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Sample records for hot-pressed veneer products

  1. Numerical simulation of hot-pressed veneer products: Forming - Spring back – Distortion

    DEFF Research Database (Denmark)

    Ormarsson, Sigurdur; Sandberg, Dick

    2007-01-01

    Customers demand very high quality of veneered furniture products with regard to surface appearance, shape stability and stiffness. To meet these requirements, it is important to improve the manufacturing process by a better understanding of the thermo-hygro-mechanical behaviour of the individual...... veneers. During the manufacture of strongly curved products, the veneers are exposed to large membrane and bending deformations and to high pressure in the radial fibre direction. When hot-press forming is used, the veneers are also exposed to a high surface temperature during the pressing time (curing...... time). These severe conditions can result in plastic deformation perpendicular to the veneer surface as well as mechano-sorptive strains in the curved regions, since the heating can have a significant influence on the moisture distribution. How strong an influence these factors have on the distortion...

  2. [Esthetic restoration for anterior teeth with the hot pressed porcelain laminate veneers].

    Science.gov (United States)

    Xu, Shao-ping; Luo, Xiao-ping; Shi, Yu-juan

    2012-10-01

    To evaluate the esthetic effect of anterior porcelain veneers fabricated with the heat pressed glass ceramic. Thirty-two patients, who wanted to receive a aesthetic restorative treatment for 206 anterior teeth were selected. Among them, 20 were for dental fluorosis, 8 were for light tetracycline stained teeth, the other 4 were labial enamel hypoplasia or obvious crack on the surface of enamel. According to the color of adjacent teeth,skin and lips, heat pressed IPS e.max ingots of different color were chosen to mold the restorations. Afterwards, special straining technique was conducted on the marginal ridge and incisor ridge of the veneers after carefully trimmed in the mouth. Restorations were them bonded with Variolink II resin cement. After 7 years of follow-up, a modified USPHS criterion was used to evaluate the esthetic effect. The translucency of veneers was superior. Marginal integrity of the veneers was perfect and it docked well with the marginal terminate line of the abutment. There was no edge coloring after the veneers were used for 7 years, and the veneers produce an excellent chameleon effect by absorbing the color of adjacent teeth and gums, at the same time, veneers could produce a feature of surface morphology of natural enamel after careful carve. In the long-term clinical observation, 5 of the 206 veneers were fractured or fell off. This porcelain laminate veneers fabricated from the heat pressed IPS e.max Press ingots include the following advantages, such as simple operating procedure, high mechanical strength, very little dental tissue was ground off and nice aesthetic effect. Ultra-thin veneers are especially suitable for aesthetic practice to dental fluorosis, light tetracycline and natural worn teeth.

  3. Hot-pressed geopolymer

    DEFF Research Database (Denmark)

    Ranjbar, Navid; Mehrali, Mohammad; Maheri, Mahmoud R.

    2017-01-01

    /FA, duration of hot-pressing and sodium concentration are studied. Together with detailed experimental studies, our results reveal that the most dominant factor is the induced pressure. The main results indicated that the highest compressive strength of the geopolymer (134 MPa) could be obtained by employing...... the hot pressing, temperature and duration of 41.4 MPa, 350 °C and 20 min, respectively. The microstructure of the hot-pressed specimens showed more developed geopolymer matrix compared with conventional ones leading to higher compressive strength in much shortest time. The improved mechanical properties...

  4. Production of Porous β-Type Ti–40Nb Alloy for Biomedical Applications: Comparison of Selective Laser Melting and Hot Pressing

    Directory of Open Access Journals (Sweden)

    Ksenia Zhuravleva

    2013-12-01

    Full Text Available We used selective laser melting (SLM and hot pressing of mechanically-alloyed β-type Ti–40Nb powder to fabricate macroporous bulk specimens (solid cylinders. The total porosity, compressive strength, and compressive elastic modulus of the SLM-fabricated material were determined as 17% ± 1%, 968 ± 8 MPa, and 33 ± 2 GPa, respectively. The alloy’s elastic modulus is comparable to that of healthy cancellous bone. The comparable results for the hot-pressed material were 3% ± 2%, 1400 ± 19 MPa, and 77 ± 3 GPa. This difference in mechanical properties results from different porosity and phase composition of the two alloys. Both SLM-fabricated and hot-pressed cylinders demonstrated good in vitro biocompatibility. The presented results suggest that the SLM-fabricated alloy may be preferable to the hot-pressed alloy for biomedical applications, such as the manufacture of load-bearing metallic components for total joint replacements.

  5. Veneer-log production and receipts, North Central Region, 1970

    Science.gov (United States)

    Thomas P. Jr. Ginnaty

    1972-01-01

    The 1970 Lake States veneer-log production and mill receipts were 34.4 and 37.0 million board feet, respectively. The Central States produced 23.5 million board feet and received 30.0 million board feet of veneer logs. Veneer-log production and mill receipts dropped substantially throughout the north central region from 1968.

  6. Veneer-log production and receipts, North Central Region, 1974.

    Science.gov (United States)

    James E. Blyth; Jerold T. Hahn

    1976-01-01

    Shows 1974 veneer-log production and receipts by species in the Lake States (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data for 1972. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the Central...

  7. Veneer-log production and receipts, North Central Region, 1976.

    Science.gov (United States)

    James E. Blyth; Jerold T. Hahn

    1978-01-01

    Shows 1976 veneer-log production and receipts by species in the Lake States (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data for 1974. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the Central...

  8. Veneers

    Science.gov (United States)

    ... special cement is sandwiched between the veneer and tooth, a light beam hardens the cement. ... to your "new" teeth that have changed in size and shape. Brush and floss daily. After one or two weeks, ...

  9. 75 FR 41896 - Colville Indian Plywood and Veneer Colville Tribal Enterprise Corporation Wood Products Division...

    Science.gov (United States)

    2010-07-19

    ... Employment and Training Administration Colville Indian Plywood and Veneer Colville Tribal Enterprise..., applicable to workers of Colville Indian Plywood and Veneer, Colville Tribal Enterprise Corporation Wood... Veneer, Colville Tribal Enterprise Corporation Wood Products Division. The Department has determined that...

  10. Effects of press sizes on internal steam pressure during particleboard hot-pressing process

    Science.gov (United States)

    Zhiyong Cai; Michael Birkeland; James M. Wescott; Jane O' Dell; Jerrold E. Winandy

    2009-01-01

    Internal steam pressure produced during the hot-pressing cycle in particleboard production is critical to the newly developed bond strength that will determine the overall performance of particleboard. The difference between the accumulation of internal steam pressure for small panels made in the laboratory and that of large commercial-sized panels makes it difficult...

  11. Veneer Log Production and Receipts in the Southeast, 1969

    Science.gov (United States)

    Richard L. Welch

    1971-01-01

    In 1969, production of veneer logs was almost 657 million board feet in the Southeast, while receipts of domestic logs at the 136 mills in the area were over 690 million board feet. Pine log production now amounts to 40 percent of the total, while hardwood log production is down 17 percent from that of 1963.

  12. Production of laminated veneer lumber LVL using veneer of Schizolobium amazonicum, Eucalyptus saligna and Pinus taeda

    OpenAIRE

    Setsuo Iwakiri; Jorge Luis Monteiro de Matos; Juliana Afonso Pinto; Lívia Cássia Viana; Marina Moura de Souza; Rosilani Trianoski; Vanessa Coelho Almeida

    2010-01-01

    This research evaluated the quality of laminated veneer lumber - LVL manufactured with veneers of Schizolobium amazonicum (paricá), Eucalyptus saligna and Pinus taeda. The LVL panels were manufactured in the laboratory conditions composed by seven veneers, 2,0 mm thickness, with different structural compositions, using phenol-formaldehyde resin. The veneers of Schizolobium amazonicum- paricá- were pre-classified by using stress wave machine. The veneers of Eucalyptus saligna and Pinus taeda w...

  13. Control system for glassing hot presses

    Energy Technology Data Exchange (ETDEWEB)

    Howell, J.F.

    1984-06-13

    A software programmable control system has been developed that automates the glass fusing process used in the production of semiconductor thermopile elements. The new control system replaces an older, mostly manual, electromechanical design. This report describes the new control design and its functional features.

  14. ACTIVATED HOT PRESSING BEHAVIOR OF WC NANOPOWDERS

    Directory of Open Access Journals (Sweden)

    Edwin GEVORKYAN

    2010-06-01

    Full Text Available The questions of consolidation of nanopowders concerning hot compaction by pressing activated by electric current action are considered. Mechanisms of grain boundary creep-sliding which are sequentially prevalent in a forming of compacted structures under influence of temperature factor and in the presence of a direct electric heating are discussed. Structural-transformational sources and conditions of forming of high physical-mechanical properties of nanopowder refractory solid-state products are described.

  15. 76 FR 35474 - Colville Indian Plywood and Veneer, Colville Tribal Enterprise Corporation Wood Products Division...

    Science.gov (United States)

    2011-06-17

    ... Employment and Training Administration Colville Indian Plywood and Veneer, Colville Tribal Enterprise... Veneer, Colville Tribal Enterprise Corporation Wood Products Division, Omak, Washington. The Department's... employed on-site at the Omak, Washington location of Colville Indian Plywood and Veneer, Colville Tribal...

  16. Low-loss binder for hot pressing boron nitride

    Science.gov (United States)

    Maya, Leon

    1991-01-01

    Borazine derivatives used as low-loss binders and precursors for making ceramic boron nitride structures. The derivative forms the same composition as the boron nitride starting material, thereby filling the voids with the same boron nitride material upon forming and hot pressing. The derivatives have a further advantage of being low in carbon thus resulting in less volatile byproduct that can result in bubble formation during pressing.

  17. Production of laminated veneer lumber LVL using veneer of Schizolobium amazonicum, Eucalyptus saligna and Pinus taeda

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2010-12-01

    Full Text Available This research evaluated the quality of laminated veneer lumber - LVL manufactured with veneers of Schizolobium amazonicum (paricá, Eucalyptus saligna and Pinus taeda. The LVL panels were manufactured in the laboratory conditions composed by seven veneers, 2,0 mm thickness, with different structural compositions, using phenol-formaldehyde resin. The veneers of Schizolobium amazonicum- paricá- were pre-classified by using stress wave machine. The veneers of Eucalyptus saligna and Pinus taeda were disposed in the face layer to reinforce the structural strength of LVL panels. The LVL quality was evaluated using glue line shear strength and static bending test (MOE and MOR, edge and flat. Grading of paricá veneers based on MOEd did not affected significantly the results of the glue line shear strength and MOE and MOR edge. For the MOE and MOR flat, the use of veneers of MOEd grade 1 contributed significantly to increasing the average values of these properties. In the same way, using the Eucalyptus saligna veneers on the face of LVL resulted in higher average values of MOE and MOR, edge and flat.

  18. Hot-pressed transparent PLZT ceramics from low cost chemical processing

    Directory of Open Access Journals (Sweden)

    I.A. Santos

    2001-10-01

    Full Text Available Lanthanum-modified lead zirconate titanate (PLZT ceramics were obtained with high transmittance in the visible range by a combination of an inexpensive chemical processing and hot pressing. Optical, microstructural, pyroelectric, ferroelectric and dielectric properties characterized in this study attested the applicability of the employed method in the production of PLZT transparent ferroelectric ceramics. In fact, the corresponding analyzed physical parameters are in very good agreement with those obtained in samples traditionally prepared by other methods. Furthermore, due to high sample quality, a phenomenological analysis of the PLZT 10/65/35 relaxor features was performed in these ceramics.

  19. Hot Pressing and Characterization of Powder Based Silicon Substrates for Photovoltaic Applications.

    OpenAIRE

    Juven, Phillip

    2012-01-01

    High purity silicon material in solar cell fabrication constitutes 40% of the total cost for conventional solar cell production. One approach to reduce costs would be to use less of this expensive silicon by making thin film solar cells and use a cheaper substrate as mechanical carrier.In this work the main objective has been to manufacture silicon substrates from powder by hot-pressing. The effect of the sintering parameters has been characterized. A secondary objective was to look at the po...

  20. Microstructure characteristics of high borated stainless steel fabricated by hot-pressing sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuan; Wang, Mingjia, E-mail: mingjiawangysu@126.com; Zhao, Hongchang

    2016-04-25

    The present study investigated the microstructure of powder metallurgy (P/M) high borated stainless steel through hot-pressing sintering in a temperature range of 1000–1150 °C within 30 min under 30 MPa. Microstructure and phase examinations were carried out by applying scanning electron microscope, electron backscatter diffraction and X-ray diffraction analysis. The results of as-atomized powders demonstrated that many powders kept egg-type structure with an austenite outer layer and the eutectic borides were much finer than those in traditional cast products. Microstructure studies revealed that borides suffered Ostwald ripening and were significantly influenced by the sintering temperature. Orientation maps indicated that the inter-particle contact areas consisted of equiaxed grains and the regions consisting of large elongated grains partly inherited the microstructure characteristics of as-atomized powder particles. Furthermore, the mechanisms governing the morphological changes in microstructure were discussed. - Highlights: • Near-complete densification could be obtained through hot-pressing sintering. • There was no phase transformation and present phases were M{sub 2}B and austenite. • Borides suffered Ostwald ripening and were significantly influenced by temperature. • Inter-particle contact areas consisted of equiaxed grains for recrystallization. • Deformation-free zones exhibited elongated grains for dendritic arms coarsening.

  1. Minimizing hot-press time in the manufacturing process of wood plastic composites

    Directory of Open Access Journals (Sweden)

    Nazanin Motie

    2013-11-01

    Full Text Available In this study, the reduction in the hot press time using high thermally conductive fillers and the influenceof these fillers on physical and mechanical properties of end products was investigated. Variable factors in these treatments were type and content of fillers. Press time and other factors such as the amount of wood flour, board density, and other conditions of press were fixed. Composites were prepared from Beech (Fagus orientalis flour, Polypropylene, MAPP, and conductive fillers such as flake and powder graphite (carbonic fillers, and Alumina (ceramic filler. Fillers with contents of 5 and 10% in 15 and 20 minutes for press time were utilized. A thermocouple was utilized to measure the temperature in the core of composite and to determine the time being panel core as the same temperature as the hot press surface. It showed that fillers reduce press time as 2-4 minutes. Mechanical tests including tension, bending, impact and hardness were performed. Fillers except of flake graphite had no restriction in mechanical properties. Water uptake and swelling as physical properties were also measured and fillers didn’t have a significant effect on these tests. To validate the experimental results, thermal conductivity of composites was determined and the increase in this property was evaluated. The increase in samples contain flake and powder graphite was more remarkable than those contain Alumina.

  2. Microstructure, hardness, corrosion resistance and porcelain shear bond strength comparison between cast and hot pressed CoCrMo alloy for metal-ceramic dental restorations.

    Science.gov (United States)

    Henriques, B; Soares, D; Silva, F S

    2012-08-01

    The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal-porcelain bond strength of a CoCrMo dental alloy obtained by two routes, cast and hot pressing. CoCrMo alloy substrates were obtained by casting and hot pressing. Substrates' microstructure was examined by the means of Optical Microscopy (OM) and by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Hardness tests were performed in a microhardness indenter. The electrochemical behavior of substrates was investigated through potentiodynamic tests in a saline solution (8g NaCl/L). Substrates were bonded to dental porcelain and metal-porcelain bond strength was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Fractured surfaces as well as undestroyed interface specimens were examined with Stereomicroscopy and SEM-EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The t-test (pbond strength results. Cast specimens exhibited dendritic microstructures whereas hot pressed specimens exhibited a typical globular microstructure with a second phase spread through the matrix. The hardness registered for hot pressed substrates was greater than that of cast specimens, 438±24HV/1 and 324±8HV/1, respectively. Hot pressed substrates showed better corrosion properties than cast ones, i.e. higher OCP; higher corrosion potential (E(corr)) and lower current densities (i(corr)). No significant difference was found (pbond strength between cast (116.5±6.9 MPa) and hot pressed (114.2±11.9 MPa) substrates. The failure type analysis revealed an adhesive failure for all specimens. Hot pressed products arise as an alternative to cast products in dental prosthetics, as they impart enhanced mechanical and electrochemical properties to prostheses without compromising the metal-ceramic bond strength. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity

    Science.gov (United States)

    Lajis, Mohd Amri; Ahmad, Azlan

    2017-01-01

    Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices. PMID:28771207

  4. Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

    Directory of Open Access Journals (Sweden)

    Qingbin Luan

    2014-12-01

    Full Text Available Technologically important low-resistivity bulk Si has been usually produced by the traditional Czochralski growth method. We now explore a novel method to obtain low-resistivity bulk Si by hot-pressing B- and P-hyperdoped Si nanocrystals (NCs. In this work bulk Si with the resistivity as low as ∼ 0.8 (40 mΩ•cm has been produced by hot pressing P (B-hyperdoped Si NCs. The dopant type is found to make a difference for the sintering of Si NCs during the hot pressing. Bulk Si hot-pressed from P-hyperdoped Si NCs is more compact than that hot-pressed from B-hyperdoped Si NCs when the hot-pressing temperature is the same. This leads to the fact that P is more effectively activated to produce free carriers than B in the hot-pressed bulk Si. Compared with the dopant concentration, the hot-pressing temperature more significantly affects the structural and electrical properties of hot-pressed bulk Si. With the increase of the hot-pressing temperature the density of hot-pressed bulk Si increases. The highest carrier concentration (lowest resistivity of bulk Si hot-pressed from B- or P-hyperdoped Si NCs is obtained at the highest hot-pressing temperature of 1050 °C. The mobility of carriers in the hot-pressed bulk Si is low (≤  ∼ 30 cm-2V-1s-1 mainly due to the scattering of carriers induced by structural defects such as pores.

  5. Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Luan, Qingbin; Ni, Zhenyi; Zhu, Tiejun; Yang, Deren; Pi, Xiaodong, E-mail: xdpi@zju.edu.cn [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Koura, Setsuko [Nisshin Steel Co. Ltd., Marunouchi 3 Chome, Chiyoda-ku, Tokyo 100-8366 (Japan)

    2014-12-15

    Technologically important low-resistivity bulk Si has been usually produced by the traditional Czochralski growth method. We now explore a novel method to obtain low-resistivity bulk Si by hot-pressing B- and P-hyperdoped Si nanocrystals (NCs). In this work bulk Si with the resistivity as low as ∼ 0.8 (40) mΩ•cm has been produced by hot pressing P (B)-hyperdoped Si NCs. The dopant type is found to make a difference for the sintering of Si NCs during the hot pressing. Bulk Si hot-pressed from P-hyperdoped Si NCs is more compact than that hot-pressed from B-hyperdoped Si NCs when the hot-pressing temperature is the same. This leads to the fact that P is more effectively activated to produce free carriers than B in the hot-pressed bulk Si. Compared with the dopant concentration, the hot-pressing temperature more significantly affects the structural and electrical properties of hot-pressed bulk Si. With the increase of the hot-pressing temperature the density of hot-pressed bulk Si increases. The highest carrier concentration (lowest resistivity) of bulk Si hot-pressed from B- or P-hyperdoped Si NCs is obtained at the highest hot-pressing temperature of 1050 °C. The mobility of carriers in the hot-pressed bulk Si is low (≤  ∼ 30 cm{sup -2}V{sup -1}s{sup -1}) mainly due to the scattering of carriers induced by structural defects such as pores.

  6. Microstructural analysis of hot press formed 22MnB5 steel

    Science.gov (United States)

    Aziz, Nuraini; Aqida, Syarifah Nur; Ismail, Izwan

    2017-10-01

    This paper presents a microstructural study on hot press formed 22MnB5 steel for enhanced mechanical properties. Hot press forming process consists of simultaneous forming and quenching of heated blank. The 22MnB5 steel was processed at three different parameter settings: quenching time, water temperature and water flow rate. 22MnB5 was processed using 33 full factorial design of experiment (DOE). The full factorial DOE was designed using three factors of quenching time, water temperature and water flow rate at three levels. The factors level were quenching time range of 5 - 11 s, water temperature; 5 - 27°C and water flow rate; 20 - 40 L/min. The as-received and hot press forming processed steel was characterised for metallographic study and martensitic structure area percentage using JEOL Field Emission Scanning Electron Microscopic (FESEM). From the experimental finding, the hot press formed 22MnB5 steel consisted of 50 to 84% martensitic structure area. The minimum quenching time of 8 seconds was required to obtain formed sample with high percentage of martensite. These findings contribute to initial design of processing parameters in hot press forming of 22MnB5 steel blanks for automotive component.

  7. Hot-pressing steatite bodies; Obtencion de eseatita por prensado en caliente

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio Arroyo, E.

    1967-07-01

    Requirements for some special nuclear engineering ceramic shapes are: big size, impervious, dimensional accuracy and good mechanical and dielectric properties. Limitations of te conventional methods and advantages of te hot pressing techniques for the manufacturing of these shapes are discussed. Hot pressing characteristics of a certain steatite powder are studied. Occurrence of an optimum densification temperature just above the tale decomposition range is found. Experimental data show that the height/diameter ratio of the specimen has no effect on the sintering conditions. Increasing darkness from the graphite mould is detected above the optimum temperature. The hot-pressed steatite is compared with a fired dry-pressed sample of the same composition. (Author) 13 refs.

  8. Thermoelectric properties of hot-pressed CrSi2 samples

    Science.gov (United States)

    Solomkin, F. Yu.; Samunin, A. Yu.; Zaitsev, V. K.; Burkov, A. T.; Novikov, S. V.; Gurieva, E. A.

    2012-06-01

    Thermoelectric properties and structure of CrSi2 samples fabricated by hot-pressing from crushed textured bars and from microcrystals grown from melt-solution in tin are studied. A strong dependence of thermoelectric properties of the synthesized material and of the pressed samples on size and shape of the crystal unit cell is found.

  9. An overview of high thermal conductive hot press forming die material development

    Directory of Open Access Journals (Sweden)

    A.R. Zulhishamuddin

    2015-12-01

    Full Text Available Most of the automotive industries are using high strength steel components, which are produced via hot press forming process. This process requires die material with high thermal conductivity that increases cooling rate during simultaneous quenching and forming stage. Due to the benefit of high quenching rate, thermal conductive die materials were produced by adding carbide former elements. This paper presents an overview of the modification of alloying elements in tool steel for high thermal conductivity properties by transition metal elements addition. Different types of manufacturing processes involved in producing high thermal conductive materials were discussed. Methods reported were powder metallurgy hot press, direct metal deposition, selective laser melting, direct metal laser sintering and spray forming. Elements likes manganese, nickel, molybdenum, tungsten and chromium were proven to increase thermal conductivity properties. Thermal conductivity properties resulted from carbide network presence in the steel microstructure. To develop feasible and low cost hot press forming die material, casting of Fe-based alloy with carbide former composition can be an option. Current thermal conductivity properties of hot press forming die material range between 25 and 66 W/m.K. The wide range of thermal conductivity varies the mechanical properties of the resulting components and lifetime of HPF dies.

  10. A study on the influence of hot press forming process parameters on ...

    African Journals Online (AJOL)

    Hence an attempt is made in this work to improve the mechanical properties of green composites by optimizing the hot press forming process parameters using Taguchi experimental design. Process parameters such as temperature, pressure, heating time, cooling system and recrystallization soak time were chosen for ...

  11. Safe trapping of cesium into pollucite structure by hot-pressing method

    Energy Technology Data Exchange (ETDEWEB)

    Omerašević, Mia, E-mail: mia@vinca.rs [University of Belgrade, Institute of Nuclear Sciences “Vinča”, Materials Department, PO Box 522, 11001 Belgrade (Serbia); Matović, Ljiljana; Ružić, Jovana [University of Belgrade, Institute of Nuclear Sciences “Vinča”, Materials Department, PO Box 522, 11001 Belgrade (Serbia); Golubović, Željko [First Quantum Minerals Ltd., 543 Granville Street, Vancouver, British Colombia, V6C 1X8 (Canada); Jovanović, Uroš [University of Belgrade, Institute of Nuclear Sciences “Vinča”, Chemical Dynamics Laboratory, P.O. Box 522, 11001 Belgrade (Serbia); Mentus, Slavko; Dondur, Vera [University of Belgrade, Faculty of Physical Chemistry, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2016-06-15

    A simple one-step method with direct thermal conversion at lower temperatures for preparing a stabile Cs-aluminsilicate phase, known as pollucite, is presented. Cs-exchanged form of Na, Ca-LTA type of zeolite (Cs-LTA) was pressureless sintered and hot pressed at certain temperatures in order to obtain pollucite. XRD and FTIR analysis were used to study structural changes of Cs-LTA before and after thermal treatments. Pressureless sintered sample recrystallized into pollucite phase after heat treatment at 1000 °C (3 h) (PLS1000) and hot pressed sample at 750 °C (3 h) using pressure of 35 MPa (HP750), indicating reduced temperature of 250°. SEM micrographs confirmed that HP750 has higher density than PLS1000 which leads to higher value of compressive strength. The HP750 showed better resistance to Cs leaching than the PLS1000. Base on these results one can conclude that hot pressing is the promising method for the permanent disposal of Cs radionuclides. - Highlights: • Na, Ca-LTA zeolite showed high affinity for Cs ions. • Pollucite phase was obtained using hot pressing at temperature as low as ​750 °C. • HP750 shows better mechanical and morphological properties than PLS1000. • HP750 has lower leaching rate of Cs ions than PLS1000.

  12. Effect of Hot-Pressing Temperature on the Subsequent Enzymatic Saccharification and Fermentation Performance of SPORL Pretreated Forest Biomass

    Science.gov (United States)

    Jingzhi Zhang; Andrea Laguna; Craig Clemons; Michael P. Wolcott; Rolland Gleisner; J.Y. Zhu; Xu Zhang

    2015-01-01

    Methods to increase the energy density ofbiofuel feedstock for shipment are important towards improving supply chain efficiency in upstream processes. Towards this end, densified pretreated lignocellulosic biomass was produced using hot-pressing. The effects offiber hornification induced by hot-pressing on enzymatic digestibilities of lodgepolepine and poplar NE222...

  13. Phase Composition and Microstructure of Hot-Pressing Sintered Ti2AlN Metal-Ceramic Bulk Material

    Directory of Open Access Journals (Sweden)

    LIANG Suying

    2017-06-01

    Full Text Available Ti2AlN metal-ceramic bulk material was fabricated by hot-pressing sintering (HPS using TiN, Ti and Al powder in a stoichiometric ratio of 1:1:1.03 after mechanical mixing. XRD, SEM and TEM were employed to investigate the phase composition and microstructures of the products. The results show that the high purity Ti2AlN can be obtained by HPS at 1300 ℃ for 2.5 h. The sintered Ti2AlN presented a hexagonal system layered structure with an anisotropy. Twins are found in the Ti2AlN. There were a few nano-scale TiN particles in the products.

  14. Investigation on Indium-Filled Skutterudite Materials Prepared by Combining Hydrothermal Synthesis and Hot Pressing

    Science.gov (United States)

    Du, Y.; Cai, K. F.; Chen, S.; Qin, Z.; Shen, S. Z.

    2011-05-01

    Indium-filled CoSb3 materials have been investigated by combining hydrothermal synthesis and hot pressing. The materials were prepared as follows. Corresponding nanopowders were synthesized by a hydrothermal synthesis method, in some cases followed by melting at 1373 K, and then hot pressed at 923 K. The phase composition and microstructure of the bulk materials were analyzed by conventional methods, such as x-ray diffraction (XRD), scanning electron microscopy (SEM), and field-emission SEM equipped with energy-dispersive x-ray spectroscopy (EDS). The thermoelectric properties of the bulk materials were measured from room temperature to 773 K. The results reveal that indium can be successfully filled into the voids of the CoSb3 structure when the sample preparation procedure contains melting. The influence of the processing on the thermoelectric properties of the materials is also discussed.

  15. Influence of hot-pressing on MgB{sub 2}/Nb/Monel wires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.H., E-mail: KIM.Jungho@nims.go.j [Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Matsumoto, A. [Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Maeda, M. [Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Yamada, Y.; Wada, K.; Tachikawa, K. [School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Rindfleisch, M.; Tomsic, M. [Hyper Tech Research, Incorporated, 1275 Kinnear Road, Columbus, OH 43212 (United States); Kumakura, H. [Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2010-11-01

    Uniaxial hot-pressing was applied as an alternative way to further improve the grain connectivity of both un-doped and carbon doped MgB{sub 2}/Nb/Monel wires. In this study, hot-pressing of 100 MPa resulted in the improvement of the mass density, the critical current density, and the grain connectivity of the wires. However, this also caused additional critical current density anisotropy, which is associated with the texture of a- and b-axes oriented grains. In particular, the anisotropy factors of critical current density for the un-doped and the carbon doped conductors were estimated to be 2.6 and 1.7, respectively, under an external magnetic field of 14 T.

  16. Effect Of Hot Pressing On The Electrochemical Properties Of Ti-Ni Alloy

    Directory of Open Access Journals (Sweden)

    Balcerzak M.

    2015-06-01

    Full Text Available Ti2Ni alloy pellets were produced by mechanical alloying and hot pressing at 750°C for 0.5 h in vacuum. X-ray diffraction analysis showed that, after 8 h of milling, a starting mixture of elements mostly decomposed into an amorphous phase. Obtained powders and flakes have cleavage fracture morphology with huge number of dimples with different sizes. Hot pressing of materials caused formation of Ti2Ni main phase. Porosity of pellets strongly depended on size of agglomerates and pressure of pressing. Ti2Ni pellets were used as negative electrodes for Ni-MHx batteries. Maximum measured discharge capacity of studied materials was 220 mAh/g. Electrochemical properties resulted from size of agglomerates, degree of oxidation and pressure of pressing.

  17. Shear bond strength of a hot pressed Au-Pd-Pt alloy-porcelain dental composite.

    Science.gov (United States)

    Henriques, B; Soares, D; Silva, F S

    2011-11-01

    The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a Au-Pt-Pd alloy-porcelain composite. Several metal-porcelain composites specimens were produced by two different routes: conventional porcelain fused to metal (PFM) and hot pressing. In the latter case, porcelain was hot pressed onto a polished surface (PPPS) as well as a roughened one (PPRS). Bond strength of all metal-porcelain composites were assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Interfaces of fractured specimens as well as undestroyed interface specimens were examined with optical microscope, stereomicroscope, Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The data were analyzed using one-way ANOVA followed by Tuckey's test (pporcelain (p0.05). This study shows that it is possible to significantly improve metal-porcelain bond strength by applying an overpressure during porcelain firing. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Microstructure and Mechanical Behavior of Hot Pressed Cu-Sn Powder Alloys

    Directory of Open Access Journals (Sweden)

    Ahmed Nassef

    2016-01-01

    Full Text Available Cu-Sn based alloy powders with additives of elemental Pb or C were densified by hot pressing technique. The influence of densifying on the properties of the hot pressed materials was investigated. The properties, such as the hardness, compressive strength, and wear resistance of these materials, were determined. The hot pressed Cu-Sn specimens included intermetallic/phases, which were homogeneously distributed. The presence of graphite improved the wear resistance of Cu-Sn alloys three times. Similarly, the presence of lead improved the densification parameter of Cu-Sn alloys three times. There was no significant difference in the mechanical behavior associated with the addition of Pb to the Cu-Sn alloys, although Cu-Pb alloys showed considerably higher ultimate strength and higher elongation. The Cu-Sn-C alloys had lower strength compared with those of Cu-Sn alloys. Evidence of severe melting spots was noticed in the higher magnifications of the compression fracture surface of 85% Cu-10% Sn-5% C and 80% Cu-10% Sn-10% Pb alloys. This was explained by the release of load at the final event of the fracture limited area.

  19. Hot-pressed polymer nanofiber supported graphene membrane for high-performance nanofiltration

    Science.gov (United States)

    Wang, Zhao; Sahadevan, Rajesh; Yeh, Che-Ning; Menkhaus, Todd J.; Huang, Jiaxing; Fong, Hao

    2017-08-01

    Graphene oxide (GO) sheets can be readily surface-overlaid on hot-pressed electrospun polyacrylonitrile (PAN) nanofiber membrane to form a continuous and crack-free layer; upon thermal reduction at 150 °C for 12 h, the resulting reduced GO (rGO) layer can reject ∼90% MgSO4 with high water flux (due to the size exclusion mechanism), making the prepared PAN-rGO membranes promising nanofiltration media for water purification. It is important to note that no delamination of GO/rGO sheet layers has been observed throughout this study. We highlight that a simple processing method (i.e., hot pressing) is critical for the successful preparation of 2D materials (e.g., GO/rGO) based membranes/media. It is envisioned that the reported study can benefit many groups working on various membrane applications of 2D materials; in other words, the hot-pressed electrospun nanofiber membranes could be generally utilized as an innovative type of platform to support various 2D sheets for different separation applications such as highly efficient and cost-effective removal of dissolved components (e.g., organic molecules) and even (hydrated) ions from water.

  20. Sintering and characterization of processed YSZ using hot pressing; Sinterizacao e caracterizacao de YSZ processada por prensagem a quente

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, R.; Oliveira, W.S. [Faculdade de Engenharia Quimica, Departamento de Ciencia e Tecnologia de Materiais, Universidade Estadual de Campinas, SP (Brazil)], e-mail: r009722@dac.unicamp.br; Abrantes, J.C.C. [UIDM, ESTG, Instituto Politecnico de Viana do Castelo (Portugal); CICECO, Departamento de Ceramica e do Vidro, Universidade de Aveiro (Portugal)], E-mail: jabrantes@estg.ipvc.pt

    2010-11-15

    The hot pressing was used for sintering of Yttria stabilized zirconia (YSZ) and the consequent effects on microstructure and electric properties were evaluated. For comparison, a sample of YSZ conventionally processed was sintered (sintered at 1500 deg C with no pressure applied for 4 hours) as opposed to samples by hot pressing, sintered at 1200 deg C, 75 MPa for 4 hours too. The average sizes of grains had differences of about one order of magnitude: 0.373 {mu}m for hot pressing and 2.932 {mu}m for the obtained conventionally, maintaining both a densification near 100% density theoretical zirconia. In the samples, the total ionic conductivity had not significant differences, only a lower grain boundary conductivity of sample by hot pressing, due to the reduction of grain size. This difference is inlighted by brick layer model. (author)

  1. Ultra-low thermal conductivities of hot-pressed attapulgite and its potential as thermal insulation material

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuan; Ren, Zhifeng, E-mail: bohr123@163.com, E-mail: zren@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Wang, Xiuzhang [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology and School of Physics and Electronic Science, Hubei Normal University, Huangshi, Hubei 435002 (China); Wang, Yumei [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Tang, Zhongjia; Makarenko, Tatyana; Guloy, Arnold [Department of Chemistry, University of Houston, Houston, Texas 77204 (United States); Zhang, Qinyong, E-mail: bohr123@163.com, E-mail: zren@uh.edu [Center for Advanced Materials and Energy, Xihua University, Chengdu, Sichuan 610039 (China)

    2016-03-07

    In the past, there have been very few reports on thermal properties of attapulgite which is a widely used clay mineral. In this work, we report on extremely low thermal conductivities in attapulgite samples synthesized by hot-pressing. Attapulgite powder was hot-pressed at different temperatures into bulk samples, and a systematic study was conducted on the microstructures and thermal properties. Differential scanning calorimetry analysis shows that hot-pressing induces a rapid dehydration of the attapulgite powders. X-ray diffraction data and scanning/transmission electron microscopy reveal that the hot-pressed attapulgite features high porosity and complex microstructures, including an amorphous phase. As a result, the hot-pressed attapulgite exhibits thermal conductivity less than 2.5 W m{sup −1} K{sup −1} up to 600 °C. For one sample with porosity of 45.7%, the thermal conductivity is as low as 0.34 W m{sup −1} K{sup −1} at 50 °C. This suggests the potential of hot-pressed attapulgite as a candidate for thermal barrier materials.

  2. Model Building and Optimization Analysis of MDF Continuous Hot-Pressing Process by Neural Network

    Directory of Open Access Journals (Sweden)

    Qingfa Li

    2016-01-01

    Full Text Available We propose a one-layer neural network for solving a class of constrained optimization problems, which is brought forward from the MDF continuous hot-pressing process. The objective function of the optimization problem is the sum of a nonsmooth convex function and a smooth nonconvex pseudoconvex function, and the feasible set consists of two parts, one is a closed convex subset of Rn, and the other is defined by a class of smooth convex functions. By the theories of smoothing techniques, projection, penalty function, and regularization term, the proposed network is modeled by a differential equation, which can be implemented easily. Without any other condition, we prove the global existence of the solutions of the proposed neural network with any initial point in the closed convex subset. We show that any accumulation point of the solutions of the proposed neural network is not only a feasible point, but also an optimal solution of the considered optimization problem though the objective function is not convex. Numerical experiments on the MDF hot-pressing process including the model building and parameter optimization are tested based on the real data set, which indicate the good performance of the proposed neural network in applications.

  3. 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.

  4. Large enhancement of the electrocaloric effect in PLZT ceramics prepared by hot-pressing

    Directory of Open Access Journals (Sweden)

    Guangzu Zhang

    2016-06-01

    Full Text Available In this contribution, we demonstrate the optimization of the microstructures of the Pb0.85La0.1(Zr0.65Ti0.35O3 (PLZT relaxor ferroelectric ceramics and subsequent enhancements in their polarization and electrical resistivity by using a hot-pressing process. The resulting superior breakdown strength of hot-pressed PLZT enables the application of high electric field to induce a giant electrocaloric effect, in which the adiabatic change of temperature (ΔT and the isothermal change of entropy (ΔS are around 2 times greater than those of the samples prepared by the conventional sintering approach using muffle furnace. Moreover, the addition of extra PbO to make up the loss of Pb in the high-temperature sintering leads to the further improvements in the phase composition and electrical properties of PLZT, due to inhibition of the pyrochlore phase formation. The relationship among the sintering conditions, the content of excess PbO, and the microstructure as well as the electrical characteristics of PLZT have been investigated in a systematic manner. This work provides a facile approach to enhanced electrocaloric effect in bulk ceramics.

  5. Machining Performance of Hot-Pressed Carbon Nanotube Reinforced Alumina Cutting Tool Insert

    Science.gov (United States)

    Sarkar, Snehashis; Das, Santanu; Sarkar, Soumya; Das, Probal Kumar

    2017-06-01

    Machining performance of monolithic alumina (Al2O3) tool inserts for metal cutting through carbon nanotube (CNT) incorporation was studied in this work. 0.3 vol% multiwalled CNT(MWCNT)-Al2O3 nanocomposite was prepared by hot-pressing at 1550°C with a dwell of 1 h under 2.5 MPa uniaxial pressure in static argon atmosphere. The hot-pressed nanocomposite achieved >99.5% of its theoretical density. The specimen also offered improved fracture toughness, KIC ( 23% higher), flexural strength, σFS ( 10% higher), hardness, HV1 ( 7.5% higher) and thermal conductivity, κ ( 30% higher) compared to those of pure Al2O3 (KIC = 5.23 MPa-m0.5, σFS = 341.01 MPa, HV1 = 18.80 GPa, κ = 23.69 W/mK). Inserts developed with this nanocomposite having 0.8 and 1 mm nose radii demonstrated successful machining during turning of AISI 4340 steel rod (hardness = 38 HRC) in dry environment under different cutting conditions and showed promising applicability in machining industry.

  6. Fabrication of laminated ZrC-SiC composite by vacuum hot-pressing sintering

    Directory of Open Access Journals (Sweden)

    Yuanyuan Li

    2015-03-01

    Full Text Available Laminated ZrC-SiC ceramic was prepared through tape casting and hot pressing. The green tapes of ZrC and SiC were prepared at room temperature. In order to improve the density of composite, the binder of green tapes were removed at 550 °C for 1 h. The laminated structure and the cracks propagation path, which is not a straight line, are observed by optical metalloscope. The compact laminated ZrC-SiC composite sintered by vacuum hot-pressing at 1650 °C for 90 min under pressure of 20 MPa was researched by X-ray diffraction and scanning electron microscopy (SEM equipped with energy dispersive X-ray analysis. The results showed that interlayer bonding is tight, and no disordered phase has formed in the interlayers of ZrC or SiC, and the combination mode is physical mechanism.

  7. Fabrication and microstructures of functional gradient SiBCN–Nb composite by hot pressing

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Min, E-mail: lcxsunmin@163.com [Beijing Institute of Control Engineering, Beijing 100190 (China); Fu, Ruoyu; Chen, Jun; Mao, Xiaofang; Zhang, Jie [Beijing Institute of Control Engineering, Beijing 100190 (China); Yang, Zhihua; Liang, Bin [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150080 (China)

    2016-04-15

    A functional gradient material with five layers composed of SiBCN ceramic and niobium (Nb) was prepared successfully by hot pressing. The phase composition, morphology features and microstructures were investigated in each layer of the gradient material. The Nb-containing compounds involving NbC, Nb{sub 6}C{sub 5}, Nb{sub 4}C{sub 3}, Nb{sub 5}Si{sub 3} and NbN increase with the volume fraction of Nb increasing in the sub-layer. They are randomly scattered (≤ 25 vol.% Nb), then strip-like, and finally distribute continuously (≥ 75 vol.% Nb). The size of BN(C) and SiC grains in Nb-containing layers is larger than in 100% SiBCN layer due to the loss of the capsule-like structures. No distinct interfaces form in the transition regions indicating the gradual changes in phase composition and microstructures. - Highlights: • A functional gradient SiBCN–Nb material was prepared successfully by hot pressing. • Phase composition, morphology features and microstructures were investigated. • Thermodynamic calculation was used to aid in the phase analysis. • No distinct interfaces form typical of the functional gradient material.

  8. Evaluation of the use potential of nine species of genus Eucalyptus for production of veneers and plywood panels

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2013-06-01

    Full Text Available The objective of thisstudywas to evaluate the use potential of nine species of Eucalyptus for production of veneer sheets and multilaminated plywood panels. Veneers were cut using a pilot laminating lathe to a nominal thickness of 2.0 mm. Analysis included finding values of overall yield and yield according to three quality classes for the nine relevant species. Plywood panels were manufactured in a laboratory, consisting of five 2.0 mm veneer sheets which were bonded together with phenol-formaldehyde resin at a weight of 360 g/m2 (double line. The panels were compressed using a specific pressure of 10 kgf/cm2, a temperature of 140ºC and a pressing time of 10 minutes. Results indicated that, with the exception of E. phaeotricha and E. pellita, all other Eucalyptus species had above 50% average veneer yield after lamination. Results of glue line shear testing and static bending parallel and perpendicular demonstrated that species Eucalyptus grandis, Eucalyptus saligna, Eucalyptus dunnii, Eucalyptus globulus, Eucalyptus viminalis, Eucalyptus robusta and Eucalyptus pellita have great potential within the parameters of this study for use in the production of veneer sheets and plywood panels intended for outdoor use.

  9. VENEER AND PLYWOOD PRODUCTION OF GUAPURUVU WOOD (Schizolobium parayba Blake. COMING FROM A MIXED PLANTATION OF BRAZILIAN TREE SPECIES

    Directory of Open Access Journals (Sweden)

    Geraldo Bortoletto Júnior

    2003-01-01

    Full Text Available The objective of this study was to evaluate the potential of the guapuruvu wood(Schizolobium parayba, coming a mixed plantings of Brazilian native species, for veneer and plywoodproduction. The peeling yield was 61%, linking green veneer and peeling wood. The obtained veneers, afterclipped and dried, they were graded according to Brazilian Standards (NBR 9531/1986. Thefollowing grades o veneer were obtained: 2% of grade A, 24% of grade B, 48% of grade C and 26%of grade D. After, it was manufactured plywood of grade B/C/B, glued with urea-formaldehydeadhesive, and their properties of static bending (MOR and MOE and bonding line strength in shear test (dry and wet were appraised. Treatments (1, 2 and 3 varied according to the formulation of theglue (35, 50 and 65% of wheat flour in relation to the pure adhesive. The results indicated that theguapuruvu wood has potential for veneer and plywood production. The plywood showed significantdifference between treatments in the static bending (perpendicular MOR and shear (dry and wet. Theplywood presents possibility of interior and intermediate use for the formulations 1 and 2, and interioruse for the formulation 3. The plywood has potential for use in furniture, packing and box factory.

  10. Influence of Thinning and Pruning on Southern Pine Veneer Quality

    Science.gov (United States)

    Mark D. Gibson; Terry R. Clason; Gary L. Hill; George A. Grozdits

    2002-01-01

    This paper presents the effects of intensive pine plantation management on veneer yields, veneer grade distribution and veneer MOE as measured by ultrasonic stress wave transmission (Metriguard). Veneer production trials were done at a commercial southern pine plywood plant to elucidate the effects of silvicultural treatments on veneer quality, yield, and modulus of...

  11. Veneer, 1976 - a periodic assessment of regional timber output

    Science.gov (United States)

    James T. Bones; David R. Dickson

    1978-01-01

    The 1976 veneer industry survey in the Northeast showed that since the 1972 survey: Veneer log production rose 5 percent to 132 million board feet. Veneer log receipts at northeastern veneer plants dropped less than 1 percent. There were seven fewer veneer plants operating in the Northeast; new softwood plywood plant will be consuming northeastern timber. Exports of...

  12. A new integration of hot pressing and carbon partition process to produce high strength steel components with better toughness

    Directory of Open Access Journals (Sweden)

    Zhang Shi-hong

    2015-01-01

    Full Text Available A novel one step method for hot pressing and quench & partition (Q&P integration – hot Pressing-dynamic partitioning (HP-DP process is presented, which can be processed by regular hot pressing equipment and process. The HP-DP formed steel is an upgrade of the existing hot pressed steel especially suitable for making high strength components with superior crashworthiness due to better toughness. Corresponding steel sheet based on conventional 22MnB5 is designed and prepared. After that, the physical simulation experiments for HP-DP are carried out on thermal-mechanical simulator. Microstructure of the steel subjected to HP-DP treatment, with a typical Q&P treated feature, is mainly composed of initial quenched martensite phase, final quenched martensite phase and retained austenite phase, which indicate the occurrence of carbon diffusion concomitantly with martensite transformation. Compared with conventional hot pressed samples, the HP-DP samples show both better tensile property especially elongation and impact energy absorption ability. The effect of HP-DP parameters on the stability of retained austenite and mechanical property is also discussed. The paper illustrates the promising application potential of the HP-DP process.

  13. Manufacturing Flax Fibre-Reinforced Polypropylene Composites by Hot-Pressing

    Science.gov (United States)

    Jolly, Marc; Jayaraman, Krishnan

    The renewable characteristic of natural fibres, such as flax, and the recyclable nature of thermoplastic polymers, such as polypropylene, provide an attractive eco-friendly quality to the resulting composite materials. Common methods for manufacturing natural fibre-reinforced thermoplastic composites, injection moulding and extrusion, tend to degrade the fibres during processing. Development of a simple manufacturing technique for these composites, that minimises fibre degradation, is the main objective of this study. Flax fibres were conditioned, cut into lengths ranging from 1 mm to 30 mm with scissors and a pelletiser, and shaped into randomly oriented mats using a drop feed tower. Polypropylene in sheet form, was added to the fibres to furnish polypropylene/flax/polypropylene sandwiches with a fibre mass fraction of 25%, which were then consolidated by the hot pressing technique. Tensile, flexural and impact properties of these composite sheets were determined as functions of fibre length and processing temperature.

