigated by nano-indentation tests while the surface characterization was carried out with XRD, FTIR and SEM. Different treatments on IV and WI samples resulted in a reduction of both H and E* values, however the differences were not statistically significant (p>0.05). The combination of treatments imposes an overall effect (pdental ceramics may be affected during firing and aging resulting in increased probability of failure. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Surface degradation of dental ceramics as a function of environmental pH.

    Science.gov (United States)

    Esquivel-Upshaw, J F; Dieng, F Y; Clark, A E; Neal, D; Anusavice, K J

    2013-05-01

    We tested the hypotheses that glass-ceramic veneers and overglazes degrade by ion exchange in an acidic environment, and that they degrade by breakdown of the silica network in a basic environment. Disk specimens of glass-ceramic veneer and glaze were fabricated and immersed in pH 2, 7, or 10 buffer solutions, for 1, 3, 5, 10, 15, and 30 days. Each specimen was placed in a shaker bath containing de-ionized distilled water at 80°C. Concentrations of Al(3+), Ca(2+), Zn(2+), Li(2+), and Si(4+) were analyzed by means of inductively coupled plasma atomic emission spectrometry (ICP/AES). Statistical analyses were performed by factorial ANOVA. Significant differences occurred among leached ion concentrations as a function of material type, solution pH, and exposure time. A substantial release of Si occurred at pH 10 over time, leading to a breakdown of the glass phase. At pH 2, dissolution was controlled by an ionic exchange mechanism. We conclude that ceramic veneers and glazes may be susceptible to considerable degradation in low- and high-pH buffer solutions.

  9. Clinical acceptability of metal-ceramic fixed partial dental prosthesis fabricated with direct metal laser sintering technique-5 year follow-up.

    Science.gov (United States)

    Prabhu, Radhakrishnan; Prabhu, Geetha; Baskaran, Eswaran; Arumugam, Eswaran M

    2016-01-01

    In recent years, direct metal laser sintered (DMLS) metal-ceramic-based fixed partial denture prostheses have been used as an alternative to conventional metal-ceramic fixed partial denture prostheses. However, clinical studies for evaluating their long-term clinical survivability and acceptability are limited. The aim of this study was to assess the efficacy of metal-ceramic fixed dental prosthesis fabricated with DMLS technique, and its clinical acceptance on long-term clinical use. The study group consisted of 45 patients who were restored with posterior three-unit fixed partial denture prosthesis made using direct laser sintered metal-ceramic restorations. Patient recall and clinical examination of the restorations were done after 6months and every 12 months thereafter for the period of 60 months. Clinical examination for evaluation of longevity of restorations was done using modified Ryge criteria which included chipping of the veneered ceramic, connector failure occurring in the fixed partial denture prosthesis, discoloration at the marginal areas of the veneered ceramic, and marginal adaptation of the metal and ceramic of the fixed denture prosthesis. Periapical status was assessed using periodical radiographs during the study period. Survival analysis was made using the Kaplan-Meier method. None of the patients had failure of the connector of the fixed partial denture prostheses during the study period. Two exhibited biological changes which included periapical changes and proximal caries adjacent to the abutments. DMLS metal-ceramic fixed partial denture prosthesis had a survival rate of 95.5% and yielded promising results during the 5-year clinical study.

  10. 4种齿科CAD/CAM陶瓷材料的可加工性能研究%Machinability of Four Types of CAD/CAM Dental Ceramics.

    Institute of Scientific and Technical Information of China (English)

    黄慧; 张富强; 姚自栋; 张骋

    2011-01-01

    Objective: To evaluate the machinability of four kinds of dental machinable ceramics with several methods, and to compare the surface quality after cutting. Methods: Four dental machinable ceramics Mark II, TriLuxe,In-Ceram Alumina and In-Ceram Spinell were tested with grinding, drilling and cutting methods under the same testing parameters. And the differences of removal rate were measured. The surface roughness parameters after cutting were measured by surface roughness measuring instrument, and the surface quality was investigated by SEM. Results: The results showed that In-Ceram Alumina reached the supreme machinable efficiency. The traditional feldspar ceramic achieved higher surface quality after cutting test. Conclusion: In-Ceram Alumina and In-Ceram Spinell by In-Cream technology possessed better machinability.%目的:对VITA公司生产的4种不同齿科CAD/CAM陶瓷材料的可加工性能进行比较实验,以明确不同材料可加工性能上的差异.方法:选择临床上常用的4种CDA/CAM可切削陶瓷材料:Mark II、TriLuxe、In-Ceram Alumina和In-Ceram Spinell,主要成份分别为:长石质瓷、氧化铝和镁铝尖晶石,采用磨削、钻削和切削3种加工方法,在相同的实验条件下,检测4种陶瓷材料的磨削深度和切削面积,计算4种材料单位时间的去除率;同时在扫描电镜下观察切削面的形貌,并用表面粗糙度仪测试切削面的粗糙度.结果:在3种加工方式中,In-Ceram Alumina的加工效率最高,与另外3种材料之间存在统计学差异(P<0.05);切削面的表面粗糙度长石质瓷较In-Ceram Alumina和In-Ceram Spinell低;长石质瓷的切削面细致均匀,能清晰地看到切削所留下的规整而细致的划痕;而In-Ceram Alumina和In-Ceram Spinell切削面无明显划痕,呈多孔结构,表面凹凸不平.结论:采用In-Ceram技术的齿科修复陶瓷较长石质瓷具有更好的可加工性能.

  11. [Participation of dental auxiliary personnel in local health systems].

    Science.gov (United States)

    Frazão, P; Castellanos, R A

    1999-02-01

    Though numerous local health systems (sistemas locales de salud, or SILOS) in Brazil employ dental assistants, there is little information on the contributions these workers make to oral health programs. The purpose of this study was to examine the role of such workers in 10 SILOS in five municipalities in the state of São Paulo. Of the 325 dental assistants and dental hygienists employed in those systems, 245 (75.4%) answered a questionnaire that had been prepared. The results showed variations in the degree to which dental assistants participated in oral health promotion activities in the SILOS studied. In some SILOS, these workers devoted more time to dental health promotion activities than to helping perform dental tasks with individual patients. The most frequent oral health promotion activities were fluoride rinses, plaque detection followed by supervised brushing, and educational activities at basic health units and schools. In all cases, dental assistants working in the SILOS played a significant role in helping transform the practice of dentistry within the sphere of public health.

  12. 全瓷修复技术治疗职业性牙酸蚀病的研究%The research in the treatment of occupational dental erosion using all-ceramic dental restorations

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    目的:探讨用全瓷修复技术治疗职业性牙酸蚀病的临床效果。方法:2010年3月-2013年3月来我院就诊的23例职业性牙酸蚀病患者采用全瓷修复技术治疗。分别于修复后3个月、6个月、1年、3年复查。复查内容包括:修复体边缘、解剖外形、表面光滑度、颜色、患者使用满意度。结果:整个随访期间,23例职业性牙酸蚀病患者面部外形改善,咀嚼功能恢复良好,患者对修复体的美观及舒适性均较为满意。结论:用全瓷修复技术治疗职业性牙酸蚀病能恢复患者美观,提高咀嚼效率。同时还应加强口腔健康和个人防护宣教。%Objective To evaluate the clinical outcomes of therapy using all- ceramic dental restorations for patients with occupational dental erosion. Methods From March 2010 to March 2013, twenty- three patients with occupational dental erosion were treated with all- ceramic dental restorations.The edge of the restorations, anatomical shape,smoothness,color,patients'satisfaction had been observed at 3months,6months,1 year and 3 years after treatment. Results During the follow-up period,all patients with all-ceramic dental satisfied with the appearance and masticatory function. Conclusion The all-ceramic dental restorations showed good clinical effects in improving appearance and masticatory efficiency,at the same time the oral health education and personal protection should be strengthened.

  13. A 3-year clinical follow-up study of a ceramic (Optec) inlay system.

    Science.gov (United States)

    Molin, M; Karlsson, S

    1996-06-01

    To evaluate the clinical quality of ceramic (Optec) inlays, the inlay production of 10 dentists, served by 3 dental laboratories, was examined independently by 2 calibrated examiners. Of the 57 patients with 205 inlays participating in the first examination, 47 patients with 145 remaining inlays participated in the 3-year follow-up reexamination. For 14 of the participants in the reexamination, altogether 21 inlays had fractured. The mean time in service before fracture was 26.4 months (range, 12-53 months). The inlays were rated using the California Dental Association (CDA) quality evaluation system. This examination showed that the mismatch of color had increased from the first examination to the reexamination and registered slightly roughened surfaces. As to anatomic form, a reduced number of inlays did not receive an excellent CDA rating at the reexamination. Visible evidence of ditching along the margin had increased by almost 50%, and an apparent discoloration of the margin between the restoration and the tooth structure was seen in 73% of the reexamined inlays, compared with 7% at the first examination.

  14. Quantitative Evaluation of Contamination on Dental Zirconia Ceramic by Silicone Disclosing Agents after Different Cleaning Procedures

    Directory of Open Access Journals (Sweden)

    Sebastian Wille

    2015-05-01

    Full Text Available The aim of this study was to evaluate the effectiveness of cleaning procedures for air-abraded zirconia after contamination with two silicone disclosing agents. Air-abraded zirconia ceramic specimens (IPS e.max ZirCAD were contaminated with either GC Fit Checker white or GC Fit Checker II. Untreated zirconia specimens were used as control. Afterwards the surfaces were cleaned either with waterspray or ultrasonically in 99% isopropanol or using a newly developed cleaning paste (Ivoclean. After cleaning X-ray photoelectron spectroscopy (XPS was performed and the relative peak intensities of Zr, C and Si were used for a qualitative comparison of the residuals. There was no significant difference between the two different silicone disclosing agents. An additional cleaning step with isopropanol led to a significantly lower amount of residuals on the surface, but an additional cleaning process with Ivoclean did not reduce the amount of carbon residuals in comparison to the isopropanol cleaning. Just the silicone amount on the surface was reduced. None of the investigated cleaning processes removed all residuals from the contaminated surface. Standard cleaning processes do not remove all residuals of the silicone disclosing agent from the surface. This may lead to a failure of the resin-ceramic bonding.

  15. Static immersion and irritation tests of dental metal-ceramic alloys.

    Science.gov (United States)

    Ardlin, Berit I; Dahl, Jon E; Tibballs, John E

    2005-02-01

    The expansion of the European Union is bringing new types of metal-ceramic alloys to the market, i.e. alloys probably unknown in Western-European dentistry. The aim of this study was to investigate recent developments and "classic" alloy compositions (one iron and two cobalt alloys, unalloyed titanium and an experimental titanium-zirconium alloy, and one gold alloy containing copper and zinc). The alloys and titanium were subject to static immersion in a 0.1 mol l(-1) solution of saline lactic acid before and after oxidation, hence simulating the temperature cycles for the application of ceramic to metal. The greatest amounts of released metal ions were found in the electrolytes of the oxidized gold alloy and of a cobalt alloy not exposed to high-temperature oxidation. Corrosion of the titanium and alloy surfaces was related to the condition of the specimen. The irritation potentials of some metal ions found in the electrolyte were investigated by performing the hen's egg test-chorio-allantoic membrane (HET-CAM) procedure with 1 mmol l(-1) solutions of Ce(3+), Co(2+), Cu(2+), Zn(2+), Fe(2+), and Ti(4+) ions. The irritation potential of the electrolyte of the oxidized gold alloy with a high concentration of metal elements was also investigated. Of these solutions, only the 1 mmol l(-1) Cu(2+) solution was graded as slightly irritating.

  16. Measurement of J-integral in CAD/CAM dental ceramics and composite resin by digital image correlation.

    Science.gov (United States)

    Jiang, Yanxia; Akkus, Anna; Roperto, Renato; Akkus, Ozan; Li, Bo; Lang, Lisa; Teich, Sorin

    2016-09-01

    Ceramic and composite resin blocks for CAD/CAM machining of dental restorations are becoming more common. The sample sizes affordable by these blocks are smaller than ideal for stress intensity factor (SIF) based tests. The J-integral measurement calls for full field strain measurement, making it challenging to conduct. Accordingly, the J-integral values of dental restoration materials used in CAD/CAM restorations have not been reported to date. Digital image correlation (DIC) provides full field strain maps, making it possible to calculate the J-integral value. The aim of this study was to measure the J-integral value for CAD/CAM restorative materials. Four types of materials (sintered IPS E-MAX CAD, non-sintered IPS E-MAX CAD, Vita Mark II and Paradigm MZ100) were used to prepare beam samples for three-point bending tests. J-integrals were calculated for different integral path size and locations with respect to the crack tip. J-integral at path 1 for each material was 1.26±0.31×10(-4)MPam for MZ 100, 0.59±0.28×10(-4)MPam for sintered E-MAX, 0.19±0.07×10(-4)MPam for VM II, and 0.21±0.05×10(-4)MPam for non-sintered E-MAX. There were no significant differences between different integral path size, except for the non-sintered E-MAX group. J-integral paths of non-sintered E-MAX located within 42% of the height of the sample provided consistent values whereas outside this range resulted in lower J-integral values. Moreover, no significant difference was found among different integral path locations. The critical SIF was calculated from J-integral (KJ) along with geometry derived SIF values (KI). KI values were comparable with KJ and geometry based SIF values obtained from literature. Therefore, DIC derived J-integral is a reliable way to assess the fracture toughness of small sized specimens for dental CAD/CAM restorative materials; however, with caution applied to the selection of J-integral path.

  17. Automated dental identification system: An aid to forensic odontology

    Directory of Open Access Journals (Sweden)

    Parvathi Devi

    2011-01-01

    Full Text Available Automated dental identification system is computer-aided software for the postmortem identification of deceased individuals based on dental characteristics specifically radiographs. This system is receiving increased attention because of the large number of victims encountered in the mass disasters and it is 90% more time saving and accurate than the conventional radiographic methods. This technique is based on the intensity of the overall region of tooth image and therefore it does not necessitate the presence of sharp boundary between the teeth. It provides automated search and matching capabilities for digitized radiographs and photographic dental images and compares the teeth present in multiple digitized dental records in order to access their similarity. This paper highlights the functionality of its components and techniques used in realizing these components.

  18. New nano-sized Al2O3-BN coating 3Y-TZP ceramic composites for CAD/CAM-produced all-ceramic dental restorations. Part I. Fabrication of powders.

    Science.gov (United States)

    Yang, Se Fei; Yang, Li Qiang; Jin, Zhi Hao; Guo, Tian Wen; Wang, Lei; Liu, Hong Chen

    2009-06-01

    Partially sintered 3 mol % yttria-stabilized tetragonal zirconium dioxide (ZrO(2), zirconia) polycrystal (3Y-TZP) ceramics are used in dental posterior restorations with computer-aided design-computer-aided manufacturing (CAD/CAM) techniques. High strength is acquired after sintering, but shape distortion of preshaped compacts during their sintering is inevitable. The aim of this study is to fabricate new machinable ceramic composites with strong mechanical properties that are fit for all-ceramic dental restorations. Aluminum oxide (Al(2)O(3))-coated 3Y-TZP powders were first prepared by the heterogeneous precipitation method starting with 3Y-TZP, Al(NO(3))(3) . 9H(2)O, and ammonia, then amorphous boron nitride (BN) was produced and the as-received composite powders were coated via in situ reaction with boric acid and urea. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to analyze the status of Al(2)O(3)-BN on the surface of the 3Y-TZP particles. TEM micrographs show an abundance of Al(2)O(3) particles and amorphous BN appearing uniformly on the surface of the 3Y-TZP particles after the coating process. The size of the Al(2)O(3) particles is about 20 nm. The XRD pattern shows clearly the peak of amorphous BN among the peaks of ZrO(2).

  19. Central Dental High-Vacuum (HIVAC) Oral Evacuation Systems.

    Science.gov (United States)

    1986-05-01

    ana associated -encraiiy piumDed distribucion networKs for use in USAF dental health facilities. These specifications are interim until joint...RESPONSIBLE INDIVIDUAL 22b. TELEPHONE (Include Area Coce) 22c O-C SYMBOiL Carl D. Foster, Maior, USAF, DC (512) 53t-3302 , DSAFS ! N; DD FORM 1473, 84 MAR 33...inpatient areas . Therefore, the dental HIVAC system and distribution network are not within the jurisdiction of National Fire Protection Association

  20. Heat generation caused by ablation of dental restorative materials with an ultra short pulse laser (USPL) system

    Science.gov (United States)

    Braun, Andreas; Wehry, Richard; Brede, Olivier; Frentzen, Matthias; Schelle, Florian

    2011-03-01

    The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an Ultra Short Pulse Laser (USPL) system. Specimens of phosphate cement (PC), ceramic (CE) and composite (C) were used. Ablation was performed with an Nd:YVO4 laser at 1064 nm and a pulse length of 8 ps. Heat generation during laser ablation depended on the thickness of the restoration material. A time delay for temperature increase was observed in the PC and C group. Employing the USPL system for removal of restorative materials, heat generation has to be considered.

  1. 凝胶注模固化及真空干燥优化ZTA牙科陶瓷的性能%Optimizing of curing and vacuum drying on dental zirconia-toughened alumina ceramics formed by gel-casting

    Institute of Scientific and Technical Information of China (English)

    杨征宇; 麻健丰; 童亦萍; 金琼; 杜若茜; 王思钱

    2012-01-01

    Objective: To investigate the effects of process parameters in curing polymerization and vacuum drying process of gelcast zirconia-toughened alumina (ZTA) ceramics, and the gel-casting route was optimized for dental all-ceramic restoration applications. Methods: The ZTA composite gel system was prepared by gelcasting. ①Samples were prepared respectively under different polymerizing temperature. Change of relative surface hardness on solidifying course was measured. The strength and shrinkage of ceramic green bodies were tested before and after sintering. ②0n the basis of previous studies, all the samples were dried under different allocation of temperature and vacuum degree. Their relative moisture content at each time point was characterized, and ceramic performance was estimated by means of three-point bending strength, linear shrinkage rate while sintered. Results: ①The temperature area between 40 ℃ to 70 ℃ could improve the gel reaction rate, while ceramic performance degraded at the temperature of 80 ℃ . ②Vacuum with warming environment could shorten gel ceramic drying time vastly,however,unbalanced proportion of temperature and vacuum degree may lead to tremendous damage of ceramics. Conclusion: ZTA gel system requires only 20 min for fully curing reaction at 50~60 ℃. In condition of 70~80 ℃ heating and 0.08~0.09 MPa of vacuum degree, wet ceramic matrix were completely dried within 2.5 h. Furthermore, the specimen showed a unbroken surface, with little defect and deformation in structure. This technological process has the promising for dental all-ceramic applications and may merit further research.%目的:研究影响氧化锆增韧氧化铝(ZTA)牙科陶瓷性能的凝胶注模成型固化反应过程和真空干燥条件,探索优化可应用于全瓷牙冠制备的工艺.方法:采用凝胶注模成型制备ZTA:①在不同固化温度下分别制备样品,检测各组试样在固化过程中表面相对硬度变化;烧结各组试

  2. Dental composite resins containing silica-fused ceramic single-crystalline whiskers with various filler levels.

    Science.gov (United States)

    Xu, H H

    1999-07-01

    Currently available direct-filling composite resins are susceptible to fracture and hence are not recommended for use in large stress-bearing posterior restorations involving cusps. The glass fillers in composites provide only limited reinforcement because of the brittleness and low strength of glass. The aim of the present study was to use ceramic single-crystalline whiskers as fillers to reinforce composites, and to investigate the effect of whisker filler level on composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers, thereby improving retention in the matrix. The composite flexural strength, elastic modulus, hardness, and degree of polymerization conversion were measured as a function of whisker filler mass fraction, which ranged from 0% to 70%. Selected composites were polished simulating clinical procedures, and the surface roughness was measured with profilometry. The whisker composite with a filler mass fraction of 55% had a flexural strength (mean +/- SD; n = 6) of 196+/-10 MPa, significantly higher than 83+/-14 MPa of a microfill and 120+/-16 MPa of a hybrid composite control (family confidence coefficient = 0.95; Tukey's multiple comparison). The composite modulus and hardness increased monotonically with filler level. The flexural strength first increased, then plateaued with increasing filler level. The degree of conversion decreased with increasing filler level. The whisker composite had a polished surface roughness similar to that of a conventional hybrid composite (p>0.1; Student's t). To conclude, ceramic whisker reinforcement can significantly improve the mechanical properties of composite resins; the whisker filler level plays a key role in determining composite properties; and the reinforcement mechanisms appear to be crack pinning by whiskers and friction from whisker pullout resisting crack propagation.

  3. Physical and adhesive properties of dental enamel after radiotherapy and bonding of metal and ceramic brackets.

    Science.gov (United States)

    Santin, Gabriela Cristina; Palma-Dibb, Regina Guenka; Romano, Fábio Lourenço; de Oliveira, Harley Francisco; Nelson Filho, Paulo; de Queiroz, Alexandra Mussolino

    2015-08-01

    The increasing success rates for cancer patients treated with radiotherapy and the frequent occurrence of tooth loss during treatment have led to an increased demand for orthodontic treatment after radiotherapy. The aim of this study was to evaluate tooth enamel of irradiated teeth after the bonding and debonding of metal and ceramic brackets. Ten permanent molars were cut into enamel fragments measuring 1 mm(2) and divided into an irradiated group (total dose of 60 Gy) and a nonirradiated group. The fragments were subjected to microshear testing to evaluate whether radiotherapy altered the strength of the enamel. Furthermore, 90 prepared premolars were divided into 6 groups and subgroups (n = 15): group 1, nonirradiated and nonaged; group 2, nonirradiated and aged (thermal cycled); group 3, irradiated and aged; each group was divided into 2 subgroups: metallic and ceramic brackets. After thermal cycling and radiotherapy, the brackets were bonded onto the specimens with Transbond XT (3M Unitek, Monrovia, Calif). After 24 hours, the specimens were subjected to the shear tests. Images of the enamel surfaces were classified using the adhesive remnant index. The composite resin-enamel interface was also evaluated. Enamel fragments subjected to radiation had lower strength than did the nonirradiated samples (P enamel interface, resin tags were more extensive on irradiated tooth enamel. Radiation decreased tooth enamel strength, and the specimens treated with radiotherapy had higher frequencies of adhesive failure between the bracket and the composite resin as well as more extensive tags. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  4. Systemic Assessment of Patients Undergoing Dental Implant ...

    African Journals Online (AJOL)

    Background: Procedure‑related and patient‑related factors influence the prognosis of dental implants ... Results: Out of 51, 29 patients were males while 22 were females, with ratio of 1.32:1. ... difference of average STAI‑State subscore before and after the surgery was ... bleeding, swelling, bruising, pain, and tenderness to.

  5. 牙科可切削硅藻土全瓷材料的初步研究%Pilot Study on Dental Machinable Diatomite- based Ceramic.

    Institute of Scientific and Technical Information of China (English)

    刘梅; 殷雪萌; 章非敏; 梁慧; 顾宁

    2011-01-01

    Objective: To study the relationship between stracture and properties of a new type of dental machinable ceramic based on diatomite.Methods: By adding nanometer reinforcing agent, the new diatomite based dental machinable ceramic was fabricated.X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to characterize the crystal form and microstructure.The mechanical properties and the maehinability of this new ceramic were evaluated.Results: The color of the ceramic after sintering was oyster white and its surface was smooth.SEM images presented polycrystalline structure and the grain edge was clear with decreased porosities.The flexure strength, mierohardness and fracture toughness of the new ceramic reached 177.23±7.02MPa, 9.73±0.64 GPa and 3.93±0.58MPa · m1/2 respectively.The machinability of the material sintered at 700 degrees was good.Conclusion: The mechanical and esthetic properties of the new type of diatomite-based dental machinable ceramic were acceptable but the mechanical strength still needs to be enhanced.%目的:制备一种新型的牙科可切削硅藻土陶瓷材料,探讨其结构和性能的关系.方法:选取硅藻土为原料,通过添加纳米增韧剂制备陶瓷材料.采用X射线衍射仪分析陶瓷的晶相成分,扫描电镜观察陶瓷的显微结构,并测量材料的机械性能和切削性能.结果:硅藻土全瓷材料表面光滑,呈现乳白色;电镜下观察材料内部呈现致密多晶结构,晶界清晰,气孔较少;其三点弯曲强度(177.23±7.02)MPa,显微硬度(9.73±0.64)GPa,断裂韧性(3.93±0.58)MPa·m1/2.初烧结的陶瓷材料中烧结温度为700℃的切削性能较好.结论:该材料符合牙科可切削陶瓷材料的基本要求,但强度仍需进一步提高.

  6. A panorama of dental CAD/CAM restorative systems.

    Science.gov (United States)

    Liu, Perng-Ru

    2005-07-01

    In the last 2 decades, exciting new developments in dental materials and computer technology have led to the success of contemporary dental computer-aided design/computer-aided manufacturing (CAD/CAM) technology. Several highly sophisticated chairside and laboratory CAD/CAM systems have been introduced or are under development. This article provides an overview of the development of various CAD/CAM systems. Operational components, methodologies, and restorative materials used with common CAD/CAM systems are discussed. Research data and clinical studies are presented to substantiate the clinical performance of these systems.

  7. Panorama of dental CAD/CAM restorative systems.

    Science.gov (United States)

    Liu, Perng-Ru; Essig, Milton E

    2008-10-01

    In the past two decades, exciting new developments in dental materials and computer technology have led to the success of contemporary dental computer-aided design/computer-aided manufacture (CAD/CAM) technology. Several highly sophisticated in-office and laboratory CAD/CAM systems have been introduced or are under development. This article provides an overview of the development of various CAD/CAM systems. Operational components, methodologies, and restorative materials used with common CAD/CAM systems are discussed. Research data and clinical studies are presented to substantiate the clinical performance of these systems.

  8. Ceramic Defects in Metal-Ceramic Fixed Dental Prostheses Made from Co-Cr and Au-Pt Alloys: A Retrospective Study.

    Science.gov (United States)

    Mikeli, Aikaterini; Boening, Klaus W; Lißke, Benjamin

    2015-01-01

    Ceramic defects in porcelain-fused-to-metal (PFM) restorations may depend on framework alloy type. This study assessed ceramic defects on cobalt-chromium- (Co-Cr-) and gold-platinum- (Au-Pt-) based PFM restorations. In this study, 147 Co-Cr-based and 168 Au-Pt-based PFM restorations inserted between 1998 and 2010 (139 patients) were examined for ceramic defects. Detected defects were assigned to three groups according to clinical defect relevance. Ceramic defect rates (Co-Cr-based: 12.9%; Au-Pt-based: 7.2%) revealed no significant difference but a strong statistical trend (U test, P = .082). Most defects were of little clinical relevance. Co-Cr PFM restorations may be at higher risk for ceramic defects compared to Au-Pt-based restorations.

  9. Expert System Diagnosis Dental Disease Using Certainty Factor Method

    Directory of Open Access Journals (Sweden)

    Whisnu Ulinnuha Setiabudi

    2017-05-01

    Full Text Available Technological development is growing rapidly among with the increasing of human needs especially in mobile technology where the technology that often be used is android. The existence of this android facilitates the user in access of information. This android can be used for healthy needs, for example is detecting dental disease. One of the branches of computer science that can help society in detecting dental disease is expert system. In this research, making expert system to diagnosis dental disease by using certainty factor method. Dental disease diagnosis application can diagnose the patient based on griping of the patient about dental disease so it can be obtained diseases possibility of the patient itself. This application is an expert system application that operates on android platform. Furthermore, in the measurement accuracy of the system test performed by 20 patients, there were 19 cases of corresponding and 1 cases that do not fit. So, from system testing performed by 20 patients resulted in a 95% accuracy rate. 

  10. 晶化温度对牙科用云母微晶玻璃微观结构的影响%Influence of crystallization temperature on microstructures of mica-based glass-ceramics for dental restorations

    Institute of Scientific and Technical Information of China (English)

    秦燕军; 王忠义; 曹小刚; 田杰谟

    2001-01-01

    AIM To investigate the influence of crystallization temperature on microstructures of mica-based machinable glass-ceramics used for CAD/CAM dental restorations. METHODS According to the requirements of dental restorative materials, K2O-MgO-MgF2-SiO2 glass-ceramics system was chosen to make tetrasilicic fluormica glass-ceramics and three different temperatures were used to finish the crystallization procedure. Differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used to observe the crystallization behavior, crystalline phases and microstructures of the glass-ceramics. Three point bending strength was also measured. RESULTS Grain shape changes from spherical to platelike as crystallization temperature went up. Improving crystallization temperature was increase the grain size, aspect ratio and flexural strength of the mica, while the crystalline phase is not affected by temperature changes. CONCLUSION Microstructures of the glass-ceramics are determined by crystallization temperature.%目的研究晶化温度对牙科CAD/CAM加工用四硅氟云母微晶玻璃微观结构的影响. 方法选用K2O-MgO-MgF2-SiO2系统来制备云母微晶玻璃,通过差热分析(DTA)、X射线衍射分析(XRD)、扫描电子显微镜观测(SEM)及三点弯曲强度的测试,比较了三种不同晶化温度对四硅氟云母微晶玻璃的晶化特性、微观结构及抗弯强度的影响. 结果随着晶化温度的逐步升高,四硅氟云母晶粒的形态由球形转变为片层状,晶粒尺寸和径厚比逐步增大,微晶玻璃的抗弯强度也逐步升高,但其晶相组成未发生明显变化. 结论晶化温度对四硅氟云母微晶玻璃的微观结构起决定作用.

  11. Ceramics in Restorative and Prosthetic DENTISTRY1

    Science.gov (United States)

    Kelly, J. Robert

    1997-08-01

    This review is intended to provide the ceramic engineer with information about the history and current use of ceramics in dentistry, contemporary research topics, and potential research agenda. Background material includes intra-oral design considerations, descriptions of ceramic dental components, and the origin, composition, and microstructure of current dental ceramics. Attention is paid to efforts involving net-shape processing, machining as a forming method, and the analysis of clinical failure. A rationale is presented for the further development of all-ceramic restorative systems. Current research topics receiving attention include microstructure/processing/property relationships, clinical failure mechanisms and in vitro testing, wear damage and wear testing, surface treatments, and microstructural modifications. The status of the field is critically reviewed with an eye toward future work. Significant improvements seem possible in the clinical use of ceramics based on engineering solutions derived from the study of clinically failed restorations, on the incorporation of higher levels of "biomimicry" in new systems, and on the synergistic developments in dental cements and adhesive dentin bonding.

  12. Mechanical properties and porosity of dental glass-ceramics hot-pressed at different temperatures

    Directory of Open Access Journals (Sweden)

    Carla Castiglia Gonzaga

    2008-09-01

    Full Text Available The objective of this work was to evaluate biaxial-flexural-strength (σf, Vickers hardness (HV, fracture toughness (K Ic, Young's modulus (E, Poisson's ratio (ν and porosity (P of two commercial glass-ceramics, Empress (E1 and Empress 2 (E2, as a function of the hot-pressing temperature. Ten disks were hot-pressed at 1065, 1070, 1075 and 1080 °C for E1; and at 910, 915, 920 and 925 °C for E2. The porosity was measured by an image analyzer software and s f was determined using the piston-on-three-balls method. K Ic and HV were determined by an indentation method. Elastic constants were determined by the pulse-echo method. For E1 samples treated at different temperatures, there were no statistical differences among the values of all evaluated properties. For E2 samples treated at different temperatures, there were no statistical differences among the values of σf, E, and ν, however HV and K Ic were significantly higher for 910 and 915 °C, respectively. Regarding P, the mean value obtained for E2 for 925 °C was significantly higher compared to other temperatures.