  14. Characteristics of hot-pressed fiber-reinforced ceramics with SiC matrix

    Science.gov (United States)

    Miyoshi, Tadahiko; Kodama, Hironori; Sakamoto, Hiroshi; Goto, Akihiro; Iijima, Shiroo

    1989-11-01

    Silicon carbide ceramics’ matrix composites with SiC or C filaments were fabricated through hot pressing, and the effects of the filament pullout on their fracture toughness were experimentally investigated. The C-rich coating layers on the SiC filaments were found to have a significant effect on the frictional stress at the filament/matrix interfaces, through assising the filamet pullout from the matrix. Although the coating layers were apt to burn out in the sintering process of SiC matrix compposites, a small addition of carbon to the raw materials was found to be effective for the retention of the layers on the fibers, thus increasing the fracture toughness of the composites. The fracture toughness of the C filament/SiC matrix composite increased with temperature due to the larger interfacial frictional stress at higher temperatures, because of the higher thermal expansion of the filament in the radial direction than that of the matrix.

  15. Micromechanisms of deformation in high-purity hot-pressed alumina

    Energy Technology Data Exchange (ETDEWEB)

    Staehler, J.M.; Predebon, W.W.; Subhash, G. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Mechanical Engineering and Engineering Mechanics; Pletka, B.J. [Metallurgical and Materials Engineering Dept., Michigan Technological Univ., Houghton, MI (United States)

    2000-10-31

    A high-strength aluminum oxide was produced by vacuum hot pressing high-purity, submicron-size alumina powders. The uniaxial compressive fracture strength was strongly strain-rate sensitive and varied from 5.5 GPa at 10{sup -4} s{sup -1} to 8.3 GPa at 10{sup 3} s{sup -1}. A Hugoniot elastic limit of about 11.9 GPa was determined from flyer plate impact tests. The deformation/fracture process was examined using both uniaxial stress and uniaxial strain conditions. Under a uniaxial stress condition, microplasticity was observed in the form of aligned dislocations that appeared similar to shear bands in metals. Under a uniaxial strain condition, extensive dislocation activity, grain boundary microcracking and occasional twins were observed. Based on the experimental results and microscopic observations, possible mechanisms responsible for the observed high strength and high strain-rate sensitivity in this alumina are discussed. (orig.)

  16. Microstructure and fracture toughness of hot pressed zirconia-toughened sialon

    Energy Technology Data Exchange (ETDEWEB)

    Cain, M.G.; Lewis, M.H. (Univ. of Warwick, Coventry (United Kingdom))

    1993-06-01

    Zirconia-toughened sialon composites have been fabricated using conventional hot-pressing techniques. The fracture toughness and microstructure were determined for CeO[sub 2]- and Y[sub 2]O[sub 3]-stabilized ZrO[sub 2] additives and also as a function of volume percent ZrO[sub 2]. The Yttria system showed a linear increase in fracture toughness with increasing volume fraction zirconia content while the ceria-stabilized system exhibited a peak in fracture toughness at 20 vol% ZrO[sub 2] content. The fracture toughness at 800 C was measured and correlated with the microstructure. High-temperature stability was determined and it was found that the deleterious nitride phases of zirconium could be precluded from the microstructure.

  17. Investigation of microstructure in hot-pressed Nb–23Ti–15Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Wu, Duoli; Jin, Tao; Sun, Xiaofeng; Zheng, Qi, E-mail: qzheng@imr.ac.cn

    2015-07-05

    Highlights: • The Ti(O, C), a new strengthening phase, is found in Nb–Ti–Al alloys. • Ti(O, C) has a face-centered cubic structure and a lattice parameter of 4.27 Å. • Two different morphologies of Ti(O, C) are observed. • β and δ phases exhibit as large irregular blocks and equiaxed particles. • Ordering of β phase is observed in hot-pressed Nb–Ti–Al alloy. - Abstract: Microstructure of hot-pressed Nb–23Ti–15Al alloy has been systematically investigated, with emphasis on the characterization of Ti(O, C) phase. The microstructure and composition of Nb–23Ti–15Al alloy were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA). The results indicate the presence of β, δ and Ti(O, C) phases in the alloy. The β phase exhibits as large irregular blocks, while the δ phase presents as small equiaxed particles linked together around β blocks. Ordering of β phase is shown by related selected area electronic diffraction (SAED) patterns and dark-field micrograph. The Ti(O, C), a solid-solution of TiO or TiC, is characterized for the first time in Nb–Ti–Al alloy. The Ti(O, C) has a face-centered cubic (FCC) structure and a moderate lattice parameter between that of TiO and TiC. Two different morphologies of Ti(O, C) are observed in the alloy: large cobblestone-like aggregated particles and small dispersive particles. The formation of Ti(O, C) phase can potentially increase high-temperature strength of Nb–Ti–Al alloy.

  18. The Novel Design and Manufacturing Technology of Densified RDF from Reclaimed Landfill without a Mixing Binding Agent Using a Hydraulic Hot Pressing Machine

    Directory of Open Access Journals (Sweden)

    Kerdsuwan Somrat

    2016-01-01

    Full Text Available The manufacturing of RDF (Refuse Derived Fuel from a conventional cold press extrusion machine is not suitable for producing RDF from reclaimed landfill since it is not identical in shape and form after production due to the swelling of the plastic fraction contained inside the reclaimed landfill and hence needs a very high compression force. Moreover, a binder agent is needed in order to keep the RDF in a similar shape and form. A novel design and manufacturing technology for a hydraulic hot pressing machine has been established and can produce high-quality RDF without any binder. The two electrical heaters are installed at the inner core and on the surface of the mold. The compression force on the mold is performed by a hydraulic jack. In addition, a newly-designed locking plate system which is designed by a slider to open and close along the paired horizontal slots, can reduce the cycle time of the manufacturing process and yield higher productivity. The testing properties of the RDF produced by the novel hydraulic hot pressing machine include the examination of size, shape, weight, unit density, bulk density, compression strength, moisture content, and heating value. The results showed that the RDF is suitable to be used as feedstock in an incinerator or gasifier to produce green and clean energy from reclaimed landfill.

  19. Importance of Electrode Hot-Pressing Conditions for the Catalyst Performance of Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Larsen, Mikkel Juul

    2015-01-01

    The catalyst performance in a proton exchange membrane fuel cell (PEMFC) depends on not only the choice of materials, but also on the electrode structure and in particular on the interface between the components. In this work, we demonstrate that the hot-pressing conditions used during electrode...

  20. Effect of Furnish on Temperature and Vapor Pressure Behavior in the Center of Mat Panels during Hot Pressing

    Directory of Open Access Journals (Sweden)

    Muhammad Navis Rofii

    2014-07-01

    Full Text Available Particleboard achieves its overall performance characteristics during hot pressing process. As this process is influenced by several factors, particularly temperature and pressure, it is very important to understand the behavior of both. This study investigates the effects of furnish materials on temperature and vapor pressure behavior inside particleboard mat panels during hot pressing. Strand type particles from hinoki and ring-flaker recycled wood particles were used as furnish for laboratory-scale particleboard panels with a target density of 0.76 g/cm³. Mat panels with a moisture content of about 10% were hot pressed at a platen temperature of 180°C and an initial pressure of 3 MPa until the mat center reached the same temperature as the platen. A press monitoring device (PressMAN Lite was used for detecting the temperature and vapor pressure change in the center of the mat panels. The study showed that the furnish type affected the temperature and vapor behavior inside the mat panels. Particleboard made of hinoki strand resulted in a longer plateau time, a higher plateau temperature and a higher gas pressure generated during hot pressing than those of ring-flaker recycled wood particles. Mixed board resulted in values between those of the two other furnish materials.

  1. Mechanical and electromagnetic properties of 3D printed hot pressed nanocarbon/poly(lactic) acid thin films

    Science.gov (United States)

    Kotsilkova, R.; Ivanov, E.; Todorov, P.; Petrova, I.; Volynets, N.; Paddubskaya, A.; Kuzhir, P.; Uglov, V.; Biró, I.; Kertész, K.; Márk, G. I.; Biró, L. P.

    2017-02-01

    We constructed a new type of light-weight, nanocarbon based thin film material having good mechanical properties, thermal stability, and electromagnetic shielding efficiency. Our method, 3D printing combined with hot pressing, is a cheap and industrially upscalable process. First a sandwich structure was created by layer-to-layer deposition of alternating 100 μm thick nanocarbon containing plastic layers and 100 μm thick pristine plastic layers, repeated as building blocks. The 3D printed samples were hot pressed to obtain thin films of 10-30 μm thickness. We used a commercial nanocarbon 3D printing filament (Black Magic). TEM investigations revealed the nanocarbon filler to be a mixture of graphene sheets, short carbon nanotubes, fishbone nanotubes, graphitic nanoparticles, and carbon black. Small-angle X-ray scattering and X-ray diffraction studies showed some amorphization of the nanocarbon filler as a consequence of the hot pressing. The nanoindentation hardness, nanoscratch hardness, and Young's modulus increase gradually by increasing the number of layers in the films, due to an increase of the amount of nanocarbon filler. Microwave absorption also increases continuously with the number of nanocarbon layers, reaching 40% for 3 nanocarbon layers. We demonstrate that unlike most conventional composites loaded with nanocarbons having pronounced dielectric properties, when the real part of permittivity Re(ɛ) is much higher than its imaginary part Im(ɛ) at high frequencies, a combination of 3D printing and hot pressing allows the fabrication of composites with Re ɛ ≈ Im ɛ in a very broad frequency range (0.2-0.6 THz). Our new 3D printed—hot pressed thin films may compete with the CVD graphene sandwiches in electromagnetic shielding applications because of their easier processability and low cost.

  2. Microstructure and optical properties of hot-pressed Er:CaF{sub 2} transparent ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zuodong [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Mei, Bingchu, E-mail: bcmeilab@163.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Song, Jinghong [Center of Materials Research and Analysis, Wuhan University of Technology, Wuhan 430070 (China); Yuan, Dan; Wang, Zhe [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2015-10-15

    CaF{sub 2} nanoparticles doped with different Er concentrations were synthesized by a co-precipitation method. The phase compositions and morphology of the obtained Er:CaF{sub 2} nanoparticles were characterized by X-ray diffraction and transmission electron microscopy analysis. It was found that the size and shape of obtained CaF{sub 2} nanoparticles were modified through Er{sup 3+} doping. High quality Er:CaF{sub 2} transparent ceramics were fabricated by hot-pressed sintering method in a vacuum environment. The influence of Er{sup 3+} doping concentrations and sintering temperatures on optical transmission and microstructure of Er:CaF{sub 2} transparent ceramics were investigated. When doped with 5 mol% Er{sup 3+}, the CaF{sub 2} ceramic sintered at 800 °C showed the best optical transmission, and for the 2 mm thickness sample, the optical transmission reached about 90% in the near-infrared spectral region. - Highlights: • Er:CaF{sub 2} nanoparticles were synthesized by coprecipitation method. • The size and shape of CaF{sub 2} nanoparticles were modified through Er doping. • Influence of Er content on transmissivity and microstructure was investigated. • Influence of temperature on transmissivity and microstructure was investigated.

  3. Dynamic Failure and Fragmentation of a Hot-Pressed Boron Carbide

    Science.gov (United States)

    Sano, Tomoko; Vargas-Gonzalez, Lionel; LaSalvia, Jerry; Hogan, James David

    2017-12-01

    This study investigates the failure and fragmentation of a hot-pressed boron carbide during high rate impact experiments. Four impact experiments are performed using a composite-backed target configuration at similar velocities, where two of the impact experiments resulted in complete target penetration and two resulted in partial penetration. This paper seeks to evaluate and understand the dynamic behavior of the ceramic that led to either the complete or partial penetration cases, focusing on: (1) surface and internal failure features of fragments using optical, scanning electron, and transmission electron microscopy, and (2) fragment size analysis using state-of-the-art particle-sizing technology that informs about the consequences of failure. Detailed characterization of the mechanical properties and the microstructure is also performed. Results indicate that transgranular fracture was the primary mode of failure in this boron carbide material, and no stress-induced amorphization features were observed. Analysis of the fragment sizes for the partial and completely penetrated experiments revealed a possible correlation between larger fragment sizes and impact performance. The results will add insight into designing improved advanced ceramics for impact protection applications.

  4. Characterization and Formability of Titanium/Aluminum Laminate Composites Fabricated by Hot Pressing

    Science.gov (United States)

    Qin, Liang; Wang, Hui; Cui, Shengqiang; Wu, Qian; Fan, Minyu; Yang, Zonghui; Tao, Jie

    2017-07-01

    The Ti/Al laminate composites were prepared by hot pressing to investigate the forming performance due to the corresponding potential applications in both the aerospace and auto industry. The bonding interface morphology and element distributions were characterized by SEM and EDS. The phase constituent was detected by XRD. It was observed that these composites presented good bonding interfaces between Ti and Al layers, and no low-sized voids and intermetallic compounds formed at the interface. In addition, the formability of these laminate composites was studied by the uniaxial tension tests, the limit drawing ratio (LDR) and the forming limit curve (FLC) experiments, respectively. The results indicated that the flow stress increased along with the strain rate increment. A constitutive equation was developed for deformation behavioral description of these laminate composites. The LDR value was 1.8, and the most susceptible region to present cracks was located at the punch profile radius. The forming limit curve of the laminate composites was located between the curves of titanium and aluminum and intersected with the major strain line at approximately 0.31. The macroscopic cracks of the FLC sample demonstrated a saw-toothed crack feature.

  5. Compound Control Strategy for MDF Continuous Hot Pressing Electrohydraulic Servo System with Uncertainties and Input Saturation

    Directory of Open Access Journals (Sweden)

    Zhu Liang-kuan

    2016-01-01

    Full Text Available A compound control strategy is investigated for Medium Density Fiberboard (MDF continuous hot pressing electrohydraulic servo system (EHSS with uncertainties and input saturation. Firstly, a hyperbolic tangent function is applied to approximate saturation nonlinearity in the system. And thus the mathematical model is continuous and differentiable. Subsequently, the slab thickness tracking controller is constructed by using a dynamic surface control (DSC method, which introduces first-order low-pass filters to calculate derivatives of virtual control input in each step. Compared with the conventional backstepping controller, complexity of the design procedure is alleviated obviously. Moreover, a composite disturbance of uncertainties and input saturation is estimated by a nonlinear disturbance observer for compensation of the control law. Finally, an appropriate Lyapunov function is chosen to prove that all signals of the closed-loop system are semiglobally uniformly ultimately bounded and the tracking error converges to zero asymptotically. Numerical simulation results are also exhibited to authenticate and validate the benefits of the proposed control scheme.

  6. Tunability of laser based on Yb-doped hot-pressed CaF2 ceramics

    Science.gov (United States)

    Sulc, Jan; Doroshenko, Maxim E.; Jelínková, Helena; Basiev, Tasoltan T.; Konyushkin, Vasilii A.; Osiko, Vyacheslav V.

    2012-06-01

    The aim of presented study was an investigation of tunability of diode pumped laser based on hot-pressed Yb:CaF2 ceramics. The tested Yb:CaF2 sample was in the form of 3.5mm thick plane-parallel face-polished plate (without AR coatings). The Yb3+ concentration was 5.5 %. A fiber (core diameter 200 μm, NA= 0.22) coupled laser diode (LIMO, HLU25F200-980) with emission at wavelength 976 nm, was used for longitudinal Yb:CaF2 pumping. The laser diode was operating in the pulsed regime (4 ms pulse length, 20 Hz repetition rate). The duty-cycle 8% ensured a low thermal load even under the maximum diode pumping power amplitude 10W (crystal sample was only air-cooled). This radiation was focused into the crystal (pumping beam waist diameter ~ 170 μm). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.01 - 1.09 μm, HT @ 0.97 μm) and curved (r = 150mm) output coupler with a reflectivity of ~ 98% @ 1.01 - 1.09 μm. Tuning of the ytterbium laser was accomplished by using a birefringent filter (single 1.5mm thick quartz plate) placed inside the optical resonator at the Brewster angle between the output coupler and the laser active medium. The extremely broad and smooth tuning was obtained. The laser was continuously tunable over ~ 66nm (from 1015nm to 1081 nm) and the tuning band was mostly limited by free spectral range of used birefringent filter. The tunability FWHM was 40 nm corresponding bandwidth 10 THz results in Fourier limited gaussian pulse width ~ 40 fs (FWHM). The maximum output power amplitude 0.68W was obtained at wavelength 1054nm for absorbed pump power amplitude 6W. The laser slope efficiency was 15%.

  7. The Electrical conductivities and Tribological properties of Vacuum Hot-Pressed Cu/Reduced Graphene Oxide Composite

    Science.gov (United States)

    Jia, Zhengfeng; Zhao, Pipeng; Ni, Junjie; Shao, Xin; Zhao, Limin; Huang, Baoxu; Ge, Bo; Ban, Chaolei

    2017-09-01

    The nanoscale reduced graphene oxide/copper (rGO/Cu) pellets were synthesized by reducing aqueous solution of graphene oxide and CuSO4. The Cu/rGO composite disks with high conductivity were fabricated by a vacuum hot-pressing sintering method. The composites were characterized by transmission electron microscopy, field emission scanning electron microscopy, x-ray diffraction. The results show that the vacuum hot-pressing sintering process can produce Cu/rGO composite successfully. The conductivities and wear resistance of the sintered Cu/rGO disks are improved, respectively, as rGO nanosheets being added into the matrix and/or increasing sintering temperatures, which are attributed to the destruction of the pores and the increasing compactness.

  8. 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.

  9. Production and characterization of Al-xNi in situ composites using hot pressing

    Directory of Open Access Journals (Sweden)

    Yamanoglu R.

    2014-01-01

    Full Text Available In this study, a new metal matrix composite of aluminium was designed with the addition of nickel alloy particles. To produce in situ intermetallic formation, aluminium-nickel powder mixtures with different ratios ranging from 5 to 40 wt% Ni were consolidated at 550ºC for 15 minutes under 40 MPa pressure. The interlayer phase formed during sintering was determined using X-ray diffraction and energy dispersive X-ray spectroscopy. The effect of nickel and Al-Ni intermetallics on the mechanical properties of the material was studied. The results demonstrated that the addition of nickel enhanced the hardness and wear behaviour of aluminium by forming a strong bonding interface between the aluminium and nickel particles.

  10. Use of wet-laid techniques to form flax-polypropylene nonwovens as base substrates for eco-friendly composites by using hot-press molding

    OpenAIRE

    Fages, Eduardo; GIRONÉS BERNABÉ, SAGRARIO; Sánchez Nacher, Lourdes; García Sanoguera, David; Balart Gimeno, Rafael Antonio

    2012-01-01

    The wet-laid process with flax (base) and polypropylene (binder) fibers has been used to obtain nonwovens for further processing by hot-press molding. Mechanical characterization of nonwovens has revealed that slight anisotropy is obtained with the wet-laid process as better tensile strength is obtained in the preferential deposition direction. The thermo-bonding process provides good cohesion to nonwovens, which is critical for further handling/shaping by hot-press molding. Flax:PP composite...

  11. Midwest veneer industry

    Science.gov (United States)

    Joe F. Christopher; Herbert S. Sternizke

    1964-01-01

    This report presents information on 1963 veneer log production and consumption in the Midsouth. The information is from a canvass of the industry made by the Southern Forest Experiment Station. Though an effort was made to locate all active plants, a few may have been overlooked. Omission of a firm, therefore, is no reflection upon its activities, nor does inclusion...

  12. Surface hardening of St41 low carbon steel by using the hot-pressing powder-pack boriding method

    Science.gov (United States)

    Sutrisno, Soegijono, Bambang

    2014-03-01

    This research describes a powder-pack boriding process by using hot-pressing technic for St41 low carbon steel which will improve the hardness on the substrate by forming boride layer solid solution. Those method can reduce the operational cost of the research if it is compared by the conventional method with the asmospheric condition both vacuum system and gas inert condition. The concept of boriding by hot-pressing technic was verified in a laboratory scale. Welldefined and reusedable technic was achieved by using the stainless steel 304 as the container and sealed with a 5 ton pressure. This container was filled boronizing powder consisting of 5%B4C, 90%SiC, and 5%KBF4 to close the St41 low carbon steel specimen inside the container. The St41 boriding specimen was treated at the temperature of 900°C for 8 hours. The boride layer on the substrate was found as FeB and Fe2B phase with the hardness about 1800 HV. This value was more than ten times if compared with the untreated specimen that only had the hardness of 123 HV. Depend on heat treatment temperature, heat treatment time, and powder-pack boriding pressure, the depth of boride layer range from 127 to 165 μm, leading to a diffusion controlled process.

  13. Improvement of linerboard compressive strength by hot-pressing and addition of recovered lignin from spent pulping liquor

    Directory of Open Access Journals (Sweden)

    Saidan Motasem N.

    2015-01-01

    Full Text Available This paper evaluates the effect of addition of precipitated lignin, from spent pulping black liquor, to a wet single-ply linerboard handsheet followed by hot-pressing at different temperatures, on the improvement of its compressive strength. Linerboard handsheets for testing the effect of lignin addition were prepared so that the lignin-modified sheets would have the same basis weights as the control handsheets. Both the commercial and the black liquor lignin were added as a powder to wet handsheets after couching from the handsheet mold. The experiments and testing of the physical and strength properties of dried handsheets were conducted according to TAPPI test methods. The results revealed that the addition of the recovered lignin (at pH of 2 to the wet handsheet followed by hot-pressing at 150°C increased the compressive strength of linerboard handsheets by 10% to 20% above that for handsheets made without the addition of lignin. The same results were achieved using purchased lignin. However, with a 16% addition to linerboard, purchased lignin would be too expensive. These results indicate that inclusion of kraft lignin in linerboard sheets could be proved as an attractive option to reduce linerboard basis weight.

  14. Biodegradable Poly(Lactic Acid/Multiwalled Carbon Nanotube Nanocomposite Fabrication Using Casting And Hot Press Techniques

    Directory of Open Access Journals (Sweden)

    Park S.G.

    2015-06-01

    Full Text Available Biodegradable advanced polymer composites have recently received a large amount of attention. The present study aimed to design poly(lactic acid multiwalled carbon nanotube nanocomposites (PLA/MWCNTs using a simple fabrication technique. A PLA sheet was first dissolved in dichloromethane, and MWCNTs were subsequently added at various concentrations (0.5, 1.5 and 5% while applying shear strain stirring to achieve dispersion of carbon nanotubes (CNTs. These solutions were then molded and a hot press was used to generate sheets free of voids with entrapped solvent. The prepared samples were characterized using field emission scanning electron microscopy (FE-SEM, x-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, and thermogravimetric analysis (TGA. Our data showed composite samples free of defects and voids, indicating that the hot press is capable of generating sufficiently compact polymer matrices. Additionally, TGA and FTIR showed significant bonding interactions between the PLA matrix and the nano-fillers. Collectively, our results suggest that incorporation of CNTs as nano-fillers into biodegradable polymers may have multiple applications in many different sectors.

  15. Microstructure, Mechanical and Wear Behaviors of Hot-Pressed Copper-Nickel-Based Materials for Diamond Cutting Tools

    Science.gov (United States)

    Miranda, G.; Ferreira, P.; Buciumeanu, M.; Cabral, A.; Fredel, M.; Silva, F. S.; Henriques, B.

    2017-08-01

    The current trend to replace cobalt in diamond cutting tools (DCT) for stone cutting has motivated the study of alternative materials for this end. The present study characterizes several copper-nickel-based materials (Cu-Ni; Cu-Ni-10Sn, Cu-Ni-15Sn, Cu-Ni-Sn-2WC and Cu-Ni-Sn-10WC) for using as matrix material for diamond cutting tools for stone. Copper-nickel-based materials were produced by hot pressing, at a temperature of 850 °C during 15 min and under an applied pressure of 50 MPa. The mechanical properties were evaluated though the shear strength and hardness values. The microstructures and fracture surfaces were analyzed by SEM. The wear behavior of all specimens was assessed using a reciprocating ball-on-plate tribometer. The hot pressing produced compacts with good densification. Sn and WC promoted enhanced mechanical properties and wear performance to Cu-Ni alloys. Cu-Ni-10Sn and Cu-Ni-10Sn-2WC displayed the best compromise between mechanical and wear performance.

  16. An Experimental Study Of Aluminum Alloy Matrix Composite Reinforced SiC Made By Hot Pressing Method

    Directory of Open Access Journals (Sweden)

    Suśniak M.

    2015-06-01

    Full Text Available The present work investigates the possibility of using powder metallurgy processing for producing a metal matrix composite. Materials were prepared from AlSi5Cu2 chips with reinforcement of 10, 15, 20 wt. % silicon carbide. Aluminum alloy chips were milled with SiC powder in a high-energy ball mill by 40 hours. Mechanical alloying process lead to obtain an uniform distribution of hard SiC particles in the metallic matrix and refine the grain size. The consolidation of composite powders was performed by vacuum hot pressing at 450°C, under pressure of 600 MPa by 10 min. The results shows that the addition of SiC particles has a substantial influence on the microstructure and mechanical properties of composite powder as well as consolidated material. Hot pressing is an effective consolidation method which leads to obtain dense AlSi5Cu2/SiC composite with homogeneous structure and advanced mechanical properties.

  17. Facile Fabrication of a Flexible LiNbO3 Piezoelectric Sensor through Hot Pressing for Biomechanical Monitoring.

    Science.gov (United States)

    Xu, Muzhen; Kang, Hua; Guan, Li; Li, Huayi; Zhang, Meining

    2017-10-11

    Wearable pressure sensors have attracted increasing attention for biomechanical monitoring due to their portability and flexibility. Although great advances have been made, there are no facile methods to produce sensors with good performance. Here, we present a simple method for manufacturing flexible and self-powered piezoelectric sensors based on LiNbO3 (LN) particles. The LN particles are dispersed in polypropylene (PP) doped with multiwalled carbon nanotubes (MWCNTs) by hot pressing (200 °C) to form a flexible LN/MWCNT/PP piezoelectric composite film (PCF) sensor. This cost-effective sensor has high sensitivity (8 Pa), fast response time (ca. 40 ms), and long-term stability (>3000 cycles). Measurements of pressure changes from peripheral arteries demonstrate the applicability of the LN/MWCNT/PP PCF sensor to biomechanical monitoring as well as its potential for biomechanics-related clinical diagnosis and forecasting.

  18. Mechanochemical Effects on the Synthesis of Copper Orthophosphate and cyclo-Tetraphosphate Bulks by the Hydrothermal Hot Pressing Method

    Directory of Open Access Journals (Sweden)

    Isao Tanaka

    2009-01-01

    Full Text Available Copper orthophosphate, Cu3(PO42, and cyclo-tetraphosphates, Cu2P4O12, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and milled samples were characterized by X-ray diffraction (XRD and Fourier transform infrared (FT-IR spectroscopy. SEM images, particle size distribution, specific surface area, UV-Vis reflectance spectra were also used to evaluate the materials. The un-milled and milled materials were used to fabricate copper phosphate bulks by a hydrothermal hot pressing method. The influence of powder condition on the sintering behavior of the copper phosphates was studied.

  19. Influence of silane surface modification of veneer on interfacial adhesion of wood-plastic plywood

    Science.gov (United States)

    Fang, Lu; Chang, Liang; Guo, Wen-jing; Chen, Yongping; Wang, Zheng

    2014-01-01

    In this study, wood-plastic plywood was fabricated with high density polyethylene (HDPE) film and poplar veneer by hot-pressing. To improve the interfacial adhesion between the wood veneer and HDPE film, silane A-171 (vinyltrimethoxysilane) was used to treat the surface of poplar veneer by spraying. The effects of silane agent on the veneer surface properties as well as the physical-mechanical performance of wood-plastic plywood were evaluated. The adsorption of several prehydrolyzed alkoxysilanes onto the veneer surface and the existence of a covalent bonding between the wood veneer and silane agent were confirmed using FTIR, XPS and contact angle. Silane surface treatment resulted in enhancement of shear strength and water resistance. When one layer HDPE film was used as adhesive, it caused 293.2% increase in shear strength, 34.6% and 40.8% reduction in water absorption and thickness swelling, respectively. In addition, the wood failure also increased from 5% to 100% due to the silane modification. Dynamic mechanical analysis (DMA) results showed that treated plywood have higher storage modulus, lower tan δ peak value and lagged temperature for tan δ peak value with respect to untreated plywood. Experimental results of interfacial morphology by SEM further revealed better interaction between silane A-171 treated veneer and HDPE film.

  20. Hot pressing effect on the shear bond strength of dental porcelain to CoCrMoSi alloy substrates with different surface treatments.

    Science.gov (United States)

    Henriques, B; Faria, S; Soares, D; Silva, F S

    2013-01-01

    The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a CoCrMoSi alloy to a low-fusing feldspathic porcelain, for two types of surface treatments: polished and grit-blasted. Moreover, the shear strength of hot pressed porcelain was also compared with that of conventional vacuum sintered porcelain. Bond strength of metal-porcelain composites were assessed by the means of a shear test performed in a universal test machine until fracture. Fracture surfaces and interfaces were investigated by optical microscope, stereomicroscope and SEM/EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The 2-way ANOVA followed by Tukey HSD multiple comparison test was used to compare shear bond strength results and the t-test was used to compare the porcelain shear strength (pporcelain. This study revealed that metal-ceramic bond strength is maximized for hot pressed porcelain onto rough metal substrates, with lower variability in results. Hot pressing technique was also shown to enhance the cohesion of porcelain. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Optimization of quenching process in hot press forming of 22MnB5 steel for high strength properties for publication in

    Science.gov (United States)

    Aziz, Nuraini; Aqida, S. N.

    2013-12-01

    This paper presents hot press forming of 22MnB5 steel blanks for high strength automotive components. The hot press forming was performed using Schenck press PEZ0673 machine with maximum press force of 1000 kN. Samples were square 22MnB5 blanks, of 50 × 60 mm dimension. A high temperature furnace was used to heat up the blanks to austenite temperature of 950°C. Samples were held at the austenite temperature prior to forming and quenching process. Three independent controlled parameters were cooling water temperature, press holding time and flow rate of water. Pressed samples were characterized for metallographic study, hardness properties and tensile properties. Metallographic study was conducted using Meiji optical microscope. Hardness was measured using Vickers indenter with load 1000gf. From metallographic study, the hot pressed 22MnB5 boron steel samples produced lath martensitic microstructure. Hardness of hot pressed samples increased with decreasing cooling time. The yield strength and the ultimate tensile strength of samples after hot forming were between 1546 and 1923 N/mm2. These findings were important to design tailored ultra-high strength in automotive components at different process parameter settings.

  2. Volatile organic compound emissions during hot-pressing of southern pine particleboard : panel size effects and trade-off between press time and temperature

    Science.gov (United States)

    Wenlong Wang; Douglas J. Gardner; Melissa G.D. Baumann

    2002-01-01

    In previous research, it was shown that decreasing either press temperature or press time generally resulted in decreased volatile organic compound (VOC) emissions during the hot-pressing of southern pine particleboard. However, because it is impossible to reduce both pressing time and temperature while maintaining panel physical and mechanical properties, this study...

  3. Growth and characterization of Mn-doped AgInS{sub 2} grown by a hot-press method

    Energy Technology Data Exchange (ETDEWEB)

    Akaki, Yoji [Department of Electrical and Computer Engineering, Miyakonojo National College of Technology, 473-1 Yoshio, Miyakonojo, Miyazaki (Japan); Shirahata, Yasuhiro; Yoshino, Kenji [Department of Electrical and Electronics Engineering, Miyazaki University, 1-1 Gakuen Kibanadai-nishi, Miyazaki (Japan); Ohno, Yutaka; Yonenaga, Ichiro [Institute for Materials Research, Tohoku University, Aoba-ku, Sendai (Japan)

    2009-05-15

    Mn-doped AgInS{sub 2} crystals are grown by a hot-press method at 700 C for 1 hour under high pressure of 25 MPa from stoichiometric Ag{sub 2}S and In{sub 2}S{sub 3} powders with the Mn atoms with a concentration between 5 and 20 mol.%. Mn-doped crystals showed diffraction lines of orthorhombic AgInS{sub 2} and AgIn{sub 5}S{sub 8} in addition to the dominant lines of chalcopyrite AgInS{sub 2}. The S composition in the crystals is slightly deficient independent of the Mn concentration. Electron states of Mn are studied by an electron spin resonance (ESR) at room temperature. The ESR intensity of the Mn-doped crystals increases with an increase in the Mn concentration. The g-factors at room temperature of the Mn-doped crystals are in the range 1.980-1.982 with the peak-to-peak linewidth in the range 4.5-8.9 mT. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Effect of sintering temperature and boron carbide content on the wear behavior of hot pressed diamond cutting segments

    Directory of Open Access Journals (Sweden)

    Islak S.

    2015-01-01

    Full Text Available The aim of this study was to investigate the effect of sintering temperature and boron carbide content on wear behavior of diamond cutting segments. For this purpose, the segments contained 2, 5 and 10 wt.% B4C were prepared by hot pressing process carried out under a pressure of 35 MPa, at 600, 650 and 700 °C for 3 minutes. The transverse rupture strength (TRS of the segments was assessed using a three-point bending test. Ankara andesite stone was cut to examine the wear behavior of segments with boron carbide. Microstructure, surfaces of wear and fracture of segments were determined by scanning electron microscopy (SEM-EDS, and X-ray diffraction (XRD analysis. As a result, the wear rate decreased significantly in the 0-5 wt.% B4C contents, while it increased in the 5-10 wt.% B4C contents. With increase in sintering temperature, the wear rate decreased due to the hard matrix.

  5. Oxidation Characterization of Hafnium-Based Ceramics Fabricated by Hot Pressing and Electric Field-Assisted Sintering

    Science.gov (United States)

    Gasch, Matt; Johnson, Sylvia; Marschall, Jochen

    2010-01-01

    Ceramic borides, such as hafnium diboride (HfB2) and zirconium diboride (ZrB2), are members of a family of materials with extremely high melting temperatures referred to as Ultra High Temperature Ceramics (UHTCs). UHTCs constitute a class of promising materials for use in high temperature applications, such as sharp leading edges on future-generation hypersonic flight vehicles, because of their high melting points. The controlled development of microstructure has become important to the processing of UHTCs, with the prospect of improving their mechanical and thermal properties. The improved oxidation resistance of HfB2 has also become important if this material is to be successfully used at temperatures above 2000 C. Furthermore, the use of UHTCs on the leading edges of vehicles traveling at hypersonic speeds will mean exposure to a mixed oxidation environment comprised of both molecular and atomic oxygen. The current study has investigated the high-temperature oxidation behavior of HfB2-based materials in a pure O2 environment, as well as in environments containing different levels of dissociated oxygen (O/O2). Materials were processed by two techniques: conventional hot pressing (HP) and electric field-assisted sintering (FAS). Their oxidation behavior was evaluated in both a tube furnace at 1250 C for 3 hours and in a simulated re-entry environment in the Advanced Heating Facility (AHF) arcjet at NASA Ames Research Center, during a 10-minute exposure to a cold wall heat flux of 250W/sq cm and stagnation pressure of 0.1-0.2 atm. The microstructure of the different materials was characterized before and after oxidation using scanning electron microscopy (SEM).

  6. Hot pressing in conduit faults during lava dome extrusion: Insights from Mount St. Helens 2004-2008

    Science.gov (United States)

    Ryan, Amy G.; Friedlander, Elizabeth A.; Russell, James K.; Heap, Michael J.; Kennedy, Lori A.

    2018-01-01

    Rhyodacitic volcanoes such as Mount St. Helens (MSH), Soufrière Hills, Mount Unzen and Mount Pelée erupt spines mantled by layers of magma-derived cataclasite and fault gouge. MSH produced seven lava spines from 2004-2008 composed of low-porosity, compositionally uniform, crystalline dacite. Dome extrusion was attended by continuous 'drumbeat' seismicity, derived from faulting along the conduit margin at 0.5-1 km depth, and evidenced by the enveloping gouge layers. We describe the properties of the gouge-derived fault rocks, including laboratory measurements of porosity and permeability. The gouge varies from unconsolidated powder to lithified low-porosity low-permeability fault rocks. We reconstruct the subsurface ascent of the MSH magma using published field observations and create a model that reconciles the diverse properties of the gouge with conditions in the conduit during ascent (i.e. velocity, temperature). We show lithification of the gouge to be driven by 'hot pressing' processes, wherein the combination of elevated temperature, confining pressure and dwell-time cause densification and solid-state sintering of the comminuted, crystal-rich (glass-poor) gouge. The degree of gouge lithification corresponds with residence time in the conduit such that well-lithified materials reflect extended times in the subsurface due to slower ascent rates. With this insight, we suggest that gouge competence can be used as a first-order estimate of lava ascent rates. Furthermore we posit gouge lithification, which reduces porosity and permeability, inhibits volcanic outgassing thereby increasing the potential for explosive events at spine-producing volcanoes.

  7. Mechanical Properties of 3 Ply Plywood Made from Acacia Mangium Veneers and Green Starch-based Adhesives

    Directory of Open Access Journals (Sweden)

    Chiang Liew Kang

    2016-01-01

    Full Text Available Recently, starch has attracted great consideration as a raw material on wood adhesives in the wood industry. Cassava and sago starchbased adhesive are renewable, biodegradable and environmental friendly product when compared with other petroleum-based adhesives. In this study, different starches-based adhesive has been produced. Mechanical properties of plywood made from Acacia mangium veneers with different starches-based adhesives (cassava and sago as binder cured at different curing temperatures (100°C, 120°C and 140°C has been determined. All materials (starch, vinegar, water and glycerol were cooked and stirred until the mixture reached 70°C - 80°C which become sticky and whitish. After that, starch-based adhesives were applied on the veneers by using spreader, and the plywood were pre-pressed for 30 minutes with 20 kg load before hot-press. Cassava starch-based adhesive showed the highest Modulus of Elasticity which was 12410.56 N/mm2 than sago starch-based adhesive, while Modulus of Rupture of the cassava starch-based adhesive at 100°C showed highest mean value at 74.19 N/mm2. Sago-starch based adhesive at 140°C showed the highest shear strength with 1.11 N/mm2. In short, cassava and sago starch-based adhesives gave good performance in mechanical properties such as bending for pressed temperature (100°C and 120°C, and shear at 140°C pressed temperature.

  8. Life-Cycle Inventory Analysis of Laminated Veneer Lumber Production in the United States

    Science.gov (United States)

    Richard D. Bergman

    2015-01-01

    Documenting the environmental performance of building products is becoming increasingly common. Developing environmental product declarations (EPDs) based on life-cycle assessment (LCA) data is one way to provide scientific documentation. Many U.S. structural wood products have LCA-based “eco-labels” using the ISO standard. However, the standard requires underlying...

  9. The Investigation on Feasibility of Oriented Strand Boards to Parquet Production from Mixed Residual Veneer Popular and Beech

    Directory of Open Access Journals (Sweden)

    Saeid Kamrani

    2013-06-01

    Full Text Available The objective of this study was to investigate of feasibility of using residual veneer (popular and beechto manufacture oriented strand board (OSB parquet. Percentage of mixed residual veneer popular to beech was 40%to 60% respectly. In this study press time (6, 8 and 10 min and press temperature (170º, 180ºwere selected as variables, other factors being kept constant. Results indicated that increase of press temperature had no significant effect on modules of rupture, modules of elasticity and hardness but had significant effect on internal bonding, water absorption and thickness swelling. However results indicated that increase of press time had significant effect on total physical and mechanical properties of boards.

  10. Properties of an Al/(Al2O3+TiB2+ZrB2) hybrid composite manufactured by powder metallurgy and hot pressing

    Science.gov (United States)

    Farhadinia, F.; Sedghi, A.; Nooghani, M. T.

    2017-05-01

    The properties and microstructure of an Al/(Al2O3 + TiB2 + ZrB2) hybrid composite made by using hot pressing of aluminum combined with different amounts of TiB2, ZrB2, and Al2O3 powders are studied. The mechanical properties of the composites are investigated on the basis of microhardness and compression tests. The results show that the microstructure of the composites is uniform and the particles are well distributed in the matrix.

  11. Veneer industry and timber use, North Central Region, 1988.

    Science.gov (United States)

    W. Brad Smith; Ronald L. Hackett

    1990-01-01

    Shows 1988 veneer-log production and receipts by species in the Lake States (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data in 1984. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the Central...

  12. Veneer industry and timber use, North Central Region, 1980.

    Science.gov (United States)

    James E. Blyth; W. Brad Smith

    1984-01-01

    Shows 1980 veneer-log production and receipts by species in the Lake State (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data collected in 1976. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the...

  13. Mechanical and Impact Properties of PLA/2 × 2 Twill and 4 × 4 Hopsack Weave Flax Textile Composites Produced by the Interval Hot Pressing Technique

    Science.gov (United States)

    Siengchin, S.; Wongmanee, S.

    2014-07-01

    Polylactide (PLA)/2 × 2 twill and 4 × 4 hopsack weave flax textile composites were produced by the interval hot pressing technique. The dispersion of structural elements of the composites was inspected by the scanning electron microscopy (SEM). The composites were subjected to instrumented falling-weight impact tests. Their mechanical properties (tensile strength and stiffness) were determined in tensile and dynamic mechanical thermal tests. The SEM showed that the interfacial gaps around pulled-out fibers diminished when the interval hot pressing was used. It was also found that both the types of flax composites had a higher impact resistance than the neat PLA. The tensile strength and stiffness of the PLA/flax composites were also markedly higher than those of PLA and reflected the effect of their structures. The storage creep compliance was determined by using the relations of linear viscoelastic materials and the time-temperature superposition principle. The calculated creep response of the flax composites was much lower than that of the neat PLA.

  14. 40 CFR 429.30 - Applicability; description of the veneer subcategory.

    Science.gov (United States)

    2010-07-01

    ... veneer subcategory. 429.30 Section 429.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS TIMBER PRODUCTS PROCESSING POINT SOURCE CATEGORY Veneer Subcategory § 429.30 Applicability; description of the veneer subcategory. This subpart applies to discharges...

  15. Marginal gap, internal fit, and fracture load of leucite-reinforced ceramic inlays fabricated by CEREC inLab and hot-pressed techniques.

    Science.gov (United States)

    Keshvad, Alireza; Hooshmand, Tabassom; Asefzadeh, Farokh; Khalilinejad, Foroogh; Alihemmati, Mohammad; Van Noort, Richard

    2011-10-01

    This in vitro study was designed to evaluate and compare the marginal gap, internal fit, and fracture load of resin-bonded, leucite-reinforced glass ceramic mesio-occlusal-distal (MOD) inlays fabricated by computer-aided design/manufacturing (CAD/CAM) or hot pressing. Fifty caries-free extracted human molars were prepared for standardized MOD inlays. Impressions of each specimen were made and poured using type IV dental stone. Dies were randomly divided into two equal groups. Twenty-five ceramic inlays were fabricated by the hot-pressed technique using IPS Empress leucite-reinforced glass ceramics, and the other 25 ceramic inlays were produced by CAD/CAM technology using ProCAD leucite-reinforced ceramic blocks and CEREC inLab facilities. Inlays were bonded to the teeth using a dual-cured resin cement. The specimens were stored in distilled water at 37°C for 24 hours and then thermocycled for 5000 cycles. The marginal gap measurements were taken with a stereomicroscope. Specimens in each group of inlay systems were randomly divided into two subgroups of 10 and 15 specimens each. Ten specimens in each subgroup were sectioned mesiodistally for evaluation of the internal fit. The fracture load of specimens in the second subgroup (n = 15) of the two inlay systems was determined under compressive load in a universal testing machine. Data were analyzed using Student's t-test at a significance level of p internal gap size in both IPS Empress and ProCAD inlays were less than 100 μm; however, the marginal gap for the IPS Empress restorations was significantly higher than that of ProCAD restorations (p internal fit or the fracture load between the two glass ceramic inlays (p > 0.05). The leucite-reinforced glass ceramic inlay restorations fabricated by CEREC inLab (CAD/CAM) and the hot-pressed technique provided clinically acceptable marginal and internal fit with comparable fracture loads after luting. © 2011 by The American College of Prosthodontists.

  16. Lathe Check Characteristics of Fast Growing Sengon Veneers and Their Effect on LVL Glue-Bond and Bending Strength

    OpenAIRE

    MASSIJAYA, Yusram; KABE, Abigael; RAHAYU, Istie; DENAUD, Louis; OZARSKA, Barbara

    2014-01-01

    Fast growing sengon (Paraserianthes moluccana) is largely rotary-cut to produce veneer for core plywood production. In order to provide better information on veneer production and utilization, in this study the effects of wood juvenility and veneer thickness on lathe checks of rotary-cut sengon veneers were evaluated. Before veneer manufacturing, sengon logs were boiled at 50 oC and 75 oC for 4 and 8 hours respectively. The boiled logs were peeled to produce veneer of 1 mm, 1.5 mm...

  17. Thermoelectric properties of I-doped n-type Bi2Te3-based material prepared by hydrothermal and subsequent hot pressing

    Directory of Open Access Journals (Sweden)

    Fang Wu

    2017-04-01

    Full Text Available I-doped Bi2Te3−xIx (x=0, 0.05, 0.1, 0.2 flower-like nanoparticles were synthesized by a hydrothermal method through a careful adjustment of the amount of ethylenediamine tetraacetic acid surfactant. The nanopowders of flower-like nanoparticles were hot-pressed into bulk pellets and the thermoelectric properties of the pellets were investigated. The results showed that I-doping decreased the electrical resistivity effectively, and the thermal conductivitives of the Bi2Te3−xIx bulk samples was lower because of the closer atomic mass of I compared to Te. As a result, a ZT value of 1.1 was attained at 448 K for the Bi2Te2.9I0.1 sample.

  18. Development of Duplex Stainless Steels by Field-Assisted Hot Pressing: Influence of the Particle Size and Morphology of the Powders on the Final Mechanical Properties

    Science.gov (United States)

    García-Junceda, A.; Rincón, M.; Torralba, J. M.

    2018-01-01

    The feasibility of processing duplex stainless steels with promising properties using a powder metallurgical route, including the consolidation by field-assisted hot pressing, is assessed in this investigation. The influence of the particle size and morphology of the raw austenitic and ferritic powders on the final microstructure and properties is also evaluated for an austenitic content of 60 wt pct. In addition, the properties of a new microconstituent generated between the initial constituents are analyzed. The maximum sintered density (98.9 pct) and the best mechanical behavior, in terms of elastic modulus, nanohardness, yield strength, ultimate tensile strength, and ductility, are reached by the duplex stainless steel processed with austenitic and ferritic gas atomized stainless steel powders.

  19. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing

    Energy Technology Data Exchange (ETDEWEB)

    Somunkiran, Ilyas [Firat Univ., Elazig (Turkey). Metallurgical and Materials Engineering Dept.; Balin, Ahmet [Siirt Univ. (Turkey). Dept. of Vocational High School

    2016-02-01

    In this study, Co-based Cr-Mo powder alloy was produced at different pressing temperatures by using hot pressing technique and abrasive wear behaviors of the produced specimens were examined. Produced specimens were exposed to abrasive wear experiment using block on disc wear test device by applying a load of 50 N with 100-mesh SiC abrasive paper. Each specimen was investigated at 25, 50, 75 and 100 m. At the end of the experiment, abrasive wear results of the specimens were determined by calculating their mass losses. Microstructural properties of the specimens which were produced at different pressing temperatures were investigated by optical and SEM examinations and their wear resistances were examined by abrasive wear experiments. Consequently, it was observed that in Co-based Cr-Mo powder alloy produced by hot pressing technique; as sintering temperature increased, size of neck formations between the powder grains increased, porosity decreased and abrasive wear resistance increased. [German] In diesem Beitrag zugrunde liegenden Studie wurde eine Co-basierte Cr-Mo-Legierung mittels Heisspressens hergestellt und der Abrasivverschleisswiderstand dieser Proben untersucht. Die hergestellten Proben wurden dem Abrasivverschleissversuch durch einen Block-Scheibe-Versuchsaufbau unterzogen, wobei eine Kraft von 50 N mit einem SiC-Papier (100 mesh) verwendet wurde. Jede Probe wurde ueber eine Distanz von 25, 50, 75 und 100 m untersucht. Am Ende der jeweiligen Experimente wurden die Abrasivverschleissergebnisse ermittelt, indem die Massenverluste berechnet wurden. Die mikrostrukturellen Eigenschaften der Proben, die bei verschiedenen Presstemperaturen hergestellt wurden, wurden mittels optischer und Rasterelektronenmikroskopie bestimmt und ihr Verschleisswiderstand anhand der Verschleissversuche ermittelt. Schliesslich wurde beobachtet, dass bei steigender Sintertemperatur der heissgespressten Co-basierten Cr-Mo-Pulverlegierung die Groesse der Einschnuerungen zwischen den

  20. Nickel-graphite composites of variable architecture by graphitization-accompanied spark plasma sintering and hot pressing and their response to phase separation

    Directory of Open Access Journals (Sweden)

    Dudina D.V.