  13. Enhanced Hydrophilicity and Biocompatibility of Dental Zirconia Ceramics by Oxygen Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Ching-Chou Wu

    2015-02-01

    Full Text Available Surface properties play a critical role in influencing cell responses to a biomaterial. The objectives of this study were (1 to characterize changes in surface properties of zirconia (ZrO2 ceramic after oxygen plasma treatment; and (2 to determine the effect of such changes on biological responses of human osteoblast-like cells (MG63. The results indicated that the surface morphology was not changed by oxygen plasma treatment. In contrast, oxygen plasma treatment to ZrO2 not only resulted in an increase in hydrophilicity, but also it retained surface hydrophilicity after 5-min treatment time. More importantly, surface properties of ZrO2 modified by oxygen plasma treatment were beneficial for cell growth, whereas the surface roughness of the materials did not have a significant efficacy. It is concluded that oxygen plasma treatment was certified to be effective in modifying the surface state of ZrO2 and has the potential in the creation and maintenance of hydrophilic surfaces and the enhancement of cell proliferation and differentiation.

  14. Surface Modifications of Dental Ceramic Implants with Different Glass Solder Matrices: In Vitro Analyses with Human Primary Osteoblasts and Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Jana Markhoff

    2014-01-01

    Full Text Available Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP and aluminum toughened zirconia (ATZ were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants.

  15. Flexural strength and microstructure of two lithium disilicate glass ceramics for CAD/CAM restoration in the dental clinic

    Directory of Open Access Journals (Sweden)

    Suk-Ho Kang

    2013-08-01

    Full Text Available Objectives There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent and Rosetta SM (Hass, and to observe their crystalline structures. Materials and Methods Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi and x-ray diffraction (XRD, Rigaku analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05. The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

  16. A ceramic matrix composite thermal protection system for hypersonic vehicles

    Science.gov (United States)

    Riccitiello, Salvatore R.; Love, Wendell L.; Pitts, William C.

    1993-01-01

    The next generation of hypersonic vehicles (NASP, SSTO) that require reusable thermal protection systems will experience acreage surface temperatures in excess of 1100 C. More important, they will experience a more severe physical environment than the Space Shuttle due to non-pristine launching and landing conditions. As a result, maintenance, inspection, and replacement factors must be more thoroughly incorporated into the design of the TPS. To meet these requirements, an advanced thermal protection system was conceived, designated 'TOPHAT'. This system consists of a toughened outer ceramic matrix composite (CMC) attached to a rigid reusable surface insulator (RSI) which is directly bonded to the surface. The objective of this effort was to evaluate this concept in an aeroconvective environment, to determine the effect of impacts to the CMC material, and to compare the results with existing thermal protection systems.

  17. Exotic encounters with dental implants: managing complications with unidentified systems.

    Science.gov (United States)

    Mattheos, N; Janda, M Schittek

    2012-06-01

    As the application of dental implants increases worldwide, so is the number of technical and biological complications that general dental practitioners will be called to manage, while maintaining implant patients. In addition, the greater patient mobility encountered today combined with a growing trend of 'dental implant tourism' will very often result in situations where the dentist is requested to deal with complications in implants placed elsewhere and which sometimes might be of an 'exotic' system one cannot directly recognize. Such a situation can pose significant challenges to even experienced clinicians. The challenges are not only in the scientific field, but often include professional and ethical implications. This case report will discuss strategies for the management of implant complications in cases of unidentified implant systems. Critical factors in such situations would be the clinician's experience and special training, the correct radiographic technique, as well as access to the appropriate tools and devices.

  18. Development of sprayed ceramic seal systems for turbine gas path sealing

    Science.gov (United States)

    Bill, R. C.; Shiembob, L. T.; Stewart, O. L.

    1978-01-01

    A ceramic seal system is reported that employs plasma-sprayed graded metal/ceramic yttria stabilized zirconium oxide (YSZ). The performance characteristics of several YSZ configurations were determined through rig testing for thermal shock resistance, abradability, and erosion resistance. Results indicate that this type of sealing system offers the potential to meet operating requirements of future gas turbine engines.

  19. Clinical analysis of ZrO2 ceramic dental restoration of patients with dental defects%二氧化锆烤瓷牙修复牙体缺损的临床分析

    Institute of Scientific and Technical Information of China (English)

    祖国红

    2014-01-01

    了解二氧化锆烤瓷牙修复技术治疗牙体缺损的临床效果。方法:对我院2012年3月至2014年3月收治的牙体缺损患者进行抽样,选取64例患者随机分成两组,对照组应用常规牙体缺损修复技术进行治疗,试验组应用二氧化锆烤瓷牙修复技术进行治疗,观察两组患者临床疗效。结果:试验组总有效率(93.75%)明显优于对照组(68.75%),且牙体功能复常时间、治疗操作时间均优于对照组,差异具有显著统计学意义(P<0.05)。结论:二氧化锆烤瓷牙修复技术治疗牙体缺损临床疗效确切,值得临床大力推广使用。%Objective To investigate the clinical effect of ZrO2 ceramic dental restoration technique in the treatment of dental defect. Methods in our hospital from 2012 March to 2014 March were tooth defect were sampling, we selected 64 cases of patients were randomly divided into two groups, the control group were treated with conventional dental defect repair technology, used in the experimental group ZrO2 ceramic dental restoration technology treatment.

  20. How dental utilisation in the Netherlands was affected by a radical reform of the dental insurance system

    NARCIS (Netherlands)

    Abraham, E.A.; Bronkhorst, E.M.; Truin, G.J.; Felling, A.J.A.; Severens, J.L.

    2003-01-01

    OBJECTIVES: To establish the effects of the 1995 insurance system reform on dental utilisation. STUDY DESIGN: Four categories of patients experiencing homogeneous insurance changes - public/private insurance with and without additional private dental insurance--were analysed. The reform was

  1. How dental utilisation in the Netherlands was affected by a radical reform of the dental insurance system

    NARCIS (Netherlands)

    Abraham, E.A.; Bronkhorst, E.M.; Truin, G.J.; Felling, A.J.A.; Severens, J.L.

    2003-01-01

    OBJECTIVES: To establish the effects of the 1995 insurance system reform on dental utilisation. STUDY DESIGN: Four categories of patients experiencing homogeneous insurance changes - public/private insurance with and without additional private dental insurance--were analysed. The reform was hypothes

  2. Integrated Medical-Dental Delivery Systems: Models in a Changing Environment and Their Implications for Dental Education.

    Science.gov (United States)

    Jones, Judith A; Snyder, John J; Gesko, David S; Helgeson, Michael J

    2017-09-01

    Models and systems of the dental care delivery system are changing. Solo practice is no longer the only alternative for graduating dentists. Over half of recent graduates are employees, and more than ever before, dentists are practicing in groups. This trend is expected to increase over the next 25 years. This article examines various models of dental care delivery, explains why it is important to practice in integrated medical-dental teams, and defines person-centered care, contrasting it with patient-centered care. Systems of care in which teams are currently practicing integrated oral health care delivery are described, along with speculation on the future of person-centered care and the team approach. Critical steps in the education of dental and other health care professionals and the development of clinical models of care in moving forward are considered. This article was written as part of the project "Advancing Dental Education in the 21(st) Century."

  3. 牙科用云母微晶玻璃的微观结构对其力学性能的影响%Influence of microstructure on mechanical properties of mica-based glass-ceramics for dental restorations.

    Institute of Scientific and Technical Information of China (English)

    秦燕军; 王忠义; 曹小刚; 田杰谟

    2001-01-01

    目的:研究牙科CAD/CAM加工用四硅氟云母微晶玻璃的微观结构对其力学性能的影响。方法:采用K2O-MgO-MgF2-SiO2系统来研制云母微晶玻璃,通过差热分析(DTA)、X射线衍射分析(XRD)、扫描电子显微镜观测(SEM)及力学性能测试,比较了三种不同晶化温度下,四硅氟云母微晶玻璃的微观结构对其力学性能影响。结果:随着晶化温度的逐步升高,四硅氟云母的晶粒大小和径厚比逐步增大,抗弯强度和断裂韧性亦逐渐增高,维氏硬度和脆性指数随温度升高而降低。结论:云母微晶玻璃的微观结构对其力学性能起决定作用,而微观结构与晶化温度密切相关。%Objective:To investigate the influence of microstructure onmechanical properties of mica-based machinable glass-ceramics used for CAD/CAM restorations.Methods:According to the requirements of dental restorative materials, K2O-MgO-MgF2-SiO2 system was chosen to form tetrasilicic fluormica glass-ceramics and three different temperatures were used to finish crystallization process.Differential thermal analysis(DTA),X-ray diffractometer(XRD) and scanning electron microscopy(SEM) were used to observe the crystallization behavior,crystalline phases and microstructures of the glass-ceramics.Influence of microstructure on mechanical properties of the glass-ceramics was compared.Results:Improving crystallization temperature can increase the grain sizes and aspect ratio of mica and improve the three-point bending strength and fracture toughness of the glass-ceramics.Vickers hardness and the index of brittleness decrease with increasing of temperature.Conclusion:The mechanical properties of the glass-ceramic are determined by its microstructure,while the latter has a close relationship with crystallization temperature.

  4. A new classification system for dental treatment under general anesthesia.

    Science.gov (United States)

    Loyola-Rodriguez, Juan Pablo; Zavala-Alonso, Veronica; Patiño-Marin, Nuria; Friedman, Clive

    2006-01-01

    The provision of comprehensive care for patients with special needs using dental general anesthesia (DGA) has changed over time, and now includes more complex procedures and the participation of many services. As a result, it is necessary to integrate, organize and describe all of the procedures that are carried out in different DGA settings. The aim of this study was to propose a systematic classification for dental treatment procedures be delivered under DGA, and to compare this classification system with an existing system. This new classification system has three distinct components: type, frequency and length of time needed to complete dental procedures for both primary and permanent teeth. A wide range of oral surgery procedures and endodontic treatment was also included. A retrospective cohort study utilizing 84 subjects was used to develop and compare the two classification systems. When comparing the different categories of procedures by both classifications, there were significant statistical differences between them (p dental or medical specialties. The classification system in this study includes detailed information regarding the procedures involved in the DGA. This helps to provide a clear understanding and specific information that enables the comparison of clinical experiences across populations where a DGA has been used for patients with special needs.

  5. Ceramic Integration Technologies for Aerospace and Energy Systems: Technical Challenges and Opportunities

    Science.gov (United States)

    Singh, Mrityunjay

    2007-01-01

    Ceramic integration technology has been recognized as an enabling technology for the implementation of advanced ceramic systems in a number of high-temperature applications in aerospace, power generation, nuclear, chemical, and electronic industries. Various ceramic integration technologies (joining, brazing, attachments, repair, etc.) play a role in fabrication and manufacturing of large and complex shaped parts of various functionalities. However, the development of robust and reliable integrated systems with optimum performance requires the understanding of many thermochemical and thermomechanical factors, particularly for high temperature applications. In this presentation, various challenges and opportunities in design, fabrication, and testing of integrated similar (ceramic-ceramic) and dissimilar (ceramic-metal) material systems will be discussed. Experimental results for bonding and integration of SiC based LDI fuel injector, high conductivity C/C composite based heat rejection system, solid oxide fuel cells system, ultra high temperature ceramics for leading edges, and ceramic composites for thermostructural applications will be presented. Potential opportunities and need for the development of innovative design philosophies, approaches, and integrated system testing under simulated application conditions will also be discussed.

  6. Ceramic Hot Gas Filter with Integrated Failsafe System

    Energy Technology Data Exchange (ETDEWEB)

    Heidenreich, S.; Haag, W.; Walch, A.; Scheibner, B.; Mai, R.; Leibold, H.; Seifert, H.

    2002-09-18

    In order to integrate a failsafe system and to improve the cleaning intensity a new cleaning method was recently developed, the CPP (coupled pressure pulse) cleaning (Heidenreich et al. 2001). For the CPP method the cleaning system is directly coupled with the filter candles. One feature of this new technique is that the cleaning gas pressure exceeds the system pressure only by 0.05 to 0.1 MPa, whereas in case of conventional jet pulse systems two times the system pressure (at least 0.6 MPa) is standard. The key advantage of the coupled pressure pulse cleaning is that a safety filter for each filter candle can be integrated in the clean gas side of the filter. Thus, a candle failure is not longer a serious problem. The integrated safety filter enables the operation of the filter system also in case a filter candle breaks. This increases the availability of the filter and prevents an unscheduled costly shut-down of the system. In this paper the design of the ceramic filter wit h the failsafe system and the CPP cleaning will be described. The new developed safety filter elements, their pressure drop and their filtration and clogging behavior will be shown. Tests of single system components, of the whole filter system and first experiences of operating this system will be reported.

  7. The effect of ceramic thickness and number of firings on the color of a zirconium oxide based all ceramic system fabricated using CAD/CAM technology

    Science.gov (United States)

    Aras, Meena Ajay

    2011-01-01

    PURPOSE Ceramics have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic core strength. However, there is a lack of information on how color is affected by fabrication procedure. The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of zirconium oxide all-ceramic system (Lava™) fabricated using CAD/CAM technology. MATERIALS AND METHODS Thirty disc-shaped cores, 12 mm in diameter with a 1 mm thickness were fabricated from zirconium oxide based all ceramic systems (Lava™, 3M ESPE, St Paul, MN, USA) and divided into three groups (n = 10) according to veneering with dentin ceramic thicknesses: as 0.5, 1, or 1.5 mm. Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade, VITA Zahnfabrik, Bad Säckingen, Germany) and data were expressed in CIELAB system coordinates. A repeated measures ANOVA and Bonferroni post hoc test were used to analyze the data (n = 10, α=.05). RESULTS L*a*b* values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001) and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in L*a*b* values between the number of firings and ceramic thickness (P<.001). An increase in number of firings resulted in significant increase in L* values for both 0.5 mm and 1.5 mm thicknesses (P<.01, P=.013); however it decreased for 1 mm thickness (P<.01). The a* values increased for 1 mm and 1.5 mm thicknesses (P<.01), while it decreased for 0.5 mm specimens. The b* values increased significantly for all thicknesses (P<.01, P=.022). As the dentin ceramic thickness increased, significant reductions in L* values (P<.01) were recorded. There were significant increases in both a

  8. Accuracy of optical scanning methods of the Cerec®3D system in the process of making ceramic inlays

    Directory of Open Access Journals (Sweden)

    Trifković Branka

    2010-01-01

    Full Text Available Background/Aim. One of the results of many years of Cerec® 3D CAD/CAM system technological development is implementation of one intraoral and two extraoral optical scanning methods which, depending on the current indications, are applied in making fixed restorations. The aim of this study was to determine the degree of precision of optical scanning methods by the use of the Cerec®3D CAD/CAM system in the process of making ceramic inlays. Methods. The study was conducted in three experimental groups of inlays prepared using the procedure of three methods of scanning Cerec ®3D system. Ceramic inlays made by conventional methodology were the control group. The accuracy of optical scanning methods of the Cerec®3D system computer aided designcomputer aided manufacturing (CAD/CAM was indirectly examined by measuring a marginal gap size between inlays and demarcation preparation by scanning electron microscope (SEM. Results. The results of the study showed a difference in the accuracy of the existing methods of scanning dental CAD/CAM systems. The highest level of accuracy was achieved by the extraoral optical superficial scanning technique. The value of marginal gap size inlays made with the technique of extraoral optical superficial scanning was 32.97 ± 13.17 μ. Techniques of intraoral optical superficial and extraoral point laser scanning showed a lower level of accuracy (40.29 ± 21.46 μ for inlays of intraoral optical superficial scanning and 99.67 ± 37.25 μ for inlays of extraoral point laser scanning. Conclusion. Optical scanning methods in dental CAM/CAM technologies are precise methods of digitizing the spatial models; application of extraoral optical scanning methods provides the hightest precision.

  9. Ceramic fragments and metal-free full crowns: a conservative esthetic option for closing diastemas and rehabilitating smiles.

    Science.gov (United States)

    Miranda, M E; Olivieri, K A; Rigolin, F J; Basting, R T

    2013-01-01

    Dental ceramics make it possible to restore anterior teeth that have been esthetically compromised, presenting a high resistance to wear, biocompatibility, color stability, and low thermal conductivity. The development of different types of ceramic and techniques for adhesive cementation have made it possible to produce more conservative restorations without involving the healthy dental structure and with minimally invasive preparation, such as the bonding of ceramic fragments. The purpose of this article is to describe a clinical case in which diastemas were closed by using nanofluorapatite ceramic (e.max Ceram, Ivoclar-Vivadent) fragments on teeth 7 and 10 with minimal tooth preparation and metal-free ceramic crowns (e-max Ceram) reinforced with zirconia copings through a computer-aided design/computer-aided manufacturing system (Lava, 3M-ESPE) on teeth 8 and 9.

  10. Transparent Ceramics for High-Energy Laser Systems (Preprint)

    Science.gov (United States)

    2010-10-01

    s t r a c t We demonstrate that transparent magnesium aluminate spinel ceramic possesses excellent thermo-opti- cal properties, a record low...are required. We have developed transparent magnesium aluminate spinel (MgAl2O4) ceramic as a rugged win- dow and dome material for protecting EO/IR...public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT We demonstrate that transparent magnesium aluminate spinel ceramic

  11. Bond strength durability of a resin composite on a reinforced ceramic using various repair systems

    NARCIS (Netherlands)

    Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Leite, Fabiola; Bottino, Marco Antonio

    2009-01-01

    Objectives. This study compared the durability of repair bond strength of a resin composite to a reinforced ceramic after three repair systems. Methods. Alumina-reinforced feldspathic ceramic blocks (Vitadur-alpha(R)) (N=30) were randomly divided into three groups according to the repair method: PR-

  12. Research on Variable Structure Parametric Design System of Ceramic Tile Mould Based on Modular

    Institute of Scientific and Technical Information of China (English)

    DAI Xiao-bo; DONG Yu-de; QIN Lei

    2014-01-01

    To solve the existing problems during the ceramic mold enterprises product design and development process, the variable structure parametric design system based on modular of ceramic mold has been developed. The system uses the object-oriented technology and top-down design concept as a guide, establishes a ceramic mold parametric design process, divides the process of ceramic mold design into modules of different levels and creates a component model library based on the functional analysis. Expanding modular thinking to parts structure design level is an effective solution to the difficulty of changing the structure during the product design process. Examples show that the system can achieve a ceramic mold product design, improve design efficiency.

  13. Development of the CEREC dental system and cutting materials%CEREC系统及切削材料进展

    Institute of Scientific and Technical Information of China (English)

    王林虎; 董青山; 马毅慧

    2012-01-01

    CEREC (chairside economical restoration of esthetic ceramic)是一种椅旁计算机辅助设计和计算机辅助制作(com-puter aided design/computer aided manufacturing,CAD/CAM)系统,它引领着牙科数字化发展方向.作为一种高便捷、高质量、高审美的的数字化牙科修复系统,吸引了无数牙医和患者的青睐,临床应用日趋广泛.文中就CEREC的CAD/CAM系统的发展过程、构成及工作原理、CEREC系统发展以及可切削材料改进作一综述.%The CEREC system is a chairside CAD/CAM (computer aided design /computer aided manufacturing) dental restoration system. It leads the dental digital development. As a high-convenient, high-quality, high-aesthetic digital dental restoration system, it attracts many dentists and patients to favor. There is an increasingly wide range of its clinical application. This article describes the development of the CEREC system, its work principle, the newest product of CEREC system and the cutting materials used to fabricate the restoration.

  14. Influence of sodalite zeolite infiltration on the coefficient of thermal expansion and bond strength of all-ceramic dental prostheses.

    Science.gov (United States)

    Naji, Ghassan Abdul-Hamid; Omar, Ros Anita; Yahya, Rosiyah

    2017-03-01

    In all-ceramic systems, a high incidence of veneer chip-off has been reported in clinical studies. Coefficient of thermal expansion (CTE) behaviour is one of the factors that may increase residual stress in the interface and influence the veneer/core bond strength. Therefore, this study aimed to evaluate the effect of sodalite zeolite-infiltration on the CTE behaviour and bond strength of different all-ceramic prostheses. The case-study groups were synthesized sodalite zeolite-infiltrated alumina (IA-SOD) and synthesized sodalite zeolite-infiltrated zirconia-toughened alumina (ZTA) (IZ-SOD), while the control groups were glass-infiltrated alumina (IA-glass) and glass-infiltrated ZTA (IZ-glass). Forty cylindrical-shaped samples measuring 5 mm in diameter and 10 mm in height were tested for CTE using a thermo-mechanical analyser machine, and forty disc-shaped ceramic samples measuring 12 mm in diameter and 1.2 ± 0.2 mm in thickness were prepared using specially designed stainless steel split mould and veneered by cylinder-shaped (2 mm high × 2 mm diameter) low-fusing porcelain (Vita VM7). The veneer/core samples were sintered and tested for shear bond strength using a high precision universal testing machine. Scanning electron microscope, stereo microscope, atomic force microscope, and energy-dispersive X-ray spectroscopy were used to investigate the structural characteristics of samples at the fracture surface. The collected data were analyzed with a one-way ANOVA and Tukey HSD test (α=.05). IZ-SOD revealed highest CTE and shear bond strength values, while the IA-glass revealed the lowest values than the other groups. There was no significant difference in CTE and bond strength among IZ-SOD, IA-SOD and IZ-glass samples (p>0.05). The experimental SOD zeolite-infiltrated samples revealed higher CTE mismatch and bond strength along with a more favourable mode of failure than did the commercial glass-infiltrated samples. Sandblast technique is considered as effective

  15. Assessment of exposures and potential risks to the US adult population from the leaching of elements from gold and ceramic dental restorations.

    Science.gov (United States)

    Richardson, G Mark; James, Kyle Jordan; Peters, Rachel Elizabeth; Clemow, Scott Richard; Siciliano, Steven Douglas

    2016-01-01

    Using data from the 2001 to 2004 US National Health and Nutrition Examination Survey (NHANES) on the number and placement of tooth restorations in adults, we quantified daily doses due to leaching of elements from gold (Au) alloy and ceramic restorative materials. The elements with the greatest leaching rates from these materials are often the elements of lowest proportional composition. As a result, exposure due to wear will predominate for those elements of relatively high proportional composition, while exposure due leaching may predominate for elements of relatively low proportional composition. The exposure due to leaching of silver (Ag) and palladium (Pd) from Au alloys exceeded published reference exposure levels (RELs) for these elements when multiple full surface crowns were present. Six or more molar crowns would result in exceeding the REL for Ag, whereas three or more crowns would be necessary to exceed the REL for Pd. For platinum (Pt), the majority of tooth surfaces, beyond just molar crowns, would be necessary to exceed the REL for Pd. Exposures due to leaching of elements from ceramic dental materials were less than published RELs for all components examined here, including having all restorations composed of ceramic.

  16. Internal fit of two all-ceramic systems and metal-ceramic crowns

    OpenAIRE

    Leandro Moura Martins; Fabio Cesar Lorenzoni; Alcides Oliveira de Melo; Luciana Mendonça da Silva; José Luiz G. de Oliveira; Pedro Cesar Garcia de Oliveira; Gerson Bonfante

    2012-01-01

    Objectives: The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA - In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD), and metal-ceramic (MC - Ni-Cr alloy) crowns. Material and Methods: Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns wa...

  17. Adhesive luting of all-ceramic restorations--the impact of cementation variables and short-term water storage on the strength of a feldspathic dental ceramic.

    LENUS (Irish Health Repository)

    Addison, Owen

    2008-08-01

    To investigate the impact of resin cement luting variables and short-term water storage on the strength of an adhesively luted all-ceramic restorative material. An understanding of the strengthening mechanisms will result in optimisation of operative techniques and materials selection criteria.

  18. Basic research in crystalline and noncrystalline ceramic systems. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Kingery, W. D.; Coble, R. L.

    1968-04-01

    Various research subjects on ceramics have been investigated, including heat conduction, surface characteristics, diffusion in oxides, high-temperature kinetic processes, microstructure development, effects of microstructure on properties, structure and properties of noncrystalline ceramics, dissolution kinetics, and solid-vapor reactions. (DLC)

  19. Effect of sandblasting, silica coating, and laser treatment on the microtensile bond strength of a dental zirconia ceramic to resin cements.

    Science.gov (United States)

    Mahmoodi, Nasrin; Hooshmand, Tabassom; Heidari, Solmaz; Khoshro, Kimia

    2016-02-01

    The purpose of this in vitro study was to evaluate the effect of laser irradiation as well as other surface treatment methods on the microtensile bond strength of a dental zirconia ceramic to the two types of resin cements. Zirconia ceramic blocks (ICE Zirkon) were sintered according to the manufacturer's instructions and duplicated in resin composites. The ceramic specimens were divided into four groups according to the following surface treatments: no surface treatment (control), sandblasting with alumina, silica coating plus silanization, and Nd:YAG laser irradiation. The specimens were divided equally and then bonded with Panavia F2.0 (self-etching resin cement) and Clearfil SA Luting (self-adhesive resin cement) to the composite blocks. The bonded ceramic-composite blocks were stored in distilled water at 37 °C for 72 h, cut to prepare bar-shaped specimens with a bonding area of approximately 1 mm(2), and thermocycled for 3000 cycles between 5 and 55 °C, and the microtensile bond strengths were measured using a universal testing machine. The data were analyzed by ANOVA and Tukey post hoc test. The results showed that the self-adhesive resin cement used in this study did not improve the microtensile bond strength when the zirconia surface was sandblasted by alumina. The use of the Nd:YAG laser did not enhance the bond strength between the zirconia and both types of resin cements. In addition, silica coating of the zirconia surfaces plus silane application significantly improved the bond strength regardless of the type of resin cement utilized.

  20. CO2 and Nd:YAP laser interaction with lithium disilicate and Zirconia dental ceramics: A preliminary study

    Science.gov (United States)

    Rocca, Jean-Paul; Fornaini, Carlo; Brulat-Bouchard, Nathalie; Bassel Seif, Samy; Darque-Ceretti, Evelyne

    2014-04-01

    Lithium disilicate and Zirconia ceramics offer a high level of accuracy when used in prosthetic dentistry. Their bonding using different resins is highly dependent on micro-mechanical interlocking and adhesive chemical bonding. Investigation of the performances of high strength ceramics when their surface is modified for chemical and mechanical bonding is then required. The aim of this study is to investigate the possibility of using laser for surface treatment of different high strength CAD/CAM ceramics and thus to improve their mechanical and chemical properties. Thirty two CAD/CAM ceramic discs were divided into two different groups: lithium disilicate ceramics (IPS e.max CAD®, Ivoclar, Vivadent, Italy) and Zirconia ceramics (IPS e.max ZirCAD®, Ivoclar, Vivadent, Italy). The Laser surface treatment was performed by Carbon Dioxide laser (Dream Pulse Laser®, Daeshin Enterprise Corp., Korea) at 20 W, 25 W and 30 W CW and by Neodymium Yttrium Aluminum Perovskite laser (Nd:YAP Lokki®, Lobel Medical, France) at 10 W and 30 Hz. Physical modifications of the irradiated ceramic discs were observed by scanning electron microscopy (SEM) and chemically analyzed by Energy-Dispersive Spectroscopy (EDS). Surface wettability was tested using the water drop test and the crystalline structure was investigated using X-ray diffraction (XRD). The macroscopic observation showed a shinier structure in all the groups, while at the SEM observation only CO2 25 W and 30 W treated groups showed cracks and fissures. In the conditions of this study, CO2 laser and Nd:YAP laser with the parameters used create chemical and physical surface modifications of the ceramics, indicating the possibility of an improvement in adhesion of the tested ceramics.

  1. Techniques used to fabricate all-ceramic restorations in the dental practice.

    Science.gov (United States)

    Puri, Sameer

    2005-07-01

    Porcelain is an increasingly popular material to use for restorations. This article will discuss the 3 main ways to fabricate porcelain restorations. The first method involves waxing up the restoration to the proper form and casting it in molten porcelain similar to the lost wax technique for gold. The second technique requires the use of porcelain in a powder form to be stacked on top of a refractory die or a platinum foil and then fired in the oven. The third main technique is the use of a CAD/CAM system to mill the porcelain restoration from a solid block of porcelain. All 3 techniques are valid and the clinician should have a thorough understanding of which techniques are appropriate in various clinical situations.

  2. Mechanical, thermal, and chemical analyses of the binary system Au-Ti in the development of a dental alloy.

    Science.gov (United States)

    Fischer, J

    2000-12-15

    Investigations in the binary system gold-titanium (Au-Ti) were performed in regard to the development of a universal dental alloy suited for inlays, for the conventional crown and bridge technique, as well as for the ceramic-fused-to-metal technique. With nine alloys with increasing Ti content from 0-10 atom %, microstructure, mechanical properties, thermal properties, and corrosion were determined in the as-cast state and after simulation of ceramic firing. The microstructure shows an increasing formation of a second phase with increasing Ti content, crystallizing dendritically, which, according to the binary phase diagram must be the intermetallic phase TiAu(4). The results of the measurements reveal that with increasing Ti content, hardness, Young's modulus, proof stress, and tensile strength strongly increase in the range of 2-6 atom % Ti and with higher Ti content remain constant. Elongation after fracture decreases with a Ti content above 2 atom %. The coefficient of thermal expansion decreases linearly with increasing Ti content. Thermal distortion decreases exponentially with increasing Ti content. The corrosion test showed an increasing release of Ti with increasing Ti content. Lowest corrosion was observed in the simulated state with intact oxide layer. Appropriate properties for dental application were found in the range of 6.5 at% Ti. Copyright 2000 John Wiley & Sons, Inc.

  3. Mechanisms governing the interfacial delamination of thermal barrier coating system with double ceramic layers

    Science.gov (United States)

    Xu, Rong; Fan, Xueling; Wang, T. J.

    2016-05-01

    A systematic study of factors affecting the interfacial delamination of thermal barrier coating system (TBCs) with double ceramic layers (DCL) is presented. Crack driving forces for delaminations at two weak interfaces are examined. The results show that a thicker outermost ceramic layer can induce dramatic increase in crack driving force and make the interface between two ceramic coatings become more prone to delamination. The behavior is shown to be more prominent in TBCs with stiffer outmost coating. The thickness ratio of two ceramic layers is an important parameter for controlling the failure mechanisms and determining the lifetime of DCL TBCs under inservice condition. By accounting for the influences of thickness ratio of two ceramic layers and interfacial fracture toughnesses of two involved interfaces, the fracture mechanism map of DCL TBCs has been constructed, in which different failure mechanisms are identified. The results quanlitatively agree with the aviliable experimental data.

  4. Ceramic on Ceramic or Ceramic-on-polyethylene for Total Hip Arthroplasty: A Systemic Review and Meta-analysis of Prospective Randomized Studies

    Directory of Open Access Journals (Sweden)

    Yu-Lei Dong

    2015-01-01

    Full Text Available Background: Wear debris of polyethylene has become a restraining factor of the durability for total hip arthroplasty (THA. Ceramic on ceramic (COC has better wear resistance while the squeaking sound and prosthesis fracture are of concern. It is still a controversy that bearing couples are better for THA. Methods: We performed a systematic review of all English articles identified from PubMed (1966-, Embase (1980- and the Cochrane Library. Clinical outcomes, complications, revision rates, and radiographic outcomes of COC-THA and ceramic on polyethylene (COP-THA were compared and evaluated. Results: Eight prospective randomized trials enrolling a total of 1508 patients and 1702 THA surgeries were identified. Our results demonstrated the prosthesis fracture and the squeaking sound is significantly higher in COC group and higher wear rate of the COP. Hip function, loosening rate, dislocation rate, revision rate, and the osteolysis rate were comparable between two groups. According to Grading of Recommendations Assessment, Development and Evaluation system assessment, the strength of evidence was high for prosthesis fracture, dislocation, osteolysis, and moderate for radiolucent line or loosening, hip noise, and revision. Conclusions: Up to now, there is insufficient evidence to identify any clinical advantage of COC compared with COP. Longer follow-up of larger randomized trial is needed to clarify the outcomes.