    2015-01-01

    Full Text Available We report the formation and phase separation response of nickel-graphite composites with variable-architecture phases by graphitization-accompanied consolidation via Spark Plasma Sintering and hot pressing. It was shown that the application of pressure during consolidation is crucial for the occurrence of graphitization and formation of 3D graphite structures. We evaluated the suitability of the synthesized composites as precursors for making porous structures. Nickel behaved as a space holder with the particle size and spatial distribution changing during consolidation with the temperature and determining the structure of porous graphite formed by phase separation by dissolution in HCl. The response of the consolidated Ni-Cgr to separation of carbon by its burnout in air was studied. The result of the carbon removal was either the formation of a dense and continuous NiO film on the surface of the compacts or oxidation through the compact thickness. The choice between these two options depended on the density of the compacts and on the presence of carbon dissolved in nickel. It was found that during the burnout of graphite from Ni-Cgr composites, sintering, rather than formation of pores, dominated.

  1. Scratch Testing of Hot-Pressed Monolithic Chromium Diboride (CrB2) and CrB2 + MoSi2 Composite

    Science.gov (United States)

    Bhatt, B.; Murthy, T. S. R. Ch.; Singh, K.; Sashanka, A.; Vishwanadh, B.; Sonber, J. K.; Sairam, K.; Nageswara Rao, G. V. S.; Srinivasa Rao, T.; Kain, Vivekanand

    2017-10-01

    The tribological performance of hot-pressed monolithic CrB2 and a newly developed CrB2 + 20 vol.% MoSi2 composite was investigated by using scratch test. The test was carried out under progressive loading ranging from 0.9 to 30 N over a scratch distance of 3 mm. In situ values of coefficient of friction (COF), depth of penetration and acoustic emission were recorded. The wear volume and fracture toughness were also calculated. COF of both materials is increased with increasing the scratch length and progressive load. COF of the composite was observed to be slightly higher compared to the monolithic CrB2. The wear volume of the composite is 60% higher compared to monolithic CrB2. Fracture toughness values of 2.48 and 2.81 MPa m1/2 were calculated for monolithic CrB2 and CrB2 + 20 vol.% MoSi2 composite, respectively. Microstructural characterization indicates that the abrasive wear is the dominant wear mechanism in both the materials.

  2. Analysis of the Microstructure and Mechanical Properties of Titanium-Based Composites Reinforced by Secondary Phases and B₄C Particles Produced via Direct Hot Pressing.

    Science.gov (United States)

    Montealegre-Melendez, Isabel; Arévalo, Cristina; Ariza, Enrique; Pérez-Soriano, Eva M; Rubio-Escudero, Cristina; Kitzmantel, Michael; Neubauer, Erich

    2017-10-27

    In the last decade, titanium metal matrix composites (TMCs) have received considerable attention thanks to their interesting properties as a consequence of the clear interface between the matrix and the reinforcing phases formed. In this work, TMCs with 30 vol % of B₄C are consolidated by hot pressing. This technique is a powder metallurgy rapid process. Incorporation of the intermetallic to the matrix, 20 vol % (Ti-Al), is also evaluated. Here, the reinforcing phases formed by the reaction between the titanium matrix and the ceramic particles, as well as the intermetallic addition, promote substantial variations to the microstructure and to the properties of the fabricated composites. The influences of the starting materials and the consolidation temperature (900 °C and 1000 °C) are investigated. By X-ray diffraction, scanning and transmission electron microscopy analysis, the in-situ-formed phases in the matrix and the residual ceramic particles were studied. Furthermore, mechanical properties are studied through tensile and bending tests in addition to other properties, such as Young's modulus, hardness, and densification of the composites. The results show the significant effect of temperature on the microstructure and on the mechanical properties from the same starting powder. Moreover, the Ti-Al addition causes variation in the interface between the reinforcement and the matrix, thereby affecting the behaviour of the TMCs produced at the same temperature.

  3. Fabrication of a Nano-ZnO/Polyethylene/Wood-Fiber Composite with Enhanced Microwave Absorption and Photocatalytic Activity via a Facile Hot-Press Method

    Directory of Open Access Journals (Sweden)

    Baokang Dang

    2017-11-01

    Full Text Available A polyethylene/wood-fiber composite loaded with nano-ZnO was prepared by a facile hot-press method and was used for the photocatalytic degradation of organic compounds as well as for microwave absorption. ZnO nanoparticles with an average size of 29 nm and polyethylene (PE powders were dispersed on the wood fibers’ surface through a viscous cationic polyacrylamide (CPAM solution. The reflection loss (RL value of the resulting composite was −21 dB, with a thickness of 3.5 mm in the frequency of 17.17 GHz. The PE/ZnO/wood-fiber (PZW composite exhibited superior photocatalytic activity (84% methyl orange degradation within 300 min under UV light irradiation. ZnO nanoparticels (NPs increased the storage modulus of the PZW composite, and the damping factor was transferred to the higher temperature region. The PZW composite exhibited the maximum flexural strength of 58 MPa and a modulus of elasticity (MOE of 9625 MPa. Meanwhile, it also displayed dimensional stability (thickness swelling value of 9%.

  4. The Effect of Veneer Layers on the Bending Shear Strength and Delamination of Laminated Veneer Lumber (LVL) from Oil Palm Trunk (OPT)

    Science.gov (United States)

    Jamaludin, M. A.; Nordin, K.; Bahari, S. A.; Ahmad, M.

    2010-03-01

    The aim of this study was to evaluate the effects of the number of veneer layers on the bending shear strength and delamination of Laminated Veneer Lumber (LVL) from oil palm trunk (OPT). Five (5), Six (6) and Seven (7) veneer layers of OPT LVL were manufactured. The dimension of the boards was 45 cm by 45 cm by 1.9 cm. The boards were hot pressed for 13 minutes at a pressure of 31 kgf per m2. Urea formaldehyde (UF) supplied by a local adhesive manufacturer was used as the binder for the boards. The bending shear tests consisted of the edgewise and flatwise tests, whereas the delamination test consisted of the cold and hot water boil tests. The preparation of the test specimens and tests set-up was in accordance to the Japanese Standards, JAS-1991 [1]. Six replications were used for each test. The results were analyzed by Analysis of Variance (ANOVA) using the Duncan's Multiple Range Test to test for significant differences. The results indicated that as the number of layers increased the strength also increased. All the boards passed the standard. The difference in strength between the different types of samples was significant at 95 percent confidence level. Bending shear failures were primarily in the veneers. It is possible to use the boards as light weight interior building and furniture components. Over the years, the supply of quality timber resources from the natural forest has decrease as the wood-based industry experienced rapid growth. The supply of rubberwood for the furniture industry is also decreasing as a result of increase latex price. Accordingly, OPT LVL can be an alternative or supplementary raw material for the wood-based industry.

  5. Thermoelectric Properties of Alumina-Doped Bi0.4Sb1.6Te3 Nanocomposites Prepared through Mechanical Alloying and Vacuum Hot Pressing

    Directory of Open Access Journals (Sweden)

    Chung-Kwei Lin

    2015-11-01

    Full Text Available In this study, γ-Al2O3 particles were dispersed in p-type Bi0.4Sb1.6Te3 through mechanical alloying to form γ-Al2O3/Bi0.4Sb1.6Te3 composite powders. The composite powders were consolidated using vacuum hot pressing to produce nano- and microstructured composites. Thermoelectric (TE measurements indicated that adding an optimal amount of γ-Al2O3 nanoparticles improves the TE performance of the fabricated composites. High TE performances with figure of merit (ZT values as high as 1.22 and 1.21 were achieved at 373 and 398 K for samples containing 1 and 3 wt % γ-Al2O3 nanoparticles, respectively. These ZT values are higher than those of monolithic Bi0.4Sb1.6Te3 samples. The ZT values of the fabricated samples at 298–423 K are 1.0–1.22; these ZT characteristics make γ-Al2O3/Bi0.4Sb1.6Te3 composites suitable for power generation applications because no other material with a similarly high ZT value has been reported at this temperature range. The achieved high ZT value may be attributable to the unique nano- and microstructures in which γ-Al2O3 nanoparticles are dispersed among the grain boundary or in the matrix grain, as revealed by high-resolution transmission electron microscopy. The dispersed γ-Al2O3 nanoparticles thus increase phonon scattering sites and reduce thermal conductivity. The results indicated that the nano- and microstructured γ-Al2O3/Bi0.4Sb1.6Te3 alloy can serve as a high-performance material for application in TE devices.

  6. On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process.

    Science.gov (United States)

    Ahmad, Azlan; Lajis, Mohd Amri; Yusuf, Nur Kamilah

    2017-09-19

    Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.

  7. Some Comparative Properties of Reconstituted Poplar Veneer Replicating Wenge With Classic Veneer of the Same Species

    Directory of Open Access Journals (Sweden)

    Lidia GURAU

    2010-12-01

    Full Text Available Eco-friendly alternative options to traditional wood veneer have become available around the world in reconstituted veneers. This paper is exploring some properties of reconstituted poplar veneer replicating wenge in indirect testing, which meant to evaluate the bending properties of veneered particleboards and in direct testing that envisaged the veneer density and water absorption. The properties of reconstituted poplar replicating wenge were compared with those of poplar and wenge veneer tested in the same conditions. The results show a slightly lower MOE and MOR for the particleboard veneered with reconstituted veneer compared to the classic veneer, in spite of a higher veneered panel density. The reason may be a discontinuous structure of the engineered veneer compared to the traditional veneer. However, the addition of veneer to particleboards has increased their MOE app. 1.4-1.7 times and doubled their MOR. Smaller standard deviation values of the MOE, MOR and density were recorded for the particleboard veneered with reconstituted poplar replicating wenge compared with the ones veneered with poplar or natural wenge, which may indicate a more homogenous structure for the reconstituted veneer compared with the natural veneers. The reconstituted poplar veneer replicating wenge had higher density than the poplar veneer and it absorbed less water. However, compared with natural wenge, the replica made of poplar had lower performances. Further tests could examine the finishing behaviour of reconstituted veneer and its resistance to scratches and spots.

  8. Some properties of LVL composed of poplar and beech veneer and possibilities of their application for window frames

    Directory of Open Access Journals (Sweden)

    Zdravković Vladislav

    2017-01-01

    Full Text Available The subject of this paper was a research of physical and mechanical properties of LVL composed of peeled poplar veneers in core layers and only outer layers of beech peeled veneers, so as the examination of window frame glue joint strength produced of this material. LVL boards have been hot pressed in industrial conditions, using appropriate phenol formaldehyde (PP adhesive. Samples for corner window frame glue joint strength testing were glued with PVAc D4 class adhesive. Statistical analysis showed that there were significant differences both in moisture content and density of LVL boards regarding their thickness, while in the case of hardness this difference did not exist. Examinations of LVL glue line shear strength showed that both phenol formaldehyde (PP and PVAc D4 class adhesives fulfilled standard requirements. The results of corner window frame double tenon glue joint strength produced from combined poplar-beech veneer LVL indicated that such material could be used to produce window frame corner joint, strong enough to withstand the additional load, without an increase of the cross section.

  9. Tribocorrosion behavior of veneering biomedical PEEK to Ti6Al4V structures.

    Science.gov (United States)

    Sampaio, Miguel; Buciumeanu, Mihaela; Henriques, Bruno; Silva, Filipe S; Souza, Júlio C M; Gomes, José R

    2016-02-01

    In dentistry, prosthetic structures must be able to support masticatory loads combined with a high biocompatibility and wear resistance in the presence of a corrosive environment. In order to improve the simultaneous wear and corrosion response of highly biocompatible prosthetic structures, a veneering poly-ether-ether-ketone (PEEK) to Ti6Al4V substrate was assessed by tribocorrosion analyses under conditions mimicking the oral environment. Samples were synthesized by hot pressing the PEEK veneer onto Ti6Al4V cylinders. The tribocorrosion tests on Ti6Al4V or PEEK/Ti6Al4V samples were performed on a reciprocating ball-on-plate tribometer at 30N normal load, 1Hz and stroke length of 3mm. The tests were carried out in artificial saliva at 37°C. Open circuit potential (OCP) was measured before, during and after reciprocating sliding tests. The worn surfaces were characterized by scanning electron microscopy. The results revealed a lower wear rate on PEEK combined with a lower coefficient of friction (COF), when compared to Ti6Al4V. In fact, PEEK protected Ti6Al4V substrate against the corrosive environment and wear avoiding the release of metallic ions to the surrounding environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Chipping behaviour of all-ceramic crowns with zirconia framework and CAD/CAM manufactured veneer.

    Science.gov (United States)

    Schmitter, M; Mueller, D; Rues, S

    2012-02-01

    The aim of this in vitro study was to assess the ultimate load to failure of zirconia based crowns veneered with CAD/CAM manufactured ceramic. 32 identical, anatoform zirconia (Sirona inCoris ZI, mono L F1) frameworks (thickness 0.6mm) were constructed (Sirona inLab 3.80). Afterwards, 16 crowns were completed using a CAD/CAM manufactured lithium disilicate ceramic veneer (IPS e.max CAD, Ivoclar Vivadent). The remaining 16 frames were veneered using conventional manual layering technique. For the CAD/CAM manufactured veneers, the connection between framework and veneer was accomplished via a glass fusion ceramics. Before fracture tests, half of the specimens underwent thermocycling and chewing simulation (1.2 million chewing cycles, force magnitude F(max)=108 N). To further investigate the new technique, finite element computations were carried out on the basis of the original geometry. Nearly all (87.5%) conventionally veneered crowns failed already during chewing simulation, whereas crowns with CAD/CAM manufactured veneers were non-sensitive to artificial ageing. Crowns veneered with lithium disilicate ceramic displayed ultimate loads to failure of about 1600 N. The CAD/CAM production of veneers for restorations with zirconia framework is a promising way to reduce failures originating from material fatigue. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Production of plywood panels from Pinus taeda using veneers of differing densities and phenol-formaldehyde resin with high and low molecular weights

    Directory of Open Access Journals (Sweden)

    Graciela Ines Bolzon de Muniz

    2013-06-01

    Full Text Available This study aimed to evaluate the bonding quality of plywood panels from Pinus taeda using low and high molecular weight phenol-formaldehyde resin and veneers from three different density classes. The experiment consisted of six treatments, each of which produced three panels (replicates. Tests were conducted to evaluate glue line strength to shear stress after two boiling cycles and after 24 hours of cold water immersion. Also determined was the percentage of defects in wood samples. Results indicated that the density classes being assessed differed statistically. However, no significant difference was found between panels produced with high and panels produced with low molecular weight resin as to the mean values of glue line strength, whether subjecting them to two boiling cycles or after 24 hours of cold water immersion. Interactions between different density classes and adhesive formulations were found not significant either. Low molecular weight resin (BPM and panels produced with higher density veneers were found to have better behavior, regarding both bonding strength and percentage of defects. It was concluded that the bonding quality of plywood panels from Pinus taeda was satisfactory after using different densities of veneer and also high and low molecular weight phenolic resins. All treatments were found to comply with minimum requirements established in European standard EN 314-1/1993, which addresses bonding quality of plywood panels.

  12. Influence of vacuum hot-pressing temperature on the microstructure and mechanical properties of Ti-3Al-2.5V alloy obtained by blended elemental and master alloy addition powders

    Energy Technology Data Exchange (ETDEWEB)

    Bolzoni, L., E-mail: bolzoni.leandro@gmail.com [Department of Materials Science, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid (Spain); Ruiz-Navas, E.M.; Gordo, E. [Department of Materials Science, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid (Spain)

    2012-12-14

    This study addresses the processing of near-net-shape, chemically homogeneous and fine-grained Ti-3Al-2.5V components using vacuum hot-pressing. Two Ti-3Al-2.5V starting powders were considered. On one side, hydride-dehydride (HDH) elemental titanium was blended with an HDH Ti-6Al-4V prealloyed powder. On the other side, an Al:V master alloy was added to the HDH elemental titanium powder. The powders were processed applying a uniaxial pressure of 30 MPa. The sintering temperatures studied varied between 900 Degree-Sign C and 1300 Degree-Sign C. The relative density of the samples increased with processing temperature and almost fully dense materials were obtained. The increase of the sintering temperature led also to a strong reaction between the titanium powders and the processing tools. This phenomenon occurred particularly with boron nitride (BN) coating, which was used to prevent the direct contact between titanium and graphite tools. The flexural properties of the Ti-3Al-2.5V samples increased with vacuum hot-pressing temperature and are comparable to those specified for wrought titanium medical devices. Therefore, the produced materials are promising candidates for load bearing applications as implant materials. -- Highlights: Black-Right-Pointing-Pointer Almost fully dense Ti-3Al-2.5V alloy components are obtained by means of hot-pressing. Black-Right-Pointing-Pointer The bending properties of the Ti-3Al-2.5V alloy are studied in details. Black-Right-Pointing-Pointer The reaction that occurs between the Ti-3Al-2.5V powder and the BN coating is analysed. Black-Right-Pointing-Pointer Microstructural evolution of blending elemental and master alloy materials with the temperature.

  13. Fracture strengths of chair-side-generated veneers cemented with glass fibers.

    Science.gov (United States)

    Turkaslan, S; Bagis, B; Akan, E; Mutluay, M M; Vallittu, P K

    2015-01-01

    CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.

  14. Evaluation of zirconia bonding to veneering porcelain

    OpenAIRE

    Aneta Mijoska; Mirjana Popovska

    2014-01-01

    Zirconium dioxide as core ceramic material for dental crowns and bridges, possess high strength, chemical stability and superior aesthetics after veneering. Veneering ceramic is considered to be the weakest part of all-ceramic restorations. The adhesion between the core and veneering porcelain is based on the manner in which the connection occurs in metal-ceramic structures. Standard procedures for connecting zirconia to hard dental tissues and veneering materials do not achieve the requir...

  15. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    Introduction: CAD/CAM (computer‑aided design and computer‑aided manufacturing) systems have refreshed the idea of chair‑side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of ...

  16. Thinning Pole-Sized Aspen Has no Effect on Number of Veneer Trees or Total Yield

    Science.gov (United States)

    Bryce E. Schlaegel; Stanley B. Ringlod

    1971-01-01

    Thinning 37-year-old aspen in north central Minnesota did not increase either total volume production or the number of veneer-sized trees after 10 years. Thinning is not recommended for stands nearing rotation age.

  17. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers.

    Science.gov (United States)

    Mahmood, Deyar Jallal Hadi; Linderoth, Ewa H; Wennerberg, Ann; Vult Von Steyern, Per

    2016-01-01

    To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) fixed dental prostheses (FDPs) with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1-7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8-11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. There was a significant difference (Pveneering materials and techniques tested in the study, split-file, over-press, built-up porcelains, and glass-ceramics are, with a great safety margin, sufficient for clinical use both anteriorly and posteriorly. Analysis of the fracture pattern shows differences between the milled veneers and over-pressed or built-up veneers, where the milled ones show numerically more veneer cracks and the other groups only show complete connector fractures.

  18. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers

    Science.gov (United States)

    Mahmood, Deyar Jallal Hadi; Linderoth, Ewa H; Wennerberg, Ann; Vult Von Steyern, Per

    2016-01-01

    Aim To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) fixed dental prostheses (FDPs) with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. Materials and methods A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1–7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8–11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. Results There was a significant difference (Pveneering materials and techniques tested in the study, split-file, over-press, built-up porcelains, and glass–ceramics are, with a great safety margin, sufficient for clinical use both anteriorly and posteriorly. Analysis of the fracture pattern shows differences between the milled veneers and over-pressed or built-up veneers, where the milled ones show numerically more veneer cracks and the other groups only show complete connector fractures. PMID:26929667

  19. Determination of native (wood derived) formaldehyde by the desiccator method in particleboards generated during panel production

    Science.gov (United States)

    Michael J. Birkeland; Linda Lorenz; James M. Wescott; Charles R. Frihart

    2010-01-01

    Hot-pressing wood, particularly in the production of wood composites, generates significant ‘‘native’’ (wood-based) formaldehyde (FA), even in the absence of adhesive. The level of native FA relates directly to the time and temperature of hot-pressing. This native FA dissipates in a relatively short time and is not part of the long-term FA emission issue commonly...

  20. Evaluation of veneer yields and grades from yellow-poplar, white oak, and sweetgum from the southeast

    Science.gov (United States)

    Robert H. McAlister

    1980-01-01

    Dry volume yields and standard grades of veneer are given for yellow-poplar, sweetgum, and white oak by tree diameter and location within the stem. Results show that the typical stands of mixed southern pine and hardwood timer yield enough veneer to utilize almost 90 percent of the stand volume in the production of COM-PLY lumber and panels

  1. Prefabricated veneers - bond strengths and ultramorphological analyses.

    Science.gov (United States)

    Perdigão, Jorge; Sezinando, Ana; Muñoz, Miguel A; Luque-Martinez, Issis V; Loguercio, Alessandro D

    2014-04-01

    To measure the microshear bond strengths (μSBS) of composite resin to the intaglio surface of prefabricated indirect veneers and analyze the FE-SEM ultramorphology of the pretreated intaglio surfaces as well as the fracture modes. Three veneer systems (veneer and respective luting material) were used in this study: two prefabricated veneer types, Cerinate One-hour (CER, DenMat) and Componeer (CMP, Coltene), and a laboratory- made veneer, IPS e.max Press (IPS, Ivoclar Vivadent) used as the control. For each group, 10 veneers were used. After delimitation of the bonding area with a double-faced adhesive tape, 0.8-mm-diameter cylinders of composite luting material were bonded to the pretreated intaglio surface. After polymerization, the specimens were fractured in shear mode using the wire-loop method in a universal testing machine. The pretreated intaglio surface of two extra veneers and four fractured specimens per group were morphologically characterized using FE-SEM. CER resulted in statistically lower mean μSBS (7.1 ± 1.2 MPa) than the other two veneer systems, CMP (15.2 ± 2.5 MPa) and IPS (14.7 ± 1.7 MPa) at p veneer systems resulted in greater bond strengths than those of the CER veneer system.

  2. Wet-preserved hemp fibreboard properties improvement with veneering

    Science.gov (United States)

    Kirilovs, E.; Kukle, S.; Gusovius, H.-J.

    2015-03-01

    The initial research describes a new type of fiber boards for the furniture interior design, developed in cooperation with ATB (Leibniz-Institute for Agricultural Engineering) by using a new method of raw materials preparation and specific production technologies of ATB. The main raw materials are aerobically aged hemp stalks. The samples are made of hemp chips with a long preservation time and fastened together with the UF glue. Specimens are 8 mm thick and correspond to a medium-density fiberboard, fitting standard EN622. Due to the fact that non-veneered material can be used only in non-load-bearing constructions, material improving technologies were studied, such as increase of board density, increase of glue percentage, partially substitution of wet-preserved hemp chips with a dry hemp and/or wooden chips to equalize moisture content of obtained mixture. The particular article describes how the new material is veneered with the oak veneer obtaining three-ply composite board with the improved mechanical properties that allows to use these boards in a load-bearing constructions. Tests are performed with the veneered material to determine such parameters as static bending strength (MOR), modulus of elasticity in static bending (MOE), swelling in thickness and hardness.

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

    OpenAIRE

    Marrelli, Massimo; Maletta, Carmine; Inchingolo, Francesco; Alfano, Marco; Tatullo, Marco

    2013-01-01

    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 bend...

  4. PROPERTIES OF LAMINATED VENEER LUMBER MANUFACTURED FROM HEAT TREATED VENEER

    Directory of Open Access Journals (Sweden)

    Hamiyet Sahin KOL

    2016-06-01

    Full Text Available The objective of this study was to determine and compare properties of laminated veneer lumber (LVL panels manufactured from heat treated (212o C, 2h and untreated pine veneer with melamine urea formaldehyde (MUF adhesive. The results showed that, heat treatment considerably decreased all investigated physical properties of LVL. The reductions in density (D, moisture content (MC, and thickness swelling (TS were 8.33%, 33.78% and 14.03%, respectively. The findings of this study demonstrated that heat treatment resulted in adverse effect on bending strength and hardness of LVL panels. Heat treatment caused a decrease in bending strength (MOR by 31.85% and in hardness (HT by 25.44%. However, modulus of elasticity (MOE and compressive strength (CS values of LVL panels were higher than those of untreated groups. Compressive strength and modulus of elasticity (MOE of LVL panels made of heat treated veneer respectively were 11.17% and 7.46% higher than untreated LVLs

  5. ALL CERAMIC VENEERS: A CASE REPORT

    OpenAIRE

    Dileep Soni; Prateek Agarwal; Rakesh Jain; Disha Kumar; Bhavana Pareek

    2016-01-01

    Porcelain veneers are one of the best restorative treatment options available from biological, functional, mechanical and esthetic perspectives. The use of porcelain laminate veneers to solve esthetic and/or functional problems has been shown to be a valid management option, especially in the anterior esthetic zone. The present case reports the case of attrition, anterior teeth in a healthy dentition by means of sectional porcelain veneers simply cemented onto the natural teeth an...

  6. LAMINATE VENEER - CAD / CAM: CASE REPORTS

    OpenAIRE

    soygun, koray; Gülnahar, Evrem; Bolayır, Giray

    2014-01-01

    ABSTRACTThe recent increase in the variety and functionality of materials and the innovations in the application techniques invigorated the conservative efforts within dental prosthetics to achieve natural looking aesthetic results. Porcelain laminate veneers are very effective tools in terms of both aesthetic and functional rehabilitation. This study narrates and explains the clinical application and cementation stages of porcelain laminate veneers techniques.Key words: Laminate veneer, zirc...

  7. Modeling of ultrathin occlusal veneers.

    Science.gov (United States)

    Magne, Pascal; Stanley, Kyle; Schlichting, Luís Henrique

    2012-07-01

    The purpose of this investigation was to compare stresses within bonded porcelain and composite resin ultra-thin occlusal veneers to restore advanced erosive lesions. A sound maxillary molar was digitized with a micro-CT scanner. The 2D image data were converted in a 3D model using an interactive medical image processing software (Mimics). Standard triangle language files (STL files) of enamel and dentin surfaces were then exported to the software 3-matic to execute design and meshing operations. Solid 3-dimensional (3-D) models acquired in a finite element software (Marc/Mentat) were subjected to nonlinear contact analysis to simulate occlusal loading at 200N and 800N. Values of maximum principal stress and ultimate tensile strength were used to calculate the risk of fracture and for validation with existing experimental data. There were marked differences in stress distributions both at 200N (maximum peak values of 21.59, 28.63, 31.04MPa) and 800N (96.16, 115.73, 134.90MPa) for all restorative materials (MZ100, Empress CAD and e.max CAD, respectively). High tensile stresses (measured in the central groove) were found at 800N with the ceramic occlusal veneers showing occlusal stress peaks 17-29% higher than composite resin. The estimated risk of fracture was decreased for ultrathin composite resin occlusal veneers, which correlated with the existing validation data. Ultra-thin composite resin (MZ100) and lithium disilicate (e.max CAD) occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of severe erosive lesions in the posterior dentition. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Evaluation of a novel multiple phase veneering ceramic.

    Science.gov (United States)

    Sinthuprasirt, Pannapa; van Noort, Richard; Moorehead, Robert; Pollington, Sarah

    2015-04-01

    To produce a new veneering ceramic based on the production of a multiple phase glass-ceramic with improved performance in terms of strength and toughness. A composition of 60% leucite, 20% diopside and 20% feldspathic glass was prepared, blended and a heat treatment schedule of 930°C for 5 min was derived from differential thermal analysis (DTA) of the glasses. X-ray diffraction (XRD) and SEM analysis determined the crystalline phases and microstructure. Chemical solubility, biaxial flexural strength (BFS), fracture toughness, hardness, total transmittance and coefficient of thermal expansion (CTE) were all measured in comparison to a commercial veneering ceramic (VITA VM9). Thermal shock resistance of the leucite-diopside and VITA VM9 veneered onto a commercial high strength zirconia (Vita In-Ceram YZ) was also assessed. Statistical analysis was undertaken using Independent Samples t-test. Weibull analysis was employed to examine the reliability of the strength data. The mean chemical solubility was 6 μg/cm(2) for both ceramics (P=1.00). The mean BFS was 109 ± 8 MPa for leucite-diopside ceramic and 79 ± 11 MPa for VITA VM9 ceramic (P=0.01). Similarly, the leucite-diopside ceramic demonstrated a significantly higher fracture toughness and hardness. The average total transmittance was 46.3% for leucite-diopside ceramic and 39.8% for VITA VM9 (P=0.01). The leucite-diopside outperformed the VITA VM9 in terms of thermal shock resistance. Significance This novel veneering ceramic exhibits significant improvements in terms of mechanical properties, yet retains a high translucency and is the most appropriate choice as a veneering ceramic for a zirconia base core material. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Defining Hardwood Veneer Log Quality Attributes

    Science.gov (United States)

    Jan Wiedenbeck; Michael Wiemann; Delton Alderman; John Baumgras; William Luppold

    2004-01-01

    This publication provides a broad spectrum of information on the hardwood veneer industry in North America. Veneer manufacturers and their customers impose guidelines in specifying wood quality attributes that are very discriminating but poorly defined (e.g., exceptional color, texture, and/or figure characteristics). To better understand and begin to define the most...

  10. Hot pressing and lithification of gouge during the Mount St. Helens 2004-2008 eruption: insights from high temperature deformation experiments

    Science.gov (United States)

    Ryan, Amy G.; Russell, James K.; Heap, Michael J.

    2017-04-01

    as a result of atomic diffusion across grain boundaries (i.e., the process occurring during the industrial production of ceramics by hot (isostatic) pressing), is the dominant mechanism operating at high T and under pressure. While viscous sintering (i.e. welding) operates in many "melt-glass-rich" volcanic systems, solid-state sintering has yet to be explored as a densification mechanism operating on fine granular crystalline volcanic materials at conditions and timescales relevant to volcanic processes.

  11. Study of structural and dimensional characteristics of the melt spun p-Bi0.5Sb1.5Te3 powders compacted by vacuum hot pressing and spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Andrei A. Melnikov

    2015-12-01

    Full Text Available P-type thermoelectric Bi0,5Sb1,5Te3 powders were obtained by the melt spinning technique (extremely rapid quenching from the liquid state and their structural and dimensional characteristics were characterized. The crystallographic group and the lattice parameters of the powders correspond to those for Bi0,5Sb1,5Te3 crystallized in equilibrium conditions which suggests the identity of the crystal structure. The powders were compacted by vacuum hot pressing and spark plasma sintering. We found that the partial axial texture [001] directed along the axis of pressure application could be formed during the compacting of the powders. Temperature dependences of the thermoelectric characteristics of the compacted material were measured in a direction perpendicular to the pressure application axis in the 100–700 K range. It is demonstrated that the compacted samples possess low thermal conductivity while retaining the Seebeck coefficient and the electrical conductivity values comparable to crystallized material; therefore ZT reaches 1.05–1.15 in the 330–350 K range which indicates high prospects of applying these technologies.

  12. Preparation of in situ and ex situ reinforced Fe-10Cr-1Cu-1Ni-1Mo-2C containing NbC particles by milling and hot pressing

    Science.gov (United States)

    Li, Xiao-qiang; Li, Zi-yang; Ye, Yong-quan; Hu, Ke

    2015-02-01

    An in situ and ex situ reinforced powder metallurgy (PM) steel was prepared by the combination of high-energy ball milling and subsequent hot pressing of elemental mixed powders of Fe-10Cr-1Cu-1Ni-1Mo-2C by mass with the addition of NbC particles. A 40-h milling pretreatment makes the powder particles nearly equiaxed with an average diameter of ˜8 μm, and the ferrite grain size is refined to ˜6 nm. The sintered density reaches 99.0%-99.7% of the theoretical value when the sintering is conducted at temperatures greater than 1000°C for 30 min. In the sintered bulk specimens, the formation of an in situ M7C3 (M = Cr, Fe, Mo) phase is confirmed. M7C3 carbides with several hundred nanometers in size are uniformly distributed in the matrix. Some ultra-fine second phases of 50-200 nm form around the ex situ NbC and in situ M7C3 particles. The sintered steel exhibits an excellent combination of hardness (> Hv 500) and compressive strength (2100-2420 MPa).

  13. 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

    2013-01-01

    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 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. PMID:24932126

  14. Direct Composite Laminate Veneers: Three Case Reports

    Science.gov (United States)

    Korkut, Bora; Yanıkoğlu, Funda; Günday, Mahir

    2013-01-01

    Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolo-rations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here. PMID:23875090

  15. The effect of veneers on cosmetic improvement.

    Science.gov (United States)

    Nalbandian, S; Millar, B J

    2009-07-25

    This clinical study was designed to compare the patient's opinion of the cosmetic improvement after the placement of direct composite and indirect porcelain veneers. This retrospective study involved a survey of 145 patients (96 responses) each treated with 10 direct composite (Vitalescence) or 10 porcelain (Fortress) veneers. Patients subjectively evaluated multiple aspects of their smile using visual analogue scales before and after treatment for colour, shape, size, smile line and overall facial appearance. There were no statistical differences between the cosmetic improvement achieved for porcelain and composite (p > or = 0.05). Cost factors were not significant. Significant factors were: tooth conservation (p veneers over the porcelain veneers. Correlation findings relating to what patients feel as the key components of the smile for overall cosmetic improvement showed medium to high correlations (0.301 resin vs porcelain) when constructing maxillary anterior veneers does not significantly affect the patient's perception of cosmetic improvement. However, there was a preference towards accepting the composite veneer option. Overall aesthetic satisfaction is multifactorial. The results support the opinion that the more conservative composite veneers are justified and that, given the choice and information, patients may prefer this option.

  16. Direct Composite Laminate Veneers: Three Case Reports

    Directory of Open Access Journals (Sweden)

    Bora Korkut

    2013-05-01

    Full Text Available Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolorations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here.

  17. [Clinical biocompatibility of diacrilic resin veneers].

    Science.gov (United States)

    Dima, Raluca

    2012-01-01

    The great variety of modern composite resins developed recently by manufacturers, offered to clinicians multiple choices of restoring esthetic of frontal teeth. The present study was performed over a period of 8 months. The patients were devided in two groups: A consisted of patients that received indirect veneers; and B consisted of patients that received direct veneers. The clinical evaluation showed no major differences between group A and B, concerning the gingival recesion data and also concerning the plaque index. The data obtained from the study made us assess that direct and indirect composite materials have a clinically acceptable result in terms of biocompatibility when used for frontal veneers.

  18. Porcelain veneers - preparation design: A retrospective review

    Directory of Open Access Journals (Sweden)

    Obradović-Đuričić Kosovka B.

    2014-01-01

    Full Text Available This paper discusses the preparation of tooth design for porcelain veneers. It follows the literature more than three decades back in the past. From the very beginning, porcelain veneers were placed to no/minimally prepared tooth substance, showing different problems in clinical use. Later, the technique of etching the porcelain and controlling the reduction of tooth structure, presented the great steps forward in porcelain veneers accepting. A special accent concerning the preparative design was placed on variations of incisal edge preparation - the problem, which is still present in current practice. Additionally, the paper emphasizes the extremely demanding protocols in making the porcelain veneers as well as their expanded clinical indications.

  19. Direct Composite Laminate Veneers: Three Case Reports

    OpenAIRE

    Korkut, Bora; Yan?ko?lu, Funda; G?nday, Mahir

    2013-01-01

    Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are...

  20. The clinical microscope and direct composite veneer

    DEFF Research Database (Denmark)

    Pascotto, Renata C; Benetti, Ana Raquel

    2010-01-01

    This paper presents the advantages and limitations related to the use of a clinical microscope in restorative dentistry, and it demonstrates the aid of magnification during preparation and restoration of a direct composite veneer. Good illumination and visibility is important to adequately viewing...... the adjacent dental tissues so that the resin composite buildup can mimic natural teeth. The reproduction of details results in a naturally esthetic direct veneer....

  1. Veneer recovery from Douglas-fir logs.

    Science.gov (United States)

    E.H. Clarke; A.C. Knauss

    1957-01-01

    During 1956, the Pacific Northwest Forest and Range Experiment Station made a series of six veneer-recovery studies in the Douglas-fir region of Oregon and Washington. The net volume of logs involved totaled approximately 777 M board-feet. Purpose of these studies was to determine volume recovery, by grade of veneer, from the four principal grades of Douglas-fir logs...

  2. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers

    Directory of Open Access Journals (Sweden)

    Mahmood DJH

    2016-02-01

    Full Text Available Deyar Jallal Hadi Mahmood, Ewa H Linderoth, Ann Wennerberg, Per Vult Von Steyern Department of Prosthetic Dentistry, Faculty of Odontology, Malmö University, Malmö, Sweden Aim: To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP fixed dental prostheses (FDPs with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. Materials and methods: A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1–7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8–11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. Results: There was a significant difference (P<0.05 between the core designs, but not between the different types of Y-TZP materials. The split-file designs with VITABLOCS® (1,806±165 N and e.max® ZirPress (1,854±115 N and the state-of-the-art design with VITA VM® 9 (1,849±150 N demonstrated the highest mean fracture values. Conclusion: The shape of a split-file designed all-ceramic reconstruction calls for a different dimension protocol, compared to traditionally shaped ones, as the split-file design leads to sharp approximal indentations acting as fractural impressions, thus decreasing the overall strength. The design of a framework is a crucial factor for the load bearing capacity of an all-ceramic FDP. The state-of-the-art design is preferable since the split-file designed cores call for a cross-sectional connector area at least 42% larger, to have the same load bearing capacity as the state-of-the-art designed

  3. Anterior restorations: The performance of ceramic veneers.

    Science.gov (United States)

    Edelhoff, Daniel; Prandtner, Otto; Saeidi Pour, Reza; Liebermann, Anja; Stimmelmayr, Michael; Güth, Jan-Frederik

    2018-01-01

    Adhesive bonding techniques in combination with tooth-colored restorative materials are one of the greatest achievements of restorative dentistry. Adhesively bonded veneers made from various silicate ceramic materials have contributed significantly to this. Ceramic veneers had long been considered to be only esthetic implements. However, their range of indications has been steadily increasing, making ceramic veneers a highly viable alternative to classic, far more invasive forms of restorative treatment. Today these veneers are used to restore the biomechanics of the dentition, to establish adequate function, to mask highly discolored endodontically treated teeth, and for many other purposes. The present article explains the principles of modern veneer technology based on clinical examples, with special emphasis on collaboration with the dental laboratory and communication within the dental team. This includes analyzing the case, defining the treatment goal, determining the right shade, selecting the most suitable ceramic material, finding the best preparation design, and choosing the most appropriate adhesive concept. The article will also explore the long-term prognosis of ceramic veneers as reported by a number of scientific studies.

  4. Evaluation of zirconia bonding to veneering porcelain

    Directory of Open Access Journals (Sweden)

    Aneta Mijoska

    2014-10-01

    Full Text Available Zirconium dioxide as core ceramic material for dental crowns and bridges, possess high strength, chemical stability and superior aesthetics after veneering. Veneering ceramic is considered to be the weakest part of all-ceramic restorations. The adhesion between the core and veneering porcelain is based on the manner in which the connection occurs in metal-ceramic structures. Standard procedures for connecting zirconia to hard dental tissues and veneering materials do not achieve the required strength of bonding. The aim of the paper is to investigate different surface treatments of the zirconium dioxide ceramic core and find the best, for achieving highest adhesive bonding values to veneering porcelain. The study was primarily designed to investigate the bonding strength of the veneering porcelain to zirconia with in vitro Macro shear bond strength test. The specimens with different surface treatment of the zirconia were divided in five groups of twelve according to the treatment of zirconium surface and results showed highest bonding values for specimens treated with Rocatec system.

  5. Effect of wood grain and veneer side on loblolly pine veneer wettability

    Science.gov (United States)

    Todd E. Shupe; Chung Y. Hse; Elvin T. Choong; Leslie H. Groom

    1998-01-01

    Research was initiated to determine the effect of veneer side (tight or loose), and wood grain (earlywood or latewood) on the wettability of loblolly pine veneer. Contact angle measurements were performed with phenol-formaldehyde resin and distilled water. The resin and distilled water showed slightly higher contact angle mean values on the latewood portion for both...

  6. Room-Temperature and High-Temperature Tensile Mechanical Properties of TA15 Titanium Alloy and TiB Whisker-Reinforced TA15 Matrix Composites Fabricated by Vacuum Hot-Pressing Sintering.

    Science.gov (United States)

    Feng, Yangju; Zhang, Wencong; Zeng, Li; Cui, Guorong; Chen, Wenzhen

    2017-04-18

    In this paper, the microstructure, the room-temperature and high-temperature tensile mechanical properties of monolithic TA15 alloy and TiB whisker-reinforced TA15 titanium matrix composites (TiBw/TA15) fabricated by vacuum hot-pressing sintering were investigated. The microstructure results showed that there were no obvious differences in the microstructure between monolithic TA15 alloy and TiBw/TA15 composites, except whether or not the grain boundaries contained TiBw. After sintering, the matrix microstructure presented a typical Widmanstätten structure and the size of primary β grain was consistent with the size of spherical TA15 titanium metallic powders. This result demonstrated that TiBw was not the only factor limiting grain coarsening of the primary β grain. Moreover, the grain coarsening of α colonies was obvious, and high-angle grain boundaries (HAGBs) were distributed within the primary β grain. In addition, TiBw played an important role in the microstructure evolution. In the composites, TiBw were randomly distributed in the matrix and surrounded by a large number of low-angle grain boundaries (LAGBs). Globularization of α phase occurred prior, near the TiBw region, because TiBw provided the nucleation site for the equiaxed α phase. The room-temperature and high-temperature tensile results showed that TiBw distributed at the primary β grain boundaries can strengthen the grain boundary, but reduce the connectivity of the matrix. Therefore, compared to the monolithic TA15 alloy fabricated by the same process, the tensile strength of the composites increased, and the tensile elongation decreased. Moreover, with the addition of TiBw, the fracture mechanism was changed to a mixture of brittle fracture and ductile failure (composites) from ductile failure (monolithic TA15 alloy). The fracture surfaces of TiBw/TA15 composites were the grain boundaries of the primary β grain where the majority of TiB whiskers distributed, i.e., the surfaces of the

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

    Science.gov (United States)

    Marrelli, Massimo; Maletta, Carmine; Inchingolo, Francesco; Alfano, Marco; Tatullo, Marco

    2013-01-01

    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. PMID:23533415

  8. 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.

  9. Three-point bending tests of zirconia core/veneer ceramics for dental restorations.

    Science.gov (United States)

    Marrelli, Massimo; Maletta, Carmine; Inchingolo, Francesco; Alfano, Marco; Tatullo, Marco

    2013-01-01

    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.

  10. Porcelain laminate veneers: A minimally invasive esthetic procedure

    OpenAIRE

    Rafael de Almeida Decurcio; Paula de Carvalho Cardoso

    2011-01-01

    Technological advances in materials and techniques have been allowing to obtain natural esthetic results with conservative interventions. Ceramic veneers are very effective tools for both esthetic and functional rehabilitation. This study describes the use of ceramic veneers without tooth wear, reinforcing the concept that minimally invasive porcelain laminate veneers could become versatile and conservative allies in the fi eld of esthetic dentistry.

  11. A CT-based Simulator for Hardwood Log Veneering

    Science.gov (United States)

    Daniel L. Schmoldt; Pei Li; Philip A. Araman

    1995-01-01

    Profits for hardwood veneer manufacturers are dependent on proper initial log breakdown (flitching) decisions. While human skill is often adequate to ãreadä bark indicators of internal defects, it is much more difficult to envision potential veneer patterns that result from different flitching options. Different veneer patterns greatly affect potential markets and...

  12. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers

    OpenAIRE

    Mahmood, Deyar Jallal Hadi; Linderoth, Ewa H; Wennerberg, Ann; Vult Von Steyern, Per

    2016-01-01

    Deyar Jallal Hadi Mahmood, Ewa H Linderoth, Ann Wennerberg, Per Vult Von Steyern Department of Prosthetic Dentistry, Faculty of Odontology, Malmö University, Malmö, Sweden Aim: To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) fixed dental prostheses (FDPs) with respect to the choice of core material, veneering ma...

  13. Influence of veneer thickness on residual stress profile in veneering ceramic: measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2012-02-01

    The veneering process of frameworks induces residual stresses and can initiate cracks when combined with functional stresses. The stress distribution within the veneering ceramic as a function of depth is a key factor influencing failure by chipping. This is a well-known problem with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objective of this study is to investigate the influence of veneer thickness on the stress profile in zirconia- and metal-based structures. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. The stress profile was measured in bilayered disc samples of 20 mm diameter, with a 1 mm thick zirconia or metal framework. Different veneering ceramic thicknesses were performed: 1 mm, 1.5 mm, 2 mm, 2.5 mm and 3 mm. All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth up to 0.5-1.0 mm from the surface, and then becoming compressive again near the framework, except for the 1.5 mm-veneered zirconia samples which exhibited interior tensile stresses. Stresses in the surface of metal samples were not influenced by veneer thickness. Variation of interior stresses at 1.2 mm from the surface in function of veneer thickness was inverted for metal and zirconia samples. Veneer thickness influences in an opposite way the residual stress profile in metal- and in zirconia-based structures. A three-step approach and the hypothesis of the crystalline transformation are discussed to explain the less favorable residual stress development in zirconia samples. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Effect of core/veneer thickness ratio and veneer translucency on absolute and relative translucency of CAD-On restorations

    Directory of Open Access Journals (Sweden)

    Mennatallah Mohie el-Din Wahba, (BDS, MSc

    2017-06-01

    Conclusions: Only veneer translucency had significant effect over contrast ratio values, while on the other hand, absolute translucency values were significantly affected by the core/veneer thickness ratio, veneer translucency and interaction between them. It was clear that absolute translucency measurements showed higher translucency values for the restorations than contrast ratio measurements.

  15. Estimating the spread rate of urea formaldehyde adhesive on birch (Betula pendula Roth) veneer using fluorescence

    Science.gov (United States)

    Toni Antikainen; Anti Rohumaa; Christopher G. Hunt; Mari Levirinne; Mark Hughes

    2015-01-01

    In plywood production, human operators find it difficult to precisely monitor the spread rate of adhesive in real-time. In this study, macroscopic fluorescence was used to estimate spread rate (SR) of urea formaldehyde adhesive on birch (Betula pendula Roth) veneer. This method could be an option when developing automated real-time SR measurement for...

  16. Digital workflow for virtually designing and milling ceramic lithium disilicate veneers: a clinical report.

    Science.gov (United States)

    Zandinejad, A; Lin, W S; Atarodi, M; Abdel-Azim, T; Metz, M J; Morton, D

    2015-01-01

    Laminate veneers have been routinely used to restore and enhance the appearance of natural dentition. The traditional pathway for fabricating veneers consisted of making conventional polyvinyl siloxane impressions, producing stone casts, and fabricating final porcelain prostheses on stone dies. Pressed ceramics have successfully been used for laminate veneer fabrication for several years. Recently, digital computer-aided design/computer-aided manufacturing scanning has become commercially available to make a digital impression that is sent electronically to a dental laboratory or a chairside milling machine. However, technology has been developed to allow digital data acquisition in conjunction with electronically transmitted data that enables virtual design of restorations and milling at a remote production center. Following the aforementioned workflow will provide the opportunity to fabricate a physical cast-free restoration. This new technique has been reported recently for all-ceramic IPS e.max full-coverage pressed-ceramic restorations. However, laminate veneers are very delicate and technique-sensitive restorations when compared with all-ceramic full-coverage ones made from the same material. Complete digital design and fabrication of multiple consecutive laminate veneers seems to be very challenging. This clinical report presents the digital workflow for the virtual design and fabrication of multiple laminate veneers in a patient for enhancing the esthetics of his maxillary anterior teeth. A step-by-step process is presented with a discussion of the advantages and disadvantages of this novel technique. Additionally, the use of lithium disilicate ceramic as the material of choice and the rationale for such a decision is discussed.

  17. Texturing of superconducting Bi-Pb-Sr-Ca-Cu-O ceramics by combining the effect of a magnetic field and hot pressing in one direction; Texturation des ceramiques supraconductrices Bi-Pb-Sr-Ca-Cu-O par combinaison des effets du champ magnetique et de la contrainte uniaxiale a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Noudem, J.G.

    1995-10-27

    Superconducting Bi-(Pb)-Sr-Ca-Cu-O (Bi:2223) ceramics have a weak 77 K transport critical current density (Jc) due to porosity and the presence of misaligned platelets. In order to obtain higher critical current densities in these materials, it is necessary to increase their density and induce a preferential crystallographic orientation. We have developed a texturing process using solidification in a magnetic field combined with hot pressing. The experimental set-up provides a uniaxial pressure of 60 MPa and temperature up to 1100 deg C in a magnetic field of 8 T. Magnetic melt texturing (MMT) proved to be very effective in producing bulk oriented samples of polycrystalline Bi:2223 (crystallite c-axis oriented parallel to the field direction). These samples have Jc values of up to 1450 A/cm{sup 2} and a density of 5.1 g/cm{sup 3}. The texturing by hot pressing (HP) gives homogeneous, dense ({approx} 6 g/cm{sup 3}; 95 % of the theoretical limit) ceramics with a Jc of 2500 A/cm{sup 2}. Tapes of Ag/Bi:2223 provided by Alcatel Alsthom were also successful textured using HP. Finally we have demonstrated that the combination of solidification in a magnetic field with hot pressing (MMHPT) improves both the texture and density of the samples. Moreover the samples are very homogeneous and mechanically resistant. The 77 K transport critical current densities have values up to 3800 A/cm{sup 2} and 1100 A/cm{sup 2} along the (ab) and c-axis respectively. We have demonstrated that these samples are of potential use a current limiters. (author) 146 refs.

  18. Production and processing of Cu-Cr-Nb alloys

    Science.gov (United States)

    Ellis, David L.; Michal, Gary M.; Orth, Norman W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling.

  19. An indirect veneer technique for simple and esthetic treatment of anterior hypoplastic teeth

    Directory of Open Access Journals (Sweden)

    Amit Khatri

    2010-01-01

    Full Text Available This study describes a technique for treating anterior hypoplastic teeth using indirect nanocomposite veneer restoration. The prime advantage of an indirect veneer technique is that it provides an esthetic and conservative result. One of the most frequent reasons that patients seek dental care is discolored anterior teeth. Although treatment options such as removal of surface stains, bleaching, microabrasion or macroabrasion, veneering, and placement of porcelain crowns are available, conservative approach such as veneer preserves the natural tooth as much as possible. Full veneers are recommended for the restoration of localized defects or areas of intrinsic discoloration, which are caused by deeper internal stains or enamel defects. Indirectly fabricated veneers are much less sensitive compared to a operator′s technique and if multiple teeth are to be veneered, indirect veneers can be usually placed much more expeditiously. Indirect veneers last much longer than the direct veneers. Therefore, indirectly fabricated veneers are more advantageous than directly fabricated veneers in many cases.

  20. Er:YAG laser debonding of porcelain veneers.

    Science.gov (United States)

    Morford, Cynthia K; Buu, Natalie C H; Rechmann, Beate M T; Finzen, Frederick C; Sharma, Arun B; Rechmann, Peter

    2011-12-01

    The removal of porcelain veneers using Er:YAG lasers has not been previously described in the scientific literature. This study was designed to systematically investigate the efficacy of an Er:YAG laser on veneer debonding, possibly without damage to the underlying tooth, and preservation of the veneer integrity. The Fourier Transform Infrared Spectroscopy was used on 10 flat veneer samples (IPS Empress Esthetic, e.max Press HT) to assess which infrared laser wavelengths transmits through a veneer. Additionally, Fourier Transform Infrared (FTIR) spectra for a bonding cement (RelyX) were obtained. Consequently, Er:YAG laser energy transmission (wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 µseconds at 133 mJ/pulse) through different veneer thicknesses was measured. Twenty-four veneers were bonded to freshly extracted and prepared incisors. The energy necessary for debonding was determined and then the veneers were debonded with the laser. Time needed for total debonding was measured and possible damage to the underlying tooth structure was assessed by light microscopy. While the veneer materials did not show any characteristic water absorption bands in the FTIR, the bonding cement showed a broad H(2) O/OH absorption band. The veneers transmitted between 11.5% and 43.7% of the incident Er:YAG energy with Emax transmitting twice the energy as EE at comparable thicknesses. Initial signs of cement ablation occurred at 1.8-4.0 J/cm(2) with the fiber tip positioned at a distance of 3-6 mm from the veneer surface and 133 mJ output energy. All 24 bonded veneers were completely removed with an average removal time of 113 ± 76 seconds. Underlying tooth structure was not damaged. The debonding mainly occurred at the cement/veneer interface. None of the Emax veneers fractured during debonding, while 36% of the EE did. Er:YAG laser irradiation effectively debonds porcelain veneers while preserving tooth structure. Maintaining veneer

  1. Hot rolling effect on mechanical properties of copper alloys strengthened by dispersion and uniaxially hot pressed; Efecto de un laminado en caliente en la evolucion de las propiedades mecanicas de aleaciones base cobre endurecidas por dispersion y compactas uniaxialmente en caliente

    Energy Technology Data Exchange (ETDEWEB)

    Camurri, C.; Lopez, M.; Inostroza, J.; Guzman, M.; Jimenez, J. A.

    2003-07-01

    Copper powder of 140 {mu}m mean size was mechanical alloyed with several compounds, 2% B, C, 2% ZrC, 1% CrB, 2% Cr{sub 3}C{sub 2}, 1 and 2 vol % ZrB{sub 2} in a RETSCH PM high energy balls mill. The alloying process was carried out in stainless steel containers during 6 or 8 h of milling, under argon atmosphere, and the ball to powder charge ratio was 5:1. Instead of HIP processing, the alloyed powders were consolidated by uniaxial hot pressing at 650 degree centigree for 2 h at a pressure of 90 MOa in argon atmosphere. Afterward the compact samples of 30x10x10 mm were hot rolled at 850 degree centigree with area reduction from 10 to 40%. If an homogeneous hot pressing process is obtained, the subsequent hot rolling can be avoided as only an annealing effect is produced,characterized by a small decrease in hardness and tensile strength with a small increase in ductility. (Author) 18 refs.

  2. Fabrication and characterization of reversible thermochromic wood veneers.

    Science.gov (United States)

    Zhu, Xiaodong; Liu, Yu; Dong, Ningwen; Li, Zhao

    2017-12-05

    Leuco dyes are widely used as functional materials for their thermosensitive chromogenic nature. The influences of thermochromic compounds and impregnation processing conditions on thermochromic wood veneer properties were investigated in this paper. The thermochromic compounds included thermochromic dye (ODB-2), color developer (bisphenol A) and solvent (1-tetradecanol). To achieve the maximum color change, the optimum mixing ratio of ODB-2 to bisphenol A to 1-tetradecanol was 1:2:60. Juglans mandshurica veneers were ultrasonically impregnated with reversible thermochromic compound suspensions. Analysis of variance showed that the influences of impregnation parameters on veneer color change were significant at the 0.05 level. The optimum thermochromic wood veneer can be obtained by impregnating with a thermochromic compound suspension for 2.0 min at 65 °C. In this paper, the thermochromic properties of wood veneers were evaluated, and functional thermochromic veneers exhibited excellent properties and thermostability.

  3. Heat and current coming from the Lengwil TG veneering plant; Chaleur et courant provenant de l'usine de placage de Lengwil TG

    Energy Technology Data Exchange (ETDEWEB)

    Keel, A.

    1998-07-01

    With the recent cogeneration installation of the Lengwil TG veneering plant, the firm Schmid-Holzenergie-Contracting AG showed the possibility to produce current from wood (coupling strength-heat or cogeneration). The implemented installation is described with a special interest in the example of contracting: situations where the operating is different from the energy consumer. In this example the wastes wood of the veneering plant are recovered to feed the energy production system. (A.L.B.)

  4. Digital veneering system enhances microtensile bond strength at zirconia core-veneer interface.

    Science.gov (United States)

    Kim, Ki-Yeon; Kwon, Taek-Ka; Kang, Tae-Joo; Yang, Jae-Ho; Lee, Shin-Jae; Yeo, In-Sung

    2014-01-01

    This study investigated the effect of digital veneering system (DVS) on strengthening the bond between a zirconia core and ceramic veneer. Specimens for Groups 1 (negative control), 2 (positive control), 3, and 4 used conventional porcelain veneering technique on untreated, sandblasted, coloring agent-treated, and modifier-treated zirconia cores respectively. Group 5 used DVS, where glass ceramic veneers—produced by computer-aided milling—were fused to zirconia cores. Microtensile bond strengths (MTBS) at the interface were measured. MTBS results of Groups 1 to 5, expressed in mean (standard deviation), were 28.1 (7.3), 27.8 (6.3), 30.0 (10.2), 32.9 (8.1), and 37.8 (8.1) MPa. The DVS group had significantly higher MTBS than the negative and positive controls (pzirconia core and ceramic veneer, indicating that this system could reduce adhesive failure-related complications that frequently occur at the zirconia core-veneer interface.

  5. Evaluation of shear bond strength of veneering ceramics and zirconia fabricated by the digital veneering method.

    Science.gov (United States)

    Sim, Ji-Young; Lee, Wan-Sun; Kim, Ji-Hwan; Kim, Hae-Young; Kim, Woong-Chul

    2016-04-01

    The purpose of this study was to evaluate the shear bond strength (SBS) of veneering ceramic and zirconia fabricated by the digital veneering method. A total of 50 specimens were fabricated, i.e., 10 specimens each for the metal-ceramic (control) group and the four zirconia groups. The zirconia groups comprised specimens fabricated by the digital veneering method, the heat pressing method, and hand layering method for two groups, respectively. Furthermore, the shear bond strength was measured with a universal testing machine (Model 3345, Instron, Canton, MA, USA) and statistically analyzed using one-way ANOVA set at a significance level of Pveneering method (28.29MPa), the heat pressing method (18.89MPa), and the layering method (18.65, 17.21MPa). The samples fabricated by digital veneering had a significantly higher SBS than the other zirconia samples (PVeneering ceramic with a zirconia core that was fabricated via the digital veneering method is believed to be effective in clinical use since, its shear bond strength is significantly higher than that resulting from the conventional method. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  6. Management of anterior diastema with veneer restoration: Review of literature

    OpenAIRE

    Sri Eka Sari; Nurhayaty Natsir

    2016-01-01

    Diastema in the anterior teeth is a common aesthetic problem, which interfere confidence of patients. The cause of a diastema let known with certainty in advance before preparing the treatment plan. Management diastema closure on anterior teeth can use veneer. Veneer restorations can be made by direct technique with composite materials and indirect use porselen material. The purpose of this literature review is to discuss case management of diastema in the anterior teeth using veneer restorat...

  7. Tensile strength of bilayered ceramics and corresponding glass veneers

    OpenAIRE

    Anunmana, Chuchai; Champirat, Tharee; Jirajariyavej, Bundhit

    2014-01-01

    PURPOSE To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. MATERIALS AND METHODS Blocks of core ceramics (IPS e.max® Press and Lava™ Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm2 in cross-sectional area (n = 30/group). Additionally, monolithic microbars of thes...

  8. Minimally invasive veneers: current state of the art.

    Science.gov (United States)

    Vanlıoğlu, Burçin Akoğlu; Kulak-Özkan, Yasemin

    2014-01-01

    Ceramic veneers are considered a conservative solution for patients requiring improvement of the shape, color, or position of their anterior teeth. Ceramic veneers have been extensively and successfully used to mask intrinsic staining, to give the appearance of straightening, and to correct minor malformations of anterior teeth without the removal of substantial amounts of sound tooth substance. The current literature was reviewed to search for the most important parameters determining the long-term success and correct application of ceramic veneers.

  9. Minimally invasive veneers: current state of the art

    Science.gov (United States)

    Vanlıoğlu, Burçin Akoğlu; Kulak-Özkan, Yasemin

    2014-01-01

    Ceramic veneers are considered a conservative solution for patients requiring improvement of the shape, color, or position of their anterior teeth. Ceramic veneers have been extensively and successfully used to mask intrinsic staining, to give the appearance of straightening, and to correct minor malformations of anterior teeth without the removal of substantial amounts of sound tooth substance. The current literature was reviewed to search for the most important parameters determining the long-term success and correct application of ceramic veneers. PMID:25506248

  10. 3D Molding of Veneers by Mechanical and Pneumatic Methods

    Science.gov (United States)

    Gaff, Milan; Gašparík, Miroslav

    2017-01-01

    This paper deals with the influence of selected methods (mechanical and pneumatic) as well as various factors (wood species, moisture content, veneer shape, punch diameter, laminating foil thickness, holding method, plasticizing) on 3D molding of veneers. 3D molding was evaluated on the basis of maximum deflection of birch and beech veneers. Cracks and warping edges were also evaluated in selected groups of mechanical molding. Mechanical methods tested veneers with various treatments (steaming, water and ammonia plasticizing and lamination). The pneumatic method was based on veneer shaping using air pressure. The results indicate that birch veneers are more suitable for 3D molding. The differences between the mechanical and pneumatic methods were not considerable. The most suitable method for mechanical 3D molding was the veneer lamination by polyethylene foils with thicknesses of 80 and 125 μm, inasmuch as these achieved better results than veneer plasticized by steam. The occurrence of cracks was more frequent in beech veneers, whereas, edge warping occurred at similar rates for both wood species and depends rather on holding method during 3D molding. Use of the ammonia solution is more suitable and there occurs no marked increase in moisture as happens when soaking in water. PMID:28772684

  11. Microleakage patterns of porcelain and castable ceramic laminate veneers.

    Science.gov (United States)

    Tjan, A H; Dunn, J R; Sanderson, I R

    1989-03-01

    This investigation evaluated the microleakage of conventional porcelain and Dicor castable ceramic laminate veneers bonded either entirely on acid-etched enamel or with the cervical margins on dentin. Three brands of light-activated composite resin cement systems were used and compared. Laminate veneers were bonded to extracted human maxillary central incisors and the extent of the marginal microleakage was measured. The findings indicated minimal marginal microleakage under both types of ceramic veneers bonded to all-enamel preparations. A markedly greater leakage at the dentin-composite resin interface was observed in veneers with cervical margins placed on dentin.

  12. Determining tensile properties of sweetgum veneer flakes

    Science.gov (United States)

    E.W. Price

    1976-01-01

    Rotary-cut 8weetgum veneer flakes measuring 3 inchee along the grain, 3/8 inch wide, and 0.015 inch thick, were stressed in tension parallel to the grain at gage lengths from 0.00 to 1.25 inchee for unpressed control and at 0.75 inch gage length for flakes pressed in a flakeboard mat. The control flakes had an average tensile strength of 9,400 psi for the smaller age...

  13. Porcelain veneers produced by refractory die method

    OpenAIRE

    Zlatanovska, Katerina; Zarkova-Atanasova, Julija; Radeska-Panovska, Ana; Denkova, Natasa; Papakoca, Kiro

    2015-01-01

    Nowadays porcelain veneers are constantly increasing in popularity among dental practitioners because of their excellent clinical performance. As materials and techniques develop they have become most utilized, high aesthetic and less invasive therapeutic possibility used for conservative restoration of unaesthetic anterior teeth. Technological advances today make it easy to obtain natural aesthetic result with conservative interventions. The many all-ceramic systems available to dentists and...

  14. Tooth preparation techniques for porcelain laminate veneers.

    Science.gov (United States)

    Brunton, P A; Aminian, A; Wilson, N H

    2000-09-09

    The purpose of this study was to determine the effect that two guides to tooth preparation had on an operator's ability to appropriately and consistently prepare teeth for porcelain laminate veneers. In-vitro study. Thirty typodont central incisor teeth were randomly allocated into three groups and a general dental practitioner was asked to prepare the teeth for porcelain laminate veneers. Group A were prepared freehand while Groups B and C were prepared with the assistance of a silicone index and depth preparation bur respectively. Images of the prepared teeth were used to calculate the mean labial depth of preparation and incisal reduction of teeth in each group. The mean labial reduction for Groups A, B and C was 0.37 mm (SD 0.13), 0.62 mm (SD 0.17) and 0.61 mm (SD 0.15) and the mean incisal reduction for Groups A, B and C was 1.0 mm (SD 0.28), 1.0 mm (SD 0.38) and 1.03 mm (SD 0.26) respectively. It is suggested that consideration be given to the use of a silicone index or depth gauge bur when teeth are prepared for porcelain laminate veneers.

  15. Yield and ultrasonic modulus of elasticity of red maple veneer

    Science.gov (United States)

    Robert J. Ross; Steven Verhey; John R. Erickson; John W. Forsman; Brian K. Brashaw; Crystal L. Pilon; Xiping Wang

    2004-01-01

    The purpose of the study was to assess the potential for using red maple sawlogs to manufacture laminated veneer lumber (LVL). The primary objective was to determine the yield of ultrasonically graded veneer from red maple logs. A sample of 48 logs was obtained from six Eastern and Lake States in the United States. The logs were visually graded and shipped to a plywood...

  16. Relationship between stress wave velocities of green and dry veneer

    Science.gov (United States)

    Brian K. Brashaw; Xiping Wang; Robert J. Ross; Roy F. Pellerin

    2004-01-01

    This paper evaluates the relationship between the stress wave velocities of green and dry southern pine and Douglas-fir veneers. A commercial stress wave timer and a laboratory signal analysis system were used to measure the transit time required for an induced stress wave to travel the longitudinal length of each veneer. Stress wave transit times were measured in the...

  17. Factors affecting the quality of walnut lumber and veneer

    Science.gov (United States)

    Daniel L. Cassens

    2004-01-01

    Walnut is a unique species in both its timber and wood characteristics. Although market conditions vary it is generally considered a valuable species. Because of these factors, setting quality (value) levels for both lumber and veneer can be involved. Lumber grades are quantitative thus straight forward once the system is understood. Determining quality in veneer is...

  18. Prefabricated composite veneers: historical perspectives, indications and clinical application.

    Science.gov (United States)

    Dietschi, Didier; Devigus, Alessandro

    2011-01-01

    Veneering anterior teeth is a well-established technique, which was brought to Dentistry by Dr Pincus as early as 1937. From the mid-1970s, boosted by the development of composites and adhesive techniques, various concepts emerged including direct composite restorations, prefabricated composite veneers and of course, individualized porcelain indirect veneers. The prefabricated composite veneer option was however soon abandoned due to former technological limitations. Recently, the creation of a new shade guide comprising enamel shells revitalized this "old idea," and in combination with a high pressure and temperature molding process followed by a laser surface vitrification, a novel, improved composite prefabricated system (Venear, Edelweiss Dentistry) was born. This paper provides an overview of the potential indications and clinical protocol of this original veneering technique.

  19. Dental-gingival remodeling with BOPT no-prep veneers.

    Science.gov (United States)

    Agustín-Panadero, Rubén; Ausina-Escrihuela, Daniel; Fernández-Estevan, Lucía; Román-Rodríguez, Juan-Luis; Faus-López, Joan; Solá-Ruíz, María-Fernanda

    2017-12-01

    Recent years have seen increasing demand for treatments aimed at improving dental esthetics. In this context, both patients and dentists prefer to preserve dental structures as far as possible; thanks to technological advances, especially in adhesive dentistry, new materials and minimally invasive techniques such as "no-prep" (no preparation) veneers have made this possible. Nevertheless, no-prep veneers have specific indications and suffer certain disadvantages. This clinical case describes the rehabilitation of the upper anterior region by means of no-prep veneers, with BOPT (Biologically Oriented Preparation Technique) cervical margins. The patient had requested an aesthetic treatment to improve irregularities of the gingival margins associated with the presence of diastemata resulting from microdontia. Key words:BOPT, micro-veneers, hybrid ceramic, ultra-fine veneers, diastemata, without prosthetic finish line, no-prep.

  20. Shear bond strength of veneering porcelain to porous zirconia.

    Science.gov (United States)

    Nakamura, Takashi; Sugano, Tsuyoshi; Usami, Hirofumi; Wakabayashi, Kazumichi; Ohnishi, Hiroshi; Sekino, Tohru; Yatani, Hirofumi

    2014-01-01

    In this study, two types of porous zirconia and dense zirconia were used. The flexural strength of non-layered zirconia specimens and those of the layered zirconia specimens with veneering porcelain were examined. Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 306 MPa for porous zirconia. The flexural strength of the layered specimens was 360 MPa for dense zirconia and 132 to 156 MPa for porous zirconia, when a load was applied to the porcelain side. The shear bond strength of porcelain veneered to dense zirconia was 27.4 MPa and that of porcelain veneered to porous zirconia was 33.6 to 35.1 MPa. This suggests that the veneering porcelain bonded strongly to porous zirconia although porous zirconia has a lower flexural strength than dense zirconia.

  1. 40 CFR 63.2264 - Initial compliance demonstration for a hardwood veneer dryer.

    Science.gov (United States)

    2010-07-01

    ... hardwood veneer dryer. 63.2264 Section 63.2264 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Initial Compliance Requirements § 63.2264 Initial compliance demonstration for a hardwood veneer dryer. If you operate a hardwood veneer dryer, you must record the annual volume percentage of softwood veneer...

  2. 40 CFR 63.2266 - Initial compliance demonstration for a veneer redryer.

    Science.gov (United States)

    2010-07-01

    ... veneer redryer. 63.2266 Section 63.2266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Initial Compliance Requirements § 63.2266 Initial compliance demonstration for a veneer redryer. If you operate a veneer redryer, you must record the inlet moisture content of the veneer processed in the...

  3. Phase Relations and Stability Studies in the Si3N4-SiO2-Y2O3 Pseudo- Ternary System. (6) Development of Microstructure, Strength and Fracture Toughness of Hot-Pressed Si3N4. (7) Sintering of SiC with Boron Compounds. (8).

    Science.gov (United States)

    1976-04-01

    8217repressed discs of the ccriposite powders were hot-pressed in a 5 cm I.D. graphite dic-susceptor lined with grafoi1 at a pressure of 28 MN /nr...repeated fabrication of this composition results in two phases,* viz., H-phase and *llamon et al. , Cll) who have synthesized many apatite -like...0.001 ɘ.001 -- B ɘ.01 < 0.003 -- Ca 0.011 ɘ.005 < 0.005 Co 0.002 < 0.003 -- Cr 0.02 ɘ.003 -- Fe >0.10 0.012 ɘ.001 Mg 0.003 0.001 < 0.005 Mn

  4. Microtensile bond strength of different components of core veneered all-ceramic restorations. Part 3: double veneer technique

    NARCIS (Netherlands)

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

    2008-01-01

    Purpose: The bond strength of zirconia veneer has been considered a weak link in the layered all-ceramic restoration. In a previous study, this bond was improved using a new category of veneering ceramics adopting the pressing technique; however, the resulting esthetic quality lacked the individual

  5. Effect of Nondestructive Evaluation of Veneers on the Properties of Laminated Veneer Lumber (LVL from a Tropical Species

    Directory of Open Access Journals (Sweden)

    Geraldo Bortoletto

    2013-04-01

    Full Text Available This study aimed at evaluating the potential of Schizolobium parahyba to produce laminated veneer lumber (LVL and the feasibility of a nondestructive method for grading the veneers. Initially, 64 S. parahyba veneers were nondestructively tested using the stress wave method, and stress wave velocity (wv and veneer dynamic modulus of elasticity (EdV were determined. Afterwards, the veneers were graded according to EdV descending values and used to manufacture 8-ply LVL boards. After the manufacturing, the boards were also nondestructively tested, and the board dynamic modulus of elasticity (EdB was determined. Simple linear regression analysis was run to evaluate the relationship between the nondestructive and mechanical properties of veneers/boards. A positive effect of veneer stress wave properties on the LVL properties was found. Therefore, the higher the EdV values, the higher the LVL properties. The relationships between EdV and EdB properties were highly significant with all mechanical properties. It was clearly observed that when this grading procedure was used, the veneers were indirectly graded by their density. Finally, it could be concluded that S. parahyba showed good potential to produce LVL.

  6. Alternate Method for Determination of Glue-line Tensile Strength of Spliced Veneers in Czech Republic

    Directory of Open Access Journals (Sweden)

    Pavel Král

    2015-01-01

    Full Text Available Quality control is a crucial part of any manufacturing unit, as it assures compliance to established standards as well as maintenance of product quality for internal management purposes. Quality control of spliced veneer in Czech wood based industries is mainly based on ČSN 49 2315 and ČSN 49 2320 standards, which rely on measurement of crack length in finished product. This method has been satisfactorily used since 1985 but requirements of wood based industry has changed a lot in these years. We propose an alternate method for mesurement of tensile strength of spliced veneers. Samples of specified size spliced were taken as mentioned in details and they were subjected to tensile stength measurement. An addtional adhesive tape was used to avoid intra-material fibres disjointing, so that inter-material tensile strength can be measured for spliced veneers. This test can be used for on – site optimization of splicing machine units as well as regular quality control of spliced venners.

  7. Porcelain laminate veneers: Clinical survey for evaluation of failure

    Science.gov (United States)

    Alhekeir, Diemah F.; Al-Sarhan, Rana A.; Al Mashaan, Abdulmohsen F.

    2014-01-01

    Objective To investigate the association of the failure of porcelain laminate veneers with factors related to the patient, material, and operator. Methods This clinical survey involved 29 patients (19 women and 10 men) and their dentists, including undergraduate and postgraduate dental students and dental interns. Two questionnaires were distributed to collect information from participants. All patients were clinically examined. Criteria for failure of the porcelain laminate veneers included color change, cracking, fracture, and/or debonding. Results A total of 205 porcelain laminate veneers were evaluated. All of the restorations were fabricated from IPS e.max Press and cemented with Variolink Veneer (Ivoclar Vivadent, Schaan, Principality of Liechtenstein) or RelyX veneer cement (3M ESPE, St. Paul, MN, USA). The preparations were generally located in enamel (58.6%), and most veneers had an overlapped design (89.7%). Ten patients (34.48%) showed veneer failure, most often in terms of color change (60%). Overall, 82.8% of patients were satisfied with their restorations. Conclusion Insufficient clinical skills or operator experience resulted in restoration failure in one-third of patients. PMID:25408598

  8. Porcelain laminate veneers: Clinical survey for evaluation of failure.

    Science.gov (United States)

    Alhekeir, Diemah F; Al-Sarhan, Rana A; Al Mashaan, Abdulmohsen F

    2014-04-01

    To investigate the association of the failure of porcelain laminate veneers with factors related to the patient, material, and operator. This clinical survey involved 29 patients (19 women and 10 men) and their dentists, including undergraduate and postgraduate dental students and dental interns. Two questionnaires were distributed to collect information from participants. All patients were clinically examined. Criteria for failure of the porcelain laminate veneers included color change, cracking, fracture, and/or debonding. A total of 205 porcelain laminate veneers were evaluated. All of the restorations were fabricated from IPS e.max Press and cemented with Variolink Veneer (Ivoclar Vivadent, Schaan, Principality of Liechtenstein) or RelyX veneer cement (3M ESPE, St. Paul, MN, USA). The preparations were generally located in enamel (58.6%), and most veneers had an overlapped design (89.7%). Ten patients (34.48%) showed veneer failure, most often in terms of color change (60%). Overall, 82.8% of patients were satisfied with their restorations. Insufficient clinical skills or operator experience resulted in restoration failure in one-third of patients.

  9. Biaxial flexural strength of bilayered zirconia using various veneering ceramics.

    Science.gov (United States)

    Chantranikul, Natravee; Salimee, Prarom

    2015-10-01

    The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (α=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength.

  10. Advances in dental veneers: materials, applications, and techniques.

    Science.gov (United States)

    Pini, Núbia Pavesi; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite; Lovadino, José Roberto; Terada, Raquel Sano Suga; Pascotto, Renata Corrêa

    2012-01-01

    Laminate veneers are a conservative treatment of unaesthetic anterior teeth. The continued development of dental ceramics offers clinicians many options for creating highly aesthetic and functional porcelain veneers. This evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case. The current literature was reviewed to search for the most important parameters determining the long-term success, correct application, and clinical limitations of porcelain veneers.

  11. Management of anterior diastema with veneer restoration: Review of literature

    Directory of Open Access Journals (Sweden)

    Sri Eka Sari

    2016-06-01

    Full Text Available Diastema in the anterior teeth is a common aesthetic problem, which interfere confidence of patients. The cause of a diastema let known with certainty in advance before preparing the treatment plan. Management diastema closure on anterior teeth can use veneer. Veneer restorations can be made by direct technique with composite materials and indirect use porselen material. The purpose of this literature review is to discuss case management of diastema in the anterior teeth using veneer restorations with direct and indirect techniques.

  12. Advances in dental veneers: materials, applications, and techniques

    Science.gov (United States)

    Pini, Núbia Pavesi; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite; Lovadino, José Roberto; Terada, Raquel Sano Suga; Pascotto, Renata Corrêa

    2012-01-01

    Laminate veneers are a conservative treatment of unaesthetic anterior teeth. The continued development of dental ceramics offers clinicians many options for creating highly aesthetic and functional porcelain veneers. This evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case. The current literature was reviewed to search for the most important parameters determining the long-term success, correct application, and clinical limitations of porcelain veneers. PMID:23674920

  13. The efficiency of different light sources to polymerize resin cement beneath porcelain laminate veneers.

    Science.gov (United States)

    Usumez, A; Ozturk, A N; Usumez, S; Ozturk, B

    2004-02-01

    Plasma arc light units for curing resin composites have been introduced with the claim of relatively short curing times. The purpose of this study was to evaluate the efficiency of two different light sources to polymerize dual curing resin cement beneath porcelain laminate veneers. Twenty extracted healthy human maxillary centrals were used. Teeth were sectioned 2 mm below the cemento-enamel junction and crown parts were embedded into self-cure acrylic resin, labial surface facing up. Cavity preparation was carried out on labial surfaces. These teeth were divided into two groups of 10 each. The resin cement/veneer combination was exposed to two different photo polymerization units. A conventional halogen light (Hilux 350, Express Dental Products) and a plasma arc light (Power PAC, ADT) were used to polymerize resin cement. Ten specimens were polymerized conventionally (40 s) and the other specimens by plasma arc curing (PAC) (6 s). Two samples from each tooth measuring 1.2 x 1.2 x 5 mm were prepared. These sections were subjected to microshear testing and failure values were recorded. Statistically significant differences were found between the bond strength of veneers exposed to conventional light and PAC unit (P < 0.001). Samples polymerized with halogen light showed better bond strength. The results of this study suggest that the curing efficiency of PAC through ceramic was lower compared with conventional polymerization for the exposure durations tested in this study.

  14. The influence of fire retardants on the properties of beech and poplar veneers and plywood

    Directory of Open Access Journals (Sweden)

    Miljković Jovan

    2005-01-01

    Full Text Available Rising demands for fire resistance properties of wood construction and elements matching new standards have been an important part of building codes during the last decade. On the other side, lack of more detailed research on interaction between wood species and selected fire retardant chemicals even with basically one is evident. This is particularly truth with domestic wood species. In this research, beech and poplar veneers were immersed in 25% solutions of monoammonium phosphate (MP and sodium acetate (SA and impregnated for different periods of time. To determine the preliminary level of fire retardancy achieved in veneers before manufacturing of finished plywood, thermo gravimetric (TG and derivative thermo gravimetric (DTG methods were used. TG and DTG analyses of treated and untreated wood, as well as of fire retardants alone, were performed. The next properties of impregnated and no impregnated veneers and plywood were determined: absorption of imp regnant solution (A, weight percent gain (WPG of imp regnant, equilibrium moisture content (EMC, pH values, and in the case of plywood, strength and fire resistance. Fire resistance of plywood was tested in accordance with standard test for resistance to the effects of fire and the most efficient fire retardant, monoammonium phosphate, had the same result as TG/DTG analyses, which pointed out the validity of TG methods in predicting fire resistance of future products.

  15. The Effect of Veneers Roughness on Bonding and Some Mechanical Properties of Plywood

    Directory of Open Access Journals (Sweden)

    Ismail AYDIN

    2013-03-01

    Full Text Available Bonding technology is one of the keytechnologies for producing wood-based materials.Surface quality of solid wood products is one of themost important properties influencing furthermanufacturing processes such as finishing orstrength of adhesive joint. The aim of this study wasto determine the influence of sanding with differentgrit sizes on bonding strength and some mechanicalproperties of poplar and beech plywood. For thisreason, 2mm thick rotary cut veneers obtained fromfreshly cut (not treated poplar (Populus deltoides I-77/51 and beech (Fagus orientalis logs were usedas material. The surfaces of some veneers weresanded with 80 and 180 grit size. Three-layerplywoodwere produced from sanded and nonsandedveneers using phenol formaldehyde glueresins to evaluate the effects of sanding somemechanical properties of plywood. Rz roughnessparameter was measured to evaluate surfaceroughness of veneer according to DIN 4768.Bonding and bending strength values of plywoodmanufactured from sanded and non-sanded veneersvaried depending on wood species and grit size.Bonding strength values of plywood increased withdecreasing surface roughness values of veneersboth of two wood species.

  16. Shear bond strength of veneering porcelain to porous zirconia

    National Research Council Canada - National Science Library

    NAKAMURA, Takashi; SUGANO, Tsuyoshi; USAMI, Hirofumi; WAKABAYASHI, Kazumichi; OHNISHI, Hiroshi; SEKINO, Tohru; YATANI, Hirofumi

    2014-01-01

    .... Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 306 MPa for porous zirconia...

  17. Mandibular ceramic veneers: an examination of complex cases.

    Science.gov (United States)

    Nixon, R L

    1995-05-01

    The indications for mandibular anterior ceramic veneers, tooth preparation design, provisionalization considerations, and placement procedures were presented in a previous article by the author. The functional utility, tissue biocompatibility, and dissimilarities of mandibular veneers, in comparison to maxillary anterior ceramic veneers, were explored, along with indications and contraindications for this form of treatment. This article demonstrates the aesthetic range of these restorations in the context of more complex cases. The learning objective of this article is to illustrate the viability of mandibular ceramic veneers in realigning teeth nonorthodontically, while sustaining the biologic health of the periodontium, stability of the occlusion, and aesthetic parameters of each case. The importance of wax mock-ups is outlined for visualization of the final result, as well as the evaluation of root proximity to avoid subgingival ledging of the teeth and subsequent periodontal disease. Orthodontics and other methods for the correction of anterior crowding are discussed.

  18. Esthetic rehabilitation with laminated ceramic veneers reinforced by lithium disilicate.

    Science.gov (United States)

    Soares, Paulo Vinícius; Spini, Pedro Henrique Rezende; Spini, Pedro Henrique; Carvalho, Valessa Florindo; Souza, Paula Gomes; Gonzaga, Ramon Corrêa de Queiroz; Gonzaga, Ramon Corrêa; Tolentino, Andrea Barros; Machado, Alexandre Coelho

    2014-02-01

    Because of their predictable results and conservation of tooth structure, ceramic veneers are indicated for the esthetic treatment of anterior teeth with anomalous positions or appearance. The objective of this case report is to highlight the steps in dental rehabilitation using ceramic veneers reinforced by lithium disilicate. In this case the patient had diastemas between the mandibular incisors. After preliminary procedures, diagnostic models, waxing, and mock-up were completed, an impression was made with addition silicone, and the veneers were fabricated and cemented with light-cure cement. As a result, the esthetics and function expected by the patient were achieved. The use of ceramic veneers enabled a conservative and esthetically successful rehabilitation treatment.

  19. Damage Maps of Veneered Zirconia under Simulated Mastication

    Science.gov (United States)

    Kim, Jae-Won; Kim, Joo-Hyung; Janal, Malvin N.; Zhang, Yu

    2016-01-01

    Zirconia based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesize that veneer chipping/delamination is a result of the propagation of near-contact induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, flat porcelain veneered zirconia plates were cemented to dental composites and cyclically loaded (contact–slide–liftoff) at an inclination angle as a simplified model of zirconia based restorations under occlusion. In the light of in-situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, postmortem damage evaluation of porcelain/zirconia/composite trilayers using a sectioning technique revealed that deep penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed. PMID:19029080

  20. Minimally invasive veneers: current state of the art

    Directory of Open Access Journals (Sweden)

    Vanlıoğlu BA

    2014-11-01

    Full Text Available Burçin Akoğlu Vanlioğlu, Yasemin Kulak-Özkan University of Marmara, Department of Prosthetic Dentistry, Istanbul, TurkeyAbstract: Ceramic veneers are considered a conservative solution for patients requiring improvement of the shape, color, or position of their anterior teeth. Ceramic veneers have been extensively and successfully used to mask intrinsic staining, to give the appearance of straightening, and to correct minor malformations of anterior teeth without the removal of substantial amounts of sound tooth substance. The current literature was reviewed to search for the most important parameters determining the long-term success and correct application of ceramic veneers. Keywords: ceramic veneers, esthetic treatment

  1. Clinical considerations in managing severe tooth discoloration with porcelain veneers.

    Science.gov (United States)

    Chu, Frederick C S

    2009-04-01

    Although porcelain veneer has been proposed as the treatment of choice in cases of severe tooth discoloration, clinicians should consider a multidisciplinary approach when treating complex cases. Clinicians also need to understand the masking ability of veneer restorations. A 20-year-old woman had severe tooth discoloration, enamel hypoplasia and malocclusion. The patient first underwent orthodontic treatment to correct the dental alignment after the author extracted her hypoplastic first molars. The author then placed porcelain veneers with high-density alumina cores on the patient's maxillary and mandibular anterior teeth. The restorations were in service for seven years without complications. and Managing severe tooth discoloration requires thorough consideration of all patient factors, treatment provided in a logical sequence and the use of porcelain veneers with adequate masking ability.

  2. Straight studs from southern pine veneer cores and cordwood

    Science.gov (United States)

    Peter Koch

    1968-01-01

    An economically feasible system has been developed for converting southern pine veneer cores into straight 8-foot studs (2). Prototype studs - two per core - were 100 percent SPIB stud grade and better.

  3. Primary forest products industry and timber use, Wisconsin, 1973.

    Science.gov (United States)

    James E. Blyth; Eugene F. Landt; James W. Whipple; Jerold T. Hahn

    1976-01-01

    Discusses recent Wisconsin forest industry trends; timber removals for industrial roundwood in 1973; production and receipts in 1973 of pulpwood, saw logs, veneer logs, and other industrial roundwood products. Shows trends in pulpwood and veneer log production and compares saw log production in 1967 and 1973. Discusses primary wood-using plant residue and its...

  4. Veneer retention of preveneered primary stainless steel crowns after crimping.

    Science.gov (United States)

    Gupta, Monica; Chen, Jung-Wei; Ontiveros, Joe C

    2008-01-01

    The purpose of this study was to determine if crimping the lingual aspect of commercially available, preveneered, anterior stainless steel primary crowns affects the fracture resistance of the veneer facings. Twenty-six anterior NuSmile crowns (size A1) were divided into 2 groups: group 1 served as the control, and group 2 was manually crimped evenly on the lingual cervical portion. All crowns were cemented onto a screw-mounted resin core duplicated from a manually prepared Kilgore tooth and tested under compression. Recorded were fracture resistance, percent of veneer facing loss, and fracture to the gingival margin. Differences between the control and experimental groups were analyzed by independent t test and chi-square (alpha=0.05). The mean shear force required to fracture the veneers of the noncrimped crowns was 510.11 N (+/-79.66 SD), and 511.02 N (+/-62.37) for the crimped crowns. The mean percentage of veneer facing removed in the noncrimped crowns was 33% (+/-12.18), and 43% (+/-14.30) in the crimped crowns. No significant difference in shear strengths (P=.970) and in percentage of veneer loss (P=.063) was shown between crimped and noncrimped crowns. A mean of 8% of the noncrimped crowns and 23% of the crimped crowns had veneers fracturing to the gingival margin. The chi-square test showed no significant difference (P=.297). The veneer resistance to fracture for the crimped crowns was comparable to noncrimped crowns. The crimped crowns, however, were associated with greater veneer surface area loss.

  5. Porcelain laminate veneers: Clinical survey for evaluation of failure

    OpenAIRE

    Alhekeir, Diemah F.; Al-Sarhan, Rana A.; Al Mashaan, Abdulmohsen F.

    2014-01-01

    Objective: To investigate the association of the failure of porcelain laminate veneers with factors related to the patient, material, and operator. Methods: This clinical survey involved 29 patients (19 women and 10 men) and their dentists, including undergraduate and postgraduate dental students and dental interns. Two questionnaires were distributed to collect information from participants. All patients were clinically examined. Criteria for failure of the porcelain laminate veneers incl...

  6. Fracture Resistance of Composite Veneers with Different Preparation Designs

    OpenAIRE

    Zlatanovska Katerina; Guguvcevski Ljuben; Popovski Risto; Dimova Cena; Minovska Ana; Mijoska Aneta

    2016-01-01

    Background: The aim of this in vitro study was to examine the fracture load of composite veneers using three different preparation designs. Material and methods: Fifteen extracted, intact, human maxillary central incisors were selected. Teeth were divided into three groups with different preparation design: 1) feather preparation, 2) bevel preparation, and 3) incisal overlap- palatal chamfer. Teeth were restored with composite veneers, and the specimens were loaded to failure. The localizatio...

  7. Orthodontic treatment finishing with minimally invasive resin composite veneers.

    OpenAIRE

    Maenosono, Rafael Massunari; Department of Operative Dentistry, Endodontics and Dental Materials – Bauru School of Dentistry – University of São Paulo – Bauru – São Paulo – Brazil.; Ramos, Carla Muller; Department of Operative Dentistry, Endodontics and Dental Materials – Bauru School of Dentistry – University of São Paulo – Bauru – São Paulo – Brazil.; Brianezzi, Letícia Ferreira de Freitas; Department of Operative Dentistry, Endodontics and Dental Materials – Bauru School of Dentistry – University of São Paulo – Bauru – São Paulo – Brazil.; Oda, Denise Ferracioli; Department of Operative Dentistry, Endodontics and Dental Materials – Bauru School of Dentistry – University of São Paulo – Bauru – São Paulo – Brazil.; Mondelli, Rafael Francisco Lia; Department of Operative Dentistry, Endodontics and Dental Materials – Bauru School of Dentistry – University of São Paulo – Bauru – São Paulo – Brazil.; Ishikiriama, Sérgio Kiyoshi; Department of Operative Dentistry, Endodontics and Dental Materials – Bauru School of Dentistry – University of São Paulo – Bauru – São Paulo – Brazil.

    2015-01-01

    Anatomic alterations caused by incisal guide wear, even being small, cause the aspect of an aged smile. The objective of this clinical case is to report a highly conservative esthetical treatment, performed through the association of in-office bleaching and resin composite veneers. In-office bleaching was performed with 35% hydrogen peroxide, and in the following week minimal invasive resin composite veneers were implemented on upper incisors and canines. In the next appointment, finishing an...

  8. Minimally Invasive Aesthetic Solutions - Porcelain Veneers and Lumineers

    OpenAIRE

    Zlatanovska, Katerina; Dimova, Cena; Zarkova, Julija

    2017-01-01

    Porcelain veneers present a conservative solution for patients who demand improvement of the shape, position and color of their anterior teeth without the removal of substantial amounts of tooth substance. No-or minimal-preparation veneers associated with enamel preservation offer an excellent results in aesthetic dentistry and become an essential component in creating restorations that are functional and have increased longevity. The current literature was reviewed to search for the most ess...

  9. Minimally invasive veneers: current state of the art

    OpenAIRE

    Vanlıoğlu BA; Kulak-Özkan Y

    2014-01-01

    Burçin Akoğlu Vanlioğlu, Yasemin Kulak-Özkan University of Marmara, Department of Prosthetic Dentistry, Istanbul, TurkeyAbstract: Ceramic veneers are considered a conservative solution for patients requiring improvement of the shape, color, or position of their anterior teeth. Ceramic veneers have been extensively and successfully used to mask intrinsic staining, to give the appearance of straightening, and to correct minor malformations of anterior teeth without the rem...

  10. Fracture load and failure types of different veneered polyetheretherketone fixed dental prostheses

    OpenAIRE

    Taufall, Simon; Eichberger, Marlis; Schmidlin, Patrick R; Stawarczyk, Bogna

    2016-01-01

    OBJECTIVE The aim of this study is to investigate the fracture load of different veneered PEEK 3-unit fixed dental prosthesis (FDPs) after different aging regimens. METHODS Congruently anatomically shaped 3-unit FDPs were milled using a master stl-data set and randomly divided into four groups (N = 120, n = 30 per veneering group), which were veneered using different veneering methods: (i) digital veneering with breCAM.HIPC, (ii) conventional veneering with crea.lign, (iii) conventional wi...

  11. Residual stress measurement in veneering ceramic by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2011-05-01

    Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. The hole drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. Incisal preparation design for ceramic veneers: A critical review.

    Science.gov (United States)

    Chai, Sy Yin; Bennani, Vincent; Aarts, John M; Lyons, Karl

    2018-01-01

    The authors reviewed and identified the evidence for the various incisal preparation designs for ceramic veneers. The authors searched MEDLINE with PubMed and Ovid to identify any articles in the English language related to the topic up through March 2017 using a combination of key words: "porcelain veneer or ceramic veneer or dental veneer or labial veneer" AND "preparation," NOT "composite veneer," NOT "crown," NOT "implant," NOT "fixed partial denture or bridge or denture," NOT "porcelain-fused-to-metal," NOT "marginal gap or fit." In vitro studies showed that the palatal chamfer preparation design increases the risk of developing ceramic fractures. The butt joint preparation design had the least effect on the strength of the tooth. Surveys show the 2 most common incisal preparation designs provided are butt joint and feathered-edge. Clinical studies have identified that incisal ceramic is the most common location of ceramic fracture. In addition, there is a lack in standardization of the modeling structures and type of finite element analysis. The evidence seems to support the use of butt joint over palatal chamfer incisal preparation design. Fracture or chipping is the most frequent complication and the risk increases with time. Incisal ceramic is the most common location of ceramic fracture. Copyright © 2018 American Dental Association. Published by Elsevier Inc. All rights reserved.

  13. Simplified treatment of severe dental erosion with ultrathin CAD-CAM composite occlusal veneers and anterior bilaminar veneers.