  5. Ceramic on Ceramic or Ceramic-on-polyethylene for Total Hip Arthroplasty: A Systemic Review and Meta-analysis of Prospective Randomized Studies

    Institute of Scientific and Technical Information of China (English)

    Yu-Lei Dong; Tao Li; Ke Xiao; Yan-Yan Bian; Xi-Sheng Weng

    2015-01-01

    Background:Wear debris of polyethylene has become a restraining factor of the durability for total hip arthroplasty (THA).Ceramic on ceramic (COC) has better wear resistance while the squeaking sound and prosthesis fracture are of concern.It is still a controversy that bearing couples are better for THA.Methods:We performed a systematic review of all English articles identified from PubMed (1966-),Embase (1980-) and the Cochrane Library.Clinical outcomes,complications,revision rates,and radiographic outcomes of COC-THA and ceramic on polyethylene (COP)-THA were compared and evaluated.Results:Eight prospective randomized trials enrolling a total of 1508 patients and 1702 THA surgeries were identified.Our results demonstrated the prosthesis fracture and the squeaking sound is significantly higher in COC group and higher wear rate of the COP.Hip function,loosening rate,dislocation rate,revision rate,and the osteolysis rate were comparable between two groups.According to Grading of Recommendations Assessment,Development and Evaluation system assessment,the strength of evidence was high for prosthesis fracture,dislocation,osteolysis,and moderate for radiolucent line or loosening,hip noise,and revision.Conclusions:Up to now,there is insufficient evidence to identify any clinical advantage of COC compared with COP.Longer follow-up of larger randomized trial is needed to clarify the outcomes.

  6. MICROSTRUCTURE AND INFRARED EMISSIVITY AT NORMAL TEMPERATURE IN TRANSITIONAL METAL OXIDES SYSTEM CERAMICS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The fabrication of Fe2O3-MnO2-Co2O3-CuO system ceramics, and the composite system ceramics of transitional metal oxides-cordierite and transitional metal oxides-kaolinit are presented in this work. The research was carried out with the main attention to the infrared emissivity in the band of 8~14μm at room temperature,the microstructure of the ceramics and the relation between them. High infrared emissivities exceeding 0.9 in the band of 8~14μm at room temperature were gained in the transitional metal oxide ceramics and the composite system ceramics. It is suggested that the formation of inverse spinels and partially inverse spinels, such as Fe3O4, CoFe2O4, CuFe2O4 and CuMn2O4, is beneficial to the enhancement of the infrared emissivity of the transitional metal oxide ceramics. The transitional metal oxides play an important role in determining the infrared emissivity of the composite system ceramics.

  7. STRUCTURE AND PROPERTIES OF A CERAMIC BRICK MODIFIED WITH TECHNOGENIC MINERAL SYSTEMS

    Directory of Open Access Journals (Sweden)

    DEREVIANKO V. N.

    2016-07-01

    Full Text Available Summary. Problem statement. One way to conserve the scarce high-quality raw materials resources and to reduce transport and energy costs is to use the accumulated technogenic mineral systems, as well as to study technogenic raw materials which were not previously used [1-3]. A shortage of high plasticity clays determines the need for using local low-grade loamy raw materials for the manufacture of wall ceramics. Strength properties of the ceramic brick can be improved by using expensive corrective additives or local technogenic raw materials [4-7]. Purpose. Development of compositions for the ceramic brick, modified with technogenic mineral systems. Conclusion. The author has studied the influence of the mixture ratio on the structure and fundamental physical and mechanical properties of the ceramic brick modified with technogenic mineral systems. The author has also developed the best ceramic batch compositions based on technogenic mineral systems conferring the required physical and mechanical parameters of the ceramic brick; they consist of: overburden (67%, refuse heap (28% and red mud from NGZ (Mykolaiv Alumina Refinery (5% for making 150 Grade ceramic brick with an average density of 1,650-1,730 kg/m3 at a temperature of 850°C, which allows to reduce firing energy costs. It has been established that the sintering initiation temperature of the modified mixture decreases by 150-200°C compared to the unmodified one.

  8. Zirconia as a Dental Biomaterial

    Directory of Open Access Journals (Sweden)

    Alvaro Della Bona

    2015-08-01

    Full Text Available Ceramics are very important in the science of dental biomaterials. Among all dental ceramics, zirconia is in evidence as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia has been applied as structural material for dental bridges, crowns, inserts, and implants, mostly because of its biocompatibility, high fracture toughness, and radiopacity. However, the clinical success of restorative dentistry has to consider the adhesion to different substrates, which has offered a great challenge to dental zirconia research and development. This study characterizes zirconia as a dental biomaterial, presenting the current consensus and challenges to its dental applications.

  9. Degree of Conversion and Mechanical Properties of Resin Cements Cured Through Different All-Ceramic Systems

    OpenAIRE

    Lopes, Camila de Carvalho Almança; Rodrigues, Renata Borges; André Luis Faria e Silva; Paulo Cézar SIMAMOTO JÚNIOR; Soares, Carlos José; Novais,Veridiana Resende

    2015-01-01

    Abstract: The aim of this study was to verify the degree of conversion (DC), Vickers microhardness (VH) and elastic modulus (E) of resin cements cured through different ceramic systems. One 1.5-mm-thick disc of each ceramic system (feldspathic, lithium dissilicate and zircônia veneered with feldspathic) was used. Three dual-cured (Allcem, Variolink II and RelyX U200) and one chemically-cured (Multilink) resin cements were activated through ceramic discs. For dual-cured resin cements was used ...

  10. Intraoral treatment of veneering porcelain chipping of fixed dental restorations: a review and clinical application.

    Science.gov (United States)

    Kimmich, Magdalena; Stappert, Christian F J

    2013-01-01

    Every dental ceramic system can experience failure of the veneering porcelain. However, the increasing popularity of all-ceramic crowns and fixed dental prostheses (FDPs) seems to have led to an increasing need to repair chipped veneering porcelain. The authors compared different methods to repair fractured ceramic restorations (porcelain-fused-to-metal and all-ceramic) and explain the basic principles of adhesion in these systems. They also evaluated the frequency and causes of failure in dental ceramic systems. This review is based on the results of PubMed and Google Scholar searches, as well as on a hand search of the scientific literature, resulting in 300 articles from 1977 to 2012. The authors used multiple key words (ceramic, repair, bonding, hydrofluoric acid, air abrasion, silane, phosphates, silicon dioxide) and different strategies (connecting different key words with OR, NOR and AND and truncation of the stem of words) to search the databases. Because of differences in the material composition of ceramic systems (composed of metal, alumina or zirconia, glass-ceramics and feldspathic ceramics), different treatments are required for the exposed material surfaces after chipping. Use of hydrofluoric acid etching, air abrasion, tribochemical coating, silanization and metal primers or zirconia primers seem to be the most successful conditioning methods for durable bonding and repair. Intraoral repair of a restoration offers a satisfying option for the patient when the restoration cannot be removed or replaced. Its success depends largely on the conditioning methods used for the fractured surfaces.

  11. Clinical decision support system in dental implantology

    OpenAIRE

    Alexandra Polášková; Jitka Feberová; Taťjána Dostálová; Pavel Kříž; Michaela Seydlová

    2013-01-01

    Implantology is rapidly developing interdisciplinary field providing enormous amounts of data to be classified, evaluated and interpreted. The analysis of clinical data remains a big challenge, because each new system has specific requirements. The aim of study was prepare specific tool for treatment planning. Decision support system is built on Expert system. It is interactive software which provides clinical recommendations and treatment planning. Expert systems are knowledge-based computer...

  12. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  13. Internal fit of two all-ceramic systems and metal-ceramic crowns

    Science.gov (United States)

    MARTINS, Leandro Moura; LORENZONI, Fabio Cesar; de MELO, Alcides Oliveira; da SILVA, Luciana Mendonça; de OLIVEIRA, José Luiz G.; de OLIVEIRA, Pedro Cesar Garcia; BONFANTE, Gerson

    2012-01-01

    Objectives The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA - In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD), and metal-ceramic (MC - Ni-Cr alloy) crowns. Material and Methods Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns was measured using the replica technique, which employs a light body polyvinyl siloxane impression material to simulate the cement layer thickness. The data were analyzed according to the surfaces obtained for the occlusal space (OS), axial space (AS) and total mean (TM) using two-way ANOVA with Tukey's multiple comparison test (p<0.05). Results No differences among the different areas were detected in the MC group. For the Y-TZP and ICA groups, AS was statistically lower than both OS and TM. No differences in AS were observed among the groups. However, OS and TM showed significantly higher values for ICA and Y-TZP groups than MC group. Comparisons of ICA and Y-TZP revealed that OS was significantly lower for Y-TZP group, whereas no differences were observed for TM. Conclusions The total mean achieved by all groups was within the range of clinical acceptability. However, the metal-ceramic group demonstrated significantly lower values than the all-ceramic groups, especially in OS. PMID:22666843

  14. Internal fit of two all-ceramic systems and metal-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Leandro Moura Martins

    2012-04-01

    Full Text Available OBJECTIVES: The aim of this study was to investigate the internal fit (IF of glass-infiltrated alumina (ICA - In-Ceram Alumina, yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD, and metal-ceramic (MC - Ni-Cr alloy crowns. MATERIAL AND METHODS: Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each according to the core material used (metal, ICA or Y-TZP. The IF of the crowns was measured using the replica technique, which employs a light body polyvinyl siloxane impression material to simulate the cement layer thickness. The data were analyzed according to the surfaces obtained for the occlusal space (OS, axial space (AS and total mean (TM using two-way ANOVA with Tukey ’s multiple comparison test (p<0.05. RESULTS: No differences among the different areas were detected in the MC group. For the Y-TZP and ICA groups, AS was statistically lower than both OS and TM. No differences in AS were observed among the groups. However, OS and TM showed significantly higher values for ICA and Y-TZP groups than MC group. Comparisons of ICA and Y-TZP revealed that OS was significantly lower for Y-TZP group, whereas no differences were observed for TM. CONCLUSIONS: The total mean achieved by all groups was within the range of clinical acceptability. However, the metal-ceramic group demonstrated significantly lower values than the all-ceramic groups, especially in OS.

  15. Ceramic Composite Mechanical Fastener System for High-Temperature Structural Assemblies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Under Phase I, the feasibility of a novel thermal stress-free ceramic composite mechanical fastener system suitable for assembly of high-temperature composite...

  16. Outcome of bonded vs all-ceramic and metal- ceramic fixed prostheses for single tooth replacement.

    Science.gov (United States)

    Karl, Matthias

    2016-01-01

    The conventional treatment of a single missing tooth is most frequently based on the provision of a fixed dental prosthesis (FDPs). A variety of designs and restorative materials are available which have an impact on the treatment outcome. Consequently, it was the aim of this review to compare resin-bonded, all-ceramic and metal-ceramic FDPs based on existing evidence. An electronic literature search using "metal-ceramic" AND "fixed dental prosthesis" AND "clinical, all-ceramic" AND "fixed dental prosthesis" AND "clinical, resin-bonded" AND "fixed dental prosthesis" AND "clinical, fiber reinforced composite" AND "clinical, monolithic" AND "zirconia" AND "clinical" was conducted and supplemented by the manual searching of bibliographies from articles already included. A total of 258 relevant articles were identified. Metal-ceramic FDPs still show the highest survival rates of all tooth-supported restorations. Depending on the ceramic system used, all-ceramic restorations may reach comparable survival rates while the technical complications, i.e. chipping fractures of veneering materials in particular, are more frequent. Resin-bonded FDPs can be seen as long-term provisional restorations with the survival rate being higher in anterior locations and when a cantilever design is applied. Inlay-retained FDPs and the use of fiber-reinforced composites overall results in a compromised long-term prognosis. Recently advocated monolithic zirconia restorations bear the risk of low temperature degradation. Several variables affect treatment planning for a given patient situation, with survival and success rates of different restorative options representing only one factor. The broad variety of designs and materials available for conventional tooth-supported restorations should still be considered as a viable treatment option for single tooth replacement.

  17. Zirconia as a Dental Biomaterial

    OpenAIRE

    Alvaro Della Bona; Oscar E. Pecho; Rodrigo Alessandretti

    2015-01-01

    Ceramics are very important in the science of dental biomaterials. Among all dental ceramics, zirconia is in evidence as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia has been applied as structural material for dental bridges, crowns, inserts, and implants, mostly because of its biocompatibility, high fracture toughness, and radiopacity. However, the clinical success of restorative dentistry has to consider the adhesion to different subs...

  18. Zirconia as a Dental Biomaterial

    OpenAIRE

    Alvaro Della Bona; Pecho, Oscar E.; Rodrigo Alessandretti

    2015-01-01

    Ceramics are very important in the science of dental biomaterials. Among all dental ceramics, zirconia is in evidence as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia has been applied as structural material for dental bridges, crowns, inserts, and implants, mostly because of its biocompatibility, high fracture toughness, and radiopacity. However, the clinical success of restorative dentistry has to consider the adhesion to different subs...

  19. Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

    Directory of Open Access Journals (Sweden)

    Bandar Mohammed Abdullah Al-Makramani

    2010-12-01

    Full Text Available Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. OBJECTIVES: The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. MATERIAL AND METHODS: Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995 were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M Sdn Bhd, Puchong, Selangor, Malaysia], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany, which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. RESULTS: The mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA at a preset significance level of 5% because of unequal group variances (P<0.001. There was statistically significant difference between the three core ceramics (P<0.05. Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N. CONCLUSIONS: Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.

  20. Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems.

    Science.gov (United States)

    Al-Makramani, Bandar Mohammed Abdullah; Razak, Abdul Aziz Abdul; Abu-Hassan, Mohamed Ibrahim

    2010-12-01

    Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. The mean biaxial flexural strength values were: Turkom-Cera: 506.8 ± 87.01 MPa, In-Ceram: 347.4 ± 28.83 MPa and Vitadur-N: 128.7 ± 12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (Pcore ceramics (Pstrength, followed by In-Ceram and Vitadur-N. Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.

  1. Ballistic performance of porous-ceramic, thermal protection systems

    Science.gov (United States)

    Miller, Joshua E.; Bohl, William E.; Christiansen, Eric C.; Davis, Bruce A.; Foreman, Cory D.

    2012-03-01

    Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on 8 lb/ft3 alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrousinsulation/ reaction-cured-glass layer (TUFI/RCG). A semi-empirical, first principles impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. Model extensions to look at the implications of greater than 10 GPa equation of state is also discussed. Predicted penetration probabilities for a vehicle visiting the International Space Station is 60% lower for orbital debris and 95% lower for meteoroids with this model compared to an energy scaled approach.

  2. A New Model for Reactive Wetting of Metal/Ceramic System

    Institute of Scientific and Technical Information of China (English)

    Fusheng Pan; Jian Chen; Tianmo Liu; Jing Zhang

    2000-01-01

    @@ A new model has been suggested for illustrating the effects of interfacial reactions on the wettability of metal / ceramic system. It is shown that both the free energy change released by the reaction (△Gr) and the change in the nature of interfaces (△δr) are the important factors affecting reactive wetting of metal / ceramic system, but sometimes either of them will become the decisive one.

  3. Corrosion of coupled metals in a dental magnetic attachment system.

    Science.gov (United States)

    Iimuro, F T; Yoneyama, T; Okuno, O

    1993-12-01

    Implants and magnetic attachments are becoming widespread in dental treatment. Their associated use, implants and magnetic attachments, can be seen often too. In those cases, it is difficult to avoid coupling of different metals. The corrosion behavior of the metals is expected to be different depending on whether it is found in an isolated or a coupled condition. Potential corrosion couples in a dental magnetic attachment system among titanium, ferromagnetic stainless steel, gold alloy type IV, and gold-silver-palladium alloy were studied by an immersion test in 1% lactic acid for 7 days and potential/current density curves were measured. Corrosion of titanium and ferromagnetic stainless steel seemed to be accelerated by coupling with gold alloys or gold-silver-palladium alloys. On the other hand, the corrosion amount of gold alloy and gold-silver-palladium alloys were attenuated by coupling.

  4. Maintenance of an Adequate Dental Hygiene Education System.

    Science.gov (United States)

    Ley, Eugene; And Others

    1984-01-01

    Administrative decisions about the future of dental hygiene programs are often based on inadequate information about employment trends and about the importance of the dental hygienist in dental practices. Studies indicate that demand for dental hygiene services will remain high in the 1980s. (Author/MLW)

  5. Porosity Dependence of Piezoelectric Properties for Porous Potassium Niobate System Ceramics

    Science.gov (United States)

    Wada, S.; Mase, Y.; Shimizu, S.; Maeda, K.; Fujii, I.; Nakashima, K.; Pulpan, P.; Miyajima, N.

    2011-10-01

    Porous potassium niobate (KNbO3, KN) system ceramics were prepared by a conventional sintering method using carbon black (CB) nanoparticles. First, KN nanoparticles with a size of 100 nm was mixed with CB nanoparticles and binder using ball milling with ethanol. The mixture was dried, and pressed into pellets using uniaxial pressing. After binder burnout, these ceramics was sintered in air. Their piezoelectric properties were measured and discussed a relationship between porosity and piezoelectric properties. As the results, with increasing porosity, piezoelectric g33 constant increased significantly, which suggested that porous ceramics were effective for stress sensor application.

  6. Effect of Ceramic Thickness and Luting Agent Shade on the Color Masking Ability of Laminate Veneers.

    Science.gov (United States)

    Begum, Zubeda; Chheda, Pratik; Shruthi, C S; Sonika, Radhika

    2014-12-01

    The main objective of the study was to recognize the effect of ceramic thickness and luting agent on the extent to which the restoration masks color variations that may be present in the underlying dental structure. Two pressable ceramics were used: Lithium disilicate reinforced (IPS e.max- Ivoclar Vivadent) and Leucite reinforced (Cergo- Dentsply). Fifteen ceramic discs were manufactured from each ceramic and divided into three groups, according to the thickness (0.5, 1, 1.5 mm). To simulate the color of a dark underlying dental structure, background discs, color C3, with 20 mm diameter, were made using resin composite. The ceramic discs with varying thicknesses were seated on the dark background of the resin composite with either resinous opaque cement or resinous cement. The color parameters were determined by the CIE Lab system of colors using a spectrophotometer and color differences (ΔE) were calculated. The results were then statistically analyzed, using ANOVA test and Tukey HSD test. The ΔE values of both ceramic systems were affected by both the luting agent and the ceramic thickness (P veneers, higher values in the color parameters were obtained for both ceramic materials. The color masking ability of ceramics used for laminate veneers is significantly affected by the thickness of the ceramic and the shade of the luting agent used.

  7. Effects of Dental 3D Multimedia System on the Performance of Junior Dental Students in Preclinical Practice: A Report from China

    Science.gov (United States)

    Hu, Jian; Yu, Hao; Shao, Jun; Li, Zhiyong; Wang, Jiawei; Wang, Yining

    2009-01-01

    Background: Computer-assisted tools are rarely adopted for dental education in China. In China, 3D digital technology, such as Virtual Reality Systems, are often rejected in the dental field due to prohibitive pricing. There is also a reluctance to move away from traditional patterns of dental education. Objective: The current study is one of a…

  8. Effects of Dental 3D Multimedia System on the Performance of Junior Dental Students in Preclinical Practice: A Report from China

    Science.gov (United States)

    Hu, Jian; Yu, Hao; Shao, Jun; Li, Zhiyong; Wang, Jiawei; Wang, Yining

    2009-01-01

    Background: Computer-assisted tools are rarely adopted for dental education in China. In China, 3D digital technology, such as Virtual Reality Systems, are often rejected in the dental field due to prohibitive pricing. There is also a reluctance to move away from traditional patterns of dental education. Objective: The current study is one of a…

  9. Electrochemical behavior of dental implant system before andafter clinical use

    Institute of Scientific and Technical Information of China (English)

    Chae-Heon CHUNG; Hee-Jung KIM; Yong-Tae JEONG; Mee-Kyoung SON; Yong-Hoon JEONG; Han-Cheol CHOE

    2009-01-01

    Electrochemical behavior of dental implant system before and after clinical use (in vivo and in vitro) was researched by using abutment and titanium fixture. To simulate an oral environment, the samples of clinically used and non-used implant systems as a working electrode were exposed to artificial saliva at (36.5±1) ℃. Electrochemical tests were carried out using a potentiostat. After electrochemical test, the corrosion morphology of each sample was investigated by FE-SEM and EDS. The corrosion potential and pitting potential of clinically used implant system are lower than those of non-used implant system, and clinically used implant system exhibits a lower range of passivation, indicating a less degree of inherent resistance against chloride ion. The polarization resistance decreases in the case of clinically used implant system, whereas, Rp for clinically non-used implant system increases compared with clinically used implant system.

  10. The effect of ZrO2 and TiO 2 on solubility and strength of apatite-mullite glass-ceramics for dental applications.

    Science.gov (United States)

    Fathi, Hawa M; Miller, Cheryl; Stokes, Christopher; Johnson, Anthony

    2014-03-01

    The effect of ZrO2 and TiO2 on the chemical and mechanical properties of apatite-mullite glass-ceramics was investigated after sample preparation according to the ISO (2768:2008) recommendations for dental ceramics. All materials were characterized using differential thermal analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. X-ray fluorescence spectroscopy was used to determine the concentrations of elements present in all materials produced. The chemical solubility test and the biaxial flexural strength (BFS) test were then carried out on all the samples. The best solubility value of 242 ± 61 μg/cm(2) was obtained when HG1T was heat-treated for 1 h at the glass transition temperature plus 20 °C (Tg + 20 °C) followed by 5 h at 1200 °C. The highest BFS value of 174 ± 38 MPa was achieved when HG1Z and HG1Z+T were heat-treated for 1 h at the Tg + 20 °C followed by 7 h at 1200 °C. The present study has demonstrated that the addition of TiO2 to the reference composition showed promise in both the glass and heat-treated samples. However, ZrO2 is an effective agent for developing the solubility or the mechanical properties of an apatite-mullite glass-ceramic separately but does not improve the solubility and the BFS simultaneously.

  11. Development of Sensors for Ceramic Components in Advanced Propulsion Systems. Phase 2; Temperature Sensor Systems Evaluation

    Science.gov (United States)

    Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

    1994-01-01

    The 'development of sensors for ceramic components in advanced propulsion systems' program is divided into two phases. The objectives of Phase 1 were to analyze, evaluate and recommend sensor concepts for the measurement of surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. The results of this effort were previously published in NASA CR-182111. As a result of Phase 1, three approaches were recommended for further development: pyrometry, thin-film sensors, and thermographic phosphors. The objective of Phase 2 were to fabricate and conduct laboratory demonstration tests of these systems. Six materials, mutually agreed upon by NASA and Pratt & Whitney, were investigated under this program. This report summarizes the Phase 2 effort and provides conclusions and recommendations for each of the categories evaluated.

  12. Bond strength of the porcelain repair system to all-ceramic copings and porcelain.

    Science.gov (United States)

    Lee, Sang J; Cheong, Chan Wook; Wright, Robert F; Chang, Brian M

    2014-02-01

    The purpose of this study was to investigate the shear bond strength of the porcelain repair system on alumina and zirconia core ceramics, comparing this strength with that of veneering porcelain. Veneering ceramic (n = 12), alumina core (n = 24), and zirconia core (n = 24) blocks measuring 10 × 5 × 5 mm(3) were fabricated. Veneering ceramic blocks were used as the control. Alumina and zirconia core blocks were divided into 2 groups (n = 12 each), and a slot (2 × 2 × 4 mm(3)) filled with veneering ceramics was prepared into one of the alumina and zirconia core groups (n = 12). Followed by surface treatments of micro-abrasion with 30 μm alumina particles, etching with 35% phosphoric acid and silane primer and bond, composite resin blocks (2 × 2 × 2 mm(3)) were built up and light polymerized onto the treated surfaces by 3 configurations: (a) composite blocks bonded onto veneering ceramic surface alone, (b) composite blocks bonded onto alumina core or zirconia core surfaces, (c) a 50% surface area of the composite blocks bonded to veneering ceramics and the other 50% surface area of the composite blocks to alumina core or zirconia core surfaces. The shear bond strength of the composite to each specimen was tested by a universal testing machine at a 0.5 mm/min crosshead speed. The shear bond strength was analyzed by unpaired t-tests for within the configuration groups and ANOVA for among the different configuration groups. When the mean shear bond strength was compared within groups of the same configuration, there were no statistically significant differences. Comparison of the shear bond strength among groups of different configurations revealed statistically significant differences. The mean shear bond strength of composite onto 100% veneering ceramic surface and composite onto 50% veneering 50% all-ceramic cores was statistically higher than that of composite onto 100% all-ceramic cores; however, the differences of the shear bond strength of composite bonded

  13. Planar ceramic membrane assembly and oxidation reactor system

    Science.gov (United States)

    Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohm, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, deceased, Paul Nigel

    2007-10-09

    Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

  14. Emerging Ceramic-based Materials for Dentistry

    Science.gov (United States)

    Denry, I.; Kelly, J.R.

    2014-01-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. PMID:25274751

  15. Avaliação da tenacidade à fratura de diferentes sistemas cerâmicos Relative fracture toughness of differents dental ceramics

    Directory of Open Access Journals (Sweden)

    Clovis Pagani

    2003-03-01

    Full Text Available Embora as cerâmicas possuam alta resistência à compressão, apresentam friabilidade devido à sua baixa resistência à tração e, desta forma, possuem menor capacidade de absorver impactos. Este trabalho avaliou a tenacidade à fratura de diferentes sistemas cerâmicos, que refere-se à medida da habilidade de absorção da energia de deformação de um material friável. Foram confeccionados 30 corpos-de-prova em forma de discos (5mmx3mm utilizando-se três diferentes materiais cerâmicos, os quais foram divididos em 3 grupos: G1-10 amostras confeccionadas com a cerâmica Vitadur Alpha (Vita-Zahnfabrik; G2-10 amostras confeccionadas com a cerâmica IPS Empress 2 (Ivoclar-Vivadent e G3-10 amostras confeccionadas com a cerâmica In-Ceram Alumina (Vita-Zahnfabrik. Para a obtenção dos valores de tenacidade foi utilizada a técnica da indentação que se baseia na série de fissuras que se formam sob uma carga pesada. Foram realizadas 4 impressões por amostra, utilizado um microdurômetro (Digital Microhardness Tester FM com uma carga de 500gf, durante 10 segundos. A análise estatística dos dados (Testes ANOVA de Kruskal-Wallis e Dunn, indica que a cerâmica In-Ceram Alumina apresentou valor mediano (2,96N/m3/2, estatisticamente diferente do apresentado pela IPS Empress 2 (1,05N/m3/2, enquanto que a cerâmica Vitadur Alpha apresentou valores intermediários (2,08N/m3/2, sem diferenças estatísticas dos outros dois materiais. Conclui-se que as cerâmicas apresentam diferentes desempenhos de tenacidade à fratura, sendo a In-Ceram capaz de absorver maior energia comparada a Vitadur Alpha e ao IPS Empress2.Although ceramics present high compressive strength, they are brittle materials due to their low tensile strength so they have lower capacity to absorb shocks. This study evaluated the fracture toughness of different ceramic systems, which refers to the ability of a friable material to absorb defformation energy. Three ceramic systems were

  16. Cementing all-ceramic restorations: recommendations for success.

    Science.gov (United States)

    Vargas, Marcos A; Bergeron, Cathia; Diaz-Arnold, Ana

    2011-04-01

    Several all-ceramic restorative systems of various compositions, properties and indications are available to the dental practitioner. Because of the large number of systems, the dental team faces questions and decisions when choosing the appropriate system and the appropriate means of cementation. The authors present a brief overview of the cementation options for various types of all-ceramic restorations. In this article, they discuss the cementation of current all-ceramic restorations and make clinical recommendations tailored to each type of ceramic. The clinician must have a good understanding of the ceramic type to determine whether a restoration should be cemented adhesively or nonadhesively. Other variables, such as isolation and preparation design, also influence the cementation choice. Various ceramic types demand different surface treatments before cementation. Choosing and applying the appropriate surface treatment and cementation procedure will contribute to long-lasting restorations. The literature is lacking in clinical trial results that validate current in vitro data regarding cementation of all-ceramic restorations.

  17. Ceramic/polymer functionally graded material (FGM) lightweight armor system

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; McClellan, K.J.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at room temperature. Thus, they were able to demonstrate the feasibility of producing boron carbide-aluminum and boron carbide-polymer functionally graded materials.

  18. Ceramic/polymer functionally graded material (FGM) lightweight armor system

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; McClellan, K.J.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at room temperature. Thus, they were able to demonstrate the feasibility of producing boron carbide-aluminum and boron carbide-polymer functionally graded materials.

  19. Radiation-hard ceramic Resistive Plate Chambers for forward TOF and T0 systems

    Science.gov (United States)

    Akindinov, A.; Dreyer, J.; Fan, X.; Kämpfer, B.; Kiselev, S.; Kotte, R.; Garcia, A. Laso; Malkevich, D.; Naumann, L.; Nedosekin, A.; Plotnikov, V.; Stach, D.; Sultanov, R.; Voloshin, K.

    2017-02-01

    Resistive Plate Chambers with ceramic electrodes are the main candidates for a use in precise multi-channel timing systems operating in high-radiation conditions. We report the latest R&D results on these detectors aimed to meet the requirements of the forward T0 counter at the CBM experiment. RPC design, gas mixture, limits on the bulk resistivity of ceramic electrodes, efficiency, time resolution, counting rate capabilities and ageing test results are presented.

  20. Refractory Materials for Flame Deflector Protection System Corrosion Control: Refractory Ceramics Literature Survey

    Science.gov (United States)

    Calle, Luz Marina; Hintze, Paul E.; Parlier, Christopher R.; Curran, Jerome P.; Kolody, Mark; Perusich, Stephen; Whitten, Mary C.; Trejo, David; Zidek, Jason; Sampson, Jeffrey W.; Coffman, Brekke E.

    2009-01-01

    Ceramics can be defmed as a material consisting of hard brittle properties produced from inorganic and nonmetallic minerals made by firing at high temperatures. These materials are compounds between metallic and nonmetallic elements and are either totally ionic, or predominately ionic but having some covalent character. This definition allows for a large range of materials, not all applicable to refractory applications. As this report is focused on potential ceramic materials for high temperature, aggressive exposure applications, the ceramics reviewed as part of this report will focus on refractory ceramics specifically designed and used for these applications. Ceramic materials consist of a wide variety of products. Callister (2000) 1 characterized ceramic materials into six classifications: glasses, clay products, refractories, cements, abrasives, and advanced ceramics. Figure 1 shows this classification system. This review will focus mainly on refractory ceramics and cements as in general, the other classifications are neither applicable nor economical for use in large structures such as the flame trench. Although much work has been done in advanced ceramics over the past decade or so, these materials are likely cost prohibitive and would have to be fabricated off-site, transported to the NASA facilities, and installed, which make these even less feasible. Although the authors reviewed the literature on advanced ceramic refractories 2 center dot 3 center dot 4 center dot 5 center dot 6 center dot 7 center dot 8 center dot 9 center dot 10 center dot 11 center dot 12 after the review it was concluded that these materials should not be ' the focus of this report. A review is in progress on materials and systems for prefabricated refractory ceramic panels, but this review is focusing more on typical refractory materials for prefabricated systems, which could make the system more economically feasible. Refractory ceramics are used for a wide variety of applications

  1. In vitro shear bond strength of Y-TZP ceramics to different core materials with the use of three primer/resin cement systems.