    Science.gov (United States)

    Schlichting, Luís Henrique; Resende, Tayane Holz; Reis, Kátia Rodrigues; Magne, Pascal

    2016-10-01

    Restorative treatment for patients with dental erosion requires an analysis of the degree of structural damage. Patients affected by moderate to severe dental erosion are particularly challenging because complex occlusal reconstruction will be needed. Ultrathin bonded occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of severe erosion. This article describes a complete mouth rehabilitation with ultrathin computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin occlusal veneers in a patient with a severely eroded dentition. In the maxillary anterior teeth, the bilaminar approach was chosen with lingual composite resin veneers and labial porcelain veneers. The main benefit of this approach is the possibility of using additive adhesive techniques, allowing only strategic reduction of sound dental structure or no preparation. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Cradle-to-gate life-cycle assessment of laminated veneer lumber (LVL) produced in the Pacific Northwest region of the United States

    Science.gov (United States)

    Richard D. Bergman; Sevda Alanya-Rosenbaum

    2017-01-01

    The goal of the present study was to develop life-cycle impact assessment (LCIA) data associated with laminated veneer lumber (LVL) production in the Pacific Northwest (PNW) region of the United States from cradle-to-gate mill output. The authors collected primary (survey) mill data from LVL production facilities per Consortium on Research for Renewable Industrial...

  15. Influence of the veneer-framework interface on the mechanical behavior of ceramic veneers: a nonlinear finite element analysis.

    Science.gov (United States)

    Lazari, Priscilla Cardoso; Sotto-Maior, Bruno Salles; Rocha, Eduardo Passos; de Villa Camargos, Germana; Del Bel Cury, Altair Antoninha

    2014-10-01

    The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures. The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions. The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework. Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used. Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Thermo and mechanical cycling and veneering method do not influence Y-TZP core/veneer interface bond strength.

    Science.gov (United States)

    Vidotti, Hugo Alberto; Pereira, Jefferson Ricardo; Insaurralde, Elizeu; de Almeida, Ana Lúcia Pompéia Fraga; do Valle, Accácio Lins

    2013-04-01

    The purpose of this study was to evaluate the influence of thermal and mechanical cycling and veneering technique on the shear bond strength of Y-TZP (yttrium oxide partially stabilized tetragonal zirconia polycrystal) core-veneer interfaces. Cylindrical Y-TZP specimens were veneered either by layering (n=20) or by pressing technique (n=20). A metal ceramic group (CoCr) was used as control (n=20). Ten specimens for each group were thermal and mechanical cycled and then all samples were subjected to shear bond strength in a universal testing machine with a 0.5mm/min crosshead speed. Mean shear bond strength (MPa) was analysed with a 2-way analysis of variance and Tukey's test (pstrength for all groups. The CoCr group presented the highest bond strength value (pcore-veneer bond strength. Different methods of veneering Y-TZP restorations would not influence the clinical performance of the core/veneer interfaces. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Sintering of Si C by hot-pressing with addition of Al{sub 2}O{sub 3} and concentrate of rare earths; Sinterizacao por prensagem a quente com SiC com adicao de Al{sub 2}O{sub 3} e concentrado de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, M.K.; Silva, C.R.M. [Centro Tecnico Aeroespacial (CTA-IAE), Sao Jose dos Campos, SP (Brazil). Inst. de Atividades Espaciais]. E-mail: miriamk@iae.cta.br; Nono, M.C.A.; Vieira, R.A. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    2004-07-01

    Silicon carbide (SiC) has essentially covalent bonds ({approx}88%). The high covalency bond is responsible for the good mechanical properties, although it induces a low self diffusion coefficient, making densification more difficult. For a successful densification is necessary to apply pressure on the samples, and/or the addition of sintering additives, which improves the densification. In this SiC samples with alumina (Al2O3) and concentrate of rare earth (CRE) addition were sintered by hot pressing in argon atmospheric at 20 MPa of pressure, heating rate of 20 deg C/min up to 1800 deg C and a dwell time of 1 h. Initially the CRE was calcined at 1000 deg C during 1 h. After that, three mixtures were prepared with distinct concentrations in high energy mill and the samples were sintered. The aim of this work is to improve SiC densification by the liquid phase formation during sintering owing to the additives reactions between itself. The pressure intensify the driving force for densification, taking the liquid phase to drain easier through the grain boundaries, making possible best accommodation and rearrangement of the grains. The application of the pressure on the samples during sintering contributes to improve densification and becomes possible sintering in lower temperature than conventional one. The phases of the sintered samples were analyzed by X-ray diffraction and the morphology were verified by scanning electron microscopy. (author)

  18. Residual stresses in porcelain-veneered zirconia prostheses.

    Science.gov (United States)

    Baldassarri, Marta; Stappert, Christian F J; Wolff, Mark S; Thompson, Van P; Zhang, Yu

    2012-08-01

    Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of full-contour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method. Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n=4) and porcelain specimens without zirconia cores (monolayers, n = 2). The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 ± 12 μm and 52 ± 8 μm for the bilayers and 64 ± 8 μm and 64 ± 7 μm for the monolayers. These results indicated a major hoop compressive stress (~40-50 MPa) and a moderate radial tensile stress (~10 MPa) in the bulk of the porcelain veneer. Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contribute to the large clinical chip fractures observed in these prostheses. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Residual Stresses in Porcelain-veneered Zirconia Prostheses

    Science.gov (United States)

    Baldassarri, Marta; Stappert, Christian F. J.; Wolff, Mark S.; Thompson, Van P.; Zhang, Yu

    2012-01-01

    Objectives Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of full-contour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method. Methods Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5 s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n = 4) and porcelain specimens without zirconia cores (monolayers, n = 2). Results The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 ± 12 μm and 52 ± 8 μm for the bilayers and 64 ± 8 μm and 64 ± 7 μm for the monolayers. These results indicated a major hoop compressive stress (~40 to 50 MPa) and a moderate radial tensile stress (~10 MPa) in the bulk of the porcelain veneer. Significance Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contributed to the large clinical chip fractures observed in these prostheses. PMID:22578663

  20. ”No-preparation” and Minimally Invasive Veneers in Clinical Practice: Part 1

    OpenAIRE

    Beata Smielak

    2015-01-01

    Objectives: “No preparation” veneers and veneers requiring minimal preparation of dental enamel are steadily increasing in popularity among today’s dental practitioners but they are suitable for selected individual cases. Overview: The present study discusses the indications for, and limitations to, the use of ultra-thin veneers, their drawbacks and advantages. It also describes the veneer placement procedure, taking into account the issues of proper diagnostics and treatment planning. ...

  1. Plywood made from plasma-treated veneers: Shear strength after shrinkage-swelling stress

    OpenAIRE

    Wascher, R.; Avramidis, G.; Kühn, C.; Militz, H.; Viöl, W.

    2017-01-01

    Thermally modified and unmodified beech veneers in untreated and plasma-treated state were immersed in melamine solution at different concentrations. The plasma pre-treated veneers exhibited significantly higher melamine loads than the untreated veneers at equal impregnation duration. Subsequently the veneers were manufactured into 5-layer plywood boards; the plywood samples then underwent an extreme testing procedure based on DIN-EN 314-1/2 in order to proof the bonding quality by means of s...

  2. The effect of various veneering techniques on the marginal fit of zirconia copings

    OpenAIRE

    Torabi, Kianoosh; Vojdani, Mahroo; Giti, Rashin; Taghva, Masumeh; Pardis, Soheil

    2015-01-01

    PURPOSE This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). MATERIALS AND METHODS Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measur...

  3. Raman spectra of hot-pressed boron suboxide

    CSIR Research Space (South Africa)

    Machaka, R

    2011-01-01

    Full Text Available -64 Copyright ? 2011 VBRI press. (d) The relatively sharp feature at 500 cm-1 corresponds to the symmetric stretching of the B?O?B triatomic chain, (e) The narrow line just above 500 cm-1, has been attributed to the motion of the entire B12 icosahedron...

  4. Thermal Expansion Behavior of Hot-Pressed Engineered Matrices

    Science.gov (United States)

    Raj, S. V.

    2016-01-01

    Advanced engineered matrix composites (EMCs) require that the coefficient of thermal expansion (CTE) of the engineered matrix (EM) matches those of the fiber reinforcements as closely as possible in order to reduce thermal compatibility strains during heating and cooling of the composites. The present paper proposes a general concept for designing suitable matrices for long fiber reinforced composites using a rule of mixtures (ROM) approach to minimize the global differences in the thermal expansion mismatches between the fibers and the engineered matrix. Proof-of-concept studies were conducted to demonstrate the validity of the concept.

  5. Fire and bending properties of blockboard with fire retardant treated veneers

    Science.gov (United States)

    T. Laufenberg; N. Ayrilmis; R. White

    2006-01-01

    This study evaluated fire and bending properties of blockboards with various fire retardant treated veneers. Blockboards were manufactured using untreated fir strips and sandwiched between treated ekaba veneers at final assembly. The veneers were treated with either boric acid (BA), disodium octoborate tetrahydrate (DOT), alumina trihydrate (ATH), or a BA/DOT mixture....

  6. 40 CFR 63.2265 - Initial compliance demonstration for a softwood veneer dryer.

    Science.gov (United States)

    2010-07-01

    ... softwood veneer dryer. 63.2265 Section 63.2265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Initial Compliance Requirements § 63.2265 Initial compliance demonstration for a softwood veneer dryer. If you operate a softwood veneer dryer, you must develop a plan for review and approval for minimizing...

  7. Influence of heat treatment and veneering on the storage modulus and surface of zirconia ceramic

    NARCIS (Netherlands)

    Siavikis, G.; Behr, M.; van der Zel, J.M.; Feilzer, A.J.; Rosentritt, M.

    2011-01-01

    Objectives: Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of

  8. Fracture Resistance of Composite Veneers with Different Preparation Designs

    Directory of Open Access Journals (Sweden)

    Zlatanovska Katerina

    2016-07-01

    Full Text Available Background: The aim of this in vitro study was to examine the fracture load of composite veneers using three different preparation designs. Material and methods: Fifteen extracted, intact, human maxillary central incisors were selected. Teeth were divided into three groups with different preparation design: 1 feather preparation, 2 bevel preparation, and 3 incisal overlap- palatal chamfer. Teeth were restored with composite veneers, and the specimens were loaded to failure. The localization of the fracture was recorded as incisal, gingival or combined. Results: Composite veneers with incisal overlap - palatal chamfer showed higher fracture resistance compared to feather preparation and bevel preparation. The mean (SD fracture loads were: Group 1: 100.6±8.0 N, Group 2: 107.4±6.8 N, and Group 3: 122.0±8.8 N. The most common mode of failure was debonding for veneers with feather preparation and fracture when incisal edge is reduced. The most frequent localization of fracture was incisal. Conclusion: The type of preparation has a significant effect on fracture load for composite veneers. This study indicates that using an incisal overlap- palatal chamfer preparation design significantly increases the fracture resistance compared to feather and bevel preparation designs.

  9. In vitro chipping behaviour of all-ceramic crowns with a zirconia framework and feldspathic veneering: comparison of CAD/CAM-produced veneer with manually layered veneer.

    Science.gov (United States)

    Schmitter, M; Mueller, D; Rues, S

    2013-07-01

    The purpose of this in vitro study was to assess the breaking load of zirconia-based crowns veneered with either CAD/CAM-produced or manually layered feldspathic ceramic. Thirty-two identical zirconia frameworks (Sirona inCoris ZI, mono L F1), 0·6 mm thick with an anatomically shaped occlusal area, were constructed (Sirona inLab 3.80). Sixteen of the crowns were then veneered by the use of CAD/CAM-fabricated feldspathic ceramic (CEREC Bloc, Sirona) and 16 by the use of hand-layered ceramic. The CAD/CAM-manufactured veneer was attached to the frameworks by the use of Panavia 2.0 (Kuraray). Half of the specimens were loaded until failure without artificial ageing; the other half of the specimens underwent thermal cycling and cyclic loading (1·2 million chewing cycles, force magnitude F(max) = 108 N) before the assessment of the ultimate load. To investigate the new technique further, finite element (FE) computations were conducted on the basis of the original geometry. Statistical assessment was made by the use of non-parametric tests. Initial breaking load was significantly higher in the hand-layered group than in the CAD/CAM group (mean: 1165·86 N versus 395·45 N). During chewing simulation, however, 87·5% (7/8) of the crowns in the hand-layered group failed, whereas no crown in the CAD/CAM group failed. The CAD/CAM-produced veneer was significantly less sensitive to ageing than the hand-layered veneer. © 2013 John Wiley & Sons Ltd.

  10. Fracture load and failure types of different veneered polyetheretherketone fixed dental prostheses.

    Science.gov (United States)

    Taufall, Simon; Eichberger, Marlis; Schmidlin, Patrick R; Stawarczyk, Bogna

    2016-12-01

    The aim of this study is to investigate the fracture load of different veneered PEEK 3-unit fixed dental prosthesis (FDPs) after different aging regimens. Congruently anatomically shaped 3-unit FDPs were milled using a master stl-data set and randomly divided into four groups (N = 120, n = 30 per veneering group), which were veneered using different veneering methods: (i) digital veneering with breCAM.HIPC, (ii) conventional veneering with crea.lign, (iii) conventional with crea.lign paste, and (iv) using pre-manufactured veneers visio.lign. The FDPs were then adhesively cemented on a metal abutment and fracture loads were measured in a universal testing machine (1 mm/min) before and after aging (10,000 thermal cycles, 5/55 °C). Two- and one-way ANOVA followed by post hoc Scheffé tests were used for data analysis (p veneering method on the fracture load results independent of the aging level. The highest fracture load was measured for the FDPs with digital veneering (1882 ± 152 N at baseline, 2021 ± 184 N after thermocycling). The remaining groups showed comparable results, and no impact of thermal aging was observed. Digital and conventional veneers showed cracks in the pontic region starting from the connector area as a main failure type after loading, while the pre-manufactured veneers showed predominantly adhesive failures. The digital veneering method showed the highest fracture load resistance. Thermal aging showed no impact on the fracture load of all tested veneered PEEK 3-unit FDPs. According to this study results, reliable veneering of PEEK FDPs can be achieved with digital veneering.

  11. Influence of bruxism on survival of porcelain laminate veneers.

    Science.gov (United States)

    Granell-Ruíz, Maria; Agustín-Panadero, Rubén; Fons-Font, Antonio; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda

    2014-09-01

    This study aims to determine whether bruxism and the use of occlusal splints affect the survival of porcelain laminate veneers in patients treated with this technique. Restorations were made in 70 patients, including 30 patients with some type of parafunctional habit. A total of 323 veneers were placed, 170 in patients with bruxism activity, and the remaining 153 in patients without it. A clinical examination determined the presence or absence of ceramic failure (cracks, fractures and debonding) of the restorations; these incidents were analyzed for association with bruxism and the use of splints. Analysis of the ceramic failures showed that of the 13 fractures and 29 debonding that were present in our study, 8 fractures and 22 debonding were related to the presence of bruxism. Porcelain laminate veneers are a predictable treatment option that provides excellent results, recognizing a higher risk of failure in patients with bruxism activity. The use of occlusal splints reduces the risk of fractures.

  12. Translucency of ceramic material in different core-veneer combinations.

    Science.gov (United States)

    Kursoglu, Pinar; Karagoz Motro, Pelin F; Kazazoglu, Ender

    2015-01-01

    Understanding the translucency of ceramic materials is important to achieve good esthetics. Ceramic thickness is related to translucency; however, less information about core-veneer thickness in combination is available. The purpose of this study was to investigate the translucency parameters of core-veneer thicknesses in 2 different ceramic materials. A total of 56 ceramic disks of different thickness were fabricated as cores according to the manufacturer's recommendations and divided into groups (n=7). Each was veneered with its compatible veneer ceramic with a different thickness (0.2, 0.5, 0.7 mm). One group of each ceramic type was left without veneer. The groups were named according to core names (group IPS e.max Press [EP], group IPS Empress Esthetic [EE]), and numbers were given according to thickness combination: 1=(1.00+0.5); 2=(0.8+0.7); 3=(1.00); 4=(0.8+0.2). All surfaces were measured by profilometry to ensure consistency within the groups. A glass disk (1.5 mm) positive control (group P) and a metal core (1.5 mm) negative control (group N) were prepared. The translucency parameter values were calculated by using spectrophotometry to calculate the color differences of the specimens over black and white backgrounds. A 1-way ANOVA found significant differences among the translucency parameter values of the ceramic groups (P.05). Total ceramic thickness affected the translucency; higher combined ceramic thickness resulted in lower translucency parameter values. When total thickness decreases, the translucency of core material has more effect than that of veneer material on translucency parameter values. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Tensile strength of bilayered ceramics and corresponding glass veneers.

    Science.gov (United States)

    Anunmana, Chuchai; Champirat, Tharee; Jirajariyavej, Bundhit

    2014-06-01

    To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. Blocks of core ceramics (IPS e.max® Press and Lava™ Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm(2) in cross-sectional area (n = 30/group). Additionally, monolithic microbars of these two veneers (IPS e.max® Ceram and Lava™ Ceram; n = 30/group) were also prepared. The obtained microbars were tested in tension until fracture, and the fracture surfaces of the microbars were examined with fluorescent black light and scanning electron microscope (SEM) to identify the mode of failure. One-way ANOVA and the Dunnett's T3 test were performed to determine significant differences of the mean microtensile bond strength at a significance level of 0.05. The mean microtensile bond strength of IPS e.max® Press/IPS e.max® Ceram (43.40 ± 5.51 MPa) was significantly greater than that of Lava™ Frame/Lava™ Ceram (31.71 ± 7.03 MPa)(Pveneer layer. Furthermore, the bond strength of Lava™ Frame/Lava™ Ceram was comparable to the tensile strength of monolithic glass veneer of Lava™ Ceram, while the bond strength of bilayered IPS e.max® Press/IPS e.max® Ceram was significantly greater than tensile strength of monolithic IPS e.max® Ceram. Because fracture site occurred mostly in the glass veneer and most failures were away from the interfacial zone, microtensile bond test may not be a suitable test for bonding integrity. Fracture mechanics approach such as fracture toughness of the interface may be more appropriate to represent the bonding quality between two materials.

  14. Biaxial flexural strength of bilayered zirconia using various veneering ceramics

    OpenAIRE

    Chantranikul, Natravee; Salimee, Prarom

    2015-01-01

    PURPOSE The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:20...

  15. Masking properties of ceramics for veneer restorations.

    Science.gov (United States)

    Skyllouriotis, Andreas L; Yamamoto, Hideo L; Nathanson, Dan

    2017-10-01

    The translucency and opacity of ceramics play a significant role in emulating the natural color of teeth, but studies of the masking properties and limitations of dental ceramics when used as monolayer restorations are lacking. The purpose of this in vitro study was to determine the translucency of 6 materials used for veneer restorations by assessing their translucency parameters (TPs), contrast ratios (CRs), and potential to mask dark tooth colors. Ten square- or disk-shaped specimens (0.5-mm thickness, shade A2) were fabricated from Vitablocks Mark II (VMII; Vita Zahnfabrik), IPS e.max CAD LT (EMXC LT; Ivoclar Vivadent AG), IPS e.max CAD HT (EMXC HT; Ivoclar Vivadent AG), IPS Empress CAD LT (EMP LT; Ivoclar Vivadent AG), IPS e.max Press LT (EMXP LT; Ivoclar Vivadent AG), and CZR (CZR; Kuraray Noritake Dental Inc). Their luminance (Y) values over black and over white tiles were measured, followed by their color (CIELab) over black tiles and white tiles and shaded A2 (control group), A3.5, A4, and B4 acrylic resin blocks. All measurements were performed using a spectrophotometer in 2 different areas on each specimen. Then CRs, TPs, and color differences (over shaded backgrounds) were determined. Data were subjected to 1-way and 2-way ANOVA (α=.05) for analysis. Mean CR values of EMXP LT were significantly higher than those of the other tested materials, whereas VMII and EMXC HT had the lowest values (Pceramic materials, whereas shade B4 demonstrated the lowest mean background effect (Ptranslucency among the tested ceramics were revealed (Ptranslucent under the conditions of this study (Pceramics exhibited poor masking properties against the A4 background. The color differences of most tested ceramics were more acceptable when tested against the B4 background (ΔE*≤3.3). Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Effects of core characters and veneering technique on biaxial flexural strength in porcelain fused to metal and porcelain veneered zirconia.

    Science.gov (United States)

    Oh, Ju-Won; Song, Kwang-Yeob; Ahn, Seung-Geun; Park, Ju-Mi; Lee, Min-Ho; Seo, Jae-Min

    2015-10-01

    The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia. Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgroups with two different veneering methods (conventional powder/liquid layering technique and the heat-pressing technique). Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted. Factors influencing fracture strength were analyzed through three-way ANOVA (α≤.05) and the influence of core thickness and veneering method in each core materials was assessed using two-way ANOVA (α≤.05). The biaxial flexural strength test showed that the fabrication method of veneering porcelain has the largest impact on the fracture strength followed by the core thickness and the core material. In the metal groups, both the core thickness and the fabrication method of the veneering porcelain significantly influenced on the fracture strength, while only the fabrication method affected the fracture strength in the zirconia groups. The fabrication method is more influential to the strength of a prosthesis compared to the core character determined by material and thickness of the core.

  17. Effects of core characters and veneering technique on biaxial flexural strength in porcelain fused to metal and porcelain veneered zirconia

    OpenAIRE

    Oh, Ju-Won; Song, Kwang-Yeob; Ahn, Seung-Geun; Park, Ju-Mi; Lee, Min-Ho; Seo, Jae-Min

    2015-01-01

    PURPOSE The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia. MATERIALS AND METHODS Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgr...

  18. Some physical properties of laminated veneer lumbers (LVLs produced from rotary-peeled veneers of eucalyptus, beech, and poplar

    Directory of Open Access Journals (Sweden)

    Bekir Bal

    2013-04-01

    Full Text Available In this study, laminated veneer lumbers were produced with rotary peeled veneers from eucalyptus, beech and poplar using urea-formaldehyde, melamine-urea-formaldehyde and phenol-formaldehyde adhesives. Air-dried density, equilibrium moisture content, thickness swelling, and water absorption were determined. The obtained data were evaluated with variance analysis. Results showed that adhesives type influenced equilibrium moisture content, and equilibrium moisture content of LVLs bonded with phenol-formaldehyde was the highest, and that of LVLs bonded with melamine-urea-formaldehyde was the lowest. In addition, results showed that tree species, adhesive type, and soaking time were effective significantly on the thickness swelling and water absorption

  19. Effect of Veneering Methods on Zirconia Framework-Veneer Ceramic Adhesion and Fracture Resistance of Single Crowns.

    Science.gov (United States)

    Kanat-Ertürk, Burcu; Çömlekoğlu, Erhan M; Dündar-Çömlekoğlu, Mine; Özcan, Mutlu; Güngör, Mehmet Ali

    2015-12-01

    The aim of this study was to evaluate the fracture resistance (FR) and shear bond strength (SBS) via finite element analysis (FEA) of zirconia framework veneered with different methods. Zirconia frameworks were prepared as crowns for FR and cubic blocks for SBS (N = 60, n = 10). The specimens were veneered with one of the following veneering methods: (a) overcemented file-splitting (OCF), (b) layering (L), or (c) overpressing (P). For crowns, stainless steel dies (N = 30; chamfer: 1 mm) were scanned using a contrast spray. Bilayered design for OCF and reduced design (1 mm) for both L and P were performed by computer-aided design and manufacturing. For the SBS test, zirconia blocks were sectioned (4 × 4 × 4 mm(3)) under water cooling and sintered. Frameworks were veneered with compatible ceramics for each veneering method and subjected to mechanical tests. The milled suprastructures were bonded to zirconia frameworks using a resin composite in Group OCF and photopolymerized. Crowns were cemented to the metal dies with resin modified glass-ionomer cement. All specimens were stored at 37°C, 100% humidity for 48 hours prior to mechanical tests. Data were statistically analyzed (ANOVA, Bonferroni tests, α = 0.05). Fractured specimens were examined under scanning electron microscopy (SEM), and FEA modeling of the crowns was performed. Mean FR values (N) were significantly higher with L (6102 ± 1519) and P (4117 ± 1083) than with of OCF (1900 ± 254) (p = 0.01). The mean SBS (MPa) in OCF (24 ± 4) was significantly lower (p 0.05). For crown restorations, while only adhesive failures were found in OCF, cohesive failures within veneering ceramic were more frequent in P and L. FEA verified these findings. Veneering methods based on layering or pressing may reduce ceramic chipping but the overcemented file-splitting method does not seem to prevent this failure. Layering and overpressing veneering methods on zirconia frameworks with reduced design might decrease chipping

  20. The up to 21-year clinical outcome and survival of feldspathic porcelain veneers: accounting for clustering.

    Science.gov (United States)

    Layton, Danielle M; Walton, Terry R

    2012-01-01

    This study aimed to investigate the clinical outcome and estimated cumulative survival rate of feldspathic porcelain veneers in situ for up to 21 years while also accounting for clustered outcomes. Porcelain veneers(n = 499) placed in patients (n = 155) by a single prosthodontist between 1990 and 2010 were sequentially included, with 239 veneers (88 patients) placed before 2001 and 260 veneers (67 patients) placed thereafter. Nonvital teeth, molar teeth, or teeth with an unfavorable periodontal prognosis were excluded. Preparations had chamfer margins, incisal reduction, palatal overlap, and at least 80% enamel. Feldspathic veneers from refractory dies were etched (hydrofluoric acid), silanated, and bonded. Many patients received more than 1 veneer (mean: 5.8 ± 4.3). Clustered outcomes were accounted for by randomly selecting (random table) 1 veneer per patient for analysis. Clinical outcome (success, survival, unknown, dead, repair, failure) and Kaplan-Meier estimated cumulative survival were reported. Differences in survival were analyzed using the log-rank test. For the random sample of veneers (n = 155), the estimated cumulative survival rates were 96% ± 2% (10 years) and 96% ± 2% (20 years). For the entire sample, the survival rates were 96% ± 1% (10 years) and 91% ± 2% (20 years). Survival did not statistically differ between these groups (P = .65). Seventeen veneers in 8 patients failed, 75 veneers in 30 patients were classified as unknown, and 407 veneers in 130 patients survived. Multiple veneers in the same mouth experienced the same outcome, clustering the results. Multiple dental prostheses in the same mouth are exposed to the same local and systemic factors, resulting in clustered outcomes. Clustered outcomes should be accounted for during analysis. When bonded to prepared enamel substrate, feldspathic porcelain veneers have excellent long-term survival with a low failure rate. The 21-year estimated cumulative survival for feldspathic porcelain

  1. SURFACE INACTIVATION IN VENEER DRYING PROCESS AND ITS EFFECTS ON BONDING STRENGTH

    Directory of Open Access Journals (Sweden)

    İsmail Aydın

    2004-04-01

    Full Text Available Veneer drying process is an important stage in the production of wood based composites such as plywood and LVL panels. Because veneer drying becomes a bottleneck in the production process due to the inefficient equipment and methods. Although drying temperatures between 90-160°C may be considered normal, increased temperatures are being used to reduce the overall drying time and increase capacity. However, the reduction in drying time often results in an increase in drying related defects such as checks, splits and warp and decrease in wettability. Surface inactivation is one of these defects which occur on wood surfaces with heat effect and results in the loss of bonding ability. Surface inactivation is defined as physical and chemical modifications on the wood surfaces that results in reduced ability of the adhesive to properly wet, flow, penetrate and cure. Many investigations have been conducted to improve adhesion of inactivated wood surfaces, but no comprehensive solution has been revealed so far.

  2. Veneer grade yield from pruned Douglas-fir.

    Science.gov (United States)

    Edward J. II Dimock; Henry H. Haskell

    1962-01-01

    This paper reports actual veneer yields obtained from 10 trees pruned at age 38 and harvested 20 years later. Information of this kind is needed to help determine if and when to prune and ultimately will be essential to a thorough economic analysis of expected returns from pruning.

  3. Bleaching and/or porcelain veneers: case reports.

    Science.gov (United States)

    Putter, H

    1992-01-01

    Four case studies are presented in which the concept that bleaching, porcelain veneer restorations, or a combination of both constitute a conservative treatment approach for discolored, malformed, malaligned, and worn dentition. These treatments can be used effectively not only for aging dentitions, but also for the very young, which makes them an attractive treatment modality.

  4. Effect of Silviculture on the Yield and Quality of Veneers

    Science.gov (United States)

    Leslie H. Groom; Ray Newbold; Jim Guldin

    2002-01-01

    The structural and aesthetic value of wood is typically sacrificed in an attempt to meet demand. This paper addresses the financial and quality aspects of silvicultural choices as it relates to wood veneers. Five trees each were harvested from an uneven-aged stand and from the following even- aged stands: intensive plantation, conventional plantation, and natural...

  5. Porcelain veneer post-bonding crack repair by resin infiltration

    NARCIS (Netherlands)

    Gresnigt, Marco; Magne, Michel; Magne, Pascal

    2017-01-01

    Ceramic laminate veneer restorations are indicated in several clinical situations. Indirect restorations are usually chosen if the less-invasive options - bleaching, resin infiltration, or composite resin restorations - are not possible, or when it is too difficult to achieve an esthetically

  6. Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers

    OpenAIRE

    Re, D.; Augusti, G.; Amato, M.; Riva, G.; Augusti, D.

    2014-01-01

    No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients’ restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with...

  7. Advances in dental veneers: materials, applications, and techniques

    Directory of Open Access Journals (Sweden)

    Pini NP

    2012-02-01

    Full Text Available Núbia Pavesi Pini1, Flávio Henrique Baggio Aguiar1, Débora Alves Nunes Leite Lima1, José Roberto Lovadino1, Raquel Sano Suga Terada2, Renata Corrêa Pascotto21Area of Restorative Dentistry, Piracicaba Dental School, State University of Campinas – FOP/Unicamp – Piracicaba, São Paulo, 2Area of Restorative Dentistry, State University of Maringá – UEM – Maringá, Paraná, BrazilAbstract: Laminate veneers are a conservative treatment of unaesthetic anterior teeth. The continued development of dental ceramics offers clinicians many options for creating highly aesthetic and functional porcelain veneers. This evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case. The current literature was reviewed to search for the most important parameters determining the long-term success, correct application, and clinical limitations of porcelain veneers.Keywords: dental ceramic, porcelain veneers, aesthetic treatment

  8. Evidence of yttrium silicate inclusions in YSZ-porcelain veneers.

    Science.gov (United States)

    Stoner, Brian R; Griggs, Jason A; Neidigh, John; Piascik, Jeffrey R

    2014-04-01

    This report introduces the discovery of crystalline defects that can form in the porcelain veneering layer when in contact with yttria-stabilized zirconia (YSZ). The focus was on dental prostheses and understanding the defects that form in the YSZ/porcelain system; however the data reported herein may have broader implications toward the use and stability of YSZ-based ceramics in general. Specimens were cut from fully sintered YSZ plates and veneering porcelain was applied (veneer. Local EDAX (SEM) was performed in the regions of visible inclusions and showed significant increases in yttrium concentration. TEM specimens also showed apparent inclusions in the porcelain and selected area electron diffraction was performed on these regions and found the inclusions to be crystalline and identified as either yttrium-silicate (Y2 SiO5 ) or yttrium-disilicate (Y2 Si2 O7 ). Micro-CT data showed that yttrium-silicate precipitates were distributed throughout the thickness of the porcelain veneer. Future studies are needed to determine whether many of the premature failures associated with this materials system may be the result of crystalline flaws that form as a result of high temperature yttrium diffusion near the surfaces of YSZ. © 2013 Wiley Periodicals, Inc.

  9. Porcelain Veneers Sebagai Bahan Kosmetik Di Kedokteran Gigi

    OpenAIRE

    Sinita Fronika Sembiring

    2008-01-01

    Porcelain merupakan bahan keramik putih mempunyai sifat yang rapuh, translusen, korosi yang rendah, dan mengkilat, dimana pembakaran diperlukan pada temperatur yang tinggi. Jenis dental porcelain dapat dibagi atas berdasarkan temperatur, proses pembakaran dan kegunaannya. Komposisi dental porcelain terdiri dari feldspar, kaolin, quartz, fluks dan pigmen. Porcelain Veneers adalah lapisan tipis yang menutupi kerusakan, perubahan warna dan kelainan bentuk pada gigi. Bahan ini memiliki tekstu...

  10. Influence of bruxism on survival of porcelain laminate veneers

    Science.gov (United States)

    Agustín-Panadero, Rubén; Fons-Font, Antonio; Román-Rodríguez, Juan L.; Solá-Ruíz, María F.

    2014-01-01

    Objectives: This study aims to determine whether bruxism and the use of occlusal splints affect the survival of porcelain laminate veneers in patients treated with this technique. Material and Methods: Restorations were made in 70 patients, including 30 patients with some type of parafunctional habit. A total of 323 veneers were placed, 170 in patients with bruxism activity, and the remaining 153 in patients without it. A clinical examination determined the presence or absence of ceramic failure (cracks, fractures and debonding) of the restorations; these incidents were analyzed for association with bruxism and the use of splints. Results: Analysis of the ceramic failures showed that of the 13 fractures and 29 debonding that were present in our study, 8 fractures and 22 debonding were related to the presence of bruxism. Conclusions: Porcelain laminate veneers are a predictable treatment option that provides excellent results, recognizing a higher risk of failure in patients with bruxism activity. The use of occlusal splints reduces the risk of fractures. Key words:Veneer, fracture, debonding, bruxism, occlusal splint. PMID:23986018

  11. In situ polymerization of polyaniline in wood veneers.

    Science.gov (United States)

    Trey, Stacy; Jafarzadeh, Shadi; Johansson, Mats

    2012-03-01

    The present study describes the possibility to polymerize aniline within wood veneers to obtain a semi-conducting material with solid wood acting as the base template. It was determined that it is possible to synthesize the intrinsically conductive polymer (ICP) polyaniline in situ within the wood structure of Southern yellow pine veneers, combining the strength of the natural wood structure with the conductivity of the impregnated polymer. It was found that polyaniline is uniformly dispersed within the wood structure by light microscopy and FT-IR imaging. A weight percent gain in the range of 3-12 wt % was obtained with a preferential formation in the wood structure and cell wall, rather than in the lumen. The modified wood was found to be less hydrophilic with the addition of phosphate doped polyaniline as observed by equilibrium water swelling studies. While wood itself is insulating, the modified veneers had conductivities of 1 × 10(-4) to 1 × 10(-9) S cm(-1), demonstrating the ability to tune the conductivity and allowing for materials with a wide range of applications, from anti-static to charge-dispersing materials. Furthermore, the modified veneers had lower total and peak heat releases, as determined by cone calorimetry, because of the char properties of the ICP. This is of interest if these materials are to be used in building and furniture applications where flame retardance is of importance. © 2012 American Chemical Society

  12. Veneer-reinforced particleboard for exterior structural composition board

    Science.gov (United States)

    Chung-Yun Hse; Todd F. Shupe; Hui Pan; Fu Feng

    2012-01-01

    Two experiments were performed to determine the physical and mechanical characteristics of panels consisting of a veneer face and a particleboard core composed of mixed wood particles/powdered-recycled polyethylene (PE) bag waste (MWP) using urea-formaldehyde (UF) resin as a binder. The addition of 25 percent powdered-recycled PE bag waste to the MWP panels did not...

  13. Water removal of wet veneer by roller pressing

    Science.gov (United States)

    Koji Adachi; Masafumi Inoue; Kozo Kanayama; Roger M. Rowell; Shuichi Kawai

    2004-01-01

    High moisture content, flat sawn Japanese cedar (Cryptomeria japonica D. Don) veneer was compressed using a roller press to mechanically remove water. The amount of water removed depended on the amount of compression applied. At 60% compression, 400 kg/m3 of water was removed. The process was not dependent on the size of the wood, the degree of compression, or the feed...

  14. Shear bond strength of porcelain veneers rebonded to enamel.

    Science.gov (United States)

    St Germain, H A; St Germain, T H

    2015-01-01

    In this laboratory research, shear bond strength (SBS) and mode of failure of veneers rebonded to enamel in shear compression were determined. Three groups (A, B, and C; n=10 each) of mounted molar teeth were finished flat using wet 600-grit silicon carbide paper, and 30 leucite-reinforced porcelain veneers (5.0 × 0.75 mm) were air abraded on the internal surface with 50 μm aluminum oxide, etched with 9.5% hydrofluoric acid, and silanated. The control group (A) veneer specimens were bonded to enamel after etching with 37% phosphoric acid using bonding resin and a dual cure resin composite cement. Groups B and C were prepared similarly to group A with the exception that a release agent was placed before the veneer was positioned on the prepared enamel surface and the resin cement was subsequently light activated. The debonded veneers from groups B and C were placed in a casting burnout oven and heated to 454°C/850°F for 10 minutes to completely carbonize the resin cement and stay below the glass transition temperature (Tg) of the leucite-reinforced porcelain. The recovered veneers were then prepared for bonding. The previously bonded enamel surfaces in group B were air abraded using 50 μm aluminum oxide followed by 37% phosphoric acid etching, while group C enamel specimens were acid etched only. All specimens were thermocycled between 5°C and 55°C for 2000 cycles using a 30-second dwell time and stored in 37°C deionized water for 2 weeks. SBS was determined at a crosshead speed of 1.0 mm/min. SBS results in MPa for the groups were (A) = 20.6±5.1, (B) = 18.1±5.5, and (C) = 17.2±6.1. One-way analysis of variance indicated that there were no significant interactions (α=0.05), and Tukey-Kramer post hoc comparisons (α=0.05) detected no significant pairwise differences. An adhesive mode of failure at the enamel interface was observed to occur more often in the experimental groups (B = 40%, C = 50%). Rebonding the veneers produced SBS values that were not

  15. Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

    Science.gov (United States)

    Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

    2016-01-01

    The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

  16. Fracture resistance of ceramic veneers with different preparation designs.

    Science.gov (United States)

    Akoğlu, Burçin; Gemalmaz, Deniz

    2011-07-01

    The purpose of this study was to examine the fracture load of ceramic veneers with different preparation designs. Seventy-five extracted, intact, human maxillary central incisors were prepared according to five preparation designs (P) (n: 15) as follows: (1) P2e: 2-mm incisal reduction, preparation entirely in enamel; (2) P4e: 4-mm incisal reduction, preparation entirely in enamel; (3) P2d: 2-mm incisal reduction, preparation entirely in dentin; (4) P4d: 4-mm incisal reduction, preparation entirely in dentin; and (6) Pc: Unrestored, intact teeth as control. All preparations had a butt joint incisal finish line, rounded internal line angles, and cervical finish lines 1 mm above the cementoenamel junction. Ceramic veneers were fabricated with IPS Empress (Ivoclar Vivadent AG, Schaan, Liechtenstein) and cemented with Syntac Classic Adhesive system and Variolink II (Ivoclar) resin cement. Veneers were loaded until fracture at a 90° angle to the lingual surface of the test tooth following the thermocycling process (5° to 55°, 3500 times). Statistical analyses were performed using analysis of variance (ANOVA) and Tukey's Multiple Range Test. The mean fracture loads (SD) were (in N) as follows: (1) P2e: 262 (63); (2) P4e: 189 (40); (3) P2d: 239 (53); (4) P4d: 162 (36); and (5) Pc: 277 (66). The amount of incisal reduction exhibited a significant influence on fracture resistance regardless of the preparation depth (p veneers with preparation designs entirely on dentin with 4-mm incisal reduction yielded lower fracture loads than those prepared with 2-mm incisal reduction. Veneers with 2-mm incisal reduction exhibited fracture resistance similar to that of intact teeth for preparation designs supplied on both enamel and dentin. © 2011 by the American College of Prosthodontists.

  17. A three-dimensional finite element study on anterior laminate veneers with different incisal preparations.

    Science.gov (United States)

    Li, Zhongjie; Yang, Zheng; Zuo, Ling; Meng, Yukun

    2014-08-01

    Mechanical properties are important in the long-term success of restorations, but whether different incisal preparations can affect the behavior of veneers remains controversial. The purpose of this study was to evaluate the influence of different preparation designs on stress distribution in a maxillary incisor restored with veneers and with regard to different restorative materials and loading conditions. Based on the cone beam computed tomography scanning of a maxillary incisor, 3-dimensional finite element models for 2 different designs were developed. A static load of 50 N was applied with angulations of 60 degrees and 125 degrees to the longitudinal axis at the level of the incisal margin, simulating functional movements. Both porcelain laminate veneer and composite resin veneer were considered. The maximum stress values and stress distribution of the veneer, cement layer, and tooth structure were calculated and analyzed. The maximum stress values in the veneer and tooth were higher with the butt-joint design. Stresses were distributed more uniformly in the cement layer in the palatal chamfer design for porcelain laminate veneers, whereas a better stress distribution under protrusive movement was observed in the butt-joint design for composite resin veneers. The palatal chamfer design for porcelain laminate veneers tolerated stress better, whereas the butt-joint design was favored for composite resin veneers, particularly under protrusive movement. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. Thermal-induced residual stresses affect the fractographic patterns of zirconia-veneer dental prostheses.

    Science.gov (United States)

    Belli, Renan; Petschelt, Anselm; Lohbauer, Ulrich

    2013-05-01

    Veneer fractures in dental zirconia-veneer prostheses are more frequent clinically than in conventional metal-ceramic systems. This is thought to be due to the increased residual stresses generated within the veneer during fabrication when zirconia is the infrastructure material. This investigation aimed to analyze the fractographic features of fractured zirconia-veneer dental crowns submitted to a load-to-failure test and to a more clinically relevant in vitro chewing simulation fatigue test. As-sintered and sandblasted zirconia copings were veneered with glass-ceramic with different coefficients of thermal expansion and cooled following two cooling rates, creating, this way, different levels of stresses within the veneer. Crowns with different thermal mismatch combinations and different cooling rates were hypothesized to present particular fracture patterns. A careful examination of >1000 scanning electron microscopy images of the fracture surfaces was conducted in search of characteristic fractographic markings of fracture mechanisms connected to the stress state of the veneer. Distinctive structural features could be observed between groups veneered with the two different glass-ceramics and between fractured crowns under static and cyclic loading. The presence/absence of residual stresses zones within the veneer have shown to play the major role in the fracture pattern of zirconia-veneer dental prostheses. For the fatigue crowns, the zirconia core was never exposed, either for sandblasted and as-sintered groups. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Porcelain veneering of titanium--clinical and technical aspects.

    Science.gov (United States)

    Haag, Per

    2011-01-01

    Gold and other alloys have long been used for the production of crowns and bridges as replacements for damaged or lost teeth. However, doubts have arisen on the suitability of using these materials for dental restorations, as gold has also shown a capacity to cause side-effects such as allergic reactions. This is especially valid for alloys, which during the last decades have been used as porcelain-fused-to metal restorations. This fact has led to an interest in using titanium instead of these alloys. Trials to use titanium for this purpose were initiated in Japan in the early 1980s. Titanium as an unalloyed metal differs in two aspects from the above named alloys: it has a phase transformation at 882 degrees C, which changes its outer and inner properties, and it has an expansion that lies between that of the porcelain types available on the market at the time. In Japan a technique for casting titanium was developed, where the after-treatment of the casting was elaborate, to re-establish the original properties of titanium. The porcelain developed for veneering had shortcomings as the rendering produced a rough surface and non satisfactory esthetics. In Sweden a new concept was introduced in 1989. Here the processing of titanium was performed by industrial methods such as milling, spark erosion and laser welding. The idea behind this was to avoid phase transformation. During the 1990s a number of porcelain products were launched and a vast number of both laboratory and clinical studies were performed and published, with varying results. In the first study of this thesis a prospective clinical trial was performed at a public dental health clinic in Sweden. Twenty-five patients were provided with 40 copings of pure titanium, which were veneered with porcelain. After 2 years 36 of these crowns were evaluated and the patients were also interviewed regarding problems such as shooting pains or difficulties in cleaning around the teeth that were crowned. This evaluation

  20. Influence of Veneering Fabrication Techniques and Gas-Phase Fluorination on Bond Strength between Zirconia and Veneering Ceramics.

    Science.gov (United States)

    Pharr, Stewart W; Teixeira, Erica C; Verrett, Ronald; Piascik, Jeffrey R

    2016-08-01

    Porcelain chipping has been one of the main problems of porcelain-fused-to-zirconia restorations. This study evaluates the bond strengths of layered, pressed, and adhesively bonded porcelain to yttria-stabilized zirconia substrates that have undergone traditional preparation or gas-phase fluorination. A three-point bending test was used to evaluate the bond strength of the porcelain and zirconia interface. Sixty-six specimens were prepared (n = 11) following ISO 9693 and loaded until failure using an Instron testing machine. One-half of the zirconia substrates received gas phase fluorination treatment before veneering application. Three porcelain veneering methods were evaluated: layered, pressed, and adhesively bonded porcelain. Bond strength results were interpreted using a two-way ANOVA and a Bonferroni multiple comparisons test. Statistical significance was set at α = 0.05. ANOVA revealed a statistically significant effect of the veneering fabrication methods. No main effect was observed regarding the surface treatment to the zirconia. There was a significant effect related to the veneering method used to apply porcelain to zirconia. For untreated zirconia, layered porcelain had a significantly higher flexural strength compared to pressed or bonded, while pressed and bonded porcelains were not significantly different from one another. For zirconia specimens receiving fluorination treatment, both layered and pressed porcelains had significantly higher bond strengths than adhesively bonded porcelain. In addition, fluorinated pressed porcelain was not statistically different from the control layered or fluorinated layered porcelain. The choice of veneering fabrication technique was critical when evaluating the zirconia to porcelain interfacial bond strength. Bonded porcelain to zirconia had a lower flexural strength than layered or pressed porcelain, regardless of zirconia surface treatment. In addition, fluorination had an effect on the bond strength of pressed

  1. Protocol for a new concept of no-prep ultrathin ceramic veneers.

    Science.gov (United States)

    D'Arcangelo, Camillo; Vadini, Mirco; D'Amario, Maurizio; Chiavaroli, Zaccheo; De Angelis, Francesco

    2017-11-15

    No-prep veneers, although ideally considered the best option because of tooth structure maximum preservation, have been frequently criticized for some potential limitations including esthetic outcomes and periodontal complications. A new protocol to optimize no-prep veneers restorations is presented. A key point of the proposed technique is to identify optimal margins' positions: margin is positioned in the point of maximum convexity of teeth, avoiding the over contouring of traditional no-prep veneers. The procedure can be appreciated for the marginal accuracy and the resulting aesthetic stability. The case reports show that properly managed no-prep veneers can have biologically healthy and aesthetically pleasant tooth-restoration transitions and emergence profiles. High-quality no-prep veneers can be more challenging to realize than conventional veneers and the success seems to depend on a combination of good case selection, margins' position, sound adhesive principles, clinical, and laboratory experience. © 2017 Wiley Periodicals, Inc.

  2. Fracture Toughness of Veneering Ceramics for Fused to Metal (PFM) and Zirconia Dental Restorative Materials

    Science.gov (United States)

    Quinn, Janet B.; Quinn, George D.; Sundar, Veeraraghaven

    2010-01-01

    Veneering ceramics designed to be used with modern zirconia framework restorations have been reported to fracture occasionally in vivo. The fracture toughness of such veneering ceramics was measured and compared to that of conventional feldspathic porcelain veneering ceramics for metal framework restorations. The fracture toughness of the leucite free veneer was measured to be 0.73 MPa m ± 0.02 MPa m, which is less than that for the porcelain fused to metal (PFM) veneering ceramic: 1.10 MPa ± 0.2 MPa. (Uncertainties are one standard deviation unless otherwise noted.) The surface crack in flexure (SCF) method was suitable for both materials, but precrack identification was difficult for the leucite containing feldspathic porcelain PFM veneer. PMID:21833158

  3. Cradle-to-gate life-cycle assessment of laminated veneer lumber produced in the southeast region of the United States

    Science.gov (United States)

    Richard D. Bergman; Sevda Alanya-Rosenbaum

    2017-01-01

    The goal of the present study was to develop life-cycle impact assessment (LCIA) data associated with gate-to-gate laminated veneer lumber (LVL) production in the southeast (SE) region of the U.S. with the ultimate aim of constructing an updated cradle-to-gate mill output life-cycle assessment (LCA). The authors collected primary (survey) mill data from LVL production...