    Science.gov (United States)

    Al-Harbi, Fahad A; Ayad, Neveen M; Khan, Zahid A; Mahrous, Amr A; Morgano, Steven M

    2016-01-01

    Durability of the bond between different core materials and zirconia retainers is an important predictor of the success of a dental prosthesis. Nevertheless, because of its polycrystalline structure, zirconia cannot be etched and bonded to a conventional resin cement. The purpose of this in vitro study was to compare the effects of 3 metal primer/resin cement systems on the shear bond strength (SBS) of 3 core materials bonded to yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic retainers. Zirconia ceramic (Cercon) disks (5×3 mm) were airborne-particle abraded, rinsed, and air-dried. Disk-shaped core specimens (7×7 mm) that were prepared of composite resin, Ni-Cr, and zirconia were bonded to the zirconia ceramic disks by using one of 3 metal primer/cement systems: (Z-Prime Plus/BisCem, Zirconia Primer/Multilink Automix, or Clearfil Ceramic Primer/Clearfil SA). SBS was tested in a universal testing machine. Stereomicroscopy was used to evaluate the failure mode of debonded specimens. Data were analyzed using 2-way ANOVA and post hoc analysis using the Scheffe procedure (α=.05). Clearfil SA/Clearfil Ceramic Primer system with an Ni-Cr core yielded the highest SBS value (19.03 MPa), whereas the lowest SBS value was obtained when Multilink Automix/Zirconia Primer system was used with the zirconia core group (4.09 MPa). Differences in mean SBS values among the cement/primer groups were statistically significant, except for Clearfil SA and BisCem with both composite resin and zirconia cores. Differences in mean SBS values among the core subgroups were not statistically significant, except for zirconia core with BisCem, Multilink, and Clearfil SA. The predominant failure mode was adhesive, except for Clearfil SA and BisCem luting agents with composite resin cores, which displayed cohesive failure, and Multilink Automix with a composite resin, core as well as Clearfil SA with Ni-Cr cores, where the debonded specimens of each group displayed a mixed

  2. The effect of ceramic fibers on the immune system.

    Science.gov (United States)

    Tulinská, Jana; Kuricová, Miroslava; Lisková, Aurelia; Kováciková, Zuzana; Tatrai, Elizabeth

    2005-12-01

    Male Sprague-Dawley rats were treated by intratracheal instillation with 1 mg/animal of refractory ceramic fibers. Intratracheal exposure to ceramic fibers led to significant changes of immune response. Results of proliferative activity of spleen lymphocytes showed significantly decreased proliferative activity of T-cells in response to mitogens phytohemagglutinin and concanavalin A in animals given ceramic fibers in comparison with control rats. Similarly, T-dependent B-cell response to pokeweed mitogen was significantly suppressed. Spontaneous proliferative activity of lymphocytes in non-stimulated spleen cell cultures did not differ in exposed and control rats. No significant changes were found among groups in percentage of phagocytic blood polymorphonuclear leukocytes and percentage of cells with respiratory burst.

  3. Reactive processing of ceramic binding systems for refractory castables

    Science.gov (United States)

    Ye, Guotian

    The general applied objective of this project is to develop hydratable alumina-bonded castables of properties comparable to the high-temperature fired basic bricks. This work is focused on improving the sintering of the ceramic binding systems at relatively low temperatures (˜1300°C) through incorporation of ultrafine powders. Ultrafine magnesium aluminate spinel powders were synthesized using already known and original methods. Combustible ingredients were incorporated to prevent the direct contacts of the precursor particles during drying and the combustibles leave a continuous pore network when they burn off during calcination at 700-800°C. Mechanical activation of the spinel precursor prepared using a heterogeneous sol-gel process decreased the activation energy for spinel formation from 688 kJ/mol to 468 kJ/mol, and lowered the incipient temperature of spinel formation from 900°C to 800°C, and the temperature of complete spinellization from >1280°C to 900°C. A new method for preparing homogeneous spine] precursor was presented and completely crystallized spinel with specific surface area of 105 m2/g, and crystallite size of 13 nm was formed from the precursor after calcination at 900°C. This work established the influence of ultrafine-sized powders on the sintering and strength development of multi-sized systems rich in large particles at relatively low temperatures, with emphasis on the temperatures around 1280°C. It was found that the relationship between the strength and linear shrinkage for the powder compacts consisting of uniform particle size distribution does not apply to the binding systems with wide particle size distributions (90 nm--90 mum). The addition of the ultrafine powders (≤0.5 mum median) up to 10% had no significant influence on strength in two-component binding systems after firing at 1280°C and 1450°C. However, the ultrafine powders increased the strength of three-component binding systems presumably because the addition of

  4. MTF Optimization in Digital Dental X-ray Systems

    CERN Document Server

    Costa, E T; Costa, Eduardo Tavares; Albuquerque, Jorge Andre Girao

    2003-01-01

    In this work, we have studied the MTF optimisation relative to the detector aperture of four digital dental X-ray image systems: 1) Digora and Denoptix systems, based on PSPL detectors; 2) CDR and Sens-A-Ray 2000, based on CCD detectors. The MTF was evaluated by ERF method and linearized as a Gaussian process. The CCD based systems presented Gaussian characteristics. The PSPL based systems presented a composition of two Gaussian processes. We conclude that one process is due to the laser and stimulated light scattering inside the PSPL plate and the other is due to the laser beam focal aperture. Matching focal aperture to laser scattering allows the optimization of the PSPL systems resolution. An optimal pixel width found to be 62 um.

  5. Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

    Science.gov (United States)

    Trifkovic, B.; Budak, I.; Todorovic, A.; Hodolic, J.; Puskar, T.; Jevremovic, D.; Vukelic, D.

    2012-01-01

    The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation.

  6. Repair bond strength of resin composite to a novel CAD/CAM hybrid ceramic using different repair systems.

    Science.gov (United States)

    Elsaka, Shaymaa E

    2015-01-01

    This study evaluated the repair bond strength of a nanohybrid resin composite to a novel CAD/CAM hybrid ceramic based on four intraoral ceramic repair systems. Vita Enamic (VE) CAD/CAM hybrid ceramic was used in this study. Specimens were divided into five test groups according to the repair method performed on the ceramic surface: Gr C (No treatment; control); Gr CZ (Cimara Zircon); Gr PR (Porcelain Repair); Gr CR (Clearfil Repair); and Gr CS (CoJet system). Nanohybrid resin composite (GrandioSO) was packed onto treated ceramic surfaces for adhesion testing using microtensile bond strength test. Debonded specimens were examined with a stereomicroscope and SEM to determine the fracture mode. Data were analyzed using ANOVA and Tukey's HSD test. PR and CZ repair systems significantly enhanced the bond strength of nanohybrid resin composite to VE CAD/CAM hybrid ceramic when compared with the other tested repair systems.

  7. Influence of the photoinitiator system and light photoactivation units on the degree of conversion of dental composites

    Directory of Open Access Journals (Sweden)

    Isabel Cristina Celerino de Moraes Porto

    2010-12-01

    Full Text Available The aim of this study was to observe the influence of two light polymerization units (LED or halogen light on the degree of conversion (DC of three dental composites with lighter shades and a different photoinitiator system. The top (T and bottom (B surfaces of 60 discs of composite resin (Filtek™ Supreme, Filtek™ Z250, Tetric™ Ceram Bleach cured either by LED or by halogen lamp (HL were studied using an FT-Raman spectrometer. The degree of conversion (DC was evaluated by following the changes in the intensity of the methacrylate C=C stretching mode at 1640 cm-1. The calculated DC ranged from 54.2% (B to 73.4% (T and from 60.2% (B to 76.6% (T for the LED and HL, respectively. LED and halogen devices were able to produce an adequate DC for all the resins tested.

  8. The clinical potential and limits of the all-ceramic fixed partial denture restorations

    Directory of Open Access Journals (Sweden)

    Harry Laksono

    2007-12-01

    Full Text Available High-strength all-ceramic systems for fixed partial dentures (FPDs is gaining popularity as an alternative to the well established metal-ceramic FPDs. Several new framework materials and technique such as lithium disilicate, aluminum oxide and yttrium tetragonal zirconia polycrystal have been developed with improved strength, marginal discrepancy and esthetics. Since not every all-ceramic system can be used for a variety application, proper selection of the materials is an important for the success of all-ceramic FPDs. The longevity of dental restorations is an important health concern and the clinician placed great emphasis on mechanical properties to define the clinical indication of the ceramic materials because of their brittleness and low fracture toughness. The stronger and tougher framework material would improve the reliability and the longevity of dental restoration. To fabricated of an all-ceramic FPDs, material would be required with a flexural strength in excess of 300 MPa and fracture toughness 3 MPa/m½. Zirconium has a better mechanical properties than alumina and lithium disilicate glass-ceramic, result from the transformation toughening, free of glass phase and minimal flaws. Whereas lithium disilicate glass-ceramic has a better translucency than alumina and zirconium based ceramic, result from the higher content of glass phase than that two materials. The purpose of this article is to present the information that can guide the practioner in the decision making process about all-ceramic FPDs systems. It can be concluded that the all-ceramic FPDs are seems to be an acceptable clinically prosthodontic treatment according to the short-term studies and the lithium disilicate and alumina-based ceramic materials are acceptable for 3 units anterior FPDs, whereas zirconia-based ceramic are acceptable for 3–5 units anterior and posterior FPDs with 2 pontics. However, further investigation and more clinical long-term follow-up studies

  9. Effect of frame design and veneering material on biomechanical behavior of zirconia dental crowns veneered with overpressing ceramics.

    Science.gov (United States)

    Porojan, Liliana; Topală, Florin; Porojan, Sorin; Savencu, Cristina

    2017-05-31

    The objective of this investigation was to compare alternative framework designs of molar zirconia crowns veneered with various overpressing ceramics and to predict the biomechanical behavior based on the stress evaluation. The hypothesis of the study is that the zirconia framework design and type of the veneering material, using the same technological procedure, may influence the biomechanical behavior of the restorations. Three geometric models with differential coping designs (uniform thickness, cutback and buccal reduction) were developed and two types of hot-pressed ceramics (leucite and lithium disilicate reinforced) were analyzed for the veneers. Using finite element analysis (FEA), maximum principle stresses were recorded in the tooth structures and in the restorations for all the developed designs. Results led to the conclusion that the hypothesis was accepted.

  10. Hydrothermal degradation of tetragonal ZrO{sub 2} ceramic components used in dental applications; Efeito da degradacao em meio aquoso de componentes ceramicos a base de ZrO{sub 2} tetragonal para uso odontologico

    Energy Technology Data Exchange (ETDEWEB)

    Mukaeda, L.E.; Robin, A.; Taguchi, S.P. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Santos, C. [ProtMat Materiais Avancados, Guaratingueta, SP (Brazil)

    2009-07-01

    With the evolution of the dental restoration techniques, a considerable growth in the demand of ceramic products occurred. These materials present good strength associated to reliability. In this work, micrometric and nanometric scale tetragonal ZrO{sub 2} blocks were sintered at 1500 deg C-2h and 1350 deg C-2h, respectively, ground and polished. Ceramics with relative density higher than 98% were obtained. The specimens were immersed in hot water (150 deg C), for times ranging from 10h to 30h. The mass variation of the samples was measured and the crystalline phases present before and after the degradation tests were identified by X-ray diffractometry, in order to evaluate the capacity of these ceramics in resisting to aqueous medium exposure. Materials with nanometric structure present higher resistance to degradation than those with micrometric scale, and this interferes in structural stability after the test, and reduces the martensitic transformation. (author)

  11. 应用BEATIFIT口内修补全瓷牙崩瓷效果分析%Analysis of the effect of BEATIFIT applicated in intraoral repair porcelain of all ceramic dental

    Institute of Scientific and Technical Information of China (English)

    刘慧丽

    2015-01-01

    目的:探讨应用BEATIFIT口内修补全瓷牙崩瓷的应用效果。方法:收治需进行牙修复患者64例,随机分为试验组和对照组,各32例,试验组给予BEATIFIT口内修补全瓷牙崩瓷法治疗,对照组给予常规治疗。结果:试验组治疗效果显著优于对照组(P<0.05)。结论:应用BEATIFIT口内修补全瓷牙崩瓷,不仅恢复了患者原有牙的外形,同时也恢复了原有牙的色泽,临床效果显著。%Objective:To explore the effect of BEATIFIT applicated in intraoral repair porcelain of all ceramic dental.Methods:64 patients who needed dental restoration were selected.They were randomly divided into the experimental group and the control group with 32 cases in each.Patients in the experimental group were given BEATIFIT repair in all ceramic dental porcelain therapy,while patients in the control group were given routine treatment.Results:The treatment effect of the experimental group was significantly better than that of the control group(P<0.05).Conclusion:Application of BEATIFIT in intraoral repair porcelain of all ceramic dental not only can restore the original appearance of dental,but also restore the original color of the teeth,so it has a significant clinical effect.

  12. A novel simplified numbering system for dental burs

    Directory of Open Access Journals (Sweden)

    Hemamalathi Senthil

    2008-01-01

    Full Text Available A universally accepted standardization is of great value for any material or equipment that is used globally. A single number or name should represent the particular material or instrument throughout the world. Since the dental burs are used worldwide, a single standard numbering system, which gives a unique specification for each bur in any part of the world, is mandatory. Though the existing systems have tried to attain this goal, they have their own advantages and limitations that are explained in detail in this article. So, the idea of proposing a novel system is to formulate a simple way of mentioning each bur with its dimension and composition without the need for memorizing the numbers.

  13. Recrystallization behaviour of CaO-MgO-SiO{sub 2} system ceramic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xitang; Zhang Baoguo [Hubei Province Key Lab. of Ceramics and Refractories, Wuhan Univ. of Science and Technology, Wuhan (China)

    2007-07-01

    Various kinds of ceramic fibers are used in industries for thermal insulation. Traditional Al{sub 2}O{sub 3}-SiO{sub 2} refractory ceramic fibers have potential health hazard when they come into the lung of human beings. The bio-soluble ceramic fibers in CaO-MgO-SiO{sub 2} system, as a new group of synthetic glass fibers, have been developed recently for high-temperature insulation applications. The fibers were specially designed to have high solubility and hence low bio-durability in human body lung solution. Various calcium magnesium silicate bio-soluble glass fibers are produced at present to replace aluminium silicate ceramic fibers. In practical applications such as fiber lining of various kinds of high temperature furnace or kiln, devitrification of the fibers take place and consequently fiber surface become rougher. Formation and growth of crystal phases could cause the destruction and pulverization of the fibers after a long exposure at high temperature. For traditional Al{sub 2}O{sub 3}-SiO{sub 2} refractory ceramic fibers the recrystallization temperature of the fibers starts at 980 C with the formation of mullite and cristobalite phases. Comparing with Al{sub 2}O{sub 3}-SiO{sub 2} ceramic fibers, the relatively lower application temperature of CaO-MgO-SiO{sub 2} system bio-soluble fibers is considered. In this paper, the studies were focused on recrystallization behaviour of CaO-MgO-SiO{sub 2} system soluble ceramic fibers. (orig.)

  14. Thin Film Heat Flux Sensor Development for Ceramic Matrix Composite (CMC) Systems

    Science.gov (United States)

    Wrbanek, John D.; Fralick, Gustave C.; Hunter, Gary W.; Zhu, Dongming; Laster, Kimala L.; Gonzalez, Jose M.; Gregory, Otto J.

    2010-01-01

    The NASA Glenn Research Center (GRC) has an on-going effort for developing high temperature thin film sensors for advanced turbine engine components. Stable, high temperature thin film ceramic thermocouples have been demonstrated in the lab, and novel methods of fabricating sensors have been developed. To fabricate thin film heat flux sensors for Ceramic Matrix Composite (CMC) systems, the rough and porous nature of the CMC system posed a significant challenge for patterning the fine features required. The status of the effort to develop thin film heat flux sensors specifically for use on silicon carbide (SiC) CMC systems with these new technologies is described.

  15. Viscoelastic finite element analysis of an all-ceramic fixed partial denture.

    Science.gov (United States)

    DeHoff, Paul H; Anusavice, Kenneth J; Götzen, Nils

    2006-01-01

    In recent years metal-free ceramic systems have become increasingly popular in dental practice because of their superior aesthetics, chemical durability and biocompatibility. Recently, manufacturers have proposed new dental ceramic systems that are advertised as being suitable for posterior fixed partial dentures (FPDs). Reports indicate that some of these systems have exhibited poor clinical performance. The objective of this study was to use the viscoelastic option of the ANSYS finite element program to calculate residual stresses in an all-ceramic FPD for four ceramic-ceramic combinations. A three-dimensional finite element model of the FPD was constructed from digitized scanning data and calculations were performed for four systems: (1) IPS Empress 2, a glass-veneering material, and Empress 2 core ceramic; (2) IPS Eris a low fusing fluorapatite-containing glass-veneering ceramic, and Empress 2 core ceramic; (3) IPS Empress 2 veneer and an experimental lithium-disilicate-based core ceramic; and (4) IPS Eris and an experimental lithium-disilicate-based core ceramic. The maximum residual tensile stresses in the veneer layer for these combinations are as follows: (1) 77 MPa, (2) 108 MPa, (3) 79 MPa, and (4) 100 MPa. These stresses are relatively high compared to the flexural strengths of these materials. In all cases, the maximum residual tensile stresses in the core frameworks were well below the flexural strengths of these materials. We conclude that the high residual tensile stresses in all-ceramic FPDs with a layering ceramic may place these systems in jeopardy of failure under occlusal loading in the oral cavity.

  16. Ceramics and healthy heating and cooling systems: thermal ceramic panels in buildings. Conditions of comfort and energy demand versus convective systems

    Directory of Open Access Journals (Sweden)

    V. Echarri Iribarren

    2016-12-01

    Full Text Available Porcelain stoneware is a widely used building material. In recent years, its range of uses has expanded to encompass a new spectrum of innovative and inventive applications in architecture. In this research, we analysed the patented Thermal Ceramic Panel. This consists of a thin porcelain stoneware panel that incorporates a capillary system of polypropylene tubes measuring 3.5 mm in diameter embedded in a conductive ceramic interface. The system works with hot or cold water, producing healthy heating and cooling by means of radiant surfaces. Following an initial prototype test in which panels were placed on the walls of an office, we conducted simulations at the University of Alicante Museum using wall, ceiling and baffle panels, having previously monitored the state of the building. Thermal behaviour parameters were analysed and compared with those of other standard finishing materials, obtaining results for thermal comfort and energy savings in comparison with all-air systems.

  17. Ceramic regenerator systems development program. [for automobile gas turbine engines

    Science.gov (United States)

    Cook, J. A.; Fucinari, C. A.; Lingscheit, J. N.; Rahnke, C. J.

    1977-01-01

    Ceramic regenerator cores are considered that can be used in passenger car gas turbine engines, Stirling engines, and industrial/truck gas turbine engines. Improved materials and design concepts aimed at reducing or eliminating chemical attack were placed on durability test in Ford 707 industrial gas turbine engines. The results of 19,600 hours of turbine engine durability testing are described. Two materials, aluminum silicate and magnesium aluminum silicate, continue to show promise toward achieving the durability objectives of this program. A regenerator core made from aluminum silicate showed minimal evidence of chemical attack damage after 6935 hours of engine test at 800 C and another showed little distress after 3510 hours at 982 C. Results obtained in ceramic material screening tests, aerothermodynamic performance tests, stress analysis, cost studies, and material specifications are also included.

  18. Ceramic veneers with minimum preparation.

    Science.gov (United States)

    da Cunha, Leonardo Fernandes; Reis, Rachelle; Santana, Lino; Romanini, Jose Carlos; Carvalho, Ricardo Marins; Furuse, Adilson Yoshio

    2013-10-01

    The aim of this article is to describe the possibility of improving dental esthetics with low-thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative treatment also improved the function of the anterior guidance. It can be concluded that the conservative use of minimum thickness ceramic laminate veneers may provide satisfactory esthetic outcomes while preserving the dental structure.

  19. Effect of non-ionizing radio frequency signals of magnetic resonance imaging on physical properties of dental alloys and metal-ceramic adhesion.

    Science.gov (United States)

    El-Bediwi, Abu Bakr; El-Fallal, Abeer; Saker, Samah; Ozcan, Mutlu

    2014-10-01

    To assess the influence of non-ionizing radio frequency signals of magnetic resonance imaging (MRI) on physical properties of dental alloys and metal-ceramic adhesion. A total of 120 disk-shaped wax patterns (10 mm x 10 mm x 1 mm) were cast in a base metal alloy (Ni-Cr alloy) and commercially pure titanium (Ti) following the manufacturing recommendation. After casting, air abrasion and ultrasonic cleaning, feldspathic ceramic was applied and fired according to manufacturer's instructions using a standard mold. The specimens were subjected to 3000 thermocycles in distilled water between 5°C and 55°C, then veneered alloy specimens were randomly assigned to three groups according to MRI exposure time: a) 15 min of MRI exposure, b) 30 min of MRI exposure and c) no MRI exposure (control group). The specimens were subjected to shear loading until failure. A separate set of Ni-Cr and Ti specimens were prepared, and after exposure to MRI for 15 and 30 min, x-ray diffraction (XRD) analysis, surface roughness, and Vicker's hardness were measured. Both the alloy type (p < 0.005) and exposure duration (p < 0.005) had a significant effect on the bond results. While the control group presented the highest bond strength for Ni-Cr and Ti (36.9 ± 1.4 and 21.5 ± 1.6 MPa, respectively), 30 min MRI exposure significantly decreased the bond strength for both alloys (29.4 ± 1.5 and 12.8 ± 1.5 MPa, respectively) (p < 0.05). XRD analysis indicated formation of the crystalline phase as well as change in crystal size and position for Ni-Cr and Ti after MRI. Compared to the control group where alloys were not exposed to MRI (Ni-Cr: 0.40 μm; Ti: 0.17 μm), surface roughness increased (Ni-Cr: 0.54 μm; Ti: 1.1 μm). Vicker's hardness of both alloys decreased after 30 min MRI (Ni-Cr: 329.5; Ti: 216.1) compared to the control group c (Ni-Cr: 356.1; Ti: 662.1), being more significant for Ti (p < 0.005). Ni-Cr alloy is recommended over Ti for the fabrication of metal-ceramic restorations

  20. Comparison of two systems of tooth numbering among undergraduate dental students

    OpenAIRE

    Deepthi Kannan; Deepa Gurunathan

    2016-01-01

    Background: Dental charting is the basis of treatment in dentistry. It should be recorded to know the presence of healthy or diseased, for communication purpose with the colleagues and also used for reference purpose. The three commonly used systems are universal system, Federae Dentale Internationale numbering system (FDI) system, and Palmer/Zsigmondy system. Although these systems are in practice there are lot of confusions in referring a tooth which leads to mismanagement which eventually ...

  1. Towards long lasting zirconia-based composites for dental implants: Transformation induced plasticity and its consequence on ceramic reliability.

    Science.gov (United States)

    Reveron, Helen; Fornabaio, Marta; Palmero, Paola; Fürderer, Tobias; Adolfsson, Erik; Lughi, Vanni; Bonifacio, Alois; Sergo, Valter; Montanaro, Laura; Chevalier, Jérôme

    2017-01-15

    Zirconia-based composites were developed through an innovative processing route able to tune compositional and microstructural features very precisely. Fully-dense ceria-stabilized zirconia ceramics (84vol% Ce-TZP) containing equiaxed alumina (8vol%Al2O3) and elongated strontium hexa-aluminate (8vol% SrAl12O19) second phases were obtained by conventional sintering. This work deals with the effect of the zirconia stabilization degree (CeO2 in the range 10.0-11.5mol%) on the transformability and mechanical properties of Ce-TZP-Al2O3-SrAl12O19 materials. Vickers hardness, biaxial flexural strength and Single-edge V-notched beam tests revealed a strong influence of ceria content on the mechanical properties. Composites with 11.0mol% CeO2 or above exhibited the classical behaviour of brittle ceramics, with no apparent plasticity and very low strain to failure. On the contrary, composites with 10.5mol% CeO2 or less showed large transformation-induced plasticity and almost no dispersion in strength data. Materials with 10.5mol% of ceria showed the highest values in terms of biaxial bending strength (up to 1.1GPa) and fracture toughness (>10MPa√m). In these ceramics, as zirconia transformation precedes failure, the Weibull modulus was exceptionally high and reached a value of 60, which is in the range typically reported for metals. The results achieved demonstrate the high potential of using these new strong, tough and stable zirconia-based composites in structural biomedical applications.

  2. Ceramicrete: A novel ceramic packaging system for spent-fuel transport and storage

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D.; Jeong, S. Y.; Dwyer, K.; Abesadze, T.

    2000-02-25

    This presentation summarizes efforts to develop and apply chemically bonded phosphate ceramic (Ceramicrete{trademark}) technology for radiation shielding applications. The specific application being targeted is a packaging system for spent-fuel transport and storage. Using Ceramicrete technology under ambient conditions, the authors can produce dense and hard ceramic forms that incorporate second-phase material. Ceramicrete inherently is a superior shielding material because it contains large amounts of bound water in its crystal structure and can be cast in any shape. A parametric study was conducted on Ceramicrete that contained second-phase additions of metals and other ceramic powders. Results of various standardized tests that included mechanical performance and shielding from neutrons are presented. The fabrication of complex shapes and structures by Ceramicrete technology is discussed. Ceramicrete is compared with other currently available shielding systems that are based on concrete and polymers.

  3. Advanced Ceramics for Use as Fuel Element Materials in Nuclear Thermal Propulsion Systems

    Science.gov (United States)

    Valentine, Peter G.; Allen, Lee R.; Shapiro, Alan P.

    2012-01-01

    With the recent start (October 2011) of the joint National Aeronautics and Space Administration (NASA) and Department of Energy (DOE) Advanced Exploration Systems (AES) Nuclear Cryogenic Propulsion Stage (NCPS) Program, there is renewed interest in developing advanced ceramics for use as fuel element materials in nuclear thermal propulsion (NTP) systems. Three classes of fuel element materials are being considered under the NCPS Program: (a) graphite composites - consisting of coated graphite elements containing uranium carbide (or mixed carbide), (b) cermets (ceramic/metallic composites) - consisting of refractory metal elements containing uranium oxide, and (c) advanced carbides consisting of ceramic elements fabricated from uranium carbide and one or more refractory metal carbides [1]. The current development effort aims to advance the technology originally developed and demonstrated under Project Rover (1955-1973) for the NERVA (Nuclear Engine for Rocket Vehicle Application) [2].

  4. ADM guidance-Ceramics: all-ceramic multilayer interfaces in dentistry.

    Science.gov (United States)

    Lohbauer, Ulrich; Scherrer, Susanne S; Della Bona, Alvaro; Tholey, Michael; van Noort, Richard; Vichi, Alessandro; Kelly, J Robert; Cesar, Paulo F

    2017-06-01

    This guidance document describes the specific issues involved in dental multilayer ceramic systems. The material interactions with regard to specific thermal and mechanical properties are reviewed and the characteristics of dental tooth-shaped processing parameters (sintering, geometry, thickness ratio, etc.) are discussed. Several techniques for the measurement of bond quality and residual stresses are presented with a detailed discussion of advantages and disadvantages. In essence no single technique is able to describe adequately the all-ceramic interface. Invasive or semi-invasive methods have been shown to distort the information regarding the residual stress state while non-invasive methods are limited due to resolution, field of focus or working depth. This guidance document has endeavored to provide a scientific basis for future research aimed at characterizing the ceramic interface of dental restorations. Along with the methodological discussion it is seeking to provide an introduction and guidance to relatively inexperienced researchers. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Curriculum structure and the European Credit Transfer System for European dental schools: part I.

    NARCIS (Netherlands)

    Plasschaert, A.J.M.; Lindh, C.; McLoughlin, J.; Manogue, M.; Murtomaa, H.; Nattestad, A.; Sanz, M.

    2006-01-01

    This paper presents a proposed curriculum structure and system of European Credit Transfer (ECTS) for undergraduate dental schools throughout Europe. It is the result of the work of a Taskforce ('Taskforce II'), appointed by DentEd, a thematic network of European dental schools and the Association f

  6. A Mobile Augmented Reality System for the Learning of Dental Morphology

    Science.gov (United States)

    Juan, M.-Carmen; Alexandrescu, Lucian; Folguera, Fernando; García-García, Inmaculada

    2016-01-01

    Three-dimensional models are important when the learning content is difficult to acquire from 2D images or other traditional methods. This is the case for learning dental morphology. In this paper, we present a mobile augmented reality (AR) system for learning dental morphology. A study with students was carried out to determine whether learning…

  7. Ballistic Performance of Porous-Ceramic, Thermal Protection Systems to 9 km/s

    Science.gov (United States)

    Miller, Joshua E.; Bohl, William E.; Foreman, Cory D.; Christiansen, Eric C.; Davis, Bruce A.

    2010-01-01

    Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These materials insulate the structural components and sensitive components of a spacecraft against the intense thermal environments of atmospheric reentry. These materials are also highly exposed to solid particle space environment hazards. This paper discusses recent impact testing up to 9.65 km/s on ceramic tiles similar to those used on the Orbiter. These tiles are a porous-ceramic insulator of nominally 8 lb/ft(exp 3) alumina-fiber-enhanced-thermal-barrier (AETB8) coated with a damage-resistant, toughened-unipiece-fibrous-insulation/reaction-cured-glass layer (TUFI/RCG).

  8. Application of Technogenic-Raw Material and Burning Out Additive in Composite Ceramic System

    Directory of Open Access Journals (Sweden)

    Olga KIZINIEVIČ

    2012-09-01

    Full Text Available The investigation of the composite ceramic system containing easily fusible hydro-micous clay, technogenic finely dispersed raw material, and burning out waste additive is presented in the article. The properties of the raw materials used are described in the paper. The obtained ceramic bodies were burned at 1000 °C and 1050 °C temperatures, keeping at the highest burning temperature for 4 h. The analysis of physical-mechanical properties of composite ceramics (density, compressive strength, water absorption, its structural parameters (effective and total open porosity, reserve of pore volume, relative wall thickness of the pores and capillaries, and X-ray diffraction analysis was performed. The interdependencies between some structural parameters are described by empirical equations. DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2443

  9. Does use of an electronic health record with dental diagnostic system terminology promote dental students' critical thinking?

    Science.gov (United States)

    Reed, Susan G; Adibi, Shawn S; Coover, Mullen; Gellin, Robert G; Wahlquist, Amy E; AbdulRahiman, Anitha; Hamil, Lindsey H; Walji, Muhammad F; O'Neill, Paula; Kalenderian, Elsbeth

    2015-06-01

    The Consortium for Oral Health Research and Informatics (COHRI) is leading the way in use of the Dental Diagnostic System (DDS) terminology in the axiUm electronic health record (EHR). This collaborative pilot study had two aims: 1) to investigate whether use of the DDS terms positively impacted predoctoral dental students' critical thinking skills measured by the Health Sciences Reasoning Test (HSRT), and 2) to refine study protocols. The study design was a natural experiment with cross-sectional data collection using the HSRT for 15 classes (2013-17) of students at three dental schools. Characteristics of students who had been exposed to the DDS terms were compared with students who had not, and the differences were tested by t-tests or chi-square tests. Generalized linear models were used to evaluate the relationship between exposure and outcome on the overall critical thinking score. The results showed that exposure was significantly related to overall score (p=0.01), with not-exposed students having lower mean overall scores. This study thus demonstrated a positive impact of using the DDS terminology in an EHR on the critical thinking skills of predoctoral dental students in three COHRI schools as measured by their overall score on the HSRT. These preliminary findings support future research to further evaluate a proposed model of critical thinking in clinical dentistry.