  4. Plywood made from plasma-treated veneers: Melamine uptake, dimensional stability, and mechanical properties

    OpenAIRE

    Wascher, R.; Kühn, C.; Avramidis, G.; Bicke, S.; Militz, H.; Ohms, G.; Viöl, W.

    2017-01-01

    This study investigates the dimensional stability and mechanical properties of plywood boards made of thermally modified and unmodified beech veneers that have undergone plasma pre-treatment before melamine resin impregnation. The water and melamine resin uptake and resulting weight percent gain of the veneers were investigated, whereby the air plasma pre-treated veneers showed improved liquid uptake. Five-layer plywood boards were then manufactured and tested for their dimensional stability,...

  5. Direct anterior composite veneers in vital and non-vital teeth: a retrospective clinical evaluation.

    Science.gov (United States)

    Coelho-de-Souza, Fábio Herrmann; Gonçalves, Daiana Silveira; Sales, Michele Peres; Erhardt, Maria Carolina Guilherme; Corrêa, Marcos Britto; Opdam, Niek J M; Demarco, Flávio Fernando

    2015-11-01

    This retrospective, longitudinal clinical study investigated the performance of direct veneers using different composites (microfilled×universal) in vital or non-vital anterior teeth. Records from 86 patients were retrieved from a Dental School clinic, comprising 196 direct veneers to be evaluated. The FDI criteria were used to assess the clinical evaluation. The survival analysis was done using Kaplan-Meier method and Log-Rank test. The multivariate Cox regression with shared frailty was used to investigate the factors associated with failure. A total of 196 veneers were evaluated, with 39 failures. The mean time of service for the veneers was 3.5 years, with a general survival rate of 80.1%. In the qualitative evaluation of the restorations, microfilled composite showed slighty better esthetics. The annual failure rates (AFR) were 4.9% for veneers in vital teeth and 9.8% for non-vital teeth with statistical significance (p=0.009). For microfilled and universal veneers the respective AFRs were 6.0% and 6.2% (p>0.05). Veneers made in non-vital teeth had a higher risk of failure over time compared to those made in vital teeth (HR 2.78; 95% CI 1.02-7.56), but the type of material was not a significant factor (p=0.991). The main reason for failure was fracture of the veneer. Direct composite veneers showed a satisfactory clinical performance. Veneers performed in vital teeth showed a better performance than those placed in non-vital teeth. No difference in the survival rate for different composites was found, although microfilled composites showed a slightly better esthetic appearance. Direct composite veneers show good results in esthetic dentistry nowadays. Composite veneers in vital teeth have a lower risk of failure than those in non-vital teeth. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Another survey on etched porcelain laminate  veneers in aesthetic dentistry

    OpenAIRE

    F Farshchian

    1989-01-01

    In some clinical interventions, there have been some doubts on replacing resin veneers by etched porcelain veneers. Never the less, Public awareness and demand for more aesthetic treatments caused increased usage of laminate veneers in operative treatments as routine treatment method. Dental material companies have rapidly produced newer materials to replace the old ones and respond the needs. Thus, dental science has developed in aesthetic operative dental science. Each nov...

  7. Cervical and Incisal Marginal Discrepancy in Ceramic Laminate Veneering Materials: A SEM Analysis

    OpenAIRE

    Hemalatha Ranganathan; Dhanraj M Ganapathy; Jain, Ashish R

    2017-01-01

    Context: Marginal discrepancy influenced by the choice of processing material used for the ceramic laminate veneers needs to be explored further for better clinical application. Aims: This study aimed to evaluate the amount of cervical and incisal marginal discrepancy associated with different ceramic laminate veneering materials. Settings and Design: This was an experimental, single-blinded, in vitro trial. Subjects and Methods: Ten central incisors were prepared for laminate veneers with 2 ...

  8. Marginal adaptation of Spinell InCeram and feldspathic porcelain laminate veneers

    OpenAIRE

    Tahereh Ghaffari; Fahimeh Hamedi-Rad; Vahid Fakhrzadeh

    2016-01-01

    Background: This in vitro study investigated the marginal fit of two porcelain laminate veneers to help the selection of more accurate veneers in discolored teeth. Materials and Methods: Thirty impressions of metal master die created from the prepared labial surface of an acrylic maxillary central incisor were made and poured with Type IV stone. The dies were distributed into test groups (n = 15) for the construction of DuCeram and InCeram laminate veneers. An image-analysis program was u...

  9. DIMENSIONAL STABILITY PERFORMANCE OF FIRE RETARDANT TREATED VENEER-ORIENTED STRANDBOARD COMPOSITES

    OpenAIRE

    Zeki Candan; Nadir Ayrilmis; Turgay Akbulut

    2011-01-01

    This study investigated dimensional stability properties of oriented strandboard (OSB) panels faced with fire retardant treated (FRT) veneers. The beech (Fagus orientalis Lipsky) veneers were treated with monoammonium phosphate (MAP), diammonium phosphate (DAP), lime water (LW), and a borax/boric acid (BX/BA) (1:1) mixture. Dimensional stability tests were performed according to ASTM D-1037. The results revealed that facing veneers impregnated with fire-retardant chemicals had significant eff...

  10. Fracture of a veneered-ZrO2 dental prosthesis from an inner thermal crack

    Directory of Open Access Journals (Sweden)

    Ulrich Lohbauer

    2014-10-01

    Full Text Available Here we describe the fractographic analysis of a veneer-ZrO2 single-unit dental prosthesis that fractured in a shell-like manner. Analysis of the retrieved fragment revealed that the crack originated in the bulk of the veneer from a thermal flaw located between two layers of the veneering material. Using the measured flaw plane we showed that the conditions of loading at fracture were complex and probably involved important tangential components.

  11. The Effect of Porcelain Veneer and Coloring Pigments on Microtensile Bond Strength of a Zirconia Ceramics

    Directory of Open Access Journals (Sweden)

    Alikhasi M

    2011-12-01

    Full Text Available Background and Aims: The bond strength between veneer ceramics and zirconia frameworks is the weakest component in the layered ceramics. Due to the possible effect of adding pigments to the core materials on the bond strength between core and veneer as well as the introduction of new ceramic materials in dentistry, the aim of this study was to compare the zirconia core-veneer microtensile bond strength using two ceramic veneers with or without coloring the core.Materials and Methods: In this experimental study, 12 disc-shaped specimens were fabricated using a manually aided design- manually aided manufactured (MAD/MAM zirconia core (Zirkonzahn. Two veneering ceramics of Ceram Kiss and Zirkonzahn ICE were also used to veneer the specimens. Half of the Zirkonzahn discs were remained white and the others were colored by shade A2.Then, the discs were cut into microbars (30 for each group and the microtensile bond strength of the core-veneer was calculated. The specimens were assessed using scanning electron microscopy (SEM and the data were analyzed using two-way ANOVA and Student's t-test.Results: Significant differences with respect to veneer layer were found (P<0.001. No significant differences were seen among colored and uncolored cores (P=0.69. Conclusion: According to the apparent effect of veneering ceramics on the core-veneer bond strength, careful selection of these agents is essential to achieve adequate bond strength between core and veneer to prevent delaminating and chipping failures of zirconia veneered restorations.

  12. Comparison of Microleakage of Composite Resin Veneering Systems at the Alloy Interface

    Science.gov (United States)

    1988-09-01

    technique that there is leakage around resin veneers in gold crowns. Microleakage studies have been used primarily for the evaluation of direct...investigation is to evaluate the bond between veneering composite resin and metal substructure. Measurement of microleakage at the composite resin-alloy...34OVERPRINT" COMPARISON OF MICROLEAKAGE OF COMPOSITE RESIN VENEERING SYSTEMS AT THE ALLOY INTERFACE A THESIS Presented to the Faculty of The University

  13. Effect of tooth brush abrasion and thermo-mechanical loading on direct and indirect veneer restorations.

    Science.gov (United States)

    Rosentritt, Martin; Sawaljanow, Alexander; Behr, Michael; Kolbeck, Carola; Preis, Verena

    2015-01-01

    This study investigated toothbrush abrasion and in vitro aging on ceramic (indirect technique) and composite veneers (direct technique). Identical composite and individual human incisors were restored with industrially preformed composite veneers, indirectly produced ceramic veneers, and direct composite restorations. Surface roughness was determined before and after tooth brushing. A 5-year period of oral service was simulated by thermal cycling and mechanical loading (TCML). After TCML, all specimens were examined with microscopy and scanning electron microscopy. Specimens without failures during TCML were loaded until failure. analysis of variance; Bonferroni's post hoc analysis, Kaplan-Meier-Log Rank test (α = 0.05). Tooth brushing yielded a non-significant increase (p = 0.560) in roughness in all materials (industrial veneer, 0.12+/-0.07 μm, direct restoration, 0.18+/-0.14 μm, ceramic, 0.35+/-0.16 μm). No significant differences in roughness could be determined between the materials, neither before nor after testing (p teeth, direct and preformed composite veneers on composite teeth showed no failures or damages. Two ceramic veneers showed cracking in the labial area. After TCML of human teeth, transmission microscopy indicated a facial crack in a ceramic veneer and chipping in the cervical area of a preformed veneer. Two direct composite veneers lost retention. No significantly different survival rates were found between the three veneer groups. Fracture force on human teeth varied between 527.8+/-132.4 N (ceramic), 478.3+/-165.4 N (preformed composite), and 605.0+/-263.5 N (direct composite). All materials revealed comparable wear resistance. Indirect ceramic, direct restorative composite, and preformed composite veneers showed comparable failure rates and satisfying longevity. The results indicate similar longevity of the chosen materials for veneer restorations.

  14. DYNAMIC ADHESIVE WETTABILITY OF POPLAR VENEER WITH COLD OXYGEN PLASMA TREATMENT

    OpenAIRE

    Lijuan Tang,; Rong Zhang,; Xiaoyan Zhou,; Mingzhu Pan,; Minzhi Chen,; Xuehui Yang,; Ping Zhou,; Zhao Chen

    2012-01-01

    Effects of cold oxygen plasma treatment on activating the surface of poplar veneers and improving its wettability were investigated. The veneers were treated with cold oxygen plasma for 1, 3, 5, 7, and 9 min, and aged in air for 1, 3, 7, 14, 21, and 28 days. The dynamic adhesive wettability of veneers was assessed using the contact angle, K-value analysis, and surface free energy. The shear strength of three-layer panels produced from untreated and cold oxygen plasma treated veneers was exami...

  15. Comparison of load-fatigue testing of ceramic veneers with two different preparation designs.

    Science.gov (United States)

    Chaiyabutr, Yada; Phillips, Keith M; Ma, Polly S; Chitswe, Kinsey

    2009-01-01

    The concept of tooth preparation for ceramic veneers remains controversial regarding whether the use of a palatal chamfer would affect the longevity of restorations. This study aimed to evaluate the load-fatigue testing of ceramic veneers using two different preparation designs-an incisal shoulder finish line with or without a palatal chamfer. A pressable ceramic veneer was bonded to the prepared maxillary central incisor using resin cement. The number of cycles until fatigue failure for each tooth-veneer specimen was recorded. Results revealed that using a palatal chamfer margin design significantly increased the fatigue failure cycle count.

  16. Optical Properties and Failure Load of Thin CAD/CAM Ceramic Veneers.

    Science.gov (United States)

    Maunula, Henriika; Hjerppe, Jenni; Lassila, Lippo L V; Närhi, Timo O

    2017-06-01

    This study aimed to compare optical properties and failure load of leucite (IPS Empress CAD LT) and lithium disilicate glass ceramic (IPS e.max CAD LT) materials in incisor veneers. Four groups of veneers were made on 36 bovine incisors with Cerec 3D milling unit (n=9/group): 0.5 and 0.3 mm thick leucite glass and 0.5 and 0.3 mm lithium disilicate glass veneers. The optical features were measured with CM-700d spectrophotometer using white and yellow try-in pastes. Differences were determined by means of ΔE value and luminance. The bovine teeth with veneers were mounted on acrylic resin blocks (Palapress, Heraeus Kulzer) and static loading test was conducted (LR30K plus, Lloyd Instruments). The color difference of veneers could be noticed with yellow and white cements when the material thickness increased from 0.3 to 0.5 mm (leucite ΔE yellow 4.4, white 6.0; lithiumdisilicate ΔE yellow 2.1, white 4.1). Both materials showed similar failure load with 0.5 mm veneers (leucite 1906 +/-319 N; lithiumdisilicate 2098 +/- 309 N). The failure load of 0.3 mm thick lithium dilisilicate veneers (2002 +/- 427 N) was comparable with the 0.5mm veneers. Ultrathin lithium disilicate glass ceramic veneers (0.3 mm) could be a potential option for clinical use. Copyright© 2017 Dennis Barber Ltd.

  17. The effect of various veneering techniques on the marginal fit of zirconia copings.

    Science.gov (United States)

    Torabi, Kianoosh; Vojdani, Mahroo; Giti, Rashin; Taghva, Masumeh; Pardis, Soheil

    2015-06-01

    This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measured before and after veneering process at 18 sites on the master die using a digital microscope. Paired t-test was used to evaluate mean marginal gap changes. One-way ANOVA and post hoc tests were also employed for comparison among 3 groups (α=.05). Marginal gap of 3 groups was increased after porcelain veneering. The mean marginal gap values after veneering in the layering group (63.06 µm) was higher than press-over (50.64 µm) and CAD-on (51.50 µm) veneered groups (Pveneering methods altered the marginal fit of zirconia copings. Conventional layering technique increased the marginal gap of zirconia framework more than pressing and CAD-on techniques. All ceramic crowns made through three different veneering methods revealed clinically acceptable marginal fit.

  18. Impact of thermal misfit on shear strength of veneering ceramic/zirconia composites.

    Science.gov (United States)

    Fischer, Jens; Stawarzcyk, Bogna; Trottmann, Albert; Hämmerle, Christoph H F

    2009-04-01

    Thermal misfit is discussed as one reason for chipping of veneered zirconia restorations. The aim of the investigation was to assess the effect of thermal misfit on the shear strength of zirconia/veneering ceramic composites. Shear strengths of 12 different veneering ceramic/zirconia composites were measured (n=10). The veneering ceramics were fired onto polished Y-TZP. In order to create a strong thermal mismatch, one of the veneering ceramics was intended for use on alumina and one for the metal-ceramic technique. The glass transition temperatures of the veneering ceramics and the coefficients of thermal expansion of all ceramics were measured (n=6). Statistical analysis was performed with one-way ANOVA and a post hoc Bonferroni test (pveneer (Delta alpha) were calculated. In addition the differences between glass transition temperatures of the veneering ceramics and room temperature (Delta T) as the effective temperature range for stress formation were calculated. Highest shear strength was observed when Delta alpha Delta T approximately 1000 x 10(-6). Thermal expansion and glass transition temperature of the veneering ceramic have an impact on the shear strength of veneer/zirconia composites.

  19. Use of anterior veneered stainless steel crowns by pediatric dentists.

    Science.gov (United States)

    Oueis, Hassan; Atwan, Salwa; Pajtas, Brynn; Casamassimo, Paul S

    2010-01-01

    The purpose of this study was to evaluate the use of anterior veneered stainless steel crowns (AVSSCs) by pediatric dentists. A questionnaire was sent to 2,600 active members of the American Academy of Pediatric Dentistry with a follow-up request after 8 weeks. Respondents were asked about the utilization of AVSSCs in their practice and during their graduate training program. In addition, the participants were asked to rank, in order of preference, the type of restorations for treating primary anterior teeth, as well as factors that influenced their choice of treatment. Among 849 respondents, 456 (51%) utilized AVSSCs in their practice; 187 (41%) selected AVSSCs as their first choice for the complete coverage for primary anterior teeth; and 278 (61%) selected extent of caries as the main factor that influenced their restoration choice. The respondents' major concern (73%) was durability of AVSSCs. The anterior veneered stainless steel crown is a common restoration to treat primary anterior teeth among pediatric dentists.

  20. Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers

    Directory of Open Access Journals (Sweden)

    Dino Re

    2014-01-01

    Full Text Available No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients’ restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with laminate nanohybrid resin composite veneers. A step-by-step protocol is proposed for diagnostic evaluation, mock-up fabrication and trial, teeth preparation and impression, and adhesive cementation. The resolution of initial esthetic issues, patient satisfaction, and nice integration of indirect restorations confirmed the success of this anterior dentition rehabilitation.

  1. Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers

    Science.gov (United States)

    Riva, Giancarlo

    2014-01-01

    No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients' restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with laminate nanohybrid resin composite veneers. A step-by-step protocol is proposed for diagnostic evaluation, mock-up fabrication and trial, teeth preparation and impression, and adhesive cementation. The resolution of initial esthetic issues, patient satisfaction, and nice integration of indirect restorations confirmed the success of this anterior dentition rehabilitation. PMID:25013730

  2. Esthetic rehabilitation of discolored anterior teeth with porcelain veneers

    Science.gov (United States)

    Kamble, Vaibhav D.; Parkhedkar, Rambhau D.

    2013-01-01

    The common man is bombarded by the media extolling the virtues of “the perfect smile.” In the 21st century of esthetic dentistry, fractured, malformed, malposed, and discolored teeth can be changed and restored to highly desirable form due to introduction of wide range of esthetic materials and techniques. Porcelain veneers is a conservative method of restoring the appearance of discolored, pitted teeth, and teeth with diastemas that provide extremely good esthetic results. A 21-year-old female patient with staining in anterior teeth had reported to the Department of Prosthodontics for esthetic rehabilitation. The patient was treated with porcelain veneers on maxillary anterior teeth. The patient was satisfied with the enhanced esthetic appearance. PMID:23853471

  3. Minimally invasive vertical preparation design for ceramic veneers.

    Science.gov (United States)

    Imburgia, Mario; Canale, Angelo; Cortellini, Davide; Maneschi, Marco; Martucci, Claudio; Valenti, Marco

    The esthetic treatment of anterior teeth has always presented a challenge in clinical practice. With the improvement of dental materials, many restorative options such as composite resins, all-ceramic crowns, and ceramic veneers have become available. The current challenge in reconstructive dentistry is to obtain excellent esthetic results while preserving the biological structures involved as much as possible. Thanks to the introduction of high-strength etchable dental ceramics, clinicians and technicians have materials and procedures at their disposal that allow them to restore esthetics and function through a minimally invasive approach. New-generation all-ceramic restorations and adhesive systems allow a greater preservation of residual hard tooth structures, especially with regard to single elements. This article describes a vertical preparation technique for ceramic veneers.

  4. Esthetic rehabilitation of discolored anterior teeth with porcelain veneers

    Directory of Open Access Journals (Sweden)

    Vaibhav D Kamble

    2013-01-01

    Full Text Available The common man is bombarded by the media extolling the virtues of "the perfect smile." In the 21 st century of esthetic dentistry, fractured, malformed, malposed, and discolored teeth can be changed and restored to highly desirable form due to introduction of wide range of esthetic materials and techniques. Porcelain veneers is a conservative method of restoring the appearance of discolored, pitted teeth, and teeth with diastemas that provide extremely good esthetic results. A 21-year-old female patient with staining in anterior teeth had reported to the Department of Prosthodontics for esthetic rehabilitation. The patient was treated with porcelain veneers on maxillary anterior teeth. The patient was satisfied with the enhanced esthetic appearance.

  5. Prefabricated composite resin veneers--a clinical review.

    Science.gov (United States)

    Gomes, George; Perdigão, Jorge

    2014-01-01

    This clinical technique article is focused on the use of prefabricated veneers to enhance the esthetic appearance of the anterior dentition in patients who needed an alternative esthetic solution more affordable than traditional porcelain veneers. Because prefabricated composite veneer systems have been recently introduced, they are not widely used. The Componeer system (Coltene, Altstätten, Switzerland) contains thin pre-polymerized hybrid composite shells, several shades of a direct hybrid composite resin, an etch-and-rinse adhesive system, and restorative accessories including finishing points and disks. The prefabricated restorations can be customized in the mouth for color and shape. The technique described in this article can be used to restore function and esthetics in one office visit. The prefabricated composite veneer technique has some of the advantages of direct composite restorations, as only one session is required without the need to take impressions to send to the dental laboratory. This new treatment option may open new opportunities for dental professionals and their patients. However, it is paramount to carry out controlled clinical studies with this restorative technique prior to recommending it without restrictions in general practice. The clinical technique described in this paper has the potential for being used routinely to lengthen anterior teeth, to correct malpositioned teeth, to mask discolorations, and to close diastemas. The technique can also be used to restore extensive caries lesions and tooth fractures, and to refurbish large old anterior restorations, especially when other treatment options are out of reach for the patient for financial reasons. © 2014 Wiley Periodicals, Inc.

  6. Colour stability of laminate veneers: an in vitro study.

    Science.gov (United States)

    Turgut, Sedanur; Bagis, Bora

    2011-12-01

    Obtaining a perfect aesthetic, especially with the translucent porcelain laminate veneers; shade of the porcelain, type of the resin cement and their long term colour stability are important factors to achieve aesthetic success. The purpose of the study was to assess the effect of different resin cement systems and UV ageing on the colour of full ceramic laminates with different shades. 392 discs were made with A1, A3, HO and HT shades of IPS e.max Press with 0.5mm thickness. Different shades of light cured Variolink Veneer, Ivoclar Vivadent (+3, MO, -3); Rely X Veneer, 3M ESPE (A1, A3, White Opaque, Translucent); and dual cured Maxcem Elite, Kerr (White, Yellow, White Opaque, Clear); and Variolink II, Ivoclar Vivadent (White Opaque, Translucent) resin cements were applied on the porcelain discs with a thickness of 0.1mm. Colour differences of the porcelain substructures after cementation and 300 h (150 kJ/m(2)) of UV ageing test, were examined with a colorimeter (Shade Eye Ex, Shofu, Japan). The results were analysed statistically with Wilcoxon signed-rank and Kruskal-Wallis test. The mean values of L*, a*, and b* were also compared using Paired Sample t-test. Spearman's Rank Correlation test was used to analyse the correlation between ceramics with resin-cemented ceramics after ageing. The data analyses were evaluated at a significance level of p resin cements, which were polymerized beneath the porcelain substructure with 0.5mm thickness. Although statistically significant differences were observed for all specimens, the magnitudes of the mean colour differences were at an acceptable perception level and were considered clinically acceptable (ΔEResin cements and ageing process influence the colour of porcelain laminate veneers. Cementation of laminates with either dual or light-cure resin cements does not effect the long term colour stability differently. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Wettability of southern pine veneer by phenol formaldehyde wood adhesives

    Science.gov (United States)

    Chung-Yun Hse

    1972-01-01

    Wettability of southern pine veneers was judged by measuring the contact angles made by 36 phenol formaldehyde resins. Formulation of the resins was by factorial design, the molar ratios of sodium hydroxide to phenol being 0.4, 0.7, and 1.0, the levels of resin solids content in the reaction mixture 37, 40, and 43 percent, and the molar ratios of formaldehyde to phenol...

  8. PORCELAIN LAMINATE VENEERS: A MINIMALLY INVASIVE ESTHETIC PROCEDURE

    OpenAIRE

    Tajammul

    2013-01-01

    ABSTRACT: With the advancement in the area of cosmetic dentistry, the dental profession has been offered new opportunities in conservative and esthetic restorative procedures. Multiple options are available to treat problems arising in the zone of high esthetic sensitivity. The use of porcelain laminate veneers to solve esthetic and/or functional problems has shown to be a valid treatment option especially in the anterior esthetic zone. The techniques and the materials em...

  9. Retention of esthetic veneers on primary stainless steel crowns.

    Science.gov (United States)

    Baker, L H; Moon, P; Mourino, A P

    1996-01-01

    The purpose of this study was to ascertain the amount of shearing force necessary to fracture, dislodge or deform the esthetic veneer facings of four commercially available veneered primary incisor stainless steel crowns. The four types tested were: Cheng Crowns, [Peter Cheng Orthodontic Laboratory]; Whiter Biter Crown II, [White Bite Inc.]; Kinder Krowns, [Mayclin Dental Studio, Inc]; and NuSmile Primary Crowns, [Orthodontic Technologies, Inc]. The crowns (#4 right central incisor) from each manufacturer were obtained with the facings attached. The crowns were soaked for ninety days and thermocycled at 4 degrees C and 55 degrees C for 500 45-second cycles. The crowns were cemented to standardized chromium cobalt metal dies. Each die was placed in to a custom holder on the Instron Universal testing machine. A force was applied at the incisal edge of the veneer at 148 degrees, (the primary interincisal angle), with a crosshead speed of 0.05 inches/minute until the veneer either fractured, dislodged or deformed. The mean force (Ibs) required +/- SD to produce failure, in descending order, was as follows: Cheng (107.8 +/- 17.3); NuSmile (100.2 +/- 18.2); KinderKrown (91.3 +/- 27.4)d Whiter Biter (81.5 +/- 21.7). To test the hypothesis of no difference among the four manufacturers, an analysis of variance was performed using PROC GLM. The resultant F statistic was 2.79 (p < 0.0543), indicating a marginally statistically significant difference in the response variable "pressure" among the four groups. A posthoc test was then performed to ascertain where these differences occurred. These results, using Turkey's studentized range test for pairwise comparisons, suggested that the only difference was between the Cheng and Whiter Biter manufacturers.

  10. Graded Zirconia Glass for Resistance to Veneer Fracture

    Science.gov (United States)

    Zhang, Y.; Kim, J.-W.

    2010-01-01

    Failures of zirconia-based all-ceramic restorations appear to be predominantly chips and fractures in the porcelain veneer, from occlusally induced sliding contact damage. We hypothesized that such failure may be substantially mitigated by controlled grading of the elastic modulus at the ceramic surface. In this study, we fabricated graded structures by infiltrating glass into zirconia plates, resulting in improved aesthetics and diminished modulus at the surfaces. Individual plates were then embedded in epoxy or cemented to dental composites and subjected to single- or multi-cycle sliding contact. Plates of porcelain-veneered zirconia and monolithic zirconia served as controls. Graded zirconia-glass structures exhibited over 3 times better resistance to single-cycle sliding damage than monolithic zirconia and 25 times better than veneered zirconia, and had a fatigue sliding damage resistance comparable with that of monolithic zirconia. These zirconia-glass materials can be engineered in shades from white to yellow, and have potentially better cementation properties than homogeneous zirconia. PMID:20651092

  11. Ceramic laminate veneers: clinical procedures with a multidisciplinary approach.

    Science.gov (United States)

    Veneziani, Marco

    Complex cases with high esthetic needs represent a challenge for clinicians. A multidisciplinary approach is vital to achieve the planned result. New technological devices are needed to facilitate the collaboration between the clinical team members and to develop a fluent and effective diagnostic and therapeutic pathway. This article describes a well-defined protocol for the treatment of complex esthetic cases with the use of ceramic laminate veneers. The protocol involves different branches of dentistry: periodontal therapy, mucogingival surgery, restorative dentistry, orthodontics, and prosthodontics. Each step of the protocol should be executed in a very strict order: intra- and extraoral esthetic analysis of the patient, with photographs; digital previsualization by means of Digital Smile Design (DSD); clinical previsualization by means of a mock-up; orthodontic, mucogingival, and endodontic treatments, if needed; minimally invasive tooth preparation, driven by a mock-up and silicone indices; manufacture of ceramic laminate veneers; try-in and adhesive cementation. In this article, this protocol is illustrated by a clinical case report in which all the above-mentioned steps were carried out. The finalization was obtained by means of state-of-the-art adhesive techniques and ceramic laminate veneers. The correct use of modern materials, in combination with rigorous adhesive procedures, allows for a minimally invasive and highly esthetic treatment, with adequate function and a perfect integration that is in harmony with the patient's face.

  12. Comparison of edge chipping resistance of PFM and veneered zirconia specimens.

    Science.gov (United States)

    Quinn, Janet B; Sundar, Veeraraghavan; Parry, Edward E; Quinn, George D

    2010-01-01

    To investigate the chipping resistance of veneered zirconia specimens and compare it to the chipping resistance of porcelain fused to metal (PFM) specimens. Veneered zirconia and PFM bar specimens were prepared in clinically relevant thicknesses. The specimen edges were chipped with different magnitude forces, producing chips of various sizes. The range of sizes included small chips that did not penetrate all the way through the veneers to the substrates, and also chips that were very large and reached the zirconia or metal substrates. The relationship between force magnitude and chip size (edge distance) was graphed. The resulting curves were compared for the veneered zirconia and PFM specimens. Knoop hardness vs. force graphs for the veneers and substrates were also obtained. The zirconia and PFM veneer chipping data followed a power law (coefficient of determination, R(2)>0.93) as expected from the literature. The curves overlapped within the combined data scatter, indicating similar resistance to chipping. The chips made in both types of specimens detached and did not penetrate into the substrate when they reached the veneer/substrate intersections. The hardness-load curves for the veneers and substrates all exhibited an indentation size effect (ISE) at low loads. The Knoop hardness values with uncertainties of +/-one standard deviation at 4N loads for the metal, zirconia, and the metal and zirconia veneers are: (2.02+/-0.08, 12.01+/-0.39, 4.24+/-0.16 and 4.36+/-0.02GPa), respectively, with no statistically significant difference between the veneers (Tukey pairwise comparison at 0.95 family confidence). This work indicates that a similar resistance to chipping might be expected for veneered zirconia and PFM restorations, in spite of the large difference in substrate hardness. Differences in susceptibility to chip spalling were not detected, but the chips in both specimen types detached off the sides in a similar manner instead of extending into the substrates.

  13. 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

    OpenAIRE

    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.

  14. 75 FR 28661 - Ceda-Pine Veneer, Inc., a Subsidiary of Excaliber, Inc., Sandpoint, ID; Notice of Negative...

    Science.gov (United States)

    2010-05-21

    ... Employment and Training Administration Ceda-Pine Veneer, Inc., a Subsidiary of Excaliber, Inc., Sandpoint, ID... negative determination of the TAA petition filed on behalf of workers at Ceda-Pine Veneer, Inc., Sandpoint... veneer and lumber boards revealed no increase imports nor any increased reliance on imports on the part...

  15. Effect of zirconia type on its bond strength with different veneer ceramics

    NARCIS (Netherlands)

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

    2008-01-01

    Purpose: The bond strength between veneer ceramic and the zirconia framework is the weakest component in the layered structure. This bond was proven to be sensitive to the surface finish of the framework material and to the type of the veneer ceramic and its method of application. New colored

  16. Physical, mechanical, and fire properties of oriented strandboard with fire retardant treated veneers

    Science.gov (United States)

    Nadir Ayrilmis; Zeki Candan; Robert White

    2007-01-01

    This study evaluated physical, mechanical and fire properties of oriented strand boards (OSB) covered with fire retardant treated veneers. The beech (Fagus orientalis Lipsky) veneers were treated with either monoammonium phosphate, diammonium phosphate, lime water or a borax/boric acid (1 : 1 by weight) mixture. Physical and mechanical properties of the specimens were...

  17. Influence of framework color and layering technique on the final color of zirconia veneered restorations

    NARCIS (Netherlands)

    Aboushelib, M.N.; Dozic, A.; Liem, J.K.

    2010-01-01

    Objective: To investigate the influence of colored zirconia frameworks on the overall color match of zirconia- veneered restorations. Method and Materials: Identical natural and colored zirconia frameworks (Cercon Base, Degudent) were layered using a veneer ceramic (IPS e.max Ceram Dentin, Ivoclar

  18. Microtensile bond strength and impact energy of fracture of CAD-veneered zirconia restorations

    NARCIS (Netherlands)

    Aboushelib, M.N.; de Kler, M.; van der Zel, J.M.; Feilzer, A.J.

    2009-01-01

    Purpose: With state-of-the-art CAD/CAM technology, the fabrication of large and complex zirconia frameworks is just a click away. On the other hand, veneering of the frameworks is still operator-dependent. The aim of this work was to evaluate CAD veneering of zirconia restorations in terms of

  19. 46 CFR 32.56-50 - Combustible veneers-T/ALL.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Combustible veneers-T/ALL. 32.56-50 Section 32.56-50....56-50 Combustible veneers—T/ALL. (a) Except as provided in paragraph (b) of this section combustible veneers on bulkheads, linings, and ceilings within accommodation, service, or control spaces must be 2...

  20. Effect of veneering method on the fracture and bond strength of bilayered zirconia restorations

    NARCIS (Netherlands)

    Abou Shelib, M.N.M.; de Kler, M.; van der Zel, J.M.; Feilzer, A.J.

    2008-01-01

    This study evaluated the fracture strength and microtensile bond strength of a new computer-aided design (CAD) veneering method for zirconia frameworks. A new CAD/computer-assisted manufacture system was used to fabricate a resin replica of the esthetic ceramic required to veneer a zirconia

  1. In vitro fracture resistance of composite-resin-veneered zirconia crowns.

    Science.gov (United States)

    Peampring, Chaimongkon; Aksornmuang, Juthatip; Sanohkan, Sasiwimol

    2017-01-01

    The aim of this study is to investigate the fracture load to failure and damage mode of the composite resin-veneered zirconia crowns preparing with two different zirconia surface treatments compared conventional porcelain-veneered zirconia crowns. Metallic molar-shape dies prepared with 10° convergence angle a 1.5 mm deep chamfer finish line were used. Two groups of composite-resin-veneered zirconia crowns were prepared using different surface treatment (Group A - sandblasting and Group B - glaze-on technique). Group C (conventional porcelain-veneered zirconia crowns) was served as control. Load to failure test was performed to evaluate the fracture resistance of the crowns using a universal testing machine. One-way ANOVA was used to evaluate the differences of mean values (P resin veneering.

  2. Marginal adaptation of Spinell InCeram and feldspathic porcelain laminate veneers.

    Science.gov (United States)

    Ghaffari, Tahereh; Hamedi-Rad, Fahimeh; Fakhrzadeh, Vahid

    2016-01-01

    This in vitro study investigated the marginal fit of two porcelain laminate veneers to help the selection of more accurate veneers in discolored teeth. Thirty impressions of metal master die created from the prepared labial surface of an acrylic maxillary central incisor were made and poured with Type IV stone. The dies were distributed into test groups (n = 15) for the construction of DuCeram and InCeram laminate veneers. An image-analysis program was used to measure the gap between the veneers and the master die at the labial, lingual, and proximal margins. Statistical analysis was performed with repeated measures ANOVA. Independent t-test was used to compare the mean values between the two groups. Values of P veneer was within the clinically acceptable standard set at 120 μm.

  3. Properties of a Laminated Wood Composite Produced with Thermomechanically Treated Veneers

    Directory of Open Access Journals (Sweden)

    Larissa M. Arruda

    2016-01-01

    Full Text Available The paper aimed at evaluating the properties of plywood made from thermomechanically treated wood veneers. Veneers from Amescla (Trattinnickia burseraefolia wood were treated in a hydraulic press with electric resistance heating. Two temperature levels were applied, 140°C and 180°C, for 1 and 2 minutes with 2.7 N/mm2 of pressure. A total of 30 plywood boards were produced, including six boards produced from untreated veneers. The results showed that the thermomechanical treatment did not have any deleterious effect on glue line strength and most of the mechanical properties of plywood made from treated veneers were improved. On the other hand, plywood made from untreated veneers presented better dimensional stability. Dimensional stability properties were most affected by the temperature of the treatment, while mechanical stability, represented by the glue line shear strength, was positively affected by temperature and duration of the treatment.

  4. Influence of surface treatment on bond strength of veneering ceramics fused to zirconia.

    Science.gov (United States)

    Tada, Kouki; Sato, Toru; Yoshinari, Masao

    2012-01-01

    In all-ceramic restorations involving a zirconia framework, surface treatment of the zirconia surface is required to enhance bonding strength with the veneering ceramics and thus prevent chipping. The purpose of the present study was to investigate the influence of surface roughness and heat treatment of the zirconia and use of liner porcelain on bond strength between veneering ceramics and a zirconia framework. Debonding/crack-initiation strength (τb) was determined according to ISO 9693. No significant difference was observed among conditions, except with use of a liner under heat treatment, which yielded a τb of 26.0±2.9-28.9±1.7 MPa. Electron probe microanalysis revealed that components of the veneering ceramics remained on the zirconia surface after debonding, suggesting that fractures occur in the veneering ceramics and that improving the strength of the veneering ceramics themselves might increase bond strength.

  5. Effect of cooling rate on shear bond strength of veneering porcelain to a zirconia ceramic material.

    Science.gov (United States)

    Komine, Futoshi; Saito, Ayako; Kobayashi, Kazuhisa; Koizuka, Mai; Koizumi, Hiroyasu; Matsumura, Hideo

    2010-12-01

    The purpose of the present study was to evaluate the effect of cooling rates after firing procedures of veneering porcelain on shear bond strength between veneering porcelain and a zirconium dioxide (zirconia; ZrO₂) ceramic material. A total of 48 ZrO₂ disks were divided equally into three groups. Two veneering porcelains that are recommended for ZrO₂ material - Cerabien ZR (CZR), IPS e.max Ceram (EMX) - and one that is recommended for metal ceramics - Super Porcelain AAA (AAA) were assessed. Each group was then further divided into two subgroups (n = 8) according to cooling time (0 or 4 min) after porcelain firing. Specimens were fabricated by veneering the porcelain on the ZrO₂ disks, after which shear bond testing was conducted. Bond strength differed significantly by cooling time in ZrO₂-AAA (P veneering porcelain to a zirconia material depending on porcelain material used.

  6. Marginal adaptation of Spinell InCeram and feldspathic porcelain laminate veneers

    Science.gov (United States)

    Ghaffari, Tahereh; Hamedi-Rad, Fahimeh; Fakhrzadeh, Vahid

    2016-01-01

    Background: This in vitro study investigated the marginal fit of two porcelain laminate veneers to help the selection of more accurate veneers in discolored teeth. Materials and Methods: Thirty impressions of metal master die created from the prepared labial surface of an acrylic maxillary central incisor were made and poured with Type IV stone. The dies were distributed into test groups (n = 15) for the construction of DuCeram and InCeram laminate veneers. An image-analysis program was used to measure the gap between the veneers and the master die at the labial, lingual, and proximal margins. Statistical analysis was performed with repeated measures ANOVA. Independent t-test was used to compare the mean values between the two groups. Values of P veneer was within the clinically acceptable standard set at 120 μm. PMID:27274344

  7. Fracture mechanics analyses of ceramic/veneer interface under mixed-mode loading.

    Science.gov (United States)

    Wang, Gaoqi; Zhang, Song; Bian, Cuirong; Kong, Hui

    2014-11-01

    Few studies have focused on the interface fracture performance of zirconia/veneer bilayered structure, which plays an important role in dental all-ceramic restorations. The purpose of this study was to evaluate the fracture mechanics performance of zirconia/veneer interface in a wide range of mode-mixities (at phase angles ranging from 0° to 90°), and to examine the effect of mechanical properties of the materials and the interface on the fracture initiation and crack path of an interfacial crack. A modified sandwich test configuration with an oblique interfacial crack was proposed and calibrated to choose the appropriate geometry dimensions by means of finite element analysis. The specimens with different interface inclination angles were tested to failure under three-point bending configuration. Interface fracture parameters were obtained with finite element analyses. Based on the interfacial fracture mechanics, three fracture criteria for crack kinking were used to predict crack initiation and propagation. In addition, the effects of residual stresses due to coefficient of thermal expansion mismatch between zirconia and veneer on the crack behavior were evaluated. The crack initiation and propagation were well predicted by the three fracture criteria. For specimens at phase angle of 0, the cracks propagated in the interface; whereas for all the other specimens the cracks kinked into the veneer. Compressive residual stresses in the veneer can improve the toughness of the interface structure. The results suggest that, in zirconia/veneer bilayered structure the veneer is weaker than the interface, which can be used to explain the clinical phenomenon that veneer chipping rate is larger than interface delamination rate. Consequently, a veneer material with larger fracture toughness is needed to decrease the failure rate of all-ceramic restorations. And the coefficient of thermal expansion mismatch of the substrates can be larger to produce larger compressive

  8. Effect of veneering techniques on color and translucency of Y-TZP.

    Science.gov (United States)

    Luo, Xiao Ping; Zhang, Lei

    2010-08-01

    This study compared the color parameters and total luminous transmittance of disc specimens by different veneering techniques in order to examine the effect of veneering technique on esthetics of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) all-ceramic restorations. Thirty disc specimens (10-mm diameter, 0.50 +/- 0.01 mm thick) were fabricated of IPS e.max ZirCAD core material, and ZL1 IPS e.max ZirLiner (0.10-mm thick) was layered. The specimens were randomly divided into three groups (n = 10/group). Group ZP (fully anatomical technique) was veneered 0.60 mm by heat-pressing IPS e.max ZirPress fluorapatite glass-ceramic ingots; Group ZC (traditional layering technique) was veneered 0.60 mm by condensing and sintering IPS e.max Ceram low-fusing nano-fluorapatite veneering porcelain; Group ZPC (cutback technique) was veneered by partially pressed ingots and subsequently layered 0.30 mm with veneering porcelain. Color parameters (L*, a*, b*) and total luminous transmittance (tau) of zirconia core discs and core and veneer specimens were measured with ShadeEye NCC dental colorimeter and spectrophotometer, respectively. Color saturation (C*ab) and color difference (DeltaE) were calculated using color difference formula. One-way analysis of variance (ANOVA) combined with a Tukey multiple-range test were used to analyze the data (alpha= 0.05). As to ZP, ZPC, and ZC groups, the value of a* increased (-1.35 +/- 0.07, -0.64 +/- 0.06, -0.36 +/- 0.05, respectively) (p ceramic restoration veneered by fully anatomical technique was the most transparent and lightest, while restorations veneered by cutback technique were the least translucent and the darkest.

  9. Effect of thermocycling on the flexural strength of porcelain laminate veneers.

    Science.gov (United States)

    Subramanian, Deepa; Sivagami, G; Sendhilnathan, D; Rajmohan, Cs

    2008-10-01

    The aim of this study was to examine the impact of thermocycling on the flexural strength and development of surface flaws on the glazed surface of porcelain laminate veneer restorations with and without resin luting cement. 80 Vitadur alpha dentin porcelain discs (10 mm diameter, 0.9 mm thickness) were glazed on one side and divided into two groups: A (porcelain laminate veneer only without resin luting cement) and B (porcelain laminate veneer luted with resin cement), each containing 40 discs. The discs in groups A and B were then thermocycled at different temperatures and were subjected to SEM analysis to evaluate the effect of thermocycling on crack propagation. Mean flexural strength was determined by using the ball-on-ring test. Student's t -test was used to find out the difference between strength values of the thermocycled porcelain discs and discs luted with resin cement. SEM analysis revealed crack propagation in the subgroups subjected to extremes of temperature, i.e., 4 +/- 1 degrees C, 37 +/- 1 degrees C and 4 +/- 1 degrees C, 65 +/- 1 degrees C in the porcelain laminate veneers luted with resin cement. Flexural strength analysis revealed superior flexural strength for porcelain laminate veneers: 88.58 +/- 6.94 MPa when compared to porcelain laminate veneers luted with resin cement: 8.42 +/- 2.60 MPa. Results were tabulated and statistically analyzed using Student's t -test. Laminate veneer specimens exhibited greater flexural strength than those which were luted with resin cements. Laminate veneer specimens luted with resin cement and subjected to extremes of temperature, 4 +/- 1 degrees C and 37 +/- 1 degrees C and 4 +/- 1 degrees C and 65 +/- 1 degrees C, showed a marked decrease in flexural strength. After thermocycling at extremes of temperature, laminate veneer specimens luted with resin cement showed crack propagation. Fit of laminate veneers cannot / should not be compensated by the thickness of luting agent.

  10. Influence of veneering materials on the marginal fit and fracture resistance of an alumina core system.

    Science.gov (United States)

    Fahmy, Nadia Z

    2011-01-01

    This study was undertaken to assess the influence of three-veneering materials on the marginal fit, fracture resistance, and failure pattern of In-Ceram alumina crowns. Forty In-Ceram cores were constructed and divided into four groups of ten each. Ten alumina cores were left unveneered, forming the first group for core testing, while the other 30 copings were divided into three groups depending on the veneering material used. The vertical marginal gaps of the alumina copings were measured before and after veneer placement at 16 sites using an optical microscope. The specimens were then loaded to fracture at a crosshead speed of 1 mm/min. Fractured specimens were examined, and the fracture patterns of the crowns were recorded. Selected specimens were examined using scanning electron microscope. Data were presented as means and standard deviation values. One-way ANOVA was used to compare between mean gap areas and fracture resistance of the three materials. Duncan's post hoc test was used for pairwise comparison between the means when ANOVA test was significant. Vitadur-N-veneered crowns showed statistically the highest mean vertical gaps, while no significant difference was evident between the marginal fits of Vitadur-α- and VM7-veneered crowns. Regarding the strength, a statistically significant decrease in fracture resistance of the cores was evident after veneering with Vitadur-N; however, no significant change in mean fracture resistance value of Vitadur-α- and VM7-veneered crowns was evident compared to the alumina cores. VM7-veneered crowns showed the highest fracture resistance values. Vitadur-N-veneered crowns showed the highest mean vertical gaps and the lowest mean fracture resistance values of the tested groups, while VM7-veneered crowns combined the highest fracture resistance values and clinically acceptable margins. The best interface quality and finest ceramic texture were evident in case of VM7 material. © 2010 by The American College of

  11. Origin and mixing timescale of Earth's late veneer

    Science.gov (United States)

    Prescher, C.; Allu Peddinti, D.; Bell, E. A.; Bello, L.; Cernok, A.; Ghosh, N.; Tucker, J.; Wielicki, M. M.; Zahnle, K. J.