  10. Does Use of an Electronic Health Record with Dental Diagnostic System Terminology Promote Dental Students’ Critical Thinking?

    Science.gov (United States)

    Reed, Susan G.; Adibi, Shawn S.; Coover, Mullen; Gellin, Robert G.; Wahlquist, Amy E.; AbdulRahiman, Anitha; Hamil, Lindsey H.; Walji, Muhammad F.; O’Neill, Paula; Kalenderian, Elsbeth

    2015-01-01

    The Consortium for Oral Health Research and Informatics (COHRI) is leading the way in use of the Dental Diagnostic System (DDS) terminology in the axiUm electronic health record (EHR). This collaborative pilot study had two aims: 1) to investigate whether use of the DDS terms positively impacted predoctoral dental students’ critical thinking skills measured by the Health Sciences Reasoning Test (HSRT), and 2) to refine study protocols. The study design was a natural experiment with cross-sectional data collection using the HSRT for 15 classes (2013–17) of students at three dental schools. Characteristics of students who had been exposed to the DDS terms were compared with students who had not, and the differences were tested by t-tests or chi-square tests. Generalized linear models were used to evaluate the relationship between exposure and outcome on the overall critical thinking score. The results showed that exposure was significantly related to overall score (p=0.01), with not-exposed students having lower mean overall scores. This study thus demonstrated a positive impact of using the DDS terminology in an EHR on the critical thinking skills of predoctoral dental students in three COHRI schools as measured by their overall score on the HSRT. These preliminary findings support future research to further evaluate a proposed model of critical thinking in clinical dentistry. PMID:26034034

  11. Bond strength, microhardness, and core/veneer interface quality of an all-ceramic system.

    Science.gov (United States)

    Fahmy, Nadia Z

    2010-02-01

    This study was designed to evaluate three veneering materials for an all-ceramic alumina system in terms of bond strength, microhardness, and core/veneer interface quality. Fifteen In-Ceram cores were constructed for this study, forming three groups of five specimens each divided by the veneering ceramic disc fired on the occlusal surface of the alumina core: Vitadur N, Vitadur Alpha, or VM7. The specimens underwent shear bond and microhardness testing. Gross examination of debonded discs by SEM and EDAX analysis was conducted. Data for shear bond strength (SBS) and microhardness were presented as means and standard deviation (SD) values. One-way ANOVA and Duncan's post hoc test were used for pairwise comparison between the means when ANOVA test was significant. VM7 showed the highest shear bond value and lowest microhardness values of the three tested veneering materials. No statistically significant difference was evident between the SBSs of Vitadur N and Vitadur Alpha to the alumina cores. Vitadur Alpha showed statistically the highest mean VHN, followed by Vitadur N, while VM7 showed statistically the lowest mean values of VHN. In-Ceram core/Vitadur N disc debondings appeared to be interfacial by complete delaminations, leaving a shiny visible and quite distinct area, whereas there appeared to be perfect adhesion between the core and VM7 veneering material. VM7 appeared to possess ultra-fine texture with intimate contact to the core, forming what seemed like a transition zone where the ceramic and core appeared to blend for a distance. VM7's finer particle size has improved the core/veneer bond strength and decreased micohardness values. This new veneering material will probably enhance the performance and esthetics of the In-Ceram system.

  12. Radiopaque strontium fluoroapatite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Wolfram eHöland

    2015-10-01

    Full Text Available The controlled precipitation of strontium fluoroapatite crystals, was studied in four base glass compositions derived from the SiO2 – Al2O3 – Y2O3 – SrO – Na2O – K2O/Rb2O/Cs2O – P2O5 – F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: a Sr5(PO43F – leucite, KAlSi2O6 , b Sr5(PO43F – leucite, KAlSi2O6, and nano-sized NaSrPO4 c Sr5(PO43F – pollucite, CsAlSiO4 , and nano-sized NaSrPO4, d Sr5(PO43F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4.The proof of crystal phase formation was possible by X-ray diffraction (XRD. The microstructures, which were studied using scanning electron microscopy (SEM demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needlelike morphology. The study of the crystal growth of needlelike Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism.The formation of leucite, pollucite and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  13. Dental Implants.

    Science.gov (United States)

    Griggs, Jason A

    2017-10-01

    Systematic reviews of literature over the period between 2008 and 2017 are discussed regarding clinical evidence for the factors affecting survival and failure of dental implants. The factors addressed include publication bias, tooth location, insertion torque, collar design, implant-abutment connection design, implant length, implant width, bone augmentation, platform switching, surface roughness, implant coatings, and the use of ceramic materials in the implant body and abutment. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Parkinson disease: systemic and orofacial manifestations, medical and dental management.

    Science.gov (United States)

    Friedlander, Arthur H; Mahler, Michael; Norman, Keith M; Ettinger, Ronald L

    2009-06-01

    More than 1.5 million Americans have Parkinson disease (PD), and this figure is expected to rise as the population ages. However, the dental literature offers little information about the illness. The authors conducted a MEDLINE search using the key terms "Parkinson's disease," "medical management" and "dentistry." They selected contemporaneous articles published in peer-reviewed journals and gave preference to articles reporting randomized controlled trials. PD is a progressive neurodegenerative disorder caused by loss of dopaminergic and nondopaminergic neurons in the brain. These deficits result in tremor, slowness of movement, rigidity, postural instability and autonomic and behavioral dysfunction. Treatment consists of administering medications that replace dopamine, stimulate dopamine receptors and modulate other neurotransmitter systems. Oral health may decline because of tremors, muscle rigidity and cognitive deficits. The dentist should consult with the patient's physician to establish the patient's competence to provide informed consent and to determine the presence of comorbid illnesses. Scheduling short morning appointments that begin 90 minutes after administration of PD medication enhances the patient's ability to cooperate with care. Inclination of the dental chair at 45 degrees, placement of a bite prop, use of a rubber dam and high-volume oral evacuation enhance airway protection. To avoid adverse drug interactions with levodopa and entacapone, the dentist should limit administration of local anesthetic agents to three cartridges of 2 percent lidocaine with 1:100,000 epinephrine per half hour, and patients receiving selegiline should not be given agents containing epinephrine or levonordefrin. The dentist should instruct the patient and the caregiver in good oral hygiene techniques.

  15. Longevity of silicate ceramic restorations.

    Science.gov (United States)

    Beier, Ulrike Stephanie; Dumfahrt, Herbert

    2014-09-01

    The demand for esthetic restorations has resulted in an increased use of dental ceramics as a biocompatible and functionally sufficient alternative to conventional restorative materials. Silicate ceramic restorations are widely used for veneers, inlays, onlays, and crowns in dentistry. Long-term data are of crucial importance to optimize clinical practice. The purpose of the present article is to summarize data of the Innsbruck ceramic evaluation up to 261 months with the focus on longevity and failure characteristics.

  16. Sliding wear on metal-ceramic systems. Gleitverschleiss an Metall-Keramik-Systemen

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, G.

    1992-01-01

    The purpose of this work is the examination of sliding wear on metal-ceramic systems under constant and oscillating normal force. The experiments were carried out on a spherical washer/washer tribometer. The ceramics are two part-stabilized zirconium oxide ceramics, (Zt 35 and ZN 40) and SiSiC and TiC/SiC. The hardened steels 100 Cr6, 21MnCr 5, 42CrMo4 and LK 22 are used as the opposing steels. The amount of wear on the samples was determined gravimetrically and planimetrically. The surfaces subject to wear were examined by means REM/EDS, SIMS and XPS. The results show that the friction and/or wear of the examined systems depends on forced vibrations. The wear coefficients of the zirconium ceramics are only slightly dependent on frequency, in contrast to those of SiSiC and TiC/SiC. No clear dependence on the frequency was found for steels paired with TiC/SiC and SiSiC. However, for Zt 35/steel pairs, there is a rise in the wear coefficients of the steel counterbodies with rising frequency and with increasing hardness of the steels. The comparison of the systems examined in this work shows the lowest coefficients of friction and of wear and slight dependence on the occurring vibration for the ZN40/Steel pair. (orig.).

  17. Robust Joining and Integration Technologies for Advanced Metallic, Ceramic, and Composite Systems

    Science.gov (United States)

    Singh, M.; Shpargel, Tarah; Morscher, Gregory N.; Halbig, Michael H.; Asthana, Rajiv

    2006-01-01

    Robust integration and assembly technologies are critical for the successful implementation of advanced metallic, ceramic, carbon-carbon, and ceramic matrix composite components in a wide variety of aerospace, space exploration, and ground based systems. Typically, the operating temperature of these components varies from few hundred to few thousand Kelvin with different working times (few minutes to years). The wide ranging system performance requirements necessitate the use of different integration technologies which includes adhesive bonding, low temperature soldering, active metal brazing, diffusion bonding, ARCJoinT, and ultra high temperature joining technologies. In this presentation, a number of joining examples and test results will be provided related to the adhesive bonding and active metal brazing of titanium to C/C composites, diffusion bonding of silicon carbide to silicon carbide using titanium interlayer, titanium and hastelloy brazing to silicon carbide matrix composites, and ARCJoinT joining of SiC ceramics and SiC matrix composites. Various issues in the joining of metal-ceramic systems including thermal expansion mismatch and resulting residual stresses generated during joining will be discussed. In addition, joint design and testing issues for a wide variety of joints will be presented.

  18. Effects of different surface-treatment methods on the bond strengths of resin cements to full-ceramic systems

    Directory of Open Access Journals (Sweden)

    Gülay Kansu

    2011-09-01

    Conclusions: The in vitro findings from this study indicate that surface-treatment procedures applied to the IPS Empress and the IPS Empress 2 full-ceramic systems are important when cement types are considered. In contrast, cement types and surface-treatment methods had no effect on changing the bond strength of the In-Ceram ceramic system.

  19. The impact of the global budget system on dynamics of dental manpower and utilization of dental services

    Directory of Open Access Journals (Sweden)

    Laura Yueh-Guey Huang

    2016-01-01

    Conclusion: This study has demonstrated a stabilizing effect of the global budget system on dynamics of dental manpower in Taiwan. A relationship between HHI and dentists′ move-out rate has been found. The relationship between municipal socioeconomic status and the density of dentists has also been confirmed. In addition, reduced utilization of amalgam restorations was accompanied by increased utilization of tooth-colored material restorations. Further investigations are indicated.

  20. Effect of the Cool System on Internal Stress of CaO-Al2O3-SiO2 Glass-ceramic System

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The samples were attained through altering the cooling system of producing glass-ceramics.The X-ray diffraction was used to test the stress value of different samples. The relation of the cooling system and internal stress were also investigated. The experimental results show that the stress of glass-ceramic had a close relation with starting cool temperature. Above 800 C, glass-ceramic could be accelerated cooling and did not bring stress. Temperature between 500 C and 800℃ was an important temperature range of the formation of stress in glass-ceramic, in which the glass-ceramic stress would change obviously. Cool system was the key on how to control and eliminate internal stress in order to reduce the destroy of materials crated by internal stress. In addition, glass particles size increase, glass-ceramic stress increase in consequent.

  1. Anterior provisional restorations used to determine form, function, and esthetics for complex restorative situations, using all-ceramic restorative systems.

    Science.gov (United States)

    Reshad, Mamaly; Cascione, Domenico; Kim, Tae

    2010-02-01

    A technique is proposed for the restoration of a large and visible maxillary anterior defect. The importance of proper diagnosis, treatment planning, and communication is emphasized. Irreversible treatment should only be rendered once patient approval has been obtained through objective evaluation with provisional restorations. The techniques presented in this article use a combination of ceramic systems currently available to satisfy functional demands while achieving acceptable esthetics. A controlled series of steps, where the provisional restorative components are being replaced by the definitive ones is planned. The only difference between the provisional and definitive restorative components is the material used. The definitive restorations consisted of an implant-supported zirconium oxide framework. Individual pressed porcelain restorations were luted to the framework and a natural tooth. CLINICAL SIGNIFICANCE Provisional restorations allow an objective form of communication. Vertical and horizontal transitional lines can be effectively masked with appropriate treatment planning and a skilled ceramist. Many traditional dental laboratory steps may be eliminated or simplified without compromising the definitive restorations.

  2. Bonding between oxide ceramics and adhesive cement systems: a systematic review.

    Science.gov (United States)

    Papia, Evaggelia; Larsson, Christel; du Toit, Madeleine; Vult von Steyern, Per

    2014-02-01

    The following aims were set for this systematic literature review: (a) to make an inventory of existing methods to achieve bondable surfaces on oxide ceramics and (b) to evaluate which methods might provide sufficient bond strength. Current literature of in vitro studies regarding bond strength achieved using different surface treatments on oxide ceramics in combination with adhesive cement systems was selected from PubMed and systematically analyzed and completed with reference tracking. The total number of publications included for aim a was 127 studies, 23 of which were used for aim b. The surface treatments are divided into seven main groups: as-produced, grinding/polishing, airborne particle abrasion, surface coating, laser treatment, acid treatment, and primer treatment. There are large variations, making comparison of the studies difficult. An as-produced surface of oxide ceramic needs to be surface treated to achieve durable bond strength. Abrasive surface treatment and/or silica-coating treatment with the use of primer treatment can provide sufficient bond strength for bonding oxide ceramics. This conclusion, however, needs to be confirmed by clinical studies. There is no universal surface treatment. Consideration should be given to the specific materials to be cemented and to the adhesive cement system to be used.

  3. Dental Training Films.

    Science.gov (United States)

    Veterans Administration Medical Center, Washington, DC.

    This dental training films catalog is organized into two sections. Section I is a category listing of the films by number and title, indexed according to generalized headings; categories are as follow: anatomy, articulator systems, complete dentures, dental assisting, dental laboratory technology, dental materials, dental office emergencies,…

  4. An 8-year evaluation of sintered ceramic and glass ceramic inlays processed by the Cerec CAD/CAM system

    DEFF Research Database (Denmark)

    Pallesen, U.; Dijken van, J.W.V.

    2000-01-01

    The purpose of this study was to evaluate Cerec CAD/CAM inlays processed of two industrially made machinable ceramics during an 8-yr follow-up period. Each of 16 patients received two similar ceramic inlays. Half the number of the inlays were made of a feldspathic (Vita Mark II) and the other...... of a glass ceramic (Dicor MGC) block. The inlays were luted with a dual resin composite and evaluated clinically using modified USPHS criteria at baseline, 8 months, 2, 3, 5, 6 and 8 yr, and indirectly using models. At baseline, 84% of the inlays were estimated as optimal and 16% as acceptable. Postoperative...... sensitivity was reported by one patient for 8 months. Of the 32 inlays evaluated during the 8 yr, 3 failed due to fracture of the material. No secondary caries was found adjacent to the inlays. No significant differences in the clinical performance were found between inlays made of the two ceramics. It can...

  5. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics.

    Science.gov (United States)

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A; Divakar, Darshan Devang; Matinlinna, Jukka P; Vallittu, Pekka K

    2016-05-27

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces' microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey's test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  6. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

    Science.gov (United States)

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A.; Divakar, Darshan Devang; Matinlinna, Jukka P.; Vallittu, Pekka K.

    2016-01-01

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability. PMID:27240353

  7. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

    Directory of Open Access Journals (Sweden)

    Ravikumar Ramakrishnaiah

    2016-05-01

    Full Text Available The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™; the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching and four experimental groups (20, 40, 80 and 160 s of etching. The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  8. Effect of digluconate chlorhexidine on bond strength between dental adhesive systems and dentin: A systematic review

    National Research Council Canada - National Science Library

    Dionysopoulos, Dimitrios

    2016-01-01

    ...) on bond strength between dental adhesive systems and dentin of composite restorations. The electronic databases that were searched to identify manuscripts for inclusion were Medline via PubMed and Google search engine...

  9. Automated Dental Epidemiology System. I. Preliminary Investigation and Literature Review,

    Science.gov (United States)

    1983-03-01

    personnel contacted concerning the inadequacy of DIRS for regional and clinical management. There also was skepticism regarding the prognosis of any...for Prevalence and Incidence of Periodontal Disease. T. Periodontol. 30:51, 1959. 24. WHO. Standardization of Reporting of Dental Diseases and...264, 1982. 58. wirthlin, M. R., Hancock, E. B., Cecil, J. C. and Mandel, E. J. Periodontal Disease Among Naval Recruits. Naval Dental Research Institute

  10. Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

    Science.gov (United States)

    Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

    2016-01-01

    The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and Pporcelain.

  11. Ceramic veneers with minimum preparation

    OpenAIRE

    da Cunha, Leonardo Fernandes; Reis, Rachelle; Santana, Lino; Romanini, Jose Carlos; de CARVALHO, Ricardo Marins; Furuse, Adilson Yoshio

    2013-01-01

    The aim of this article is to describe the possibility of improving dental esthetics with low-thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative t...

  12. Avaliação das condutas adotadas por profissionais na utilização de coroas metalo-cerâmicas Assessment of clinical proceedings adopted by dental professionals regarding the employment of ceramic fused to metal crowns

    Directory of Open Access Journals (Sweden)

    Carlos Neanes Santos

    2003-12-01

    Full Text Available A fim de avaliar a opinião da classe odontológica sobre a utilização das coroas metalo-cerâmicas na prática odontológica, aplicou-se um questionário de 20 questões a cirurgiões-dentistas da cidade de Aracaju - SE, e a cirurgiões-dentistas e estudantes de pós-graduação em odontologia, na área de prótese dental, da cidade de Bauru-SP. Concluiu-se que: 1. As coroas metalo-cerâmicas são o tipo de restauração protética mais empregado em Odontologia. 2. A maioria dos dentistas refere-se às coroas metalo-cerâmicas como restaurações bem sucedidas, indicando superfícies oclusais metálicas para a maioria dos pacientes. 3. Apesar da maior parte dos profissionais utilizar as ligas de níquel-cromo nas coroas metalo-cerâmicas de seus pacientes, os mesmos prefeririam que ligas nobres ou semi-nobres fossem empregadas em suas próprias restaurações. 4. A maioria dos entrevistados emprega as coroas metalo-cerâmicas na restauração de dentes anteriores (57,23%. Entretanto, esse valor se deve à preferência dos dentistas de Aracaju (78% por esse tipo de restauração, ao passo que, em Bauru, prevaleceu o número de respostas favoráveis às coroas de porcelana pura. 5. O cimento de fosfato de zinco foi o cimento de escolha da maioria dos profissionais. 6. A preferência da maior parte dos entrevistados, com relação à porcelana utilizada foi pela porcelana Vita (34,34%, em comparação às porcelanas Noritake e Dulceram Plus (13,86%. 6. Ficou evidente o desejo dos entrevistados quanto ao desenvolvimento de mecanismos que facilitem o reparo das coroas metalo-cerâmicas.The current features of ceramic fused to metal crowns were evaluated by means of a questionnaire composed by 20 questions concerning the use of this type of restoration in the daily dental practice of professionals from Aracaju, Bauru and post-graduation students in the area of dental prosthesis. The conclusions were as follows: 1. Ceramic fused to metal crowns are

  13. Translucence in dental prosthesis based on zirconia ceramics: effect of the sintering parameters; Translucidez em proteses dentarias a base de zirconia estabilizada com itria: efeito dos parametros de sinterizacao

    Energy Technology Data Exchange (ETDEWEB)

    Santos, C., E-mail: claudinei@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil). Escola de Engenharia; Costa, L.; Habibe, R.H.; Souza, J.V.C.; Habibe, C.H. [Centro Universitario de Volta Redonda (MeMAT/UNIFOA), RJ (Brazil). Pro-Reitoria de Pesquisa e Extensao; Silva, O.M.M. [Centro Tecnico Aeroespacial (CTA/IAE/AMR), Sao Jose dos Campos, SP (Brazil)

    2011-07-01

    In this work the translucence of Zirconia dental ceramics was evaluated as function of sintering conditions (temperature and isothermal holding time). Samples with 15x15x1mm, were sintered at 1450 to 1600 deg C, with holding of 2h or 4h. Sintered samples were characterized by relative density, crystalline phases and microstructural aspects. Full density was obtained in samples sintered at 1530 and 1600 deg C, which presented higher grain sizes. Na increasing of translucence was observed in samples sintered at 1530 and 1600, correlating these properties with increasing of density and grain size of the samples. (author)

  14. Danish dental education:

    DEFF Research Database (Denmark)

    Moore, Rod

    1985-01-01

    The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed.......The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed....

  15. Danish dental education:

    DEFF Research Database (Denmark)

    Moore, Rod

    1985-01-01

    The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed.......The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed....

  16. Dental hygienists' knowledge and opinions of oral-systemic connections: implications for education.

    Science.gov (United States)

    Bell, Kathryn P; Phillips, Ceib; Paquette, David W; Offenbacher, Steven; Wilder, Rebecca S

    2012-06-01

    Although associations between periodontal and systemic health have been well established, there is little evidence regarding dental hygienists' knowledge of the oral-systemic connection. The purpose of this study was to determine the knowledge levels of North Carolina dental hygienists regarding oral-systemic connections and their attitudes and confidence about incorporating this knowledge into clinical practice. A survey was developed, pilot tested, revised, and mailed to 1,665 licensed dental hygienists in North Carolina. After three mailings, the response rate was 62 percent, with 52 percent (N=859) meeting the inclusion criteria. The majority (>80 percent) of the respondents correctly identified risk factors for diabetes and cardiovascular disease (CVD), but were less knowledgeable about risk factors for osteoporosis and adverse pregnancy outcomes. Most knew that there is strong evidence linking periodontal disease with CVD (77 percent) and diabetes (70 percent). The majority felt that dental hygienists should be trained to identify risk factors for oral-systemic disease (94 percent) and to actively manage patients with systemic disease (78 percent). Eighty-eight percent felt that dental and medical professionals should be taught to practice collaboratively. These dental hygienists had a high level of knowledge in some areas of oral-systemic disease but could improve their confidence levels and knowledge through expanded content in their educational programs and continuing education. Inter-professional education and collaboration would also assist in integration of knowledge into clinical practice.

  17. Reliability of an occlusal and nonocclusal tooth wear grading system: clinical use versus dental cast assessment.

    Science.gov (United States)

    Wetselaar, Peter; Lobbezoo, Frank; Koutris, Michail; Visscher, Corine M; Naeije, Machiel

    2009-01-01

    The reliability of a newly developed tooth wear grading system was assessed both clinically and on dental casts by two observers using 20 participants. The reliability of clinical occlusal/incisal tooth wear grading was fair-to-good to excellent, while that of most of the clinical nonocclusal/nonincisal grades was at least fair-to-good. Dental cast assessment frequently yielded poor reliabilities, especially for nonocclusal/nonincisal surfaces. Hence, occlusal/incisal wear could be graded more reliably than nonocclusal/nonincisal wear, while the clinical assessment of tooth wear was more reliable than the grading of dental casts.

  18. An Overview of Dental Adhesive Systems and the Dynamic Tooth-Adhesive Interface.

    Science.gov (United States)

    Bedran-Russo, Ana; Leme-Kraus, Ariene A; Vidal, Cristina M P; Teixeira, Erica C

    2017-10-01

    From the conception of resin-enamel adhesion to today's contemporary dental adhesive systems, clinicians are no longer afraid of exploring the many advantages brought by adhesive restorative concepts. To maximize the performance of adhesive-based restorative procedures, practitioners must be familiar with the mechanism of adhesion, clinical indications, proper handling, the inherent limitations of the materials and the biological challenges. This review provides an overview of the current status of restorative dental adhesives, their mechanism of adhesion, mechanisms of degradation of dental adhesive interfaces, how to maximize performance, and future trends in adhesive dentistry. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Reforming undergraduate dental education in India: introducing a credits and semester system.

    Science.gov (United States)

    Virdi, Mandeep S

    2011-12-01

    To make higher education in India more dynamic and responsive to a fast-developing society and its aspirations, there has been widespread recognition of a need for reform. Among the proposed changes, expert committees and the National Knowledge Commission have recommended the introduction of a credits and semester system starting in undergraduate education. Technical institutions and some universities have already adopted this system. The country's dental schools are beginning to consider such a change, which would bring them more into alignment with the structure of dental education in North America and many countries in other parts of the world. Since dental schools in most developed countries follow a quarter/semester system, there is much evidence of the merits of such a system for dental education. After providing an overview of the present curriculum structure of dental education in India and the national move toward reform, this article presents the case for a new credits and semester system for undergraduate dental education in India.

  20. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  1. Ceramic Laser Materials

    Science.gov (United States)

    Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

  2. Use of ceramic materials in waste-package systems for geologic disposal of nuclear wastes

    Energy Technology Data Exchange (ETDEWEB)

    Fullam, H.T.

    1980-12-01

    A study to investigate the potential use of ceramic materials as components in the waste package systems was conducted. The initial objective of the study was to screen and compare a large number of ceramic materials and identify the best materials for the proposed application. The principal method used to screen the candidates was to subject samples of each material to a series of leaching tests and to determine their relative resistance to attack by the leach solutions. A total of 14 ceramic materials, plus graphite and basalt were evaluated using three different leach solutions: demineralized water, a synthetic Hanford ground water, and a synthetic WIPP brine solution. The ceramic materials screened were Al/sub 2/O/sub 3/ (99%), Al/sub 2/O/sub 3/ (99.8%), mullite (2Al/sub 2/O/sub 3/.SiO/sub 2/), vitreous silica (SiO/sub 2/), BaTiO/sub 3/, CaTiO/sub 3/, CaTiSiO/sub 5/, TiO/sub 2/, ZrO/sub 2/, ZrSiO/sub 4/, Pyroceram 9617, and Marcor Code 9658 machinable glass-ceramic. Average leach rates for the materials tested were determined from analyses of the leach solutions and/or sample weight loss measurements. Because of the limited scope of the present study, evaluation of the specimens was limited to ceramographic examination. Based on an overall evaluation of the leach rate data, five of the materials tested, namely graphite, TiO/sub 2/, ZrO/sub 2/, and the two grades of alumina, exhibited much greater resistance to leaching than did the other materials tested. Based on all the experimental data obtained, and considering other factors such as cost, availability, fabrication technology, and mechanical and physical properties, graphite and alumina are the preferred candidates for the barrier application. The secondary choices are TiO/sub 2/ and ZrO/sub 2/.

  3. Evaluation of Surface Treatment Methods on the Bond Strength of Zirconia Ceramics Systems, Resin Cements and Tooth Surface

    OpenAIRE

    Akkuş Emek; Turker Sebnem Begum

    2015-01-01

    Objectives: To compare the effects of airborne-particle abrasion (APA) and tribochemical silica coating (TSC) surface treatment methods on the shear bond strength of zirconia ceramics systems, resin cements and tooth surface

  4. Evaluation of Surface Treatment Methods on the Bond Strength of Zirconia Ceramics Systems, Resin Cements and Tooth Surface

    Directory of Open Access Journals (Sweden)

    Akkuş Emek

    2015-07-01

    Full Text Available Objectives: To compare the effects of airborne-particle abrasion (APA and tribochemical silica coating (TSC surface treatment methods on the shear bond strength of zirconia ceramics systems, resin cements and tooth surface

  5. Classification and Numbering of Dental Radiographs for an Automated Human Identification System

    Directory of Open Access Journals (Sweden)

    Anny Yuniarti

    2012-03-01

    Full Text Available Dental based human identification is commonly used in forensic. This is due to the teeth are resistant to temperatures up to 200°C and are not easily got rotten. Thus, teeth are suit for victim identification of natural disaster, fire, bombing, etc. In this paper, we developed an automated human identification system based on dental radiographs. The system has two main stages, the first stage is to arrange a database consisting of labeled dental radiographs, and the second stage is the searching process in the database in order to retrieve the identification result. Both stages use a number of image processing techniques, classification methods, and a numbering system in order to generate dental radiograph’s features and patterns. Our experiments using 6 bitewing and 10 panoramic radiographs that consist of 119 tooth objects in total, has shown good performance of classification. The accuracy of dental pattern classification and dental numbering system are 91.6 % and 81.5% respectively.

  6. Comparison of three and four point bending evaluation of two adhesive bonding systems for glass-ceramic zirconia bi-layered ceramics.

    Science.gov (United States)

    Gee, C; Weddell, J N; Swain, M V

    2017-09-01

    To quantify the adhesion of two bonding approaches of zirconia to more aesthetic glass-ceramic materials using the Schwickerath (ISO 9693-2:2016) three point bend (3PB) [1] test to determine the fracture initiation strength and strain energy release rate associated with stable crack extension with this test and the Charalamabides et al. (1989) [2] four point bend (4PB) test. Two glass-ceramic materials (VITABLOCS Triluxe forte, Vita Zahnfabrik, Germany and IPS.emax CAD, Ivoclar Vivadent, Liechtenstein) were bonded to sintered zirconia (VITA InCeram YZ). The former was resin bonded using a dual-cure composite resin (Panavia F 2.0, Kuraray Medical Inc., Osaka, Japan) following etching and silane conditioning, while the IPS.emax CAD was glass bonded (IPS e.max CAD Crystall/Connect) during crystallization of the IPS.emax CAD. Specimens (30) of the appropriate dimensions were fabricated for the Schwickerath 3PB and 4PB tests. Strength values were determined from crack initiation while strain energy release rate values were determined from the minima in the force-displacement curves with the 3PB test (Schneider and Swain, 2015) [3] and for 4PB test from the plateau region of stable crack extension. Strength values for the resin and glass bonded glass ceramics to zirconia were 22.20±6.72MPa and 27.02±3.49MPa respectively. The strain energy release rates for the two methods used were very similar and for the glass bonding, (4PB) 15.14±5.06N/m (or J/m(2)) and (3PB) 16.83±3.91N/m and resin bonding (4PB) 8.34±1.93N/m and (3PB) 8.44±2.81N/m respectively. The differences in strength and strain energy release rate for the two bonding approaches were statistically significant (pceramics to zirconia. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Modeling and Simulation of Ballistic Penetration of Ceramic-Polymer-Metal Layered Systems

    Science.gov (United States)

    2016-01-01

    Jaromir Horacek Copyright © 2015 J. D. Clayton.This is an open access article distributed under the Creative Commons Attribution License, which permits...faces between layers may strongly influence performance of such systems under ballistic impact. However, the impor- tance of interfacial...experimental study of penetration resistance of ceramic armour subjected to projectile impact,” International Journal of Impact Engineering, vol. 32

  8. Dental Implant Placement using C-arm CT Real Time Imaging System: A Case Report.

    Science.gov (United States)

    Rajkumar, B; Boruah, Lalit C; Thind, Amandeep; Jain, Gaurav; Gupta, Shilpi

    2014-12-01

    C-arm computed tomography (CT) is a new and innovative imaging technique. In combination with two-dimensional fluoroscopic or radiographic imaging, information provided by three-dimensional C-arm real time imaging can be valuable for therapy planning, guidance and outcome assessment in dental implant placement. This paper reports a case of two dental implant placement using Artis zee C-arm CT system first time in field of implantology.

  9. CLINICAL CONSIDERATIONS OF DENTAL IMPLANT SYSTEM IN IMMEDIATE LOADING IMPLANT CASES

    OpenAIRE

    2015-01-01

    Immediate loading of dental implant has been researched intensively in the development of Branemark’s early concept of 2 stages implant placement. This was embarked from both patients and practiitioner’s convenience towards a simpler protocol and shorter time frame. Many recent researchers later found that micromotions derived from occlusal loading for a certain degree, instead of resulting a fibrous tissue encapsulation, can enhance the osseointegration process. Dental Implant system enhance...

  10. Dental management considerations for the patient with an acquired coagulopathy. Part 1: Coagulopathies from systemic disease

    OpenAIRE

    Lockhart, P.B.; Gibson, J; Pond, S.H.; Leitch, J

    2003-01-01

    Current teaching suggests that many patients are at risk for prolonged bleeding during and following invasive dental procedures, due to an acquired coagulopathy from systemic disease and/or from medications. However, treatment standards for these patients often are the result of long-standing dogma with little or no scientific basis. The medical history is critical for the identification of patients potentially at risk for prolonged bleeding from dental treatment. Some time-honoured laborator...

  11. Effects of bleaching agents and adhesive systems in dental pulp: a literature review

    OpenAIRE

    OLIVEIRA,Maria Antonieta Veloso Carvalho; Quagliatto,Paulo Sérgio; Magalhães,Denildo; BIFFI,João Carlos Gabrielli

    2012-01-01

    The dental pulp may be exposed to several irritants that are potentially noxious to the health and functions of this tissue. Each type of irritant or injury has different effects on the pulp, which are generally characterized by acute inflammation, chronic inflammation or necrosis. Common examples of irritants are dental caries, cavity preparation procedures, traumatic injuries, and chemical substances like bleaching agents and adhesive systems. The present study aimed to review the current k...

  12. Systems Approach for Designing Cordierite Ceramic Converters for Automotive Emissions Control

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The successful application of porous cordierite ceramic monolithic converters for automotive emissions control over the past 24 years in North America has been attributed to systems approach for optimizing the total converter package from reliability point of view. The systems approach examines the interaction between various components of monolithic converter package, namely the cordierite substrate, the alumina washcoat, the braided wire-rope end seals, the intumescent ceramic mat or steel wiremesh, and the stainless steel can, from long-term durability point of view. Such an approach has also proven successful in the Japanese, European, Korean and South American automotive industries. The key objectives of this paper are: i) to describe Corning′s methodology for assessing the impact of alumina washcoat on mechanical and thermal integrities of cordierite converter; ii) to examine the impact of mount density of ceramic mat or steel wiremesh on containment of cordierite converter against engine vibrations, gas pulsations and thermal gradients, and; iii) to analyze the impact of can design on strength and thermal shock resistance of cordierite converter. The above objectives will be illustrated by several examples of successful converter design for automobiles. This paper also addresses the Chinese automotive converter requirements and how they might be met via systems approach.

  13. Shading of ceramic crowns using digital tooth shade matching devices.

    Science.gov (United States)

    Baltzer, A; Kaufmann-Jinoian, V

    2005-04-01

    In the 1990s, there was great optimism due to the development of devices for measuring tooth shade. The frequently not so simple, visual determination of the shade of a tooth was to be done with the aid of a device which recognizes the shade and describes it accurately by reference to a color chart. However, the skepticism towards such devices was also great. It is known that the color effect frequently differs strongly when comparing a tooth from the shade guide with a metal ceramic crown, despite identical shade designation. Anyone who considers visual shade determination to be inadequate and places his hopes in digital shade matching devices will be disappointed. It is the shade-generating structures of the metal ceramic and frequently of the veneer layers that turn out to be too thin which, despite correct shade selection, cause a different color perception. Such problems have been reduced decisively with the development of fracture-proof hard porcelain caps (Vita In-Ceram) with optical characteristics similar to teeth. In addition, the Vita System 3D-Master tooth shade system developed in 1998 by Vita in cooperation with Dr. Hall from Australia, leads the practitioner to a better understanding of the primary tooth shade characteristics of "brightness (value)", "color intensity (chroma)" and "color (wave length of the visible light, hue)". These two innovations allow a more accurate estimate of the basic shade of a natural tooth (reference tooth) and the imitation in the laboratory of its natural, shade-generating structures. If digital shade measurement supplements the visual shade estimate, then a further improvement can be expected--especially in the recognition of the basic shade. Qualitative descriptions of subjective shade measurement of a natural tooth and of its imitation in the dental laboratory by ceramics can be found frequently in professional journals and publications. With digital tooth shade matching devices, which apart from the color code of

  14. 骨诱导无机材料BAM修复牙种植体周围骨缺损的实验研究%Experimental Study about BAM Osteoinduction Calcium Phosphate Ceramic in Repairing the Bone Defect around Dental Implant

    Institute of Scientific and Technical Information of China (English)

    张新风; 王鹏来; 刘超; 刘宗响; 程庆涛; 袁晟

    2012-01-01

    Objective: To evaluate the ability of BAM osteoinductrve calcium phosphate ceramic (BAMOICPC) with absorbable collagen membrane (BME-10X medical collagen membrane) in repairing the bone defect around dental implant. Methods: BLB implants coated by hydroxyapatite (HA) were implanted in femur of rabbit Standard opening bone defect on one side of implant (4mm in height, 3mm in width,2mm in thickness)was made. In the control group, the side wall bone defect was open. In the experimental group A, the side wall bone defect was covered simply by BME-10X collagen membrane. In the experimental group B, BAMOICPC were implanted on the bone defects. In the experimental group C, BAMOICPC were implanted on the bone defects and covered with BME-10X collagen membrane. On the 6th postoperative month, animals were killed and sampled. The bone with the implant segment were analyzed by HE staining and scanning electron microscopy (SEM). Results: In the control group, the surface of implants in the area of bone defect were wrapped by fibers. In group A, a little bone covered the border of bone defect. The experimental bone defects in group B were partially covered by new bone.In group C, the bone defects were completely covered by new bone. Compared with group B, the new bone in group C was high hardness, and combined with the implant more tightly by SEM observation.The mature haversian canals system were observed both in B and C experimental groups by histology methods. Conclusion: BAM osteoinductive calcium phosphate ceramics (BAMOICPC) is an ideal bone substitute material. Combined with collagen membrane, BAMOICPC repaired the bone defect around dental implants more excellently.%目的:评价骨诱导磷酸钙生物陶瓷( BAMOICPC)与可吸收胶原膜(BME-10X医用胶原膜)在牙种植体周围骨缺损中的修复能力.方法:在兔股骨上植入羟基磷灰石涂层BLB种植体,然后在其侧壁制造高4mm、宽3mm、深2mm的骨缺损.对照组为单纯侧壁骨缺损,

  15. Ballistic Performance of Porous Ceramic Thermal Protection Systems at 9 km/s

    Science.gov (United States)

    Miller, Joshua E.; Bohl, W. E.; Foreman, C. D.; Christiansen, Eric L.; Davis, B. A.

    2009-01-01

    Porous-ceramic, thermal-protection-systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components and sensitive electronic components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s on ceramic tiles similar to those used on the Orbiter. These tiles have a porous-batting of nominally 8 lb/cubic ft alumina-fiber-enhanced-thermal-barrier (AETB8) insulating material coated with a damage-resistant, toughened-unipiece-fibrous-insulation (TUFI) layer.

  16. Integral ceramic superstructure evaluation using time domain optical coherence tomography

    Science.gov (United States)

    Sinescu, Cosmin; Bradu, Adrian; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.

    2014-02-01

    Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in this case materials defects could be trapped inside the ceramic layers and those defects could lead to fractures of the entire superstructure. In this paper we demonstrate that a TD-OCT imaging system has the potential to properly evaluate the presence of the defects inside the ceramic layers and those defects can be fixed before inserting the prosthesis inside the oral cavity. Three integral ceramic superstructures were developed by using a CAD/CAM technology. After the milling, the ceramic layers were applied on the core. All the three samples were evaluated by a TD-OCT system working at 1300 nm. For two of the superstructures evaluated, no defects were found in the most stressed areas. The third superstructure presented four ceramic defects in the mentioned areas. Because of those defects the superstructure may fracture. The integral ceramic prosthesis was send back to the dental laboratory to fix the problems related to the material defects found. Thus, TD-OCT proved to be a valuable method for diagnosing the ceramic defects inside the integral ceramic superstructures in order to prevent fractures at this level.

  17. A new method for generating ceramic restorations: a CAD-CAM system.

    Science.gov (United States)

    Leinfelder, K F; Isenberg, B P; Essig, M E

    1989-06-01

    The CAD-CAM CEREC system is a small, complex unit developed for electronically designing and milling ceramic restorations. The system makes it possible to generate a restoration without taking impressions, developing temporary prostheses, and without laboratory assistance. The entire restorative procedure is performed in one appointment. Basic features include the following: the cavity preparation is scanned stereo-photogrammetrically, using a three-dimensional miniature video camera; the small microprocessor unit stores the three-dimensional pattern depicted on the screen; the video display serves as a format for the necessary manual construction via an electrical signal; the microprocessor develops the final three-dimensional restoration from the two-dimensional construction; the processing unit automatically deletes data beyond the margins of the preparation; the electronic information is transferred numerically to the miniature three-axis milling device; driven by a water turbine unit, the milling device generates a precision-fitting restoration from a standard ceramic block; the entire process of electronic designing and subsequent milling of a ceramic restoration requires approximately 10 to 15 minutes.

  18. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  19. The Army Selected Reserve Dental Readiness System: overview, assessment, and recommendations.

    Science.gov (United States)

    Honey, James R

    2013-06-01

    The Army Selected Reserve Dental Readiness System (ASDRS) is a key dental program directed by the Assistant Secretary of the Army (Manpower & Reserve Affairs) starting in fiscal year 09. The Army National Guard and Army Reserve have steadily implemented ASDRS over the past 3 years as a means to improve the historically abysmal dental readiness of the Army Reserve Component (RC). Dental readiness is essential for sustaining an Army RC Operational Force. ASDRS is a tool for RC commanders to provide contract dental readiness care in support of over 558 thousand nonmobilized Selected Reserve Citizen-Soldiers dispersed throughout the 54 states and U.S. territories, at home station before alert, and if necessary after alert (throughout the Army force generation cycle). This article examines the status of ASDRS implementation, assesses its effectiveness in improving Army RC Dental Readiness, and provides Army leadership recommendations regarding the following focus areas: (1) command emphasis, (2) program execution, and (3) synergy with the Military Health System and Department of Veterans Affairs.

  20. The International Caries Detection and Assessment System (ICDAS): an integrated system for measuring dental caries.

    Science.gov (United States)

    Ismail, A I; Sohn, W; Tellez, M; Amaya, A; Sen, A; Hasson, H; Pitts, N B

    2007-06-01

    This paper describes early findings of evaluations of the International Caries Detection and Assessment System (ICDAS) conducted by the Detroit Center for Research on Oral Health Disparities (DCR-OHD). The lack of consistency among the contemporary criteria systems limits the comparability of outcomes measured in epidemiological and clinical studies. The ICDAS criteria were developed by an international team of caries researchers to integrate several new criteria systems into one standard system for caries detection and assessment. Using ICDAS in the DCR-OHD cohort study, dental examiners first determined whether a clean and dry tooth surface is sound, sealed, restored, crowned, or missing. Afterwards, the examiners classified the carious status of each tooth surface using a seven-point ordinal scale ranging from sound to extensive cavitation. Histological examination of extracted teeth found increased likelihood of carious demineralization in dentin as the ICDAS codes increased in severity. The criteria were also found to have discriminatory validity in analyses of social, behavioral and dietary factors associated with dental caries. The reliability of six examiners to classify tooth surfaces by their ICDAS carious status ranged between good to excellent (kappa coefficients ranged between 0.59 and 0.82). While further work is still needed to define caries activity, validate the criteria and their reliability in assessing dental caries on smooth surfaces, and develop a classification system for assessing preventive and restorative treatment needs, this early evaluation of the ICDAS platform has found that the system is practical; has content validity, correlational validity with histological examination of pits and fissures in extracted teeth; and discriminatory validity.

  1. INTERACTION OF REDUCING AND CORROSIVE ENVIRONMENTS WITH CERAMIC FIBRES IN THE SYSTEM Al2O3-SiO2

    OpenAIRE

    Dietrichs, P.; Dhupia, G.; KrÖnert, W.

    1986-01-01

    Ceramic fibres from the system Al2O3-SiO2 are being increasingly employed in environments containing corrosive and reducing components such as alkalies, phosphates, water vapour metals etc. The reactions of these components with fibres of various compositions, that take place here via the gaseous phase, are only partly known. Due to the specific microstructure of the ceramic fibres as compared to dense materials large differences in reactions are observed.

  2. FIB/SEM and SEM/EDS microstructural analysis of metal-ceramic and zirconia-ceramic interfaces.

    Science.gov (United States)

    Massimi, F; Merlati, G; Sebastiani, M; Battaini, P; Menghini, P; Bemporad, E

    2012-01-10

    Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconia-ceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers' instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-to-metal) and the two zirconia-ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1 μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000-50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metal-ceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing.

  3. Patients' choice of payment system in the Swedish Public Dental Service--views on dental care and oral health.

    Science.gov (United States)

    Ostberg, Anna-Lena; Ahlström, Birgitta; Hakeberg, Magnus

    2013-01-01

    The aim of this study was to generate new knowledge of considerations and factors having impacted the patients' choice of payment system and their views on oral health. Moreover, their later attitudes to the prepaid risk-related payment system, having been enrolled or not, were explored. A qualitative design was chosen and data was collected through semi-structured interviews.Twenty patients in the Public Dental Service (PDS) in western Sweden were strategically sampled with reference to gender, age (older/younger adults), residence (rural/urban), and choice of payment system:fee-for-service or capitation plan.The interview guide covered areas concerning the payment systems, patient considerations before choosing system, views of their own oral health and experiences of received dental care within the chosen system.The analysis was performed according to basic principles of qualitative content analysis. The results revealed two themes expressing the latent content. In the theme "The individual's relation to the PDS", expectations of the care, feelings of safety and aspects of responsibility emerged.The theme"Health-related attitudes and perceptions" revealed that views on health and self-assessment of oral health influenced the patients' considerations. Moreover, the perceived influence on oral health and risk thinking emerged as important factors in this theme. The conclusion was that the individual's relation to the PDS together with his/her health-related attitudes and perceptions were the main factors impacting the choice of payment system in the PDS. A health promotion perspective should be applied, empowering the patients to develop their risk awareness and their own resources.

  4. The impact of the global budget system on dynamics of dental manpower and utilization of dental services

    Science.gov (United States)

    Huang, Laura Yueh-Guey; Huang, Boyen

    2016-01-01

    Background: This study aimed to investigate dentists’ supply and practice patterns following the implementation of the global budget system in Taiwan. Materials and Methods: Data of reimbursement claims, municipal socioeconomic status and dental manpower were collected from the National Health Insurance administration, the Ministry of Internal Affair, and the Ministry of Health and Welfare, respectively. A multivariate linear regression method was used for data analysis. Results: A municipality that reported a higher percentage of tertiary educated population (t = 3.718, P amalgam restorations in total claims reduced from 19.82% to 17.94%, while the percentage of tooth-colored material restorations increased from 25.46% to 28.79%. Conclusion: This study has demonstrated a stabilizing effect of the global budget system on dynamics of dental manpower in Taiwan. A relationship between HHI and dentists’ move-out rate has been found. The relationship between municipal socioeconomic status and the density of dentists has also been confirmed. In addition, reduced utilization of amalgam restorations was accompanied by increased utilization of tooth-colored material restorations. Further investigations are indicated. PMID:27076827

  5. CERCON- SMART CERAMICS, FROM THEORY TO PRACTICE

    Directory of Open Access Journals (Sweden)

    Daniela POPA

    2015-03-01

    Full Text Available Introduction of the CAD/CAM systems in dentistry has resulted in highly accurate and quality dentures, meeting the needs of both dental technician and dentist. The present study aims at illustrating the benefits and peculiarities of using CAD/CAM systems in current practice. To this aim, the case of a 29 year-old patient who wanted to have a 2.1 coverage crown replaced, being dissatisfied with its aesthetics, was considered. The fixed single tooth prosthesis was restored with the CAD/CAM CERCON (DeguDent - Smart Ceramics.

  6. PLZT-Modified Relaxor Piezoelectric Ceramic System for Medical Diagnostic Applications

    Directory of Open Access Journals (Sweden)

    Koduri Ramam

    2008-01-01

    Full Text Available The piezoelectric ceramic system [Pb0.978–yLa0.012Ba0.01Sry][(Zr0.534Ti0.4660.987Nb0.008]O3 (PLBSZNT has been fabricated for use in medical diagnostics applications. The fundamental pre-requisites are high-density, high dielectric constant and high piezoelectric properties that serve as compatible ceramic materials for medical diagnostic applications. It is essential for sensitive transducers that the piezoelectric ceramics must efficiently convert between electrical and mechanical energy, and so the electromechanical coupling coefficients should be high, as the fabrication process of tiny elements for medical arrays must be carried out without damaging the material and its properties. In our study, Sr-modified PLBZNT had shown single ferroelectric tetragonal phase. An analysis of different Sr doping concentration is reported, and the high dielectric permittivity, low dielectric loss along with high electromechanical properties indicate that PLBSZNT is suitable for medical diagnostic applications as well as sensors and actuators.

  7. Conditions for testing the corrosion rates of ceramics in coal gasification systems

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P.; Nowok, J.W. [Univ. of North Dakota, Grand Forks, ND (United States)

    1996-08-01

    Coal gasifier operating conditions and gas and ash compositions affect the corrosion rates of ceramics used for construction in three ways: (1) through direct corrosion of the materials, (2) by affecting the concentration and chemical form of the primary corrodents, and (3) by affecting the mass transport rate of the primary corrodents. To perform an accurate corrosion test on a system material, the researcher must include all relevant corrodents and simulate conditions in the gasifier as closely as possible. In this paper, the authors present suggestions for conditions to be used in such corrosion tests. Two main types of corrosion conditions are discussed: those existing in hot-gas cleanup systems where vapor and dry ash may contribute to corrosion and those experienced by high-temperature heat exchangers and refractories where the main corrodent will be coal ash slag. Only the fluidized-bed gasification systems such as the Sierra Pacific Power Company Pinon Pine Power Project system are proposing the use of ceramic filters for particulate cleanup. The gasifier is an air-blown 102-MWe unit employing a Westinghouse{trademark} ceramic particle filter system operating at as high as 1100{degrees}F at 300 psia. Expected gas compositions in the filter will be approximately 25% CO, 15% H{sub 2}, 5% CO{sub 2}, 5% H{sub 2}O, and 50% N{sub 2}. Vapor-phase sodium chloride concentrations are expected to be 10 to 100 times the levels in combustion systems at similar temperatures, but in general the concentrations of the minor primary and secondary corrodents are not well understood. Slag corrosiveness will depend on its composition as well as viscosity. For a laboratory test, the slag must be in a thermodynamically stable form before the beginning of the corrosion test to assure that no inappropriate reactions are allowed to occur. Ideally, the slag would be flowing, and the appropriate atmosphere must be used to assure realistic slag viscosity.

  8. Infrared Thermographic Assessment of Cooling Effectiveness in Selected Dental Implant Systems

    Directory of Open Access Journals (Sweden)

    Karol Kirstein

    2016-01-01

    Full Text Available The excessive temperature fluctuations during dental implant site preparation may affect the process of bone-implant osseointegration. In the presented studies, we aimed to assess the quality of cooling during the use of 3 different dental implant systems (BEGO®, NEO BIOTECH®, and BIOMET 3i®. The swine rib was chosen as a study model. The preparation of dental implant site was performed with the use of 3 different speeds of rotation (800, 1,200, and 1,500 rpm and three types of cooling: with saline solution at room temperature, with saline solution cooled down to 3°C, and without cooling. A statistically significant difference in temperature fluctuations was observed between BEGO and NEO BIOTECH dental systems when cooling with saline solution at 3°C was used (22.3°C versus 21.8°C. In case of all three evaluated dental implant systems, the highest temperature fluctuations occurred when pilot drills were used for implant site preparation. The critical temperature, defined in the available literature, was exceeded only in case of pilot drills (of all 3 systems used at rotation speed of 1,500 rpm without cooling.

  9. Frequency of dental caries in active and inactive systemic lupus erythematous patients: salivary and bacterial factors.

    Science.gov (United States)

    Loyola Rodriguez, J P; Galvan Torres, L J; Martinez Martinez, R E; Abud Mendoza, C; Medina Solis, C E; Ramos Coronel, S; Garcia Cortes, J O; Domínguez Pérez, R A

    2016-10-01

    The objective of this study was to determine dental caries frequency and to analyze salivary and bacterial factors associated with active and inactive systemic lupus erythematous (SLE) patients. Also, a proposal to identify dental caries by a surface, teeth, and the patient was developed. A cross-sectional, blinded study that included 60 SLE patients divided into two groups of 30 subjects each, according to the Activity Index for Diagnosis of Systemic Lupus Erythematous (SLEDAI). The decayed, missing, and filled teeth (DMFT) index and Integrative Dental Caries Index (IDCI) were used for analyzing dental caries. The saliva variables recorded were: flow, pH, and buffer capacity. The DNA copies of Streptococcus mutans and Streptococcus sobrinus were estimated by real-time PCR. The caries frequency was 85% for SLE subjects (73.3% for inactive systemic lupus erythematous (ISLE) and 100% for active systemic lupus erythematous (ASLE)); DMFT for the SLE group was 12.6 ± 5.7 and the IDCI was (9.8 ± 5.9). The ASLE group showed a salivary flow of 0.65 compared with 0.97 ml/1 min from the ISLE group; all variables mentioned above showed a statistical difference (p dental caries in epidemiological studies. © The Author(s) 2016.

  10. Dental implants in the diabetic patient: systemic and rehabilitative considerations.

    Science.gov (United States)

    Michaeli, Eli; Weinberg, Ido; Nahlieli, Oded

    2009-09-01

    Diabetes mellitus is the most prevalent endocrine disease, comprising the third highest cause of disability and morbidity in the Western world. In the past, implant placement was contraindicated in diabetic patients because of increased risk for implant failure and infection. Publications in recent years have shown success rates for dental implants in diabetic patients resembling those of the general population. Other studies, in diabetic patients, as well as in animal models, have shown an increased risk for implant failure. These results raise the question of whether diabetic patients are suitable for dental implant rehabilitation. This article reviews the literature and presents the factors used in assessing the severity of diabetes and its complications, as well as the considerations for rehabilitation planning in these patients. Integration of these factors by the dentist dictates whether as well as what type of implant-supported restoration should be preformed.

  11. Evaluation of the field size in dental diagnostic radiology system

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, P.S.; Potiens, M.P.A. [Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil)

    2006-07-01

    In this work the field size of a dental X rays machine was evaluated considering the recommendation of the Brazilian Health Ministry Regulation 453 which established basic lines of radiological protection in medical and dental diagnostic radiology. The diameter of the field should not be superior to 6 cm in the localized end point, limiting the radiated area and protecting the head-neck region. The measurements were carried out in a dental X rays machine, Dabi Atlante, model Spectro 70X Seletronic. For the field size or useful beam determination, the intra-oral films were positioned on a plain surface to be exposed in four stages and two focus-film distances (FFD), 20 cm and 27.5 cm: 1) with spacer cone; 2) without spacer cone; 3) with spacer cone and film-holding device; 4) without spacer cone and film-holding device. The results show that the diameter of the field size is satisfactory only for FFD = 20 cm. When the film-holding device is used, which is recommended by the Regulation 453, item 5.8 d(ii), the diameter of the field size exceeds the maximum recommended value of 6 cm. (authors)

  12. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  13. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  14. An investigation into the role of core porcelain thickness and lamination in determining the flexural strength of In-Ceram dental materials.

    Science.gov (United States)

    Alshehri, Sharifa Abdullah

    2011-06-01

    A biaxial flexure test was conducted to evaluate the effect of reducing the thickness of In-Ceram core material and veneering with Vitadur α dentine porcelain on its flexural strength. Four groups of 10 discs were tested; group I discs were In-Ceram discs with mean thickness of 1.58 ± 0.08 mm, group II discs were In-Ceram discs with mean thickness of 1.0 ± 0.11 mm, group III discs were laminated In-Ceram core porcelain/Vitadur α discs with a mean total thickness of 2.06 ± 0.15 mm and core porcelain thickness of 1.0 ± 0.11 mm; group IV discs were Vitadur α discs with a mean thickness of 2.08 ± 0.16 mm. Mean flexural strength values decreased between groups: 436 ± 38 MPa for group I, 352 ± 30 MPa for group II, 237 ± 24 MPa for group III, and 77 ± 14 MPa for group IV. The result of ANOVA and Tukey tests indicated that the mean flexural strength of group II was significantly less than group I, indicating that thickness of the In-Ceram core provides critical flexural strength to the final product. The addition of ≈ 1 mm of Vitadur α veneering porcelain to In-Ceram core significantly (p= 0.05) reduced the flexural strength as compared to the nonveneered In-Ceram core specimens (group II). The Vitadur α specimens (group IV) were significantly weaker than all the other groups. This study indicates that lamination should be avoided in areas where maximum strength is required for In-Ceram all-ceramic crowns and bridges. © 2011 by the American College of Prosthodontists.

  15. Demirjian's system for estimating the dental age of northeastern Brazilian children.

    Science.gov (United States)

    Maia, Maria Cristina Germano; Martins, Maria da Gloria Almeida; Germano, Francisco Alcides; Brandão Neto, Jose; da Silva, Carlos Antonio Bruno

    2010-07-15

    Since Demirjian's system of estimating dental maturity was first described, many researchers from different countries have tested its accuracy among diverse populations. Some of these studies have pointed out a need to determine population-specific standards. In Brazil, the Northeast region is the one that most suffers the negative impact of exodus, specially related to the increase of abandoned children in the cities. The aim of this study was to test the accuracy of Demirjian's system for assessing the dental maturity of northeastern Brazilian children, so as to present a scale for maturity score conversion into dental age developed specifically for this population. This could be used for forensic, anthropological and legal matters, and also as a model for other countries attempting to formulate their own conversion scales. Panoramic radiographs of 1,491 children (821 females and 670 males), aged 7 to 13 years, from Ceará state, northeast Brazil, were assessed by a single observer to determine dental age (DA) according to Demirjian's system. The mean percentage of intra-observer agreement was 86.6%, with a mean Cohen's Kappa coefficient of 0.67 (substantial agreement). The DA was compared by paired t-test to subjects' chronological age (CA). The differences between CA and DA in all age groups were statistically significant (psystem in this population, justified the determination of specific scores for dental maturity assessment.

  16. Preliminary evaluation of a virtual reality dental simulation system on drilling operation.

    Science.gov (United States)

    Wang, Dangxiao; Zhao, Siming; Li, Teng; Zhang, Yuru; Wang, Xiaoyan

    2015-01-01

    To evaluate the fidelity of the iDental system and investigate its utility and performance on simulated drilling operations, user studies consisting of objective and subjective evaluations were performed. A voxel-based drilling simulation sub-system in the iDental system was employed for evaluation. Twenty participants were enrolled to take part in the experiments and were divided into two groups: novice and resident. A combined evaluation method including objective and subjective methods was employed. The objective evaluation included two dental drilling tasks: caries removal operation and pulp chamber opening operation. In the subjective method, participants were required to complete a questionnaire to evaluate the fidelity of the system after the operation task. Based on the structured global assessment scales in the questionnaire, the average subjective evaluation scores of the proposed metrics were greater than 4.5, demonstrating that the system operated above medium fidelity. Dentists expressed great interest and positive attitudes toward the potential of the iDental system. The objective evaluation data including time spent and the volume of removed healthy and carious tissue were obtained. Although no significant differences could be found between the two groups, the volume of removed caries and the depth of pulp chamber insertion manifested small standard deviations. Evaluation results illustrated that dentists were willing to use the virtual reality training system. Several future research topics were identified, including increasing the task difficulty, improving the system fidelity and introducing appropriate finger rest points.

  17. Fracture Analysis of an All-Ceramic Bearing System

    Science.gov (United States)

    1994-09-01

    Alpha Optical Systems, Inc., 1611 Government Street, Ocean Springs, MS 39564 1 Andre Ezis, Cercom, Inc., 1960 Watson Way, Vista, CA 92083 1 Robert Feest...David R. Breton 1 Sid 0. Davis 1 Edward R. Schillemat, Jr. 1 Barry O’Dwyer Director, U.S. Army Research Laboratory, Watertown, MA 02172-0001 2 ATTN: AMSRL-OP-WT-IS, Technical Library 10 Authors 32

  18. DENTAL SERAMİKLERİN TARİHSEL GELİŞİMİ

    OpenAIRE

    TUTAL, Zeynep; ŞENER YAMANER, Işıl Damla; TUNCER, Erman Bülent

    2015-01-01

    Ceramics were probably the first materials to be artifically made by humans, and porcelain was among the first materials to be the subject of laboratory research. This review presents the evaluation of dental ceramics from 23,000BC to more recent introduction into dentistry. The development of the science and the art of dental ceramics in many ways parallels to the development of the industrial revolution. The development of high-strength dental ceramics that mimic the optical properties of e...

  19. [Covering dental defects with aluminum cast dowel construction and technology of their manufacture].

    Science.gov (United States)

    Khudonogov, G I

    1995-01-01

    Clinical and laboratory studies have revealed benefits of aluminum cast constructions. Its cast dowel inserts are used in the system of fixed metal-free dentures made from ceramics (dental bridges, single crowns, etc.). The high efficiency, availability of casting technology for aluminum reduces patients' treatment periods and ensures accurate attachment of dowel insets to the root canal and stump of a tooth.

  20. Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post systems at monotonously increasing loads.

    Science.gov (United States)

    Ottl, P; Hahn, L; Lauer, H Ch; Fay, M

    2002-02-01

    A carbon fibre post system, three non-palladium and one palladium metal post systems, two ceramic post systems, and a metal post system with a ceramic core were studied in vitro. The control group consisted of root-filled test teeth without posts. The test teeth were identical artificial roots of an upper central incisor made from a posterior composite whose module of elasticity was similar to that of natural dentine. All posts were cemented in the roots using Panavia 21 TC. Subsequently, standardized full crowns were cemented onto all roots. On a universal testing machine, the test teeth were loaded palatally at monotonously increasing loads until root fracture. The highest mean fracture loads were found for the carbon fibre post system (312.5 +/- 58.8 N). The fracture load of non-palladium metal posts (242.3-300.4 N) did not differ significantly from that of the Perma-dor post (265.9 N), which does contain palladium. Values of 300.3 +/- 89.3 N (aluminium oxide ceramics) and 193.5 +/-57.0 N (zirconia ceramics) were found for the ceramic posts. The control group exhibited a fracture load of 228.8 +/- 35.7 N. The mean distance between the vestibular end of the fracture gap and the point of force application was between 10.1 +/- 2.3 and 14.7 +/- 1.2 mm.