    2012-12-01

    Experimental studies on the partitioning behavior of highly siderophile elements (HSE) between silicate and metallic melts imply that the Earth's mantle should have been highly depleted in these elements by core formation in an early magma ocean. However, present HSE contents of the Earth's mantle are ~3 orders of magnitude higher than that expected by experiments. The apparent over-abundance of HSE has commonly been explained by the addition of meteoritic material in the "late veneer" which describes the exogenous mass addition following the moon forming impact and concluding with the late heavy bombardment at ~3.8-3.9 Ga. The strongest evidence for this theory is that the platinum group element (PGE) contents in today's mantle are present in chondritic relative abundances, as opposed to a fractionated pattern expected with metal-silicate partitioning. Archean komatiites indicate that the PGE content of the Earth's mantle increased from about half their present abundances at 3.5 Ga to their present abundances at 2.9 Ga. This secular increase in PGE content suggests a progressive mixing of the late veneer material into the Earth's mantle. However, this time scale also implies that the whole mantle was relatively well mixed by 2.9 Ga. We use a compilation of existing isotopic and trace element data in order to constrain the origin and composition of the late veneer. We use PGE abundances, W abundances and W isotopic compositions in chondritic meteorites and the primitive upper mantle to compute the amount of mass delivered during the late veneer and find the late veneer mass to be ~0.6 % the mass of the bulk silicate Earth (consistent with earlier estimates). We also use the 187Re-187Os and 190Pt-186Os systems to constrain the composition and timing of delivery of the impacting population. We model the efficiency of mantle mixing in this time frame by using 3-dimensional numerical geodynamical simulations and geochemical constraints. Initial parameters include the

  12. Indirect veneer treatment of anterior maxillary teeth with enamel hypoplasia

    Directory of Open Access Journals (Sweden)

    Devi Eka Juniarti

    2010-09-01

    Full Text Available Background: Nowadays, aesthetic rehabilitation becomes a necessity. It is affected by patient’s background, especially career, social and economic status. The aesthetic abnormality of anterior teeth i.e discoloration, malposition and malformation can affect patient’s appearance, especially during smile. These dental abnormalities, as a result, can decrease patient’s performance. Dental malformation, for instance, can be caused by developmental tooth defect, such as enamel hypoplasia. Enamel hypoplasia is a developmental defect caused by the lack of matrix amount which leads to thin and porous enamel. Enamel hypoplasia can also be caused by matrix calcification disturbance starting from the formation and development of enamel matrix causing defect and permanent changes which can occur on one or more tooth. Purpose: The aim of the study is to improve dental discoloration and tooth surface texture on anterior maxillary teeth with enamel hypoplasia by using indirect veneer with porcelain material. Case: A 20 years-old woman with enamel hypoplasia came to the Dental Hospital, Faculty of Dentistry Airlangga University. The patient wanted to improve her anterior maxillary teeth. It is clinically known that there were some opaque white spots (chalky spotted and porous on anterior teeth’s surface. Case management: Indirect veneer with porcelain material had been chosen as a restoration treatment which has excellent aesthetics and strength, and did not cause gingival irritation. As a result, the treatment could improve the confidence of the patient, and could also make their function normal. Conclusion: Indirect veneer is an effective treatment, which can improve patient’s appearance and self confidence.Latar belakang: Saat ini perbaikan estetik menjadi suatu kebutuhan. Kebutuhan akan estetik dipengaruhi latar belakang penderita, terutama karir, status sosial dan ekonomi. Hal ini disebabkan, kelainan estetik seperti diskolorasi, malposisi

  13. [An in vitro study of the fracture strength of tooth preparations for Empress 2 veneers and crowns and mandibular incisors restored with Empress 2 veneers and crowns].

    Science.gov (United States)

    Wei, Xue; Li, Yan

    2009-12-01

    To compare the fracture resistance of mandibular incisors' preparations for veneers and crowns, mandibular incisors restored with Empress 2 veneers and crowns. 50 human mandibular incisors were randomly divided into five groups. Each group consisted of ten teeth and the treatment obtained as follows: A, tooth preparations for veneers; B, tooth preparations for crowns; C, teeth restored with veneers; D, teeth restored with crowns; E, untreated group. The teeth received standardized preparation and the restorations were manufactured with Empress 2 system and cemented with resin luting agent. The fracture resistances of teeth were measured by Instron universal testing machine and statistically analyzed with one-way ANOVA. The fracture resistances of A, B, C, D, E were (576.11 +/- 91.53), (204.13 +/- 85.88), (451.50 +/- 116.81), (386.16 +/- 117.75) and (566.05 +/- 121.37) N, respectively. The statistical analysis demonstrated significant differences between five groups. There were no significant differences between group A and E, group C and D. Tooth preparations for veneers did not significantly reduce the fracture resistance of mandibular incisor. The fracture resistance of teeth restored with Empress 2 veneers and crowns did not significantly differ from each other.

  14. Do surface treatments affect the optical properties of ceramic veneers?

    Science.gov (United States)

    Turgut, Sedanur; Bağış, Bora; Korkmaz, Fatih Mehmet; Tamam, Evsen

    2014-09-01

    Surface treatments may affect the optical properties of ceramic veneers before cementation. The purpose of this study was to evaluate whether various surface treatments affect the optical properties of different types of ceramic veneers. Disk-shaped ceramic veneers (N=280) were prepared from the IPS e.max Press, e.max CAD, Empress Esthetic, e.max Ceram, and Inline ceramic systems with 0.5-mm and 1.0-mm thicknesses. The ceramics were divided into 4 groups: no surface treatments; etched with hydrofluoric acid; airborne-particle abraded with 30-μm Al2O3; and irradiated with erbium:yttrium-aluminum-garnet laser. A translucent shade of resin was chosen for cementation. Color parameters were examined with a colorimeter. Statistical analyses were done with 3-way ANOVA and the Bonferroni test (P=.05). Significant interactions were noted between the surface treatments, ceramic type, and thickness for ΔE values (P=.01), and no significant interactions were noted for L* (P=.773), a* (P=.984), and b* (P=.998). The greatest color change occurred after airborne-particle abrasion with 0.5-mm-thick e.max Press (2.9 ΔE). Significant differences in ΔE values were found among the hydrofluoric acid, airborne-particle abrasion, and laser groups for 0.5-mm-thick ceramics, except IPS Inline, and among the hydrofluoric acid, airborne-particle abrasion, and laser groups for 1.0-mm-thick ceramics, except Empress Esthetic ceramics. The color change of the ceramics increased after the surface treatments, particularly as the ceramics became thinner. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  15. Late veneer and late accretion to the terrestrial planets

    Science.gov (United States)

    Brasser, R.; Mojzsis, S. J.; Werner, S. C.; Matsumura, S.; Ida, S.

    2016-12-01

    It is generally accepted that silicate-metal ('rocky') planet formation relies on coagulation from a mixture of sub-Mars sized planetary embryos and (smaller) planetesimals that dynamically emerge from the evolving circum-solar disc in the first few million years of our Solar System. Once the planets have, for the most part, assembled after a giant impact phase, they continue to be bombarded by a multitude of planetesimals left over from accretion. Here we place limits on the mass and evolution of these planetesimals based on constraints from the highly siderophile element (HSE) budget of the Moon. Outcomes from a combination of N-body and Monte Carlo simulations of planet formation lead us to four key conclusions about the nature of this early epoch. First, matching the terrestrial to lunar HSE ratio requires either that the late veneer on Earth consisted of a single lunar-size impactor striking the Earth before 4.45 Ga, or that it originated from the impact that created the Moon. An added complication is that analysis of lunar samples indicates the Moon does not preserve convincing evidence for a late veneer like Earth. Second, the expected chondritic veneer component on Mars is 0.06 weight percent. Third, the flux of terrestrial impactors must have been low (≲10-6 M⊕ Myr-1) to avoid wholesale melting of Earth's crust after 4.4 Ga, and to simultaneously match the number of observed lunar basins. This conclusion leads to an Hadean eon which is more clement than assumed previously. Last, after the terrestrial planets had fully formed, the mass in remnant planetesimals was ∼10-3 M⊕, lower by at least an order of magnitude than most previous models suggest. Our dynamically and geochemically self-consistent scenario requires that future N-body simulations of rocky planet formation either directly incorporate collisional grinding or rely on pebble accretion.

  16. Ultra-Thin Veneers Without Tooth Preparation in Extensive Oligodontia.

    Science.gov (United States)

    Savi, Andrea; Crescini, Aldo; Tinti, Carlo; Manfredi, Maddalena

    2015-01-01

    Dental agenesis is the most commonly encountered dental anomaly in humans. Oligodontia, however, is a rare condition that involves the congenital absence of six or more teeth, excluding the third molars. Treatment of oligodontia requires an interdisciplinary approach. The prosthetic treatment plan should carefully consider esthetic and functional rehabilitation but should take a conservative approach. Adhesive techniques, combined with the new ceramic materials, permit functional and esthetic prosthetic restorations that are more conservative in comparison to those used in the past. Ultrathin occlusal veneers without tooth preparations may represent a good esthetic and conservative approach for oral rehabilitation of patients affected by severe hypodontia.

  17. [Evaluation of the esthetic effect of resin cements on the final color of ceramic veneer restorations].

    Science.gov (United States)

    Chen, Xiaodong; Zhang, Shaopu; Xing, Wenzhong; Zhan, Kangru; Wang, Yining

    2015-02-01

    To evaluate the influence of various shades of resin cements on the final color of an improved lithium-disilicate pressed glass ceramic veneers and analyze the agreement of resin cements and corresponding try-in pastes. Forty-eight artificial maxillary central incisor teeth were sequenced according to the measured color parameters and divided at random into 8 groups (n = 6). These artificial teeth were prepared following veneer preparation protocol. An improved lithium- disilicate pressed glass ceramic materials (IPS e.max Press, Ivoclar Vivadent) were selected as the veneer material. The shape and curvature of each veneer wax pattern were duplicated with the same impression to guarantee the similarity. The ceramic veneer specimens were delivered on the artificial teeth using the corresponding try-in pastes of 8 shades (Variolink Veneer, shades of LV-3, LV-2, MV, HV+2, HV+3; and 3M RelyXTM Veneer, shades of WO, TR, A3) and bonded with the resin cements. A clinical spectrophotometer was used to measure the color parameters of the ceramic veneers before the try-in, during the try-in procedure, and after cementation. ΔE values and C*ab values were calculated. The result of one-way ANOVA indicated that the color changes of ceramic veneer cementation with resin cements were statistically significantly different in the shades of resin cements (P veneer after cementation ranged from 0.93 to 6.79. The color changes of ceramic veneer specimens using the shades of LV-3, HV+3, WO were 3.31, 4.90 and 6.79, respectively (ΔE>3.3). The ΔE values of the ceramic veneer specimens between the resin cements and corresponding try-in pastes were from 0.72 to 1.79 (except the shade of HV+3). The LV-3, HV+3, WO shades were able to change the final color of a ceramic veneer. The color of resin cements and corresponding try-in pastes achieved high agreement (except the shade of HV+3).

  18. Clinical and scanning electron microscopic assessments of porcelain and ceromer resin veneers.

    Science.gov (United States)

    Dhawan, Pankaj; Prakash, Hari; Shah, Nassem

    2003-01-01

    Recently available Ceromer resin materials are promising for fabrication of esthetic anterior laminates and provices an alternative, cost effective treament modality to porcelain laminates for discolored anterior anterior teeth. It was proposed to study the esthetic quality and surface finish of veneers fbricated from ceromer resin and compare it with the standard porcelain veneers, both clinically as well as by scanning electron microscope (SEM) at baseline and at 12 months. If found comparable, ceromer resin veneer could provide an alternative to porcelain veneers which is an expensive technique for a developing country like India. Seventy-two veneers, 36 porcelain and 36 ceromer were placed in 12 subjects who were studied at 0, 6 and 12 months for clinical acceptability, and at 0 and 12 months for SEM assessment. The restorations were luted with Opal luting composite and Scotchbond multipurpose system; polyvinyl siloxane was used as the impression material. The clinical assessment was made using modified United Public Health Services criteria, whereas the SEM assessment was made by quantitative analysis of the marginal fit and surface characteristics of the two veneering materials. Ceromer exhibited good anatomical form during the study period, but depicted changes in color, surface appearance, marginal adaptation, increased marginal discoloration, and tissue response. Inability to achieve a good finish with high gloss was a major drawback of the ceromer. Porcelain exhibited better esthetics, marginal adaptation, finish qualities, and tissue response. The SEM showed good to excellent marginal fit at baselinne in ceromer and porcelain veneers, but loss of luting resin at the margins was evident in both the materials after 12 months, leading to visible gaps in a number of veneer restorations. Ceromer veneers exhibited poor surface characteristics in several restorations, which further degraded in an oral conditions over 12 months. Veneering is an effective mode of

  19. Direct or indirect composite veneers in anterior teeth: which method causes higher tooth mass loss? An in vitro study.

    Science.gov (United States)

    Machado, Alessandra Nunes; Coelho-de-Souza, Fabio Herrmann; Rolla, Juliana Nunes; Erhardt, Maria Carolina Guilherme; Demarco, Flavio Fernando

    2014-01-01

    There is little information in the literature regarding the relationship between preparations made for direct and indirect veneers and the loss of tooth structure required for each technique. This in vitro study sought to quantify the different mass losses from preparation techniques used for direct and indirect veneers. Thirty artificial teeth were weighted using a digital balance and placed in a dental manikin in the position corresponding to the right maxillary central incisor. Five clinicians-all experts in esthetic dentistry-were asked to perform conventional preparations for both a direct composite resin veneer and an indirect ceramic veneer. After preparations, specimens were weighted again in the same digital balance. Teeth undergoing veneer preparations demonstrated a statistically significant mass loss compared to unprepared teeth. Indirect ceramic veneer preparations produced more mass loss than direct composite veneer preparations (P < 0.01).

  20. Masking ability of bi- and tri- laminate all-ceramic veneers on tooth-colored ceramic discs.

    Science.gov (United States)

    Farhan, Daniel; Sukumar, Smitha; von Stein-Lausnitz, Axel; Aarabi, Ghazal; Alawneh, Ahmad; Reissmann, Daniel R

    2014-01-01

    A predictable esthetic outcome is imperative when placing ceramic veneers. Discolored teeth pose a major challenge as sufficient material thickness is required to achieve a good esthetic result. There is limited evidence in the literature that compares the masking ability of multi-laminate veneers. The aim of this in-vitro study was to compare the masking ability of bi-laminate (BL) and tri-laminate (TL) all-ceramic veneers cemented on tooth-colored ceramic discs. A total of 40 veneers (shade A1, 10-mm diameter, 0.8-mm thick) were manufactured-20 BL veneers (0.4-mm pressable ceramic coping veneered with 0.4-mm thick enamel layer) and 20 TL veneers (0.4-mm coping veneered with 0.2-mm thick opaque interlayer and 0.2-mm thick enamel layer). A bonding apparatus was utilized to adhesively cement all veneers on the ceramic discs (shade A1), simulating teeth of light and dark color. The resulting groups (N = 10 each) were the reference groups (shade A1 ceramic base) BL-1 and TL-1 veneers, and the test groups (shade A4 ceramic base) BL-4 and TL-4 veneers. The color of the cemented veneers was measured using a spectrophotometer. The data were converted to CIE L*a*b* coordinates, and ΔE* were calculated to allow for statistical analysis. The color differences between the samples with the A1 and A4 ceramic bases were significantly lower when covered with TL veneers (mean ΔE*: 3.2 units) than with BL veneers (mean ΔE*: 4.0 units: p veneers. The 0.8-mm thick TL veneer was able to mask darker tooth-colored ceramic disc within clinically acceptable limits. Increased understanding of the masking ability of ceramics and of color science is necessary in these esthetically aware times. Providing tri-laminate veneers for darker colored teeth seems to result in more predictable esthetical results than when using bi-laminate veneers. Patients with discolored/darker teeth may benefit from a more predictable esthetic result when teeth restored with tri-laminate rather than bi

  1. Effect of endodontic access cavity preparation on monolithic and ceramic veneered zirconia restorations.

    Science.gov (United States)

    Grobecker-Karl, Tanja; Christian, Mirko; Karl, Matthias

    2016-01-01

    Due to the high chipping rates observed in veneered zirconia ceramic restorations, the use of monolithic zirconia restorations has been recommended. This study tried to compare veneered and monolithic zirconia fixed dental prostheses (FDPs) with respect to the amount of damage induced by endodontic access preparation. Monolithic and ceramic veneered (n = 10) three-unit restorations (retainers: first premolar and first molar; pontic: second premolar) were subject to endodontic access cavity preparation in both retainers using a diamond rotary instrument under continuous water cooling. The number of chipping fractures and microfractures detected using the fluorescent penetrant method were recorded. Statistical analysis was based on Wilcoxon rank sum tests with Bonferroni correction (level of significance α = .05). Only one microfracture could be identified in the group of monolithic FDPs while a maximum of seven microfractures and three chipping fractures per retainer crown were recorded in the group of veneered restorations. At the premolar site, the veneered restorations showed significantly more microfractures (P = .0055) and chipping fractures (P = .0008). At the molar site, no significant difference with respect to microfractures could be detected (P = .0767), while significantly more chipping fractures occurred in the veneered samples (P = .0293). Monolithic zirconia restorations seem to be less susceptible to damage when endodontic access cavities have to be prepared as compared to veneered zirconia reconstructions. However, no conclusions can be drawn on the long-term performance of a specific restoration based on this study.

  2. Incisal coverage or not in ceramic laminate veneers: A systematic review and meta-analysis.

    Science.gov (United States)

    Albanesi, Rafael Borges; Pigozzo, Mônica Nogueira; Sesma, Newton; Laganá, Dalva Cruz; Morimoto, Susana

    2016-09-01

    There is no consensus on whether incisal coverage is a risk or a protective factor in preparations for ceramic veneers. The aim of this systematic review and meta-analysis was to evaluate the survival rates of preparation designs for ceramic veneers with and without incisal coverage. Primary clinical studies with the following characteristics were included: 1) studies related to ceramic laminate veneers and 2) prospective or retrospective studies conducted in humans. From the selected studies, the survival rates and failures rates for ceramic veneers were extracted according to preparation design, with or without incisal coverage. The Cochran Q test and the I(2) statistic were used to evaluate heterogeneity. Metaregression, meta-analysis were performed. Two reviewers searched in the MEDLINE (Pubmed) and Cochrane Central Register of Controlled Trials (Central) electronic databases, from 1977 to June 5, 2016, without language restrictions. Eight studies out of 1145 articles initially identified were included for risk of bias and systematic assessment. No study was identified for crystalline ceramic veneers. The estimated survival rate for laminate veneers with incisal coverage was 88% and 91% for those without incisal coverage. Incisal coverage presented an OR of 1.25. Irrespective of the preparation designs, with or without incisal coverage, ceramic veneers showed high survival rates. As regard implications for future clinical research studies, randomized clinical studies are necessary to compare preparation designs with and without incisal coverage, and to provide clear descriptions of these preparation designs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Retrospective study on the performance of porcelain laminate veneers delivered by undergraduate dental students.

    Science.gov (United States)

    Murphy, E; Ziada, H M; Allen, P F

    2005-03-01

    The aim of this study was to retrospectively evaluate the clinical performance of porcelain laminate veneer restorations delivered by undergraduate students at the Department of Restorative Dentistry, University Dental School and Hospital Cork and to analyze the factors that influence their prognosis and their effect on periodontal health. Patients who had veneers fitted over a period of 5 yrs. were recalled for evaluation. The recall protocol took the form of a questionnaire and a full clinical examination of the teeth involved and contra lateral control teeth. In all, 29 patients with 62 porcelain veneers were examined, only 2 of which were in the mandible. 77% of patients had veneers fitted due to discolouration, 13% in order to alter the shape or size of teeth and 10% due to palatal erosion. On the date of recall 89% of veneers had never debonded or fractured, 6% had to be rebonded since the date of insertion and 5% presented with a fracture. From this study it appears that porcelain laminate veneers are successful in the treatment of discoloured and irregular configured anterior teeth. It shows that undergraduate students can deliver satisfactory veneer restorations.

  4. In vitro evaluation of shear bond strength of veneering ceramics to zirconia.

    Science.gov (United States)

    Ozkurt, Zeynep; Kazazoglu, Ender; Unal, Ahmet

    2010-03-01

    The bond strength between veneering ceramic and zirconia framework is the weakest link in the layered structure. To investigate the shear bond strength (SBS) of veneering ceramics to zirconia, four types of zirconia ceramics (Zirkonzahn, Cercon, Lava, DC-Zirkon) were selected. For each zirconia system, 30 disk specimens were layered with IPS e.max Ceram, Vita VM9, and a manufacturer-recommended veneering ceramic. SBS test was conducted, and fracture surface analysis was also performed to determine the failure modes. One-way ANOVA, two-way ANOVA, and Tukey's HSD tests were used to analyze the data. On shear bond strength between zirconia and their recommended veneering ceramics, statistically significant differences were observed among the different zirconia systems (pveneering ceramics than their recommended veneering ceramics for DC-Zirkon and Lava. For Zirkonzahn and Cercon, similar SBS values were observed for all kinds of veneering ceramics (p>0.05). In conclusion, the bonding of manufacturer-recommended veneering ceramic to the zirconia framework differed according to zirconia type.

  5. Effect of veneering technique on the fracture resistance of zirconia fixed dental prostheses.

    Science.gov (United States)

    Chaar, M S; Witkowski, S; Strub, J R; Att, W

    2013-01-01

    To compare the fracture resistance of zirconia 3-unit posterior fixed dental prostheses (FDPs) frameworks veneered with different veneering materials and techniques before and after artificial ageing. Forty-eight zirconia 3-unit FDPs, representing a missing first molar, were adhesively cemented on human teeth. The zirconia frameworks were randomly distributed according to the veneering materials and techniques into three groups, each containing 16 samples: group LV (layering technique/Vintage ZR), group LZ (layering technique/ZIROX) and group PP (CAD/CAM and press-over techniques/PressXZr). Half of each group was artificially aged through dynamic loading and thermocycling to simulate 5 years of clinical service. Afterwards, all specimens were tested for fracture resistance using compressive load. An analysis of variance (anova) was used to assess the effect of veneering ceramic and artificial ageing on fracture resistance (P veneered with the layering technique (P veneered with the CAD/CAM and press-over techniques. All tested systems have the potential to withstand occlusal forces applied in the posterior region. The combination of the CAD/CAM and press-over techniques for the veneering process improved the overall stability after artificial ageing, relative to the layering technique. © 2012 Blackwell Publishing Ltd.

  6. Clinical approach to anterior adhesive restorations using resin composite veneers.

    Science.gov (United States)

    Mangani, Francesco; Cerutti, Antonio; Putignano, Angelo; Bollero, Raffaele; Madini, Lorenzo

    2007-01-01

    Scientific progress in adhesive dentistry has led to more conservative techniques, both direct and indirect, to solve esthetic problems in anterior teeth. This article will discuss only indirect techniques, which are clearly superior in complex cases in which it will be difficult to recreate harmonious tooth shape and color. After reviewing the literature and highlighting the properties of this technique, the indications and benefits compared to the direct technique will be assessed. This is followed by a step-by-step description of operative procedures, from treatment planning to relining and polishing of the cemented adhesive restoration. The long-term success of veneers depends mainly on the tooth preparation, which should be confined to enamel, involve proximal contact areas, maintain the cervical enamel margin, and incorporate the incisal edge to increase veneer resistance and enable correct placement. Although no clinical follow-up similar to that of ceramic materials is available, the latest-generation resin composites offer interesting features. They can withstand mechanical stress, have excellent esthetic properties, and, most importantly, can be repaired intraorally without impairing their physicochemical and mechanical properties.

  7. Treating a young adult with bonded porcelain veneers.

    Science.gov (United States)

    Roberts, Matt; Shull, G Franklin

    2011-04-01

    Esthetic dental treatment for young adults can be challenging. Practitioners often use direct composite bonding in children and teenagers, and often it serves them for many years. However, direct composite bonding has its limitations (such as staining and chipping), and bonded porcelain often is needed. The authors describe an 18-year-old woman who sought esthetic dental treatment. After her dentist discussed treatment options with her, she opted to receive bonded porcelain veneers. The dentist chose a lithium disilicate material on the basis of its strength and esthetic properties. Although the first set of veneers matched the patient's natural teeth well, they did not satisfy her objective of eliminating the white mottling that existed on her natural teeth. Therefore, the dental technician prepared a second set of restorations by cutting back the facial incisal areas slightly in wax to allow creation of incisal effects and by pressing them with a brighter ingot. Collaboration between the dentist and dental technician is essential to achieving treatment success. Likewise, it is important to secure the patient's input during the process, as he or she often has ideas regarding his or her smile that are different from those of the dental team.

  8. Cervical and Incisal Marginal Discrepancy in Ceramic Laminate Veneering Materials: A SEM Analysis.

    Science.gov (United States)

    Ranganathan, Hemalatha; Ganapathy, Dhanraj M; Jain, Ashish R

    2017-01-01

    Marginal discrepancy influenced by the choice of processing material used for the ceramic laminate veneers needs to be explored further for better clinical application. This study aimed to evaluate the amount of cervical and incisal marginal discrepancy associated with different ceramic laminate veneering materials. This was an experimental, single-blinded, in vitro trial. Ten central incisors were prepared for laminate veneers with 2 mm uniform reduction and heavy chamfer finish line. Ceramic laminate veneers fabricated over the prepared teeth using four different processing materials were categorized into four groups as Group I - aluminous porcelain veneers, Group II - lithium disilicate ceramic veneers, Group III - lithium disilicate-leucite-based veneers, Group IV - zirconia-based ceramic veneers. The cervical and incisal marginal discrepancy was measured using a scanning electron microscope. ANOVA and post hoc Tukey honest significant difference (HSD) tests were used for statistical analysis. The cervical and incisal marginal discrepancy for four groups was Group I - 114.6 ± 4.3 μm, 132.5 ± 6.5 μm, Group II - 86.1 ± 6.3 μm, 105.4 ± 5.3 μm, Group III - 71.4 ± 4.4 μm, 91.3 ± 4.7 μm, and Group IV - 123.1 ± 4.1 μm, 142.0 ± 5.4 μm. ANOVA and post hoc Tukey HSD tests observed a statistically significant difference between the four test specimens with regard to cervical marginal discrepancy. The cervical and incisal marginal discrepancy scored F = 243.408, P veneers fabricated using leucite reinforced lithium disilicate exhibited the least marginal discrepancy followed by lithium disilicate ceramic, aluminous porcelain, and zirconia-based ceramics. The marginal discrepancy was more in the incisal region than in the cervical region in all the groups.

  9. Retrospective study of extensive heat-pressed ceramic veneers after 36 months.

    Science.gov (United States)

    Rinke, Sven; Lange, Katharina; Ziebolz, Dirk

    2013-02-01

    The clinical performance of ceramic veneers is influenced by various clinical and material-related factors. Retrospective evaluation of extensive anterior ceramic veneers in the upper and lower jaw 36 months after placement in a private practice. Thirty-seven patients (21 female, 16 male) were restored with adhesively luted extensive ceramic veneers made from a heat-pressed ceramic (Cergo, DeguDent, Hanau, Germany). One dentist restored a total of 130 teeth (maxilla N = 76, mandible N = 54). Adhesive cementation was performed with an etch-and-rinse adhesive (Optibond FL, Kerr Hawe, Karlsruhe, Germany) and a dual-curing composite cement. After 36 months, the survival rate (in situ criteria) according to Kaplan-Meier was 95.1% (95% confidence interval [CI]: 0.88; 1). Reasons for failure were four ceramic fractures and one biological failure in five restored teeth. Of the restorations, 92.8% (95% CI: 0.86;1) were in service without any clinical intervention and rated successful after 36 months. Interventions were necessary in five cases (three recementations, two endodontic treatments). Clinical performance was not influenced by the veneer position (maxillar/mandibular, survival p = 0.3/success p = 0.4). Veneers with more than 50% of exposed dentin demonstrated a significantly increased risk (hazard ratio 10.6, p = 0.026) for a clinical intervention (recementation, endodontic treatment), whereas no effect on the survival rate could be detected (p = 0.17). After 36 months of clinical service, extensive veneer restorations made of a pressable ceramic showed a comparable survival and success rate in the upper and lower jaw. Large areas of exposed dentin (>50%) were associated with lower success rates. Mandibular ceramic veneers made using a heat-pressed ceramic offer the same clinical reliability as do veneers on anterior maxillary teeth. Dentin exposure significantly affects the clinical performance of heat-pressed ceramic veneers. © 2012 Wiley Periodicals, Inc.

  10. Internal adaptation, marginal accuracy and microleakage of a pressable versus a machinable ceramic laminate veneers.

    Science.gov (United States)

    Aboushelib, Moustafa Nabil; Elmahy, Waleed AbdelMeguid; Ghazy, Mohammed Hamed

    2012-08-01

    The aim of this study was to evaluate the internal adaptation and marginal properties of ceramic laminate veneers fabricated using pressable and machinable CAD/CAM techniques. 40 ceramic laminate veneers were fabricated by either milling ceramic blocks using a CAD/CAM system (group 1 n=20) or press-on veneering using lost wax technique (group 2 n=20). The veneers were acid etched using hydrofluoric acid, silanated, and cemented on their corresponding prepared teeth. All specimens were stored under water (37 °C) for 60 days, then received thermocycling (15,000 cycles between 5 and 55 °C and dwell time of 90 s) followed by cyclic loading (100,000 cycles between 50 and 100 N) before immersion in basic fuchsine dye for 24 h. Half of the specimens in each group were sectioned in labio-lingual direction and the rest were horizontally sectioned using precision cutting machine (n=10). Dye penetration, internal cement film thickness, and vertical and horizontal marginal gaps at the incisal and cervical regions were measured (α=0.05). Pressable ceramic veneers demonstrated significantly lower (F=8.916, Pveneers. The inferior marginal properties of machinable ceramic veneers were associated with significantly higher microleakage values. Pressable ceramic laminate veneers produced higher marginal adaptation, homogenous and thinner cement film thickness, and improved resistance to microleakage compared to machinable ceramic veneers. The manufacturing process influences internal and marginal fit of ceramic veneers. Therefore, dentist and laboratory technicians should choose a manufacturing process with careful consideration. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Effects of Luting Composites on the Resultant Colors of Ceramic Veneers to Intended Shade Tab.

    Science.gov (United States)

    Li, Qing

    2017-01-20

    To investigate the color differences of ceramic veneers and the intended shade tab, and evaluate the effects of luting composites on the resultant colors of ceramic veneers. Pressable leucite-reinforced feldspathic ceramic discs (IPS e.max), with nominal shade A3, were fabricated with thicknesses of 1.0 mm, 0.7 mm, and 0.5 mm (n = 10/ thickness). The ceramic specimens were cemented onto a composite background (shade Dentin) using a veneer adhesive system with five colors of luting composites (RelyX). The colors of the veneer (veneer/luting/background complexes) and corresponding shade tab (A3, Vitapan) were measured using a spectrophotometer, and subsequently converted to CIE L*a*b* values. Color differences (△E) between each complex and the shade tab were calculated and analyzed with two-way ANOVA. Tukey's multiple comparisons were used to evaluate the effects of luting composites on the △E values. The means of color differences between ceramic veneers and intended shade tab were 2.50 ± 0.38, 3.17 ± 0.48, and 3.84 ± 0.63 for the 1.0 mm, 0.7 mm, and 0.5 mm thicknesses, respectively. △E values were significantly affected by the veneer thickness and the luting composite color (p veneers to the intended shade tab was not achieved in the 0.7 mm and 0.5 mm veneer thicknesses, whichever colors of the luting composites were used. © 2017 by the American College of Prosthodontists.

  12. [In vitro study on shear bond strength of veneering ceramics to zirconia].

    Science.gov (United States)

    Hu, Xiaoping; Zhu, Hongshui; Zeng, Liwei

    2012-12-01

    To investigate the shear bond strength between veneering ceramic and zirconia core in different all-ceramic systems. Twenty disk-shaped specimens with 8 mm in diameter and 3 mm in height for each zirconia system (Lava, Cercon, IPS e.max ZirCAD, Procera) were fabricated respectively and divided into four groups: Lava group, Cercon group, IPS e.max ZirCAD group, Procera group. For each group, 10 specimens were sintered with 1 mm corresponding veneering ceramic, while the other were sintered with 2 mm corresponding veneering ceramic respectively. The shear bond strength and fracture mode of specimens were observed and determined. The values of shear bond strength for Lava, Cercon, IPS e.max ZirCAD and Procera were (13.82 +/- 3.71), (13.24 +/- 2.09), (6.37 +/- 4.15), (5.19 +/- 5.31) MPa in the group of 1 mm thicked veneering ceramics, respectively, while the values in the group of 2mm thicked veneering ceramics were (38.77 +/- 1.69), (21.67 +/- 3.34), (12.70 +/- 4.24), (9.94 +/- 6.67) MPa. The values of Lava and Cercon groups were significantly higher than that of IPS e.max ZirCAD and Procera groups (P veneering ceramic group were significantly higher than that in 1 mm thicked groups (P veneering ceramics were observed in the fracture modes of most specimens. The shear bond strength of veneering ceramic to the zirconia framework are different from the zirconia system we chose, and the thickness of veneering ceramic has a great impact on its shear bond strength.

  13. Adhesion characteristics of phenol formaldehyde pre-preg oil palm stem veneers

    OpenAIRE

    Nor Hafizah Ab. Wahab; Paridah Md. Tahir; Yeoh Beng Hoong; Zaidon Ashaari; Nor Yuziah Mohd Yunus; Mohd Khairun Anwar Uyup; Mohd Hamami Shahri

    2012-01-01

    The purpose of this study was to evaluate the adhesion properties of phenol formaldehyde-prepreg oil palm veneers that have potential for plywood manufacture. Phenol formaldehyde (PF) resin of three different molecular weights (i.e. 600 (low), 2,000 (medium), and 5,000 (commercial)) were used to pre-treat the veneers. The veneers were soaked in each type of PF resin for 20 seconds, pressed between two rollers, and pre-cured in an oven maintained at 103 ± 2 °C for 24 hours. The volume percent ...

  14. Properties of a Laminated Wood Composite Produced with Thermomechanically Treated Veneers

    OpenAIRE

    Arruda,Larissa M; Del Menezzi,Cláudio H. S

    2016-01-01

    The paper aimed at evaluating the properties of plywood made from thermomechanically treated wood veneers. Veneers from Amescla (Trattinnickia burseraefolia) wood were treated in a hydraulic press with electric resistance heating. Two temperature levels were applied, 140°C and 180°C, for 1 and 2 minutes with 2.7 N/mm2 of pressure. A total of 30 plywood boards were produced, including six boards produced from untreated veneers. The results showed that the thermomechanical treatment did not hav...

  15. Fracture and Fatigue Resistance of Cemented versus Fused CAD-on Veneers over Customized Zirconia Implant Abutments.

    Science.gov (United States)

    Nossair, Shereen Ahmed; Aboushelib, Moustafa N; Morsi, Tarek Salah

    2015-01-05

    To evaluate the fracture mechanics of cemented versus fused CAD-on veneers on customized zirconia implant abutments. Forty-five identical customized CAD/CAM zirconia implant abutments (0.5 mm thick) were prepared and seated on short titanium implant abutments (Ti base). A second scan was made to fabricate 45 CAD-on veneers (IPS Empress CAD, A2). Fifteen CAD-on veneers were cemented on the zirconia abutments (Panavia F2.0). Another 15 were fused to the zirconia abutments using low-fusing glass, while manually layered veneers served as control (n = 15). The restorations were subjected to artificial aging (3.2 million cycles between 5 and 10 kg in a water bath at 37°C) before being axially loaded to failure. Fractured specimens were examined using scanning electron microscopy to detect fracture origin, location, and size of critical crack. Stress at failure was calculated using fractography principles (alpha = 0.05). Cemented CAD-on restorations demonstrated significantly higher (F = 72, p veneers failed due to radial cracks originating from the veneer/resin interface. Branching of the critical crack was observed in the bulk of the veneer. Fused CAD-on veneers demonstrated cohesive fracture originating at the thickest part of the veneer ceramic, while manually layered veneers failed due to interfacial fracture at the zirconia/veneer interface. Within the limitations of this study, cemented CAD-on veneers on customized zirconia implant abutments demonstrated higher fracture than fused and manually layered veneers. © 2014 by the American College of Prosthodontists.

  16. In vitro fracture resistance of composite-resin-veneered zirconia crowns

    National Research Council Canada - National Science Library

    Chaimongkon Peampring; Juthatip Aksornmuang; Sasiwimol Sanohkan

    2017-01-01

    Aims: The aim of this study is to investigate the fracture load to failure and damage mode of the composite resin-veneered zirconia crowns preparing with two different zirconia surface treatments compared...

  17. Study on Flexural Creep Parameters of Overlayed Particleboard by Natural and Melaminated Veneers

    Directory of Open Access Journals (Sweden)

    Abdollah Najafi

    2012-06-01

    Full Text Available In this study, effects of natural and artificial veneer on flexural creep behavior of particleboard was investigated. Particleboard panels were prepared from Pars Neopan industries with 660 kg/m3 density and then overlaid by natural and melamine veneers. Their creep behavior was compared to control particleboard. For evaluating maximum bending load in static flexural test, specimens were cut from panels according to ASTM D 1037 with dimensions of 370×50×16 mm. Then, The flexural creep tests at 20% and 40% of failure bending load was applied to test specimens. Results of flexural tests indicated that the MOR and MOE values of veneered particleboard were highest. Results of creep showed that levels of stresses are effective on all creep parameters, but showed less effect on relative creep. Also, creep parameters less effective on specimens overlaid by natural veneer.

  18. The influences of accelerated aging on mechanical properties of veneering ceramics used for zirconia restorations.

    Science.gov (United States)

    Luo, Huinan; Tang, Xuehua; Dong, Zhen; Tang, Hui; Nakamura, Takashi; Yatani, Hirofumi

    2016-01-01

    This study evaluated the influences of accelerated aging on the mechanical properties of veneering ceramics used for zirconia frameworks. Five different veneering ceramics for zirconia frameworks were used. Twenty specimens were fabricated for each veneering ceramic. All specimens were divided into two groups. One was subjected to accelerated aging and the other was used as a control. Accelerated aging was performed in distilled water for 5 h at 200ºC and 2 atm. The density, open porosity, surface roughness, three-point flexural strength, and Vickers hardness were measured. The results showed that the density, open porosity, and surface roughness of all examined veneering ceramics were changed by the accelerated aging process. Accelerated aging was also found to have a positive effect on strength and a negative effect on the hardness.

  19. Effect of Er:YAG laser on debonding strength of laminate veneers.

    Science.gov (United States)

    Iseri, Ufuk; Oztoprak, Mehmet Oguz; Ozkurt, Zeynep; Kazazoglu, Ender; Arun, Tulin

    2014-01-01

    The purpose of this study was to evaluate the debonding strength of laminate veneers after using erbium-doped: yttrium aluminium garnet (Er:YAG) laser. A total of 60 bovine mandibular incisor teeth were divided into two groups (n = 30). Cylindrical specimens (0.7 mm × 5 mm) were fabricated from Empress II ceramic. Then, they were cemented to incisors using dual-cured resin cement (Variolink II). In the first group, no laser application was performed. The Er:YAG laser was applied on each laminate veneer at the test group for 9 s by using the scanning method. Shear force to remove the laminate veneers were applied with universal testing machine at a crosshead speed of 1 mm/min. Results of this study exhibited significant differences between the control (27.28 ± 2.24 MPa) and test group (3.44 ± 0.69 MPa) (P veneers.

  20. No-Prep Rehabilitation of Fractured Maxillary Incisors with Partial Veneers.

    Science.gov (United States)

    Vadini, Mirco; D'Amario, Maurizio; De Angelis, Francesco; Falco, Antonello; D'Arcangelo, Camillo

    2016-11-12

    Therapeutic options for dental trauma depend on the injuries' features. For patients with uncomplicated tooth fractures, adhesive materials and composite partial veneers may be a therapeutic solution that completely preserves healthy tooth structure. An ultra-conservative approach, using indirect composite partial veneers to restore fractured anterior teeth is described in these case reports. Despite the position of the finish line in the middle of the clinical crown, this solution offers functional and esthetic outcomes using an indirect composite technique, and appears to be a suitable alternative to direct composite restorations or less conservative indirect veneers. Indirect composite partial veneers present considerable advantages, such as ultra-minimally invasive properties and excellent esthetic appearances. The success seems to depend on a combination of sound adhesive principles, adequate design of the restoration, laboratory experience, and cementation techniques. (J Esthet Restor Dent 28:351-358, 2016). © 2016 Wiley Periodicals, Inc.

  1. Use of Feldspathic Porcelain Veneers to Improve Smile Harmony: A 3-Year Follow-up Report.

    Science.gov (United States)

    Federizzi, Leonardo; Gomes, Érica Alves; Báratro, Samantha Schaffer Pugilato; Baratto-Filho, Flares; Bacchi, Ataís; Spazzin, Aloísio Oro

    2016-01-01

    This case report describes an esthetic treatment to improve the shape and alignment of the anterior teeth, reestablishing smile harmony, using feldspathic porcelain veneers. Results of clinical follow up after 36 months are also presented. The advantages, disadvantages and limitations of the technique are detailed with reference to the relevant literature. This suggests that the success of treatment depends on adequate conditions of bonding between the veneers and the tooth complex, which involves parameters such as the strength and durability of the bond interface. Therefore, the clinical success of feldspathic porcelain veneers depends on the accurate selection of cases and correct execution of clinical and laboratory procedures. The rehabilitation involved from first right premolar to the left with feldspathic porcelain veneers made on refractory dies. After the 3-year follow up, excellent clinical results and patient satisfaction were achieved.

  2. Direct anterior composite veneers in vital and non-vital teeth: A retrospective clinical evaluation

    NARCIS (Netherlands)

    Coelho-de-Souza, F.H.; Goncalves, D.S.; Sales, M.P.; Erhardt, M.C.; Correa, M.B.; Opdam, N.J.M.; Demarco, F.F.

    2015-01-01

    OBJECTIVES: This retrospective, longitudinal clinical study investigated the performance of direct veneers using different composites (microfilledxuniversal) in vital or non-vital anterior teeth. METHODS: Records from 86 patients were retrieved from a Dental School clinic, comprising 196 direct

  3. Minimally invasive lithium disilicate ceramic veneers fabricated using chairside CAD/CAM: a clinical report.

    Science.gov (United States)

    Schmitter, M; Seydler B, B

    2012-02-01

    This clinical report describes the use of modern CAD/CAM technology combined with a conventional impression technique to treat a malformed tooth with ceramic veneer in a single appointment. A thin veneer (0.4 mm) made of lithium disilicate ceramic was used to correct the shape of the malformed tooth with a minimally invasive preparation using a chairside CAD/CAM system. Thus the treatment can be performed during one appointment. To facilitate the CAD/CAM process and fabrication of the veneer, a scanable model fabricated on a modified gypsum definitive cast was used. The malformed tooth was corrected on the cast by use of a composite resin and an impression was then made. This trimmed impression was used intraorally during the scanning process to facilitate fabrication of the veneer. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  4. Simultaneous VOC reduction and moisture leveling in veneer with microwave energy during early stage of drying

    Energy Technology Data Exchange (ETDEWEB)

    Abedi, Jalal [Department of Chemical & amp; Petroleum Engineering, niversity of Calgary, 2500 University Dr., NW, Calgary, Alberta (Canada T2N N4); Banerjee, Sujit [School of Chemical & amp; Biomedical Engineering, eorgia Institute of Technology, Atlanta, GA (United States)

    2007-01-15

    The main objective of this investigation was to quantitatively determine the ability of a microwave energy to level the moisture content of veneers using infrared thermography system. It is believed that the proper use of RF drying may reduce the emissions of volatile organic compounds (VOCs) from the sheets of plywood veneer as they are dried. Currently, the RF units are used after the drying, for the purpose of distributing the moisture that may be left in the pieces of veneer in some places (wet spot). Microwaving green veneer briefly under low headspace conditions evens out the moisture distribution for both softwood and hardwood, with the effect being more pronounced for softwood. The drying rate is unaffected. If successful, this could lead to significant cost savings for plywood producers. (author)

  5. Effect of Er:YAG laser on debonding strength of laminate veneers

    Science.gov (United States)

    Iseri, Ufuk; Oztoprak, Mehmet Oguz; Ozkurt, Zeynep; Kazazoglu, Ender; Arun, Tulin

    2014-01-01

    Objective: The purpose of this study was to evaluate the debonding strength of laminate veneers after using erbium-doped: yttrium aluminium garnet (Er:YAG) laser. Materials and Methods: A total of 60 bovine mandibular incisor teeth were divided into two groups (n = 30). Cylindrical specimens (0.7 mm × 5 mm) were fabricated from Empress II ceramic. Then, they were cemented to incisors using dual-cured resin cement (Variolink II). In the first group, no laser application was performed. The Er:YAG laser was applied on each laminate veneer at the test group for 9 s by using the scanning method. Shear force to remove the laminate veneers were applied with universal testing machine at a crosshead speed of 1 mm/min. Results: Results of this study exhibited significant differences between the control (27.28 ± 2.24 MPa) and test group (3.44 ± 0.69 MPa) (P veneers. PMID:24966747

  6. The effect of hydrofluoric acid surface treatment and bond strength of a zirconia veneering ceramic.

    Science.gov (United States)

    Chaiyabutr, Yada; McGowan, Steve; Phillips, Keith M; Kois, John C; Giordano, Russell A

    2008-09-01

    Clinicians are frequently faced with a challenge in selecting materials for adjacent restorations, particularly when one tooth requires a zirconia-based restoration and the next requires a veneer. While it may be desirable to use the same veneering ceramic on adjacent teeth, little information is available about the use of veneering ceramics over a zirconia-based material. The purpose of this study was threefold: (1) to study the influence of hydrofluoric acid-etched treatment on the surface topography of the zirconia veneering ceramic, (2) to test the bond strength of zirconia veneering ceramic to enamel, and (3) to evaluate the flexural strength and the elemental composition of ceramic veneers. Three zirconia veneering ceramics (Cerabien CZR (CZ), Lava Ceram (L), and Zirox (Z)) and 4 conventional veneering ceramics (Creation (C), IPS d.Sign (D), Noritake EX-3 (E), and Reflex (R)) were evaluated. Twenty ceramic bars of each material were fabricated and surface treated with hydrofluoric acid according to the manufacturer's recommendations. Ten specimens from each group of materials were examined with a profilometer, and a sample of this group was selected for quantitative evaluation using a scanning electron microscope (SEM). Another 10 acid-etched specimens from each group of materials were treated with silane prior to cementing with resin cement (Variolink II) on enamel surfaces. These luted specimens were loaded to failure in a universal testing machine in the shear mode with a crosshead speed of 0.05 mm/min. The data were analyzed with a 1-way ANOVA, followed by Tukey's HSD test (alpha=.05). An additional 10 ceramic bars from each material group were fabricated to evaluate flexural strength and elemental composition. The flexural strength (MPa) of each specimen was determined by using a 4-point-1/4-point flexure test. A Weibull statistic tested the reliability of the strength data; pairwise differences among the 7 groups were evaluated at confidence intervals

  7. The effect of light curing units, curing time, and veneering materials on resin cement microhardness

    Directory of Open Access Journals (Sweden)

    Nurcan Ozakar Ilday

    2013-06-01

    Conclusion: Light-curing units, curing time, and veneering materials are important factors for achieving adequate dual cure resin composite microhardness. High-intensity light and longer curing times resulted in the highest microhardness values.

  8. Surface roughness of composite resin veneer after application of herbal and non-herbal toothpaste

    Science.gov (United States)

    Nuraini, S.; Herda, E.; Irawan, B.

    2017-08-01

    The aim of this study was to find out the surface roughness of composite resin veneer after brushing. In this study, 24 specimens of composite resin veneer are divided into three subgroups: brushed without toothpaste, brushed with non-herbal toothpaste, and brushed with herbal toothpaste. Brushing was performed for one set of 5,000 strokes and continued for a second set of 5,000 strokes. Roughness of composite resin veneer was determined using a Surface Roughness Tester. The results were statistically analyzed using Kruskal-Wallis nonparametric test and Post Hoc Mann-Whitney. The results indicate that the highest difference among the Ra values occurred within the subgroup that was brushed with the herbal toothpaste. In conclusion, the herbal toothpaste produced a rougher surface on composite resin veneer compared to non-herbal toothpaste.

  9. Comparison of edge chipping resistance of PFM and veneered zirconia specimens

    Science.gov (United States)

    Quinn, Janet B.; Sundar, Veeraraghavan; Parry, Edward E.; Quinn, George D.