  1. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  2. Systemic assessment of patients undergoing dental implant surgeries: A trans- and post-operative analysis

    Directory of Open Access Journals (Sweden)

    Sanjay Byakodi

    2017-01-01

    Full Text Available Background: Procedure-related and patient-related factors influence the prognosis of dental implants to a major extent. Hence, we aimed to evaluate and analyze various systemic factors in patients receiving dental implants. Materials and Methods: Fifty-one patients were included in the study, in which a total of 110 dental implants were placed. Complete examination of the subjects was done before and after placement of dental implants. Implant surgery was planned, and osseointegrated dental implants were placed in the subjects. Postoperative evaluation of the dental implant patients was done after 3 weeks. Anxiety levels were determined using State-Trait Anxiety Inventory (STAI questionnaire on the surgery day and after 1 week of surgery. The participant describes how they feel at the moment by responding to twenty items as follows: (1 absolutely not, (2 slightly, (3 somewhat, or (4 very much. All the results were recorded and statistical analyzed by SPSS software. Results: Out of 51, 29 patients were males while 22 were females, with ratio of 1.32:1. Female patients' mean age was 50.18 years while male patients' mean age was 52.71 years, with statistically nonsignificant difference between them. Functional rehabilitation was the main purpose of choosing dental implants in more than 90% of the subjects. Diameter of 3.75 mm was the shortest implants to be placed in the present study, whereas in terms of length, 8.5 mm was the shortest length of dental implant used in the present study. Tooth area in which maximum implants were placed in our study was 36 tooth region. Maximum implants were placed in Type II bone quality (n = 38. Implants installed in the mandible were clamped more efficiently than implants placed in the maxilla (P < 0.001. The difference of average STAI-State subscore before and after the surgery was statistically significant (P < 0.05; significant. Conclusion: Mandibular dental implants show more clamping (torque than maxillary

  3. Effects of surface-finishing protocols on the roughness, color change, and translucency of different ceramic systems.

    Science.gov (United States)

    Akar, Gülcan Coşkun; Pekkan, Gürel; Çal, Ebru; Eskitaşçıoğlu, Gürcan; Özcan, Mutlu

    2014-08-01

    Surface-finishing protocols have a mechanical impact on ceramic surfaces that could eventually affect surface topography and light scattering. An optimum protocol is needed to avoid damaging the optical properties of ceramics. The purpose of this study was to determine the effects of different surface-finishing protocols on the surface roughness, color change, and translucency of ceramic and metal ceramic restorations. Standardized disk-shaped specimens (1.5 × 10 mm, n=128) were fabricated from 3 different ceramic core materials (aluminum oxide [Al2O3]-AL, zirconium oxide [ZrO2]-ZR, lithium disilicate [Li2Si2O5]-LIT), veneered (V) with dentin ceramics (n=32 per group), and placed in the following groups: ALV, ZRV, and LITV. The metal ceramic group acted as the control (n=32). Four different surface-finishing methods were tested. Airborne-particle abrasion with 50 μm Al2O3, polishing with adjustment kit, polishing with adjustment kit plus diamond polishing paste, and autoglazing (n=8 subgroup) were applied on the veneering ceramics. The specimens were analyzed with a profilometer for surface roughness, and color change and translucency were measured with a clinical spectrophotometer. Statistical analyses were performed with 1-way ANOVA and the Tukey honest significant difference tests (α=.05). Specimens treated with the airborne particle abrasion method showed significantly higher mean profilometer for surface roughness values in all groups (P.05). With the diamond polishing paste method, lower surface roughness values were achieved in the ZRV and metal ceramic groups acted as the control groups. Different surface-finishing methods affected the color change of the ceramic systems, except for ZRV. Surface-finishing protocols significantly affected the translucency values of the ALV, LITV, and metal ceramic groups (Pceramics tested. The airborne-particle abrasion protocol created rougher surfaces and decreased translucency, and color change in zirconia was not

  4. Potential risk factors in systemic hypoplasia and dental caries at odontogenesis stage

    Directory of Open Access Journals (Sweden)

    Kovach I.V.

    2013-03-01

    Full Text Available Lesion of hard dental tissue with caries process and lesions not connected with caries present overwhelming majority of dental diseases. Causes leading to damage of enamel integrity and dentin with progressing demineralization are known; they allow to choose justified method of primary prophylaxis. Along with it, etiology and pathogenesis of enamel lesions with demineralization signs remains unexplored. Epidemiologic study of prevalence, incidence and severity of lesion of hard dental tissues in 330 pupils, who constantly live on endemic iodine-defficient territory, of three zones – mountain zone, foothill and valley. For comparison, schoolchildren migrated to this territory 2-3 years after birth, and children – residents of favorable as for iodine level in drinking water were examined, 30 children in each group. It was established, that overwhelming number of schoolchildren of endemic zone suffer from endemic goiter of various severity, which sufficiently impacts on protein-mineral ratio of the organism, bone skeleton and teeth including. It was also established, that residents of three various levels of iodine consumption are prone to development of multiple dental caries and systemic enamel hypoplasia. Children, residents of mountain zone suffer the most, with simultaneous lesion of thyroid gland. The role of endemic goiter in systemic dental enamel hypoplasia and multiple caries, which changes protein matrix, negatively impacts on odontogenesis and mineralization degree is underlined.

  5. An investigation into the use of the FDI tooth notation system by dental schools in the UK.

    Science.gov (United States)

    Blinkhorn, A S; Choi, C L; Paget, H E

    1998-02-01

    This study investigated the use of the FDI tooth notation system in UK dental schools. In addition, the notation system used by dentists referring patients to Manchester Dental Hospital was recorded. A questionnaire was sent to the Deans of all Dental Schools in the UK and letters of referral to Manchester Dental Hospitals Paediatric GA Service were monitored for 1 month. The results showed that only Manchester University Dental School used the FDI system but 6 other schools instructed students in its use. The Palmer system was used by all the other schools for recording clinical information. 136 referral letters were received, only one used the FDI notation, 15 used both FDI and Palmer and the remainder (120) requested extractions using the Palmer notation. The FDI notation system is not used in the majority of UK dental schools. Despite the fact the Dental School in Manchester has been teaching and using the FDI system for over 10 years, it has not been adopted by General Dental Practitioners referring patients into the hospital. The FDI should review the use of their system in other countries, to ascertain whether it has fulfilled its role as an international notation system.

  6. Process engineering of ceramic composite coatings for fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.; Kim, H.; Chen, M.; Yang, Q.; Troczynski, T. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Metals and Materials Engineering

    2003-07-01

    Researchers at UBCeram at the Department of Metals and Materials Engineering at the University of British Columbia have developed a technology to chemically bond composite sol-gel (CB-CSG) coating onto metallic surfaces of complex or concave shapes. The process has been optimized for electrically resistive coatings and corrosion-resistant coatings. The CSG is sprayed onto metallic surfaces and is heat-treated at 300 degrees C to partially dehydrate the hydroxides. The CSG film is then chemically bonded through reaction of active alumina with metal phosphates, such as aluminium phosphate. A new chromate-free process is being developed to address the issue of coatings porosity. The electrodeposition technique involves polymer particles mixed with suspended fine alumina particles which are co-deposited by electrophoretic means or by electrocoagulation. The composite e-coatings have excellent mechanical properties and are being considered as a protective coating for various components of fuel cell systems. 9 refs., 7 figs.

  7. Impact Behavior of Three Notched All-Ceramic Restorations after Soaking in Artificial Saliva

    Directory of Open Access Journals (Sweden)

    Min Yan

    2015-07-01

    Full Text Available Biomechanics play a critical role in influencing the clinical applications of all-ceramic dental restorations. The restorative biomaterials have to demonstrate mechanical durability in the oral environment because they are always exposed to a variety of oral environments. This study was designed to evaluate the effect of soaking time, notch and saliva pH values on the impact energy of three commonly used all-ceramic materials for CAD/CAM. The leucite-reinforced glass ceramic (ProCAD, lithium disilicate glass ceramic (IPS e.max CAD and zirconia-based ceramic materials (IPS e.max ZirCAD were used. The experimental results indicated that the impact energy of ProCAD decreased with an increase in soaking time, but not for IPS e.max CAD and IPS e.max ZirCAD. The impact energy of the zirconia system was higher than leucite-reinforced and lithium disilicate-based ceramic systems. When subjected to preformed 0.5 mm U-shape notch on the bar specimen of 3 mm thick, the impact energy of the all-ceramic restorations revealed a markedly reduction of about 80%–90%, almost irrespective of dental compositions, which indicated the effect of flaw to a great degree. No statistically significant influence (p > 0.05 of pH values (4, 7 and 9 on impact energy was found for each group. It is concluded that the no matter which all-ceramic materials were used, it was appreciably sensitive to the presence of notches. The ceramic composition and microstructure have been shown to affect mechanical durability.

  8. Segmentation, statistical analysis, and modelling of the wall system in ceramic foams

    Energy Technology Data Exchange (ETDEWEB)

    Kampf, Jürgen, E-mail: juergen.kampf@uni-ulm.de [University of Ulm, Mathematics Department, 89069 Ulm (Germany); Schlachter, Anna-Lena [University of Kaiserslautern, Mathematics Department, 67653 Kaiserslautern (Germany); Redenbach, Claudia, E-mail: redenbach@mathematik.uni-kl.de [University of Kaiserslautern, Mathematics Department, 67653 Kaiserslautern (Germany); Liebscher, André, E-mail: liebscher@mathematik.uni-kl.de [University of Kaiserslautern, Mathematics Department, 67653 Kaiserslautern (Germany)

    2015-01-15

    Closed walls in otherwise open foam structures may have a great impact on macroscopic properties of the materials. In this paper, we present two algorithms for the segmentation of such closed walls from micro-computed tomography images of the foam structure. The techniques are compared on simulated data and applied to tomographic images of ceramic filters. This allows for a detailed statistical analysis of the normal directions and sizes of the walls. Finally, we explain how the information derived from the segmented wall system can be included in a stochastic microstructure model for the foam.

  9. 885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System

    Science.gov (United States)

    Yu, Anthony

    2012-01-01

    The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG. When compared to traditional 808-nm pump, 885-nm diodes will have 30% less thermal load (or wasted heat) and will thus see a similar percentage improvement in the overall laser efficiency. In order to provide a more efficient laser system for future flight missions that require the use of low-repetition- rate (systems are numerous. The epitaxial structures of these 885-nm diodes are aluminum-free. There is a significant reduction in the thermal load generated from the Stokes shift or quantum defects. A Stokes shift is the energetic difference between the pump and laser photons. Pumping at a wavelength band closer to the lasing wavelength can reduce the thermal load by .30% compared to traditional pumping at 808 nm, and increase the optical- to-optical efficiency by the same factor. The slope efficiency is expected to increase with a reduction in the thermal load. The typical crystalline Nd:YAG can be difficult to produce with doping level >1% Nd. To make certain that the absorption at 885 nm is on the same par as the 808-nm diode, the Nd:YAG material needs to be doped with higher concentration of Nd. Ceramic Nd:YAG is the only material that can be tailored to specific needs.

  10. Factors affecting the corrosion rates of ceramics in coal combustion systems

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P. [Univ. of North Dakota, Grand Forks, ND (United States)

    1995-08-01

    The concentrations of approximately a dozen elements in the products of coal combustion affect the corrosion rates of ceramics used to construct the combustion system. The elements, including H, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, and Fe, affect corrosion rates in three ways: as primary corrodants of the materials, as secondary corrodants that affect the activities of the primary corrodants, and by affecting the mass transport rate of the primary corrodants. A full factorial study of corrosion rates performed by varying the concentrations of these elements would involve X{sup n} tests, where X is the number of variations of each element and n is the number of different elements. For three variations (low, medium, and high concentrations) of each of 12 elements, the number of tests is 531,441 for a single temperature and pressure condition. The numbers can be reduced with the use of a fractional factorial test matrix, but the most effective way to perform corrosion tests is to base them on realistic system conditions. In this paper, the effects of the composition and physical state of the products of coal combustion on ceramic corrosion rates are given along with suggestions of appropriate test conditions for specific system components.

  11. [Do long-term care residents benefit from the dental bonus system?].

    Science.gov (United States)

    Nitschke, I; Bär, C; Hopfenmüller, W; Roggendorf, H; Stark, H; Sobotta, B; Reiber, Th

    2011-06-01

    Oral health of long-term care (LTC) residents is often poor. From 30 random German LTC facilities, 242 random residents (Berlin n=75, Northrhine-Westfalia (NRW) n=94, Saxony n=73) (median age: 82 years, female: 78.5%) were interviewed as to their use of dental services, possession of a bonus booklet (BB), and completeness of records. Only 18.6% possessed a BB. Significant regional differences were observed (Berlin=5.3%, NRW=18.1%, Saxony=32.9%) (χ(2) test p<0.01). The number of teeth was higher (Mann-Whitney test p=0.01) and the time since last dental visit shorter (p<0.01) for all residents with a BB. Only 18.6% of people possessing a BB declared not having had a dental appointment within the previous 12 months (LTC residents without BB 51.3%). As a means towards improved quality management in nursing, better oral infection control of residents and increased oral health and general quality of life, the introduction of a regular annual preventive dental screening program including the use of a dental bonus system are suggested.

  12. [Structure of dental services in a social security system: Córdoba, Argentina].

    Science.gov (United States)

    Reynoso Alvarez de Viotti, R A; Batellino, L J

    1994-01-01

    We describe here the results of a survey carried out to determine the nature, extent and distribution of the dental service provided by the Board of the University Personnel Social Assistance (Dirección de Asistencia Social del Personal Universitario [DASPU] From 1988 to 1990. Such survey was performed on the bases of a representative sample of assistance recipients. The greatest dental service demand was registered among the group of persons of 25-44 years-old (40.3% of the total), although the rendered services per person/years increased with the member's ages. Restorative Dental and Prosthesis registered the highest occurrence (50.2% of the total). Preventive Odontology practices were infrequent (1.2%) while Odontopediatric was the less demanded (0.3%). 31.8% of the assistance was provided by DASPU own services, Prothesis being the most predominant kind. As for external effectors (62.3%), the most frequent were those of Dental Operating. It is concluded that the demanded dental services were mainly curative and reparative. The reorganization of the Odontology Service may increase the system' performance efficiency and effectiveness.

  13. Conservative restorative treatment using a single-visit, all-ceramic CAD/CAM system.

    Science.gov (United States)

    Benk, Joel

    2007-01-01

    Computer-aided design/computer-aided manufacturing (CAD/CAM) continues to radically change the way in which the dental team plans, prepares, and fabricates a patient's restoration. This advancing technology offers the clinician the ability to scan the patient's failing dentition and then designs a long-lasting, reliable restoration based on this data. CAD/CAM systems also permit efficient, single-visit placement of the restoration while preserving much of the natural tooth structure. This article discusses how a chairside CAD/CAM system can be used to provide such a restoration in the posterior region in a single-visit.

  14. Clinical fit of all-ceramic three-unit fixed partial dentures, generated with three different CAD/CAM systems.

    Science.gov (United States)

    Reich, Sven; Wichmann, Manfred; Nkenke, Emeka; Proeschel, Peter

    2005-04-01

    In this study, the hypothesis was tested that the marginal and internal fit of CAD/CAM fabricated all-ceramic three-unit fixed partial dentures (FPDs) can be as good as in metal-ceramic FPDs. Twenty-four all-ceramic FPDs were fabricated and randomly subdivided into three equally sized groups. Eight frameworks were fabricated using the Digident CAD/CAM system (DIGI), another eight frameworks using the Cerec Inlab system (INLA). Vita Inceram Zirkonia blanks were used for both groups. In a third group frameworks were milled from yttrium-stabilized Zirconium blanks using the Lava system (LAVA). All frameworks were layered with ceramic veneering material. In addition, six three-unit metal-ceramic FPDs served as control group. All FPDs were evaluated using a replica technique with a light body silicone stabilized with a heavy body material. The replica samples were examined under microscope. The medians of marginal gaps were 75 microm for DIGI, 65 microm for LAVA and INLA and 54 microm for the conventional FPDs. Only the DIGI data differed significantly from those of the conventional FPDs. Within the limits of this study, the results suggest that the accuracy of CAD/CAM generated three-unit FPDs is satisfactory for clinical use.

  15. Stress Analysis of CaO-Al2O3-SiO2 System Glass-ceramic with Different Thickness

    Institute of Scientific and Technical Information of China (English)

    CHENG Jinshu; XIE Jun; HE Feng; YANG Shuzhen

    2005-01-01

    In order to study the relationship between thickness and residual stress in CaO-Al2O3-SiO2 glass-ceramics. The residual stress was measured in CaO-Al2 O3-SiO2 system glass-ceramic with different thickness, and the formation mechanism and characterization of residual stress in CAS system Glass-ceramic were analyzed by the X-ray diffraction analysis. The experimental results show the compressive residual stress increases with thickness of glass-ceramic increasing

  16. CLINICAL CONSIDERATIONS OF DENTAL IMPLANT SYSTEM IN IMMEDIATE LOADING IMPLANT CASES

    Directory of Open Access Journals (Sweden)

    Carolina Damayanti Marpaung

    2015-06-01

    Full Text Available Immediate loading of dental implant has been researched intensively in the development of Branemark’s early concept of 2 stages implant placement. This was embarked from both patients and practiitioner’s convenience towards a simpler protocol and shorter time frame. Many recent researchers later found that micromotions derived from occlusal loading for a certain degree, instead of resulting a fibrous tissue encapsulation, can enhance the osseointegration process. Dental Implant system enhancement towards maximizing the primary stability held a key factor in Branemark’s concept development. Surgical protocol and implant design was found to give a significant contribution to the prognosis of immediate-loading implants.

  17. A Cavity Preparation Evaluation System in the Skill Assessment of Dental Students.

    Science.gov (United States)

    Zou, Huiru; Jin, Shufeng; Sun, Jianping; Dai, Yanmei

    2016-08-01

    The aim of this study was to compare a computerized, laser-scanning Cavity Preparation Skill Evaluation System (CPSES) with conventional teachers' eye-hand grading assessment of dental students' Class I cavity preparation evaluations. Thirty-eight cavity preparations of lower left first molars made by junior dental students at a dental school in China were tested from September 2013 to November 2014. The outline and retention form, smoothness, depth, wall angulation, and cavity margin index of the preparations were evaluated by CPSES and then by teachers' eye-hand grading. The mean difference in scores for each method was considered, as was the variability of scores within each method. Compared with the teachers' eye-hand grading method, CPSES provided objective evaluation results that had statistically significant differences (pcavity preparation skills and encourage students in their self-paced learning and independent practice.

  18. Development of a mobile device optimized cross platform-compatible oral pathology and radiology spaced repetition system for dental education.

    Science.gov (United States)

    Al-Rawi, Wisam; Easterling, Lauren; Edwards, Paul C

    2015-04-01

    Combining active recall testing with spaced repetition increases memory retention. The aim of this study was to evaluate and compare students' perception and utilization of an electronic spaced repetition oral pathology-radiology system in dental hygiene education and predoctoral dental education. The study employed an open-source suite of applications to create electronic "flashcards" that can be individually adjusted for frequency of repetition, depending on a user's assessment of difficulty. Accessible across multiple platforms (iOS, Android, Linux, OSX, Windows) as well as via any web-based browser, this framework was used to develop an oral radiology-oral pathology database of case-based questions. This system was introduced in two courses: sophomore oral pathology for dental students and sophomore radiology for dental hygiene students. Students were provided free software and/or mobile tablet devices as well as a database of 300 electronic question cards. Study participants were surveyed on frequency and extent of use. Perception-based surveys were used to evaluate their attitudes towards this technology. Of the eligible students, 12 of 22 (54.5%) dental hygiene and 49 of 107 (45.8%) dental students responded to the surveys. Adoption rates and student feedback were compared between the two groups. Among the respondents, acceptance of this technology with respect to educational usefulness was similar for the dental and dental hygiene students (median=5 on a five-point scale; dental hygiene interquartile range (IQR)=0; dental IQR=1). Only a minority of the survey respondents (25% dental, 33% dental hygiene) took advantage of one of the main benefits of this technology: automated spaced repetition.

  19. A Difference Contour-Mapping System For The Measurement Of Wear In Dental Restorations

    Science.gov (United States)

    Jongsma, Frans H. M.; Janssen, Huub L. M. M.; Lambrechts, Paul; Vanherle, Guido

    1986-07-01

    A real-time moire contouring system, which is insensitive to specular reflections, has enlarged depth of field and is used in conjunction with a micropositioning relocation device, has been built for the measurement of wear in dental restorations. Measurements are carried out on accurate polyvinyl siloxane replicas.

  20. The development of a learning management system for dental radiology education: A technical report

    Science.gov (United States)

    Chang, Hee-Jin; Symkhampha, Khanthaly; Huh, Kyung-Hoe; Yi, Won-Jin; Lee, Sam-Sun; Choi, Soon-Chul

    2017-01-01

    Purpose This study was conducted to suggest the development of a learning management system for dental radiology education using the Modular Object-Oriented Dynamic Learning Environment (Moodle). Materials and Methods Moodle is a well-known and verified open-source software-learning management system (OSS-LMS). The Moodle software was installed on a server computer and customized for dental radiology education. The system was implemented for teaching undergraduate students to diagnose dental caries in panoramic images. Questions were chosen that could assess students' diagnosis ability. Students were given several questions corre-sponding to each of 100 panoramic images. Results The installation and customization of Moodle was feasible, cost-effective, and time-saving. By having students answer questions repeatedly, it was possible to train them to examine panoramic images sequentially and thoroughly. Conclusion Based on its educational efficiency and efficacy, the adaptation of an OSS-LMS in dental school may be highly recommended. The system could be extended to continuing education for dentists. Further studies on the objective evaluation of knowledge acquisition and retention are needed. PMID:28361030

  1. Reliability of an occlusal and nonocclusal tooth wear grading system: clinical use versus dental cast assessment

    NARCIS (Netherlands)

    Wetselaar, P.; Lobbezoo, F.; Koutris, M.; Visscher, C.M.; Naeije, M.

    2009-01-01

    The reliability of a newly developed tooth wear grading system was assessed both clinically and on dental casts by two observers using 20 participants. The reliability of clinical occlusal/incisal tooth wear grading was fair-to-good to excellent, while that of most of the clinical nonocclusal/noninc

  2. The development of a learning management system for dental radiology education: A technical report

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hee Jin; Huh, Kyung Hoe; Yi, Won Jin; Heo, Min Suk; Lee, Sam Sun; Choi, Soon Chul [Dept. of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul (Korea, Republic of); Symkhampha, Khanthaly [Div. of Oral and Maxillofacial Radiology, Dept. of Basic Science, Faculty of Dentistry, University of Health Sciences, Vientiane (Lao People' s Democratic Republic)

    2017-03-15

    This study was conducted to suggest the development of a learning management system for dental radiology education using the Modular Object-Oriented Dynamic Learning Environment (Moodle). Moodle is a well-known and verified open-source software-learning management system (OSS-LMS). The Moodle software was installed on a server computer and customized for dental radiology education. The system was implemented for teaching undergraduate students to diagnose dental caries in panoramic images. Questions were chosen that could assess students' diagnosis ability. Students were given several questions corresponding to each of 100 panoramic images. The installation and customization of Moodle was feasible, cost-effective, and time-saving. By having students answer questions repeatedly, it was possible to train them to examine panoramic images sequentially and thoroughly. Based on its educational efficiency and efficacy, the adaptation of an OSS-LMS in dental school may be highly recommended. The system could be extended to continuing education for dentists. Further studies on the objective evaluation of knowledge acquisition and retention are needed.

  3. Federal Aviation Administration (FAA airworthiness certification for ceramic matrix composite components in civil aircraft systems

    Directory of Open Access Journals (Sweden)

    Gonczy Stephen T.

    2015-01-01

    Full Text Available Ceramic matrix composites (CMCs are being designed and developed for engine and exhaust components in commercial aviation, because they offer higher temperature capabilities, weight savings, and improved durability compared to metals. The United States Federal Aviation Administration (FAA issues and enforces regulations and minimum standards covering the safe manufacture, operation, and maintenance of civil aircraft. As new materials, these ceramic composite components will have to meet the certification regulations of the FAA for “airworthiness”. The FAA certification process is defined in the Federal Aviation Regulations (Title 14 of the Code of Federal Regulations, FAA policy statements, orders, advisory circulars, technical standard orders, and FAA airworthiness directives. These regulations and documents provide the fundamental requirements and guidelines for design, testing, manufacture, quality assurance, registration, operation, inspection, maintenance, and repair of aircraft systems and parts. For metallic parts in aircraft, the FAA certification and compliance process is well-established for type and airworthiness certification, using ASTM and SAE standards, the MMPDS data handbook, and FAA advisory circulars. In a similar manner for polymer matrix composites (PMC, the PMC industry and the FAA have jointly developed and are refining parallel guidelines for polymer matrix composites (PMCs, using guidance in FAA circulars and the CMH-17 PMC handbook. These documents discuss design methods and codes, material testing, property data development, life/durability assessment, production processes, QA procedures, inspection methods, operational limits, and repairs for PMCs. For ceramic composites, the FAA and the CMC and aerospace community are working together (primarily through the CMH-17 CMC handbook to define and codify key design, production, and regulatory issues that have to be addressed in the certification of CMC components in

  4. Cost savings from a teledentistry model for school dental screening: an Australian health system perspective.

    Science.gov (United States)

    Estai, Mohamed; Bunt, Stuart; Kanagasingam, Yogesan; Tennant, Marc

    2017-06-05

    Objective The aim of the present study was to compare the costs of teledentistry and traditional dental screening approaches in Australian school children.Methods A cost-minimisation analysis was performed from the perspective of the oral health system, comparing the cost of dental screening in school children using a traditional visual examination approach with the cost of mid-level dental practitioners (MLDPs), such as dental therapists, screening the same cohort of children remotely using teledentistry. A model was developed to simulate the costs (over a 12-month period) of the two models of dental screening for all school children (2.7million children) aged 5-14 years across all Australian states and territories. The fixed costs and the variable costs, including staff salary, travel and accommodation costs, and cost of supply were calculated. All costs are given in Australian dollars.Results The total estimated cost of the teledentistry model was $50million. The fixed cost of teledentistry was $1million and that of staff salaries (tele-assistants, charters and their supervisors, as well as information technology support was estimated to be $49million. The estimated staff salary saved with the teledentistry model was $56million, and the estimated travel allowance and supply expenses avoided were $16million and $14million respectively; an annual reduction of $85million in total.Conclusions The present study shows that the teledentistry model of dental screening can minimise costs. The estimated savings were due primarily to the low salaries of dental therapists and the avoidance of travel and accommodation costs. Such savings could be redistributed to improve infrastructure and oral health services in rural or other underserved areas.What is known about the topic? Caries is a preventable disease, which, if it remains untreated, can cause significant morbidity requiring costly treatment. Regular dental screening and oral health education have the great potential

  5. THE USE OF POROUS CERAMICS FOR EVAPORATIVE AND EVAPORATIVE – VAPOR –COMPRESSION SYSTEMS

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    Cheban D.N.

    2013-04-01

    Full Text Available The use of natural evaporative cooling is one of technical solutions of problem of energy efficiency in air conditioning systems. The use of evaporative cooling in the first combined cooling stage allows reducing the load on the condenser of the cooling machine due to reducing of the condensing temperature. This combination allows the use of this type of system in any climatic conditions, including regions with small water resources. Multi-porous ceramic structure is used in evaporative air coolers and water coolers in this case. The objective of this paper is to show advantages of the using of porous ceramic as a working attachment, and to show advantages of the proposed scheme of compression-evaporation systems in comparison with standard vapor compression systems. Experimental research proved the fact, that in the film mode cooling efficiency of air flow is between EA=0,6÷0,7 and is slightly dependent of water flow. For countries with hot and dry climate where reserves of water are limited, it is recommended to use cyclical regime with EA≈0,65 value, or to use channel regime with a value of EA≈0,55. This leads to considerable energy savings. It has been determined, that combined air conditioning system is completely closed on the consumption of water at the parameters of the outside air equal to tA =32ºC and XA>13g/kg (in system with direct evaporative cooling machine, and tA=32ºC and XA>12g/kg (in system with indirect evaporative cooling machine. With these parameters, the cost of water in evaporative cooling stage can be fully compensated by condensate from the evaporator chiller.

  6. Erosion Resistance of CaO-Al2O3-SiO2 System Glass-Ceramics

    Institute of Scientific and Technical Information of China (English)

    HE Feng; NIU Feng; LOU Guang-hui; DENG Zhi-guo

    2004-01-01

    The erosion resistance tests were used to research the erosion wear behavior of CaO-Al2O3-SiO2 system glass-ceramic. With the orthogonal test method, the factors that affect the erosion wear of CaO-Al2O3-SiO2 system glass-ceramic such as particles property, impact angle, impact time, size of particles were discussed.The results show that erosion rate rises along a straight line at the early period of erosion wear.With the impact time increased,the erosion rate deviates from original staight line,tendency of the erosion rate increases.With the size of paricle increased,it will have more kinetic energy,the erosion rate of the surface of glass-ceramics ploate rises.

  7. The history and clinical application of a chairside CAD/CAM dental restoration system.

    Science.gov (United States)

    Stutes, Richard D

    2006-10-01

    Since its introduction by Sirona Dental Systems (Charlotte, North Carolina, USA and Bensheim, Germany) in 1985, the CEREC Chairside CAD/CAM restoration system has steadily earned a loyal following among dentists. This article describes the history and evolution of the CEREC System, its clinical application and treatment modality, the restorative materials used to fabricate the restorations and an overview of clinical findings regarding the in vivo performance of the materials.

  8. 牙科用氧化锆陶瓷的低温时效及其影响因素%Low temperature degradation of dental zirconia ceramic and its influencing factors

    Institute of Scientific and Technical Information of China (English)

    浩志超

    2012-01-01

    牙科用氧化锆陶瓷由于其良好的力学性能、高温稳定性、生物安全性和低热传导率,现已广泛应用于临床,特别是后牙全冠及固定桥修复.然而,在相对较低的温度及潮湿的环境下,氧化锆发生由部分稳定的四方晶相向单斜晶向的改变,即低温时效现象,影响其力学性能.本文探讨了牙科用氧化锆的低温时效及其影响因素,并讨论了改善其抗低温时效性的途径.%Dental zirconia ceramics, with their excellent mechanical properties, high temperature stability, bio-compatibility and low thermal conductivity, have been widely used for clinical all-ceramic restorations, especially for full crown and fixed bridge of posterior teeth. However, under comparatively low temperature in humid environment, partially stabilized tetragonal zirconia ceramic tends to transform into monoclinic crystal. This phenomenon is called low temperature degradation (LTD), which will result in poor mechanical properties of the material. This article discussed the LTD phenomena of the partially stabilized tetragonal zirconia and its related influencing factors, and possible approaches to improve its low temperature degradation resistance were proposed as well.

  9. Radiation dosage reduction in general dental practice using digital intraoral radiographic systems.

    Science.gov (United States)

    Hayakawa, Y; Shibuya, H; Ota, Y; Kuroyanagi, K

    1997-02-01

    This report describes the radiation dosage reduction possible in the general dental practice with two CCD (charge-coupled device)-based intraoral radiographic systems: the RVG-S (Trophy Radiologie, Vincennes, France) and the Sens-A-Ray (Regam Medical Systems, Sundsvall, Sweden). Radiation dosages (air-kerma; Gy) necessary for obtaining clinically acceptable images were measured at the cone tip using an ionization chamber type 660-1 (Nuclear Associates, Victoreen, Inc., Carle Place, New York, USA). When the RVG-S was used with an Oramatic 70 (Trophy Radiologie) X-ray generator, dosages at the cone tip ranged from 322 to 612 microGy. These corresponded to 40-60% of the dosages necessary when using Ektaspeed dental X-ray film (Eastman Kodak, Rochester, New York, USA) with a Heliodent 70 (Siemens, Erlangen, Germany) X-ray generator. At 60 kVp, the Sens-A-Ray reduced the dosage in the order of 30% compared with Ektaspeed dental X-ray film. Reduction in radiation dosage is one of the benefits of digital intraoral radiographic systems in general dental clinics. The RVG-S provides greater dose savings than does the Sens-A-Ray.

  10. Effect of moisture on dental enamel in the interaction of two orthodontic bonding systems.

    Science.gov (United States)

    Bertoz, André Pinheiro de Magalhães; de Oliveira, Derly Tescaro Narcizo; Gimenez, Carla Maria Melleiro; Briso, André Luiz Fraga; Bertoz, Francisco Antonio; Santos, Eduardo César Almada

    2013-01-01

    The purpose of this study was to assess by means of scanning electron microscopy (SEM) the remaining adhesive interface after debonding orthodontic attachments bonded to bovine teeth with the use of hydrophilic and hydrophobic primers under different dental substrate moisture conditions. Twenty mandibular incisors were divided into four groups (n = 5). In Group I, bracket bonding was performed with Transbond MIP hydrophilic primer and Transbond XT adhesive paste applied to moist substrate, and in Group II a bonding system comprising Transbond XT hydrophobic primer and adhesive paste was applied to moist substrate. Brackets were bonded to the specimens in Groups III and IV using the same adhesive systems, but on dry dental enamel. The images were qualitatively assessed by SEM. The absence of moisture in etched enamel enabled better interaction between bonding materials and the adamantine structure. The hydrophobic primer achieved the worst micromechanical interlocking results when applied to a moist dental structure, whereas the hydrophilic system proved versatile, yielding acceptable results in moist conditions and excellent interaction in the absence of contamination. The authors assert that the best condition for the application of primers to dental enamel occurs in the absence of moisture.

  11. Application of dental nanomaterials: potential toxicity to the central nervous system.

    Science.gov (United States)

    Feng, Xiaoli; Chen, Aijie; Zhang, Yanli; Wang, Jianfeng; Shao, Longquan; Wei, Limin

    2015-01-01

    Nanomaterials are defined as materials with one or more external dimensions with a size of 1-100 nm. Such materials possess typical nanostructure-dependent properties (eg, chemical, biological, optical, mechanical, and magnetic), which may differ greatly from the properties of their bulk counterparts. In recent years, nanomaterials have been widely used in the production of dental materials, particularly in light polymerization composite resins and bonding systems, coating materials for dental implants, bioceramics, endodontic sealers, and mouthwashes. However, the dental applications of nanomaterials yield not only a significant improvement in clinical treatments but also growing concerns regarding their biosecurity. The brain is well protected by the blood-brain barrier (BBB), which separates the blood from the cerebral parenchyma. However, in recent years, many studies have found that nanoparticles (NPs), including nanocarriers, can transport through the BBB and locate in the central nervous system (CNS). Because the CNS may be a potential target organ of the nanomaterials, it is essential to determine the neurotoxic effects of NPs. In this review, possible dental nanomaterials and their pathways into the CNS are discussed, as well as related neurotoxicity effects underlying the in vitro and in vivo studies. Finally, we analyze the limitations of the current testing methods on the toxicological effects of nanomaterials. This review contributes to a better understanding of the nano-related risks to the CNS as well as the further development of safety assessment systems.

  12. Gating Systems for Sizeable Castings from Al Alloys Cast into Ceramic Moulds

    Directory of Open Access Journals (Sweden)

    I. Stachovec

    2012-04-01

    Full Text Available In contrast to casting to conventional non-reusable “sand” moulds, for which calculating technique for an optimum design of the gating system is comparatively well-developed, a trial-and-error method is applied mostly for casting to ceramic shell moulds made by the investment casting technology. A technologist selects from gating systems of several types (that are standardized by the foundry mostly on the basis of experience. However, this approach is not sustainable with ever growing demands on quality of castings and also the economy of their fabrication as well as with new types of complex sizeable castings introduced to the production gradually (by new customers from the aircraft industry above all any more. The simulation software may be used as a possible tool for making the process of optimising gating systems more effective.

  13. Application of dental nanomaterials: potential toxicity to the central nervous system

    Directory of Open Access Journals (Sweden)

    Feng X

    2015-05-01

    Full Text Available Xiaoli Feng,1 Aijie Chen,1 Yanli Zhang,1 Jianfeng Wang,2 Longquan Shao,1 Limin Wei2 1Nanfang Hospital, Southern Medical University, Guangzhou, 2School and Hospital of Stomatology, Wenzhou Medical University, Wenzhou, People’s Republic of China Abstract: Nanomaterials are defined as materials with one or more external dimensions with a size of 1–100 nm. Such materials possess typical nanostructure-dependent properties (eg, chemical, biological, optical, mechanical, and magnetic, which may differ greatly from the properties of their bulk counterparts. In recent years, nanomaterials have been widely used in the production of dental materials, particularly in light polymerization composite resins and bonding systems, coating materials for dental implants, bioceramics, endodontic sealers, and mouthwashes. However, the dental applications of nanomaterials yield not only a significant improvement in clinical treatments but also growing concerns regarding their biosecurity. The brain is well protected by the blood–brain barrier (BBB, which separates the blood from the cerebral parenchyma. However, in recent years, many studies have found that nanoparticles (NPs, including nanocarriers, can transport through the BBB and locate in the central nervous system (CNS. Because the CNS may be a potential target organ of the nanomaterials, it is essential to determine the neurotoxic effects of NPs. In this review, possible dental nanomaterials and their pathways into the CNS are discussed, as well as related neurotoxicity effects underlying the in vitro and in vivo studies. Finally, we analyze the limitations of the current testing methods on the toxicological effects of nanomaterials. This review contributes to a better understanding of the nano-related risks to the CNS as well as the further development of safety assessment systems. Keywords: dental, nanomaterials, central nervous system, toxicity, testing methods, risk assessment

  14. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  15. Dynamic Systems (Complexity) theory as a new conceptual model for researching PBL in dental education.

    Science.gov (United States)

    Townsend, G C; Kim, M; Sankey, D

    2012-02-01

    Although problem-based learning (PBL) was introduced into dental education some 20 years ago, there have been relatively few well-designed studies carried out to clarify whether, how or why it works in a dental context. This paper introduces the Dynamic Systems (Complexity) theory as a new and potentially productive theoretical framework for researching PBL in dental education. This framework emphasises the importance of emergent self-organisation, perception and brain plasticity in learning. In this paper, a brief overview of the history of PBL in dentistry is presented and then the fundamentals of a Dynamic Systems Approach (DSA) are explained, drawing on two recently published papers advocating the DSA in medical education and teacher education. We focus on three key points related to this new approach: emergent self-organisation rather than simple construction of knowledge; the notion that perception drives the learning process; and the brain as the substrate of all learning. The paper also suggests how the DSA can help us move forward, both in terms of the future application of PBL in dental education and also in relation to posing new types of research questions.

  16. Clinical Performance Measures and Quality Improvement System Considerations for Dental Education.

    Science.gov (United States)

    Parkinson, Joseph W; Zeller, Gregory G

    2017-03-01

    Quality improvement and quality assurance programs are an integral part of providing excellence in health care delivery. The Dental Quality Alliance and the Commission on Dental Accreditation recognize this and have created standards and recommendations to advise health care providers and health care delivery systems, including dental schools, on measuring the quality of the care delivered to patients. Overall health care expenditures have increased, and the Affordable Care Act has made health care, including dentistry, available to more people in the United States. These increases in cost and in the number of patients accessing care contribute to a heightened interest in measurable quality improvement outcomes that reflect efficiency, effectiveness, and overall value. Practitioners and administrators, both in academia and in the "real world," need an understanding of various quality improvement methodologies available in order to select approaches that support effective monitoring of the quality of care delivered. This article compares and contrasts various quality improvement approaches, programs, and systems currently in use in order to assist dental providers and administrators in choosing quality improvement methodologies pertinent to their practice or institution.

  17. Physical evaluation system to determine medical risk and indicated dental therapy modifications.

    Science.gov (United States)

    McCarthy, F M; Malamed, S F

    1979-08-01

    The physical evaluation system allows the practitioner to rapidly classify each patient according to medical risk and thus to provide dental treatment comfortably and safely. The evaluation system serves as a guide to the level of dental therapy, deisions of management, and modification of treatment for the medically compromised patient. Extensive use of the ADA physical status classification system in dentistry would allow meaningful studies of morbidity and mortality that are related to various management protocols and could conceivably have an impact on insurance schedules associated with psychosedation modalities and general anethesia on an out patient basis. A physical evaluation system cannot substitute for knowledge and good judgment. Recommended categories of physical status and modification of treatment should not be considered as absolutes, but as guides. Wheras the guidelines may appear to be inflexible, they should not be considered as such. Deviation from recommendations is often justified and is expected.

  18. A comparison of career satisfaction amongst dental healthcare professionals across three health care systems: Comparison of data from the United Kingdom, New Zealand and Trinidad & Tobago

    Directory of Open Access Journals (Sweden)

    Newton J

    2006-03-01

    Full Text Available Abstract Background The aim of this study was to compare the expressed levels of career satisfaction of three groups of comparable dental healthcare professionals, working in Trinidad, the United Kingdom and New Zealand. Methods Three questionnaire surveys were carried out of comparable dental healthcare professionals. Dental nurses in Trinidad and dental therapists in the UK and New Zealand. Questionnaires were sent to all registered dental nurses or dental therapists. Results Career satisfaction was lowest amongst Dental Therapists working in Trinidad and Tobago. Approximately 59% of the Therapists working in New Zealand reported stated that they felt they were not a valued member of the dental team, the corresponding proportion in the United Kingdom was 32%, and for Trinidad 39%. Conclusion Dental therapists working in different healthcare systems report different levels of satisfaction with their career.

  19. Ceramic composites: Enabling aerospace materials

    Science.gov (United States)

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  20. Dental Fluorosis

    Science.gov (United States)

    ... have been broadly termed dental fluorosis. What is dental fluorosis? Dental fluorosis is a condition that causes ... less than 2 milligrams per liter. What causes dental fluorosis? Dental fluorosis is caused by taking in ...

  1. Dental Amalgam

    Science.gov (United States)

    ... Products and Medical Procedures Dental Devices Dental Amalgam Dental Amalgam Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Dental amalgam is a dental filling material which is ...

  2. Photoacoustic imaging of hidden dental caries by using a fiber-based probing system

    Science.gov (United States)

    Koyama, Takuya; Kakino, Satoko; Matsuura, Yuji

    2017-04-01

    Photoacoustic method to detect hidden dental caries is proposed. It was found that high frequency ultrasonic waves are generated from hidden carious part when radiating laser light to occlusal surface of model tooth. By making a map of intensity of these high frequency components, photoacoustic images of hidden caries were successfully obtained. A photoacoustic imaging system using a bundle of hollow optical fiber was fabricated for using clinical application, and clear photoacoustic image of hidden caries was also obtained by this system.

  3. GEL CASTING OF ALUMINA CERAMICS USING AN EGG WHITE PROTEIN BINDER SYSTEM

    Directory of Open Access Journals (Sweden)

    XING HE

    2011-02-01

    Full Text Available Egg white protein (EW is a food ingredient commonly used for its gelling properties and has been applied in ceramic fabrication. In this work, EW was used as an environmentally-friendly binder for gelcasting alumina ceramics at elevated temperature (80°C. The gelling behavior was compared with the ambient temperature drying-induced gelation processing. The processing conditions and mechanical properties of the ceramics processed from two different processing variants were compared. The results indicate that the ceramics from heat-induced gelation showed improved mechanical properties and more uniform microstructure after sintering in comparison to the drying-induced ones. Dense and complex-shaped ceramic parts via computer numerical controlled (CNC green machining have been produced from the EW gelcast ceramics.

  4. Periodontal-systemic disease education in U.S. and Canadian dental schools.

    Science.gov (United States)

    Wilder, Rebecca S; Iacopino, Anthony M; Feldman, Cecile A; Guthmiller, Janet; Linfante, Jeffrey; Lavigne, Salme; Paquette, David

    2009-01-01

    Research has proliferated in recent years regarding the relationship of oral disease to systemic conditions. Specifically, periodontal disease has been studied as a potential risk factor for multiple conditions such as cardiovascular disease (CVD) and adverse pregnancy outcomes, while other research focuses on exposures or behaviors associated with oral disease. However, few articles have been published reporting how this information is integrated into schools of dentistry, both in the classroom and clinical curriculum. For our study, a thirty-three-item survey and cover letter were electronically mailed to academic deans at sixty-five accredited dental schools in the United States and Canada in the fall of 2007. The response rate was 77 percent. According to the responses to this survey, the primary topics covered in the didactic curriculum regarding periodontal oral-systemic disease are aging, CVD, diabetes, and tobacco use. Eighty-eight percent of the respondents reported that their students are knowledgeable about the role of inflammation and its impact on oral-systemic conditions. Forty-eight percent of the respondents said they provide formal training for their students in how to discuss or communicate aspects of periodontal oral-systemic disease with patients. Only seven schools reported teaching didactic content to dental students intermixed with other health professions students, and only two schools reported conducting joint projects. Only 9 percent of the respondents said they think nurses and physicians are knowledgeable about oral-systemic disease. The findings indicate that dental schools are confident about the knowledge of their students regarding oral-systemic content. However, much work is needed to educate dental students to work in a collaborative fashion with other health care providers to co-manage patients at risk for oral-systemic conditions.

  5. Biofilm problems in dental unit water systems and its practical control.

    LENUS (Irish Health Repository)

    Coleman, D C

    2009-05-01

    Dental chair units (DCUs) contain integrated systems that provide the instruments and services for a wide range of dental procedures. DCUs use water to cool and irrigate DCU-supplied instruments and tooth surfaces during dental treatment. Water is supplied to these instruments by a network of interconnected narrow-bore (2-3 mm) plastic tubes called dental unit waterlines (DUWLs). Many studies over the last 40 years demonstrated that DUWL output water is often contaminated with high densities of micro-organisms, predominantly Gram-negative aerobic heterotropic environmental bacteria, including Legionella and Pseudomonas species. Untreated DUWLs host biofilms that permit micro-organisms to multiply and disperse through the water network and which are aerosolized by DCU instrument use, thus exposing patients and staff to these micro-organisms, to fragments of biofilm and bacterial endotoxins. This review concentrates on how practical developments and innovations in specific areas can contribute to effective DUWL biofilm control. These include the use of effective DUWL treatment agents, improvements to DCU supply water quality, DCU design changes, development of automated DUWL treatment procedures that are effective at controlling biofilm in the long-term and require minimal human intervention, are safe for patients and staff, and which do not cause deterioration of DCU components following prolonged use.

  6. A morphological analysis on the osteocytic lacunar canalicular system in bone surrounding dental implants.

    Science.gov (United States)

    Haga, Maiko; Nozawa-Inoue, Kayoko; Li, Minqi; Oda, Kimimitsu; Yoshie, Sumio; Amizuka, Norio; Maeda, Takeyasu

    2011-06-01

    Osseointegration is the most preferable interface of dental implants and newly formed bone. However, the cavity preparation for dental implants often gives rise to empty lacunae or pyknotic osteocytes in bone surrounding the dental implant. This study aimed to examine the chronological alternation of osteocytes in the bone surrounding the titanium implants using a rat model. The distribution of the osteocytic lacunar canalicular system (OLCS) in bone around the titanium implants was examined by silver impregnation according to Bodian's staining. We also performed double staining for alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP), as well as immunohistochemistry for fibroblast growth factor (FGF) 23--a regulator for the serum concentration of phosphorus--and sclerostin, which has been shown to inhibit osteoblastic activities. Newly formed bone and the injured bone at the early stage exhibited an irregularly distributed OLCS and a few osteocytes positive for sclerostin or FGF23, therefore indicating immature bone. Osteocytes in the surrounding bone from Day 20 to Month 2 came to reveal an intense immunoreactivity for sclerostin. Later on, the physiological bone remodeling gradually replaced such immature bone into a compact profile bearing a regularly arranged OLCS. As the bone was remodeled, FGF23 immunoreactivity became more intense, but sclerostin became less so in the well-arranged OLCS. In summary, it seems likely that OLCS in the bone surrounding the dental implants is damaged by cavity formation, but later gradually recovers as bone remodeling takes place, ultimately inducing mature bone. Copyright © 2011 Wiley-Liss, Inc.

  7. Wetting and dispersion in ceramic/polymer melt injection molding systems: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D.; Williams, J.W.; Batich, C.D.

    1986-11-01

    Research progress is reported in the areas of rheological characterization, mixing/deagglomeration, ceramic/polymer interface modification, polymer matrix chemistry, and microstructure characterization. (DLC)

  8. Treatment of abraded teeth using metal free ceramics and conventional metal-ceramic restorations

    Directory of Open Access Journals (Sweden)

    Bošković Mirjana V.

    2012-01-01

    Full Text Available Introduction. Contemporary reconstructive dentistry is considered to be a bioesthetic discipline, the study of the beauty of living creatures in their original form and functions. A discussion of esthetic dentistry, the sophisticated artificial restorations in the patient mouth, hardly discernible to an observer or expert eye, implies a whole series of qualities. Damage of hard tooth-tissue, which is not caused by caries, is a physiological process present throughout the whole life, but some factors can bring about great losses of the hard tissue. This damage can be caused by a combination of different etiological factors, such as genetical and functional ones. Case report. A patient is coming in dental surgery complaining of a large damage of the hard-tooth tissue, ugly appearance of his teeth, speech dysfunction and masticatory problems. An intraoral view shows the presence of a large teeth-abrasion. The treatment plan simplified the treatment with a combination of metal-ceramic restorations and a new ceramic system IPS e.max (Ivoclar Vivadentm Schaan, Liechtenstien. Conclusion. In this clinical case with presented abrasion the treatment was presented using all-ceramic restorations and classical metal-ceramic restorations to establish good health, function and estehetic. The use of restorations based on zirconium (IPS e.max ZirPress, Ivoclar Vivadent, Schaan, Liechtenstein can produce excellent clinical results in the frontal, as well as in lateral segments.

  9. Radiopaque Strontium Fluoroapatite Glass-Ceramics

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2–Al2O3–Y2O3–SrO–Na2O–K2O/Rb2O/Cs2O–P2O5–F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F – leucite, KAlSi2O6, (b) Sr5(PO4)3F – leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F – pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  10. Radiopaque Strontium Fluoroapatite Glass-Ceramics.

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2-Al2O3-Y2O3-SrO-Na2O-K2O/Rb2O/Cs2O-P2O5-F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F - leucite, KAlSi2O6, (b) Sr5(PO4)3F - leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F - pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F - Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite - pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal expansion (CTE). These

  11. Micrometric precision of prosthetic dental crowns obtained by optical scanning and computer-aided designing/computer-aided manufacturing system

    Science.gov (United States)

    das Neves, Flávio Domingues; de Almeida Prado Naves Carneiro, Thiago; do Prado, Célio Jesus; Prudente, Marcel Santana; Zancopé, Karla; Davi, Letícia Resende; Mendonça, Gustavo; Soares, Carlos José

    2014-08-01

    The current study evaluated prosthetic dental crowns obtained by optical scanning and a computer-aided designing/computer-aided manufacturing system using micro-computed tomography to compare the marginal fit. The virtual models were obtained with four different scanning surfaces: typodont (T), regular impressions (RI), master casts (MC), and powdered master casts (PMC). Five virtual models were obtained for each group. For each model, a crown was designed on the software and milled from feldspathic ceramic blocks. Micro-CT images were obtained for marginal gap measurements and the data were statistically analyzed by one-way analysis of variance followed by Tukey's test. The mean vertical misfit was T=62.6±65.2 μm; MC=60.4±38.4 μm; PMC=58.1±38.0 μm, and RI=89.8±62.8 μm. Considering a percentage of vertical marginal gap of up to 75 μm, the results were T=71.5%, RI=49.2%, MC=69.6%, and PMC=71.2%. The percentages of horizontal overextension were T=8.5%, RI=0%, MC=0.8%, and PMC=3.8%. Based on the results, virtual model acquisition by scanning the typodont (simulated mouth) or MC, with or without powder, showed acceptable values for the marginal gap. The higher result of marginal gap of the RI group suggests that it is preferable to scan this directly from the mouth or from MC.

  12. The effect of core material, veneering porcelain, and fabrication technique on the biaxial flexural strength and weibull analysis of selected dental ceramics.

    Science.gov (United States)

    Lin, Wei-Shao; Ercoli, Carlo; Feng, Changyong; Morton, Dean

    2012-07-01

    The objective of this study was to compare the effect of veneering porcelain (monolithic or bilayer specimens) and core fabrication technique (heat-pressed or CAD/CAM) on the biaxial flexural strength and Weibull modulus of leucite-reinforced and lithium-disilicate glass ceramics. In addition, the effect of veneering technique (heat-pressed or powder/liquid layering) for zirconia ceramics on the biaxial flexural strength and Weibull modulus was studied. Five ceramic core materials (IPS Empress Esthetic, IPS Empress CAD, IPS e.max Press, IPS e.max CAD, IPS e.max ZirCAD) and three corresponding veneering porcelains (IPS Empress Esthetic Veneer, IPS e.max Ceram, IPS e.max ZirPress) were selected for this study. Each core material group contained three subgroups based on the core material thickness and the presence of corresponding veneering porcelain as follows: 1.5 mm core material only (subgroup 1.5C), 0.8 mm core material only (subgroup 0.8C), and 1.5 mm core/veneer group: 0.8 mm core with 0.7 mm corresponding veneering porcelain with a powder/liquid layering technique (subgroup 0.8C-0.7VL). The ZirCAD group had one additional 1.5 mm core/veneer subgroup with 0.7 mm heat-pressed veneering porcelain (subgroup 0.8C-0.7VP). The biaxial flexural strengths were compared for each subgroup (n = 10) according to ISO standard 6872:2008 with ANOVA and Tukey's post hoc multiple comparison test (p≤ 0.05). The reliability of strength was analyzed with the Weibull distribution. For all core materials, the 1.5 mm core/veneer subgroups (0.8C-0.7VL, 0.8C-0.7VP) had significantly lower mean biaxial flexural strengths (p strength (p= 0.004) than subgroup 0.8C-0.7VP. Nonetheless, both veneered ZirCAD groups showed greater flexural strength than the monolithic Empress and e.max groups, regardless of core thickness and fabrication techniques. Comparing fabrication techniques, Empress Esthetic/CAD, e.max Press/CAD had similar biaxial flexural strength (p= 0.28 for Empress pair; p= 0

  13. The flexible requirement system for grading of clinical performance of undergraduate dental students.

    Science.gov (United States)

    ElBadrawy, H; Korayem, M

    2007-11-01

    A new grading system is presented for evaluating and grading dental students' clinical competence and performance in paediatric dentistry at the undergraduate level. The Flexible Requirements System is a clinical competence evaluation system designed to address some of the common deficiencies of other requirements-based performance evaluation systems, by utilising a unique method of collecting and manipulating certain measurements of student performance in various groups of clinical procedures. The system aimed to incorporate adequate flexibility in its requirements to afford students fair and equal opportunities, whilst maintaining adherence to departmental clinical competence criteria and standards.

  14. Ultrasonic Guided-Wave Scan System Used to Characterize Microstructure and Defects in Ceramic Composites

    Science.gov (United States)

    Roth, Don J.; Cosgriff, Laura M.; Martin, Richard E.; Verrilli, Michael J.; Bhatt, Ramakrishna T.

    2004-01-01

    Ceramic matrix composites (CMCs) are being developed for advanced aerospace propulsion applications to save weight, improve reuse capability, and increase performance. However, mechanical and environmental loads applied to CMCs can cause discrete flaws and distributed microdamage, significantly reducing desirable physical properties. Such microdamage includes fiber/matrix debonding (interface failure), matrix microcracking, fiber fracture and buckling, oxidation, and second phase formation. A recent study (ref. 1) of the durability of a C/SiC CMC discussed the requirement for improved nondestructive evaluation (NDE) methods for monitoring degradation in these materials. Distributed microdamage in CMCs has proven difficult to characterize nondestructively because of the complex microstructure and macrostructure of these materials. This year, an ultrasonic guided-wave scan system developed at the NASA Glenn Research Center was used to characterize various microstructural and flaw conditions in SiC/SiC (silicon carbide fiber in silicon carbide matrix) and C/SiC (carbon fiber in silicon carbide matrix) CMC samples.

  15. Modeling and Simulation of Ballistic Penetration of Ceramic-Polymer-Metal Layered Systems

    Directory of Open Access Journals (Sweden)

    J. D. Clayton

    2015-01-01

    Full Text Available Numerical simulations and analysis of ballistic impact and penetration by tungsten alloy rods into composite targets consisting of layers of aluminum nitride ceramic tile(s, polymer laminae, and aluminum backing are conducted over a range of impact velocities on the order of 1.0 to 1.2 km/s. Computational results for ballistic efficiency are compared with experimental data from the literature. Simulations and experiments both demonstrate a trend of decreasing ballistic efficiency with increasing impact velocity. Predicted absolute residual penetration depths often exceed corresponding experimental values. The closest agreement between model and experiment is obtained when polymer interfaces are not explicitly represented in the numerical calculations, suggesting that the current model representation of such interfaces may be overly compliant. The present results emphasize the importance of proper resolution of geometry and constitutive properties of thin layers and interfaces between structural constituents for accurate numerical evaluation of performance of modern composite protection systems.

  16. [Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance].

    Science.gov (United States)

    de Baat, C; Witter, D J; Meijers, C C A J; Vergoossen, E L M; Creugers, N H J

    2014-03-01

    The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and metal-ceramic single-unit fixed dental prosthesis is determined by the configuration's convergence angle, the height, the volume, the interocclusal space, the cervical outline design, the additional preparations, the quality of the (build-up) restoration, and the surface roughness. A silicate ceramic single-unit fixed dental prosthesis is attached through adhesion using a composite cement, but the retention and resistance of an oxide ceramic single-unit fixed dental prosthesis is dependent on the abutment tooth configuration. Most types of multi-unit fixed dental prosthesis have the following additional retention and resistance determining factors: the position in the occlusal system, the number of abutment teeth and their mutual configurations, and the length of (cantilever) pontics. A resin-bonded fixed partial denture's retention and resistance are determined by its bonding as well as its enamel surface coverage and its resistance preparations.

  17. Impact of rehabilitation with metal-ceramic restorations on oral health-related quality of life.

    Science.gov (United States)

    da Silva, Gisele Rodrigues; Roscoe, Marina Guimarães; Ribeiro, Cristianne Pacheco; da Mota, Adérito Soares; Martins, Luís Roberto Marcondes; Soares, Carlos José

    2012-01-01

    Dental ceramics present excellent ability to reproduce the natural teeth regarding esthetic and biomechanics. Recently, due to the advancement of ceramic technology, metal-free restorations were developed. However, the traditional metal-ceramic restorations still present the requirements of high strength, long survival in the oral environment and favorable aesthetics. In this context, it is essential to know the specificity of each ceramic system available in order to apply it properly to various clinical situations. This report describes an integrated rehabilitation using metal-ceramic restorations of a patient at 50 years of age, who presented edentulous spaces, and previous unsatisfactory composite and amalgam restorations, and indirect metallic restorations, leading to compromised quality of life in both functional and psychosocial aspects. The impact on quality of life was measured using a generic instrument, OHIP-14, validated for the World Health Organization, which covers both the biological and the psychosocial dimensions. This instrument was applied to the patient before and after treatment. The patient had an overall OHIP-14 score of 28 before the treatment and after treatment the score decreased to 0, showing that dental and oral health conditions are factors that do impact on the quality of life. Rehabilitation has provided functional and aesthetic restorations, harmony of the stomatognathic system and improvement of life quality.

  18. Perapation of mica-based glassceramics for denta CAD/CAM system

    Institute of Scientific and Technical Information of China (English)

    LI Hong; RAN Junguo; GOU Li; ZHAO Yunfeng

    2001-01-01

    @@ Ceramic materials have received considerable application in biomedical and dental restoration because of their relative higher mechanical properties, excellent biocompatibility and good natural aesthetics. Development of machinable glass-ceramicsin dental CAD/CAM maching system have provided a new impetus for fabrication ofceramic restorations.

  19. 3-dimensional orthodontics visualization system with dental study models and orthopantomograms

    Science.gov (United States)

    Zhang, Hua; Ong, S. H.; Foong, K. W. C.; Dhar, T.

    2005-04-01

    The aim of this study is to develop a system that provides 3-dimensional visualization of orthodontic treatments. Dental plaster models and corresponding orthopantomogram (dental panoramic tomogram) are first digitized and fed into the system. A semi-auto segmentation technique is applied to the plaster models to detect the dental arches, tooth interstices and gum margins, which are used to extract individual crown models. 3-dimensional representation of roots, generated by deforming generic tooth models with orthopantomogram using radial basis functions, is attached to corresponding crowns to enable visualization of complete teeth. An optional algorithm to close the gaps between deformed roots and actual crowns by using multi-quadratic radial basis functions is also presented, which is capable of generating smooth mesh representation of complete 3-dimensional teeth. User interface is carefully designed to achieve a flexible system with as much user friendliness as possible. Manual calibration and correction is possible throughout the data processing steps to compensate occasional misbehaviors of automatic procedures. By allowing the users to move and re-arrange individual teeth (with their roots) on a full dentition, this orthodontic visualization system provides an easy and accurate way of simulation and planning of orthodontic treatment. Its capability of presenting 3-dimensional root information with only study models and orthopantomogram is especially useful for patients who do not undergo CT scanning, which is not a routine procedure in most orthodontic cases.

  20. [Methods of disinfection of water systems in dental units by water chlorination].

    Science.gov (United States)

    Fiehn, N E; Henriksen, K

    1989-01-01

    The aim of the present study was to develop a simple disinfection method to reduce the content of bacteria in the water system of dental units to an acceptable level. The study was carried out at the Royal Dental College, Copenhagen on 250 dental units. Samples of the cooling water to the ultrasonic scalers and of the water to the water glasses were obtained from eight different units representing different parts of the school. Disinfection of the water system was carried out by addition of chlorine to the pipe water near the main water intake to the institution. The chlorination af the water was automatically regulated, and the installation was so flexible that the concentration of chlorine and the time and frequency of the chlorination could be varied. Different modes of dosage of chlorine were examined. Before chlorination the bacterial content in the water system of the units was about 10(4)-10(5) c.f.u./ml. It was found that an intermittent chlorination with 0.5-1 ppm chlorine for 10 min. every day could normally reduce the bacterial counts in the water system to about a few hundreds per ml.

  1. Methods of disinfection of the water system of dental units by water chlorination.

    Science.gov (United States)

    Fiehn, N E; Henriksen, K

    1988-12-01

    The aim of the present study was to develop a simple disinfection method for reducing the content of bacteria in the water system of dental units to an acceptable level. The study was carried out at the Royal Dental College, Copenhagen, on 250 dental units. Samples of the cooling water supplying the ultrasonic scalers and of the water supplying the water glasses were obtained from eight different units representing different parts of the school. Disinfection of the water system was carried out by addition of chlorine to the pipe water near the institution's main water intake. The chlorination of the water was automatically regulated, and the installation was so flexible that the concentration of chlorine and the time and frequency of the chlorination could be varied. Different modes of chlorine dosage were examined. Before chlorination, the bacterial content in the water system of the units was about 10(4)-10(5) cfu/mL. It was found that an intermittent chlorination with 0.5-1 ppm chlorine for 10 minutes every day could reduce the normal bacterial counts in the water system to about a few hundred per mL.

  2. User evaluation on dental care in the Unified Health System: an approach from the standpoint of humanization

    National Research Council Canada - National Science Library

    Suzely Adas Saliba Moimaz; Arinilson Moreira Chaves Lima; Clea Adas Saliba Garbin; Jose Eduardo Corrente; Nemre Adas Saliba

    2016-01-01

      The scope of this study was to assess user evaluation about dental care in the Unied Health System and analyze the associations between this evaluation, sociodemographic characteristics, and aspects...

  3. The effect of surface roughness on ceramics used in dentistry: A review of literature.

    Science.gov (United States)

    Rashid, Haroon

    2014-10-01

    Long term clinical success of modern dental ceramics depends on a number of factors. These factors include the physical properties of the material, the laboratory fabrication process, the laboratory fabrication technique and clinical procedures that may damage these brittle materials. The surface structure and composition of a dental restorative material influences the initial bacterial adhesion, and a rough