    2011-01-01

    Objectives To investigate the chipping resistance of veneered zirconia specimens and compare it to the chipping resistance of porcelain fused to metal (PFM) specimens. Methods Veneered zirconia and PFM bar specimens were prepared in clinically relevant thicknesses. The specimen edges were chipped with different magnitude forces, producing chips of various sizes. The range of sizes included small chips that did not penetrate all the way through the veneers to the substrates, and also chips that were very large and reached the zirconia or metal substrates. The relationship between force magnitude and chip size (edge distance) was graphed. The resulting curves were compared for the veneered zirconia and PFM specimens. Knoop hardness vs. force graphs for the veneers and substrates were also obtained. Results The zirconia and PFM veneer chipping data followed a power law (coefficient of determination, R2 > 0.93) as expected from the literature. The curves overlapped within the combined data scatter, indicating similar resistance to chipping. The chips made in both types of specimens detached and did not penetrate into the substrate when they reached the veneer/substrate intersections. The hardness–load curves for the veneers and substrates all exhibited an indentation size effect (ISE) at low loads. The Knoop hardness values with uncertainties of ±one standard deviation at 4 N loads for the metal, zirconia, and the metal and zirconia veneers are: (2.02 ± 0.08, 12.01 ± 0.39, 4.24 ± 0.16 and 4.36 ± 0.02 GPa), respectively, with no statistically significant difference between the veneers (Tukey pairwise comparison at 0.95 family confidence). Significance This work indicates that a similar resistance to chipping might be expected for veneered zirconia and PFM restorations, in spite of the large difference in substrate hardness. Differences in susceptibility to chip spalling were not detected, but the chips in both specimen types detached off the sides in a similar

  10. Shear bond strength between veneering ceramics and ceria-stabilized zirconia/alumina.

    Science.gov (United States)

    Fischer, Jens; Stawarczyk, Bogna; Sailer, Irena; Hämmerle, Christoph H F

    2010-05-01

    Ceria-stabilized tetragonal ZrO(2)/Al(2)O(3) nanocomposite (Ce-TZP/A) offers superior properties compared to yttria-stabilized zirconia (Y-TZP). However, the bond quality to veneering ceramics has not been investigated. The purpose of this study was to evaluate the bond strength of different veneering ceramics to Ce-TZP/A. Cubes of Ce-TZP/A (NANOZR) (edge length, 10 mm) were layered with veneering ceramics (5 mm in thickness) with or without application of a liner and sheared at the interface. The effect of different surface treatments (polished with 3-mum diamond paste or airborne-particle abraded) was evaluated with 1 veneering ceramic (Cerabien ZR). Shear bond strength of 5 additional veneering ceramics (IPS e.max, Initial ZR, Triceram, Vintage ZR, or VITA VM 9) to polished Ce-TZP/A was measured (n=10). Polished Y-TZP (Hint-ELs ZrO(2) HIP) veneered with 2 ceramics (Cerabien ZR, Vintage ZR) served as the control. Mean shear bond strength values (MPa) were calculated. The means were statistically analyzed with 2-way ANOVA for the effect of surface treatment and liner, 2-way ANOVA for the effect of different veneering ceramic brands and liner, and 3-way ANOVA for the effect of substrate, veneering ceramic brands, and liner, as well as 1-way ANOVA for the differences between the veneering ceramics. A post hoc Scheffé test was used (alpha=.05). The effects of surface treatment (P=.007) or application of liner (Pveneering ceramics showed bond strength values with means ranging between 14.2 +/-1.7 MPa (IPS e.max with liner) and 27.5 +/-4.2 MPa (VITA VM 9). A significant difference was found between the results of shear bond tests with Y-TZP and Ce-TZP/A (P=.022). The application of a liner on Y-TZP had no significant effect. Airborne-particle abrasion is not necessary to enhance the shear bond strength of the evaluated veneering ceramics to Ce-TZP/A. Liners impair the shear bond strength of veneering ceramics to Ce-TZP/A.

  11. Case report: aesthetic management of a localised periodontal defect with a gingival veneer prosthesis.

    Science.gov (United States)

    Ellis, S G; Sharma, P; Harris, I R

    2000-03-01

    Traditionally acrylic resin gingival veneer prostheses have been used to disguise aesthetic deficiencies of maxillary anterior teeth following successful periodontal therapy and have been retained by engaging horizontal undercuts distal to the canine teeth. They are, however, versatile prostheses with uses in fixed and removable prosthodontics and therapeutic treatment of gingival conditions. In the case presented a small acrylic resin gingival veneer prosthesis retained by a resilient lining material was used to manage a localised periodontal defect of the mandibular central incisor teeth.

  12. Load bearing capacity, fracture mode, and wear performance of digitally veneered full-ceramic single crowns.

    Science.gov (United States)

    Schubert, Oliver; Nold, Ephraim; Obermeier, Matthias; Erdelt, Kurt; Stimmelmayr, Michael; Beuer, Florian

    Computer-aided technologies can help to minimize clinical complications of zirconia-based restorations such as veneering porcelain fractures. The aim of this study was to evaluate different veneering approaches for zirconia single crowns regarding contact wear, fracture strength, and failure mode. Six different types of computer-aided design (CAD) crowns were manufactured and conventionally cemented on 10 metal dies each: three groups with a zirconia framework and a CAD/CAM-fabricated veneering cap ("digital veneering system": DVS, CAD-on, Infix CAD), zirconia-based crowns with pressed veneering caps (Infix Press), zirconia framework containing the dentin layer with only the incisal enamel material added (dentin-core), and conventional substructure with powder buildup veneering porcelain (layering technique). All specimens were submitted to artificial aging (120,000 mechanical cycles, 50 N load, 0.7-mm sliding movement, 320 thermocycles). After contact wear was measured with a laser scanning system, fracture resistance and failure mode were examined using a universal testing machine and a scanning electron microscope. Statistical analysis was performed at a significance level of 5%. No statistical difference was revealed regarding the contact wear of the restorations (P = 0.171; ANOVA). No significant difference was found regarding the fracture resistance of the crowns (P = 0.112; ANOVA). Failure analysis revealed three different failure patterns: cohesive veneering fracture, adhesive delamination, and total fracture, with a characteristic distribution between the groups. All tested specimens survived artificial aging and exhibited clinically acceptable wear resistance and fracture resistance. Digital veneering techniques offer a promising, time- and cost-effective manufacturing process for all-ceramic restorations and may usefully complement the digital workflow.

  13. Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

    Science.gov (United States)

    Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

    2010-01-01

    This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

  14. Color management of porcelain veneers: influence of dentin and resin cement colors.

    Science.gov (United States)

    Dozic, Alma; Tsagkari, Maria; Khashayar, Ghazal; Aboushelib, Moustafa

    2010-01-01

    Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers. A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and DE values were calculated against the preselected target color (A1). DE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured DE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match. Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match.

  15. [Color stability of ceromer veneers/resin cements after accelerated ageing].

    Science.gov (United States)

    Wang, Likai; Liu, Yanan; Zheng, Yan; Li, Pingping; Shi, Lianshui

    2014-02-01

    To investigate the color stability of ceromer veneers/resin cements after accelerated ageing, and to provide the reference for clinical application and choice. Fifteen groups of ceromer veneers/resin cements samples, five samples in each group, were prepared as experimental groups.In the fifteen groups, ceromer veneers in three thickness (1.00, 0.75, 0.50 mm) and resin cements of five shades(A1,A3, B 0.5, WO, TR), were matched through permutation and combination. Three groups of ceromer veneers with different thickness (1.00, 0.75, 0.50 mm) were used as control groups. All samples were put into xenon lamp ageing instrument to accelerate ageing.Spectrophotometer were used to measure the lightness(L(*)), red green color(a(*)) and blue yellow color(b(*)) of samples before and after accelerated ageing process, and the change of lightness (ΔL) , red green color (Δa) , blue yellow color (Δb) and color variation(ΔE) were calculated.We investigated the effect of thickness of ceromer veneer and color of resin cement on color variation by using analysis of variance. The thickness factor and color factor showed significant effect on ΔE values, and they have interaction (P veneer and the color of resin cement could both affect the color stability of ceromer veneers/resin cements. The changes of lightness and color in ceromer veneers/resin cements were considered clinically acceptable after accelerated ageing.

  16. Clinical and scanning electron microscopic assessments of porcelain and ceromer resin veneers.

    OpenAIRE

    Dhawan P; Prakash H; Shah N

    2003-01-01

    PURPOSE: Recently available Ceromer resin materials are promising for fabrication of esthetic anterior laminates and provices an alternative, cost effective treament modality to porcelain laminates for discolored anterior anterior teeth. It was proposed to study the esthetic quality and surface finish of veneers fbricated from ceromer resin and compare it with the standard porcelain veneers, both clinically as well as by scanning electron microscope (SEM) at baseline and at 12 months. If foun...

  17. Severe tetracycline dental discoloration: Restoration with conventional feldspathic ceramic veneers. A clinical report.

    Science.gov (United States)

    Faus-Matoses, Vicente; Faus-Matoses, Ignacio; Ruiz-Bell, Esther; Faus-Llácer, Vicente J

    2017-11-01

    The treatment of severe tetracycline discoloration is a challenge for the dentist. There are several treatment options and one of the most effective is the use of feldspathic veneers. The aim of this clinical case was to carry out the replacement with conventional feldspathic ceramic veneers on a patient with highly stained teeth (grade IV tetracycline) by a minimally invasive approach. Clinical examination revealed gingival retraction, color change of the veneers, ceramic cracked of 1.1 and 1.3 and incisal wear in lower anterior teeth. The decision was to retreat with feldspathic ceramic veneers from 1.6 to 2.6. Premolars and first molars were included because its dark color intensifies the width buccal corridors. Also, the restoration with veneers from 3.3 to 4.3 was considered. Firstly, the veneers were removed and the color was selected by the Vitapan 3D Master guide (Vita Zahnfabrick, Bad Säckingen, Germany). Mock-up was made to evaluate aesthetic, phonetic and functional parameters. Then, teeth were prepared through the mock-up in order to reduce the minimal amount of dental tissue possible. Opaque dentine mass of microhybrid composite (Esthet-X A2O, Dentsply Sirona, Konstanz, Germany) was placed to mask the most intense stains. The definitive impressions were taken with silicone (Aquasil Ultra XLV, Dentsply Sirona, Konstanz, Germany) were taken to fabricate conventional feldsphatic ceramic veneers (Noritake kisai Co, Ltd. Japan) by the parallel stratification masking technique. For cementing, an opaque cement was selected from the try-in tests (Calibra, Dentsply Sirona, Konstanz, Germany) and the composite was silicatized with an air-abrasion device. A favorable and minimally invasive result was achieved to treat grade IV tetracycline stains, surpassing the patient's aesthetic expectations and functional needs. Key words:Porcelain veneer, tetracycline teeth, minimally invasive, masking, opaque composite.

  18. Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

    OpenAIRE

    Alsadon, O.; Patrick, D.; Johnson, A.; Pollington, S.; Wood, D.

    2017-01-01

    The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create ...

  19. Influence of veneer application on fracture behavior of lithium-disilicate-based ceramic crowns.

    Science.gov (United States)

    Zhao, Ke; Pan, Yu; Guess, Petra C; Zhang, Xin-Ping; Swain, Michael V

    2012-06-01

    To assess the influence of veneer application on fracture behavior, namely failure load and failure mode, of standardized lithium-disilicate-based crowns. Forty molar crowns (IPS e.max Press, IvoclarVivadent) were fabricated in full anatomic (without veneer, 1.5-2.0mm at occlusal surface) and bi-layer (the occlusal surface is 0.7 mm of veneer and 0.8-1.3mm core) contour representing two groups. Crown specimens were seated and adhered on composite resin dies. All specimens were loaded with a 6mm diameter steatite sphere over the central fissure to failure. Failure modes and fractographic patterns were analyzed by optical stereo and scanning electron microscopy (SEM). Fracture loads of the two groups were compared by the t-test, while the failure modes were analyzed by Pearson Chi-square test. There was a statistically significant difference in mean fracture load values (N±S.D.) between full anatomic [(2665.4±759.2)N] and veneered crowns [(1431.1±404.3)N] (pveneered specimens predominately showed cohesive veneer and ceramic interface failure (75%); solely cohesive veneer failure (20%); and bulk fracture (5%). Within the limitations of this study, veneer application resulted in significant lower fracture load values compared to full anatomic crowns. Fracture initiated from occlusal fissures near the load application site. A combination of cohesive veneer and ceramic interface failure represents the main failure mode of lithium-disilicate-based bi-layered crowns, whereas full anatomic crowns failed mainly from ceramic bulk fracture at the occlusal fissures. Copyright © 2012 Academy of Dental Materials. All rights reserved.

  20. Ruthenium isotopic evidence for an inner Solar System origin of the late veneer.

    Science.gov (United States)

    Fischer-Gödde, Mario; Kleine, Thorsten

    2017-01-25

    The excess of highly siderophile elements in the Earth's mantle is thought to reflect the addition of primitive meteoritic material after core formation ceased. This 'late veneer' either comprises material remaining in the terrestrial planet region after the main stages of the Earth's accretion, or derives from more distant asteroidal or cometary sources. Distinguishing between these disparate origins is important because a late veneer consisting of carbonaceous chondrite-like asteroids or comets could be the principal source of the Earth's volatiles and water. Until now, however, a 'genetic' link between the late veneer and such volatile-rich materials has not been established or ruled out. Such genetic links can be determined using ruthenium (Ru) isotopes, because the Ru in the Earth's mantle predominantly derives from the late veneer, and because meteorites exhibit Ru isotope variations arising from the heterogeneous distribution of stellar-derived dust. Although Ru isotopic data and the correlation of Ru and molybdenum (Mo) isotope anomalies in meteorites were previously used to argue that the late veneer derives from the same type of inner Solar System material as do Earth's main building blocks, the Ru isotopic composition of carbonaceous chondrites has not been determined sufficiently well to rule them out as a source of the late veneer. Here we show that all chondrites, including carbonaceous chondrites, have Ru isotopic compositions distinct from that of the Earth's mantle. The Ru isotope anomalies increase from enstatite to ordinary to carbonaceous chondrites, demonstrating that material formed at greater heliocentric distance contains larger Ru isotope anomalies. Therefore, these data refute an outer Solar System origin for the late veneer and imply that the late veneer was not the primary source of volatiles and water on the Earth.

  1. Severe tetracycline dental discoloration: Restoration with conventional feldspathic ceramic veneers. A clinical report

    Science.gov (United States)

    Faus-Matoses, Vicente; Faus-Matoses, Ignacio; Ruiz-Bell, Esther

    2017-01-01

    The treatment of severe tetracycline discoloration is a challenge for the dentist. There are several treatment options and one of the most effective is the use of feldspathic veneers. The aim of this clinical case was to carry out the replacement with conventional feldspathic ceramic veneers on a patient with highly stained teeth (grade IV tetracycline) by a minimally invasive approach. Clinical examination revealed gingival retraction, color change of the veneers, ceramic cracked of 1.1 and 1.3 and incisal wear in lower anterior teeth. The decision was to retreat with feldspathic ceramic veneers from 1.6 to 2.6. Premolars and first molars were included because its dark color intensifies the width buccal corridors. Also, the restoration with veneers from 3.3 to 4.3 was considered. Firstly, the veneers were removed and the color was selected by the Vitapan 3D Master guide (Vita Zahnfabrick, Bad Säckingen, Germany). Mock-up was made to evaluate aesthetic, phonetic and functional parameters. Then, teeth were prepared through the mock-up in order to reduce the minimal amount of dental tissue possible. Opaque dentine mass of microhybrid composite (Esthet-X A2O, Dentsply Sirona, Konstanz, Germany) was placed to mask the most intense stains. The definitive impressions were taken with silicone (Aquasil Ultra XLV, Dentsply Sirona, Konstanz, Germany) were taken to fabricate conventional feldsphatic ceramic veneers (Noritake kisai Co, Ltd. Japan) by the parallel stratification masking technique. For cementing, an opaque cement was selected from the try-in tests (Calibra, Dentsply Sirona, Konstanz, Germany) and the composite was silicatized with an air-abrasion device. A favorable and minimally invasive result was achieved to treat grade IV tetracycline stains, surpassing the patient’s aesthetic expectations and functional needs. Key words:Porcelain veneer, tetracycline teeth, minimally invasive, masking, opaque composite. PMID:29302294

  2. Lumber and veneer recovery from intensively managed young-growth Douglas-fir.

    Science.gov (United States)

    Thomas D. Fahey; James M. Cahill; Thomas A. Snellgrove; Linda S. Heath

    1991-01-01

    The objective of the study was to develop models that predict lumber and veneer recovery as a function of young-growth log characteristics. Empirical lumber and veneer recovery data for logs cut from more than 300 young-growth Douglas-fir trees were used in model development. Trees were sampled from 15 stands in western Oregon and Washington and represent a wide range...

  3. Analyzing the effect of ion exchange on flexural strength of cermaco II and colorlogic veneer porcelains

    OpenAIRE

    N. Rashidan; HA. Mahgoli

    1998-01-01

      The major foible of dental ceramics is their brittle nature. Therefore, the producers of these materials have focused on the “strength” issue. A method of increasing strength is ion exchange on porcelain surface which leads to formation of a compressive crust that opposing forces should overcome before developing a crack. In current study, ion exchange in two types of porcelain, Ceramco II which is used in PFM restorations and Colorloic veneer which is used for laminates, veneers, inlays an...

  4. Tribological behaviour of unveneered and veneered lithium disilicate dental material.

    Science.gov (United States)

    Figueiredo-Pina, C G; Patas, N; Canhoto, J; Cláudio, R; Olhero, S M; Serro, A P; Ferro, A C; Guedes, M

    2016-01-01

    The friction and wear behaviour of a lithium disilicate dental ceramic against natural dental enamel is studied, including the effect of the presence of a fluorapatite veneering upon the tribological properties of the material. The tribological behaviour was assessed using reciprocating pin-on-plate test configuration, at pH 3 and pH 7. The surface energy of the plates was determined, as well as the zeta potential of fluorapatite, lithium disilicate and enamel particles in artificial saliva. It was found that the friction and wear behaviour of the tested enamel/plate material tribocouples is less severe in unveneered plates. Initial surface roughness of the plate does not affect wear results. However the topography of the resulting wear track affects the corresponding wear loss: a smoother final wear track is associated with lower wear. The surface topography of the wear track, and thus the tribological performance of the tested materials, is very sensitive to the pH of the sliding solution. This is because the dissolution trend, wettability and surface charge of the used materials are pH dependent. Overall friction and wear are higher under basic pH conditions, especially when plates are veneered. A wear model is proposed that correlates the effect of the described parameters with the observed tribological behaviour at pH 7. Attained results show that fluorapatite coating of lithium disilicate dental crowns affects tooth/crown wear behaviour, resulting in increased wear of both the artificial crown and the opposing natural teeth. Coating should therefore be avoided in occlusal crown surfaces. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Experimental Design on Laminated Veneer Lumber Fiber Composite: Surface Enhancement

    Science.gov (United States)

    Meekum, U.; Mingmongkol, Y.

    2010-06-01

    Thick laminate veneer lumber(LVL) fibre reinforced composites were constructed from the alternated perpendicularly arrayed of peeled rubber woods. Glass woven was laid in between the layers. Native golden teak veneers were used as faces. In house formulae epoxy was employed as wood adhesive. The hand lay-up laminate was cured at 150° C for 45 mins. The cut specimen was post cured at 80° C for at least 5 hours. The 2k factorial design of experimental(DOE) was used to verify the parameters. Three parameters by mean of silane content in epoxy formulation(A), smoke treatment of rubber wood surface(B) and anti-termite application(C) on the wood surface were analysed. Both low and high levels were further subcategorised into 2 sub-levels. Flexural properties were the main respond obtained. ANOVA analysis of the Pareto chart was engaged. The main effect plot was also testified. The results showed that the interaction between silane quantity and termite treatment is negative effect at high level(AC+). Vice versa, the interaction between silane and smoke treatment was positive significant effect at high level(AB+). According to this research work, the optimal setting to improve the surface adhesion and hence flexural properties enhancement were high level of silane quantity, 15% by weight, high level of smoked wood layers, 8 out of 14 layers, and low anti termite applied wood. The further testes also revealed that the LVL composite had superior properties that the solid woods but slightly inferior in flexibility. The screw withdrawn strength of LVL showed the higher figure than solid wood. It is also better resistance to moisture and termite attack than the rubber wood.

  6. In vitro color stability of double-layer veneers after accelerated aging.

    Science.gov (United States)

    Heydecke, G; Zhang, F; Razzoog, M E

    2001-06-01

    Porcelain laminates made from thin alumina shells veneered with feldspathic porcelain could be a promising alternative to conventional veneers. Long-term shade stability is critical for esthetics. This study compared changes in CIE L*a*b* color coordinates of simulated veneers made from aluminum oxide core material veneered with feldspathic porcelain after 300 hours of accelerated photothermal aging (weathering). Fifteen aluminum oxide disks (Procera) were divided into 3 groups. Each of the 5 disks was veneered with All-Ceram porcelain of the Vita shades A1 and B4, respectively. Five disks remained unfinished as controls. The disks were bonded to composite substrates simulating stained teeth. The color of the specimens was measured with a colorimeter. All specimens were subjected to 300 hours of accelerated aging under light exposure and thermocycling. Color measurements were repeated, and the data were statistically evaluated with multiple paired t tests. Color changes in the test groups involved an increase in lightness and a decrease in chroma. The calculated total color differences were not statistically significant compared with a level of 3 DeltaE units. This simulation of double-layer veneers appears to demonstrate acceptable color stability for this type of restoration. Clinical research is necessary to substantiate these in vitro findings.

  7. Clinical performance of porcelain laminate veneers: outcomes of the aesthetic pre-evaluative temporary (APT) technique.

    Science.gov (United States)

    Gurel, Galip; Morimoto, Susana; Calamita, Marcelo A; Coachman, Christian; Sesma, Newton

    2012-12-01

    This article evaluates the long-term clinical performance of porcelain laminate veneers bonded to teeth prepared with the use of an additive mock-up and aesthetic pre-evaluative temporary (APT) technique over a 12-year period. Sixty-six patients were restored with 580 porcelain laminate veneers. The technique, used for diagnosis, esthetic design, tooth preparation, and provisional restoration fabrication, was based on the APT protocol. The influence of several factors on the durability of veneers was analyzed according to pre- and postoperative parameters. With utilization of the APT restoration, over 80% of tooth preparations were confined to the dental enamel. Over 12 years, 42 laminate veneers failed, but when the preparations were limited to the enamel, the failure rate resulting from debonding and microleakage decreased to 0%. Porcelain laminate veneers presented a successful clinical performance in terms of marginal adaptation, discoloration, gingival recession, secondary caries, postoperative sensitivity, and satisfaction with restoration shade at the end of 12 years. The APT technique facilitated diagnosis, communication, and preparation, providing predictability for the restorative treatment. Limiting the preparation depth to the enamel surface significantly increases the performance of porcelain laminate veneers.

  8. Influence of enamel preservation on failure rates of porcelain laminate veneers.

    Science.gov (United States)

    Gurel, Galip; Sesma, Newton; Calamita, Marcelo A; Coachman, Christian; Morimoto, Susana

    2013-01-01

    The purpose of this study was to evaluate the failure rates of porcelain laminate veneers (PLVs) and the influence of clinical parameters on these rates in a retrospective survey of up to 12 years. Five hundred eighty laminate veneers were bonded in 66 patients. The following parameters were analyzed: type of preparation (depth and margin), crown lengthening, presence of restoration, diastema, crowding, discoloration, abrasion, and attrition. Survival was analyzed using the Kaplan-Meier method. Cox regression modeling was used to determine which factors would predict PLV failure. Forty-two veneers (7.2%) failed in 23 patients, and an overall cumulative survival rate of 86% was observed. A statistically significant association was noted between failure and the limits of the prepared tooth surface (margin and depth). The most frequent failure type was fracture (n = 20). The results revealed no significant influence of crown lengthening apically, presence of restoration, diastema, discoloration, abrasion, or attrition on failure rates. Multivariable analysis (Cox regression model) also showed that PLVs bonded to dentin and teeth with preparation margins in dentin were approximately 10 times more likely to fail than PLVs bonded to enamel. Moreover, coronal crown lengthening increased the risk of PLV failure by 2.3 times. A survival rate of 99% was observed for veneers with preparations confined to enamel and 94% for veneers with enamel only at the margins. Laminate veneers have high survival rates when bonded to enamel and provide a safe and predictable treatment option that preserves tooth structure.

  9. Stresses and distortions within zirconia-fixed dental prostheses due to the veneering process.

    Science.gov (United States)

    Dittmer, Marc Philipp; Borchers, Lothar; Stiesch, Meike; Kohorst, Philipp

    2009-10-01

    Changes in the marginal and internal fit during manufacture are detrimental to the long-term success of fixed dental prostheses (FDPs). Hence, the aim of this study was to investigate the distortion of four-unit zirconia bridges induced by the veneering process with in vitro and finite element analyses (FEA). Ten all-ceramic FDPs with zirconia frameworks were prepared. The marginal and internal fit of the restorations were determined prior to and after veneering by means of a replica technique. Additionally, a three-dimensional finite element model of the restoration was constructed and cooling after the veneering process was virtually simulated. Statistical analysis revealed significant changes in the marginal and internal fit due to the veneering process. FEA verified these observations and displayed tensile stresses (up to 65MPa) within the framework and compressive stresses (up to 10MPa) within the veneering layer. The present study showed that stresses and distortions, occurring due to the veneering process, may influence the marginal and internal fit and therefore the clinical success of dental restorations.

  10. The Effect of Core and Veneering Design on the Optical Properties of Polyether Ether Ketone.

    Science.gov (United States)

    Zeighami, S; Mirmohammadrezaei, S; Safi, M; Falahchai, S M

    2017-12-01

    This study aimed to evaluate the effect of core shade and core and veneering thickness on color parameters and translucency of polyether ether ketone (PEEK). Sixty PEEK discs (0.5 and 1 mm in thickness) with white and dentine shades were veneered with A2 shade indirect composite resin with 0.5, 1 and 1.5 mm thickness (n=5). Cores without the veneering material served as controls for translucency evaluation. Color parameters were measured by a spectroradiometer. Color difference (ΔE₀₀) and translucency parameters (TP) were computed. Data were analyzed using one-way ANOVA and Tukey's test (for veneering thickness) and independent t-test (for core shade and thickness) via SPSS 20.0 (p⟨0.05). Regarding the veneering thickness, white cores of 0.5 mm thickness showed significant differences in all color parameters. In white cores of 1 mm thickness and dentine cores of 0.5 and 1 mm thickness, there were statistically significant differences only in L∗, a∗ and h∗. The mean TP was significantly higher in all white cores of 1 mm thickness than dentine cores of 1 mm. Considering ΔE₀₀=3.7 as clinically unacceptable, only three groups had higher mean ΔE₀₀ values. Core shade, core thickness, and the veneering thickness affected the color and translucency of PEEK restorations. Copyright© 2017 Dennis Barber Ltd.

  11. [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(Pveneer.

  12. Comparative Study of Shear Bond Strength of Three Veneering Ceramics to a Zirconia Core

    Directory of Open Access Journals (Sweden)

    Aalaei Sh

    2016-03-01

    Full Text Available Statement of Problem: Fracture of veneering porcelain has been described as the most frequent reason for the failure of zirconia-based fixed restorations. Objectives: The purpose of this study was to evaluate and compare the shear bond strength of a zirconium oxide core material to three commercial veneering ceramics. Materials and Methods: Three types of veneering ceramics were selected including IPS -emax Ceram, Vita VM9, and Cerabien. Thirty block specimens of zirconia core material were prepared in 4×4×9 mm dimensions. Three groups were created and the veneering ceramic was added to each of 10 blocks. Shear bond test was conducted with universal testing machine. Data were analyzed using one-way ANOVA (p = 0.05. Results: Mean shear bond strength values and standard deviations were 26.03 MPa (6.32, 23.85 MPa (4.01, and 19.16 MPa (3.72 for Vita VM9, IPS emax Ceram, and Cerabien, respectively. Cerabien ceramic showed more failure as compared to the other ceramics. However, there was no significant difference among the three veneering groups. Conclusions: Within the limitation of this study, it can be concluded that shear bond strength between zirconia core and three veneering ceramics was not significantly different.

  13. Effect of various intermediate ceramic layers on the interfacial stability of zirconia core and veneering ceramics.

    Science.gov (United States)

    Yoon, Hyung-In; Yeo, In-Sung; Yi, Yang-Jin; Kim, Sung-Hun; Lee, Jai-Bong; Han, Jung-Suk

    2015-01-01

    The purposes of this study were to evaluate the effects of intermediate ceramics on the adhesion between the zirconia core and veneer ceramics. The polished surfaces of fully sintered Y-TZP blocks received three different treatments: (1) connector (C), (2) liner (L) or (3) wash layer (W). All the treated zirconia blocks were veneered with either (a) fluorapatite glass-ceramic (E) or (b) feldspathic porcelain (V) and divided into four groups (CE, CV, LE and WV). For the control group, the testing surfaces of metal blocks were veneered with feldspathic porcelain (VM). A half of the samples in each group (n = 21) were exposed to thermocycling, while the other half of the specimens were stored at room temperature under dry conditions. All specimens were subjected to the shear test and the failed surfaces were microscopically examined. The elemental distribution at the zirconia core/veneer interface was analyzed. The specimens in Groups CE and CV exhibited significantly greater mean bond strength values than those in Groups LE and WV, respectively (p core/veneer adhesion than the other intermediate ceramics evaluated in the study. However, thermal cycling affected the bond strength at the core/veneer interface differently according to the intermediate ceramics.

  14. In Vitro Color Change of Three Dental Veneering Resins in Tea, Coffee and Tamarind Extracts

    Directory of Open Access Journals (Sweden)

    S. Muttagi

    2011-09-01

    Full Text Available Objective: To study the in vitro color changes of three dental resin veneering materials when immersed in tea, coffee and tamarind extracts.Materials and Methods: The color changes of heat polymerized tooth colored acrylic resin (Stellondetrey, B, F14, DPI Dental products of India Ltd, Mumbai, auto polymerized tooth colored acrylic resin (DPI, B, QV5, DPI Dental products of India Ltd, Mumbai andlight polymerized resin composite (Herculite XRV, Enamel A2, part no. 22860, lot no. 910437, Kerr Corporation, West Collins Avenue, Orange, CA, USA when immersed in water extracts of tea (Tata Tea Ltd. Bangalore, India, coffee (Tata Coffee Ltd. Coorg, Indiaand tamarind were evaluated using computer vision systems. The color images were recorded in R (red, G (green and B (blue form and converted into H (hue, S (saturationand V (value.Results: Significant color change occurred for auto polymerized tooth colored acrylic resin in tamarind extract, for heat polymerized tooth colored acrylic resin in tea extract andfor light polymerized resin composite in coffee extract. Auto polymerized tooth colored acrylic resin samples showed an overall higher color change. However, for all the material samples coffee extract produced more color change.Conclusion: These results suggest that the color stability of the resins is influenced by the presence of secondary metabolites such as tartaric acid, tannins, caffeine, saponins and phenols in tamarind, tea and coffee extracts.

  15. Randomized clinical trial of indirect resin composite and ceramic veneers: up to 3-year follow-up.

    Science.gov (United States)

    Gresnigt, Marco M; Kalk, Warner; Ozcan, Mutlu

    2013-04-01

    This randomized controlled split-mouth clinical trial evaluated the short-term survival rate of indirect resin composite and ceramic laminate veneers. A total of 10 patients (mean age: 48.6 years) received 46 indirect resin composite (Estenia; n = 23) and ceramic laminate veneers (IPS Empress Esthetic; n = 23) on the maxillary anterior teeth. Veneer preparations with incisal overlap were performed and existing resin composite restorations of good quality were not removed but conditioned using silica coating (CoJet) and silanization (ESPE-Sil). Enamel and dentin were etched and rinsed; adhesive resin (ExciTE) was then applied. After cementation (Variolink Veneer), restorations were evaluated at baseline and thereafter every 6 months for up to 3 years using modified USPHS criteria. Seventeen laminate veneers were bonded onto intact teeth and 29 on teeth having existing resin composite restorations. In total, 3 failures were observed in the form of debonding (n = 1) and fracture (n = 2) in the group of resin composite laminate veneers. No significant difference was observed between the survival rates of composite and ceramic laminate veneers (Estenia: 87%, IPS Empress Esthetic: 100%; p > 0.05). The overall survival rate was 93.5% (Kaplan-Meier). Of the 43 laminate veneers, minor voids and defects were observed in 6 of the composite and 3 of the ceramic veneers. Slight staining at the margins (n = 3) and slightly rough surfaces were more frequently observed for the resin composite laminate veneers (n = 18) up to the final recall. Early findings of this clinical trial on two veneer materials showed statistically similar survival rates. Surface quality changes were more frequent in the composite veneer material.

  16. Laminating butt-jointed, log-run southern pine veneers into long beams of uniform high strength

    Science.gov (United States)

    Peter Koch; G.E. Woodson

    1968-01-01

    Twenty laminated beams were constructed of log-run, butt-jointed, loblolly pine veneers 1|6 inch thick and 100 inches long. The beams were 18 inches deep, 2 inches wide, and 25 feet long. Veneers were arranged in the beams according to their modulus of elasticity (MOE). The stiffest were placed outermost, and the most limber in the center. The veneers, which were cut...

  17. Comparative evaluation of shear bond strengths of veneering porcelain to base metal alloy and zirconia substructures before and after aging – An in vitro study

    Science.gov (United States)

    Sreekala, Laju; Narayanan, Mahesh; Eerali, Sunil M.; Eerali, Susil M.; Varghese, Joju; Zainaba Fathima, A. l.

    2015-01-01

    Objective: The aim of this study was to evaluate and compare the shear bond strength of veneering porcelain to base metal alloy and zirconia substructures before and after aging. Scanning electron microscopy (SEM) was used to determine the failure pattern. Materials and Methods: Twenty rectangular blocks (9 mm length × 4 mm height × 4 mm width) of base metal alloy (Bellabond plus, Bego, Germany) and zirconia (Will ceramZ zirconia K block) were fabricated for shear bond strength test. Surface of the base metal alloy block (4 mm × 4 mm area) was veneered with corresponding veneering porcelain (Ivoclar, IPS classic, vivadent). Similarly, surface of the zirconia rectangular block (4 mm × 4 mm) was veneered with corresponding veneering ceramic (Cercon ceram kiss, Degudent). Out of forty rectangular porcelain veneered core specimen, ten porcelain veneered base metal alloy specimen and ten porcelain veneered zirconia specimen were immersed in water at 37°C for one month to simulate the oral environment. Results: On comparison, the highest shear bond strength value was obtained in porcelain veneered base metal alloy before aging group followed by porcelain veneered base metal alloy after aging group, Porcelain veneered zirconia before aging group, porcelain veneered zirconia after aging group. SEM analysis revealed predominantly cohesive failure of veneering ceramic in all groups. Conclusion: Porcelain veneered base metal alloy samples showed highest shear bond strength than porcelain veneered zirconia samples. Study concluded that aging had an influence on shear bond strength. Shear bond strength was found to be decreasing after aging. SEM analysis revealed cohesive failure of veneering ceramic in all groups suggestive of higher bond strength of the interface than cohesive strength of ceramic. Hence, it was concluded that veneering ceramic was the weakest link. PMID:26942121

  18. Comparative evaluation of shear bond strengths of veneering porcelain to base metal alloy and zirconia substructures before and after aging - An in vitro study.

    Science.gov (United States)

    Sreekala, Laju; Narayanan, Mahesh; Eerali, Sunil M; Eerali, Susil M; Varghese, Joju; Zainaba Fathima, A L

    2015-12-01

    The aim of this study was to evaluate and compare the shear bond strength of veneering porcelain to base metal alloy and zirconia substructures before and after aging. Scanning electron microscopy (SEM) was used to determine the failure pattern. Twenty rectangular blocks (9 mm length × 4 mm height × 4 mm width) of base metal alloy (Bellabond plus, Bego, Germany) and zirconia (Will ceramZ zirconia K block) were fabricated for shear bond strength test. Surface of the base metal alloy block (4 mm × 4 mm area) was veneered with corresponding veneering porcelain (Ivoclar, IPS classic, vivadent). Similarly, surface of the zirconia rectangular block (4 mm × 4 mm) was veneered with corresponding veneering ceramic (Cercon ceram kiss, Degudent). Out of forty rectangular porcelain veneered core specimen, ten porcelain veneered base metal alloy specimen and ten porcelain veneered zirconia specimen were immersed in water at 37°C for one month to simulate the oral environment. On comparison, the highest shear bond strength value was obtained in porcelain veneered base metal alloy before aging group followed by porcelain veneered base metal alloy after aging group, Porcelain veneered zirconia before aging group, porcelain veneered zirconia after aging group. SEM analysis revealed predominantly cohesive failure of veneering ceramic in all groups. Porcelain veneered base metal alloy samples showed highest shear bond strength than porcelain veneered zirconia samples. Study concluded that aging had an influence on shear bond strength. Shear bond strength was found to be decreasing after aging. SEM analysis revealed cohesive failure of veneering ceramic in all groups suggestive of higher bond strength of the interface than cohesive strength of ceramic. Hence, it was concluded that veneering ceramic was the weakest link.

  19. Detection of artificial demineralization bordering different types of laminate veneers using visual inspection and storage phosphor radiography.

    Science.gov (United States)

    Cömlekoğlu, Erhan; Önem, Erinç; Dündar Çömlekoğlu, Mine; Baksı, B Güniz; Mert, Ali

    2013-07-01

    The objective of this study is to compare the diagnostic accuracy of visual inspection (VI) and storage phosphor plate (SPP) radiography for the detection of artificial demineralization bordering different laminate veneers. Twenty human maxillary canine teeth were prepared. All-ceramic (A) and hybrid ceramic (H) laminate veneers were fabricated and luted. Veneered teeth were covered except for a circular window on the proximal surface bordering restorations. Teeth were kept in acetic acid buffer to create demineralization and imaged with a SPP system. Ten observers evaluated all teeth first visually then with SPP images for the presence/absence of demineralization. Teeth were examined using scanning electron microscopy (SEM) as well. The accuracy was expressed as the area under the ROC curves (A(z)). Pair-wise comparisons were performed using two-way ANOVA and post hoc t test (p = 0.05). Fleiss kappa (κ) was used for agreement. SPP radiography was better than the VI for both veneers (p = 0.004). The A(z)s of two veneers were different for both VI (p veneers. Enamel demineralizations bordering hybrid and ceramic laminate veneers can be detected better with SPP radiography than VI and detectability was better for all-ceramic veneers than the hybrid ceramic ones. Early detection of enamel demineralizations bordering laminate veneers would result in time-saving and less-invasive treatment methods; therefore, SPP radiography may be recommended in clinically suspicious cases since it provides better diagnostic accuracy.

  20. Effect of surface conditioning modalities on the repair bond strength of resin composite to the zirconia core / veneering ceramic complex.

    Science.gov (United States)

    Ozcan, Mutlu; Valandro, Luiz Felipe; Pereira, Sarina Maciel; Amaral, Regina; Bottino, Marco Antonio; Pekkan, Gurel

    2013-06-01

    This study evaluated the effect of different surface conditioning protocols on the repair strength of resin composite to the zirconia core / veneering ceramic complex, simulating the clinical chipping phenomenon. Forty disk-shaped zirconia core (Lava Zirconia, 3M ESPE) (diameter: 3 mm) specimens were veneered circumferentially with a feldspathic veneering ceramic (VM7, Vita Zahnfabrik) (thickness: 2 mm) using a split metal mold. They were then embedded in autopolymerizing acrylic with the bonding surfaces exposed. Specimens were randomly assigned to one of the following surface conditioning protocols (n = 10 per group): group 1, veneer: 4% hydrofluoric acid (HF) (Porcelain Etch) + core: aluminum trioxide (50-µm Al2O3) + core + veneer: silane (ESPE-Sil); group 2: core: Al2O3 (50 µm) + veneer: HF + core + veneer: silane; group 3: veneer: HF + core: 30 µm aluminum trioxide particles coated with silica (30 µm SiO2) + core + veneer: silane; group 4: core: 30 µm SiO2 + veneer: HF + core + veneer: silane. Core and veneer ceramic were conditioned individually but no attempt was made to avoid cross contamination of conditioning, simulating the clinical intraoral repair situation. Adhesive resin (VisioBond) was applied to both the core and the veneer ceramic, and resin composite (Quadrant Posterior) was bonded onto both substrates using polyethylene molds and photopolymerized. After thermocycling (6000 cycles, 5°C-55°C), the specimens were subjected to shear bond testing using a universal testing machine (1 mm/min). Failure modes were identified using an optical microscope, and scanning electron microscope images were obtained. Bond strength data (MPa) were analyzed statistically using the non-parametric Kruskal-Wallis test followed by the Wilcoxon rank-sum test and the Bonferroni Holm correction (α = 0.05). Group 3 demonstrated significantly higher values (MPa) (8.6 ± 2.7) than those of the other groups (3.2 ± 3.1, 3.2 ± 3, and 3.1 ± 3.5 for groups 1, 2, and 4

  1. Combining Esthetic Layering and Lithium Disilicate Sintering Technique on Zirconia Frameworks: A Veneering Option to Prevent Ceramic Chipping.

    Science.gov (United States)

    Saeidi Pour, Reza; Edelhoff, Daniel; Rafael, Caroline Freitas; Prandtner, Otto; Frei, Stefan; Maziero Volpato, Claudia Angela; Liebermann, Anja

    Major and minor chipping of veneering porcelain are two of the most frequent complications in all-ceramic restorations with zirconia frameworks. In cases of major chipping, replacement of the affected restoration may be necessary. High-strength lithium disilicate ceramic offers new options to serve as veneering material in a sintering technique or as repair material for chipping in combination with the adhesive technique. The purpose of three case presentations here was to describe the use of lithium disilicate ceramic on zirconia frameworks for reliable and esthetic veneering in the posterior region and to repair extended chipping in conventional veneering materials.

  2. Degree of Conversion of a Resin Cement Light-Cured Through Ceramic Veneers of Different Thicknesses and Types

    OpenAIRE

    Runnacles, Patrício; Correr, Gisele Maria; Baratto Filho, Flares; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

    2014-01-01

    During the cementation of ceramic veneers the polymerization of resin cements may be jeopardized if the ceramics attenuate the irradiance of the light-curing device. The aim of this study was to evaluate the effect of different types and thicknesses of ceramic veneers on the degree of conversion of a light-cured resin-based cement (RelyX Veneer). The cement was light-cured after interposing ceramic veneers [IPS InLine, IPS Empress Esthetic, IPS e.max LT (low translucency) and IPS e.max HT (hi...

  3. Load-bearing capacity and failure types of anterior zirconia crowns veneered with overpressing and layering techniques.

    Science.gov (United States)

    Stawarczyk, Bogna; Ozcan, Mutlu; Roos, Malgorzata; Trottmann, Albert; Sailer, Irena; Hämmerle, Christoph H F

    2011-10-01

    The aim of this study was to test whether the load bearing capacity of anterior zirconia crowns veneered with overpressed or layered, is similar and to evaluate the failure types. Standardized zirconia frameworks were fabricated and randomly divided into 8 groups (N=120, n=15 per test group). Four groups were veneered with one of the layered veneering porcelains: Zirox, GC Initial ZR, VITA VM9 or IPS e.max Ceram and the other four groups were veneered with overpressed veneering porcelains: PressX Zr, GC Initial LF, VITA PM9 or IPS e.max ZirPress. The crowns were cemented on their corresponding CoCr abutment and the specimens were loaded at an angle of 45° in a Universal Testing Machine to determine the fracture load. Data were analyzed using one-way and two-way ANOVA, followed by a post hoc Scheffé test, t-test and Weibull analysis (alpha=0.05). Within three manufacturers of veneering porcelain, fracture load values were not statistically significant between overpressed and layered porcelain systems. Within one manufacturer of veneering porcelain, the overpressed crowns (IPS e.max ZirPress: 1519 ± 334 N) demonstrated significantly higher (pveneering porcelain was observed, all other porcelain systems showed predominantly framework fractures together with fracture of the veneering porcelain. Overpressed veneering porcelains for zirconia frameworks exhibited similar or better fracture load compared with layered ones. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Effect of thermocycling on the flexural strength of porcelain laminate veneers

    Science.gov (United States)

    Subramanian, Deepa; Sivagami, G; Sendhilnathan, D; Rajmohan, CS

    2008-01-01

    Aim: The aim of this study was to examine the impact of thermocycling on the flexural strength and development of surface flaws on the glazed surface of porcelain laminate veneer restorations with and without resin luting cement. Materials and Methods: 80 Vitadur alpha dentin porcelain discs (10 mm diameter, 0.9 mm thickness) were glazed on one side and divided into two groups: A (porcelain laminate veneer only without resin luting cement) and B (porcelain laminate veneer luted with resin cement), each containing 40 discs. The discs in groups A and B were then thermocycled at different temperatures and were subjected to SEM analysis to evaluate the effect of thermocycling on crack propagation. Mean flexural strength was determined by using the ball-on-ring test. Student's t -test was used to find out the difference between strength values of the thermocycled porcelain discs and discs luted with resin cement. Results: SEM analysis revealed crack propagation in the subgroups subjected to extremes of temperature, i.e., 4 ± 1°C, 37 ± 1°C and 4 ± 1°C, 65 ± 1°C in the porcelain laminate veneers luted with resin cement. Flexural strength analysis revealed superior flexural strength for porcelain laminate veneers: 88.58 ± 6.94 MPa when compared to porcelain laminate veneers luted with resin cement: 8.42 ± 2.60 MPa. Results were tabulated and statistically analyzed using Student's t -test. Conclusion: Laminate veneer specimens exhibited greater flexural strength than those which were luted with resin cements. Laminate veneer specimens luted with resin cement and subjected to extremes of temperature, 4 ± 1°C and 37 ± 1°C and 4 ± 1°C and 65 ± 1°C, showed a marked decrease in flexural strength. After thermocycling at extremes of temperature, laminate veneer specimens luted with resin cement showed crack propagation. Fit of laminate veneers cannot / should not be compensated by the thickness of luting agent. PMID:20351971

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

    OpenAIRE

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

    2015-01-01

    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

  6. Interface toughness of a zirconia-veneer system and the effect of a liner application.

    Science.gov (United States)

    Wang, Gaoqi; Zhang, Song; Bian, Cuirong; Kong, Hui

    2014-09-01

    Chipping of veneering porcelain and delamination of a zirconia-veneer interface are 2 common clinical failure modes for zirconia-based restorations and may be partially due to weak interface bonding. The effect of liner on the bond strength of the interface has not been clearly identified. The purpose of the research was to evaluate the interface toughness between the zirconia core and veneering porcelain by means of a fracture mechanics test and to assess the effect of liner on the bond strength of the interface. Thirty bilayered beam-shape specimens were prepared and divided into 2 groups according to liner application. The specimens in each group were subdivided into 3 subgroups in accordance with 3 different veneer thicknesses. A fracture mechanics test was used on each specimen, and the energy release rate, G, and phase angle, ψ, were calculated according to the experimental results. A video microscope was used to monitor the crack propagation, and a scanning electron microscope was used to identify the fracture mode after testing. Two-way ANOVA and the Tukey honestly significant difference test were performed to analyze the experimental data (α=.05) . At each phase angle, the interfaces without a liner had higher mean G values than the interfaces with a liner. Both of the interfaces showed mixed failure mode with thin layers of a veneer or a liner that remained on the zirconia surfaces. Liner application before veneering reduced the interface toughness between zirconia and veneer. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  7. Effect of ultraviolet aging on translucency of resin-cemented ceramic veneers: an in vitro study.

    Science.gov (United States)

    Turgut, Sedanur; Bagis, Bora; Turkaslan, Suha S; Bagis, Yildirim Hakan

    2014-01-01

    The aim of this in vitro study was to evaluate the translucency of ceramic veneers cemented with light- or dual-cured resin cements after accelerated aging. A total of 392 specimens were made of shade A1 with 0.5- and 1.0-mm thickness. Light-cured RelyX Veneer and dual-cured Maxcem Elite and Variolink II resin cements were applied on the porcelain discs with a thickness of 0.1 mm. Translucency parameter (TP) values of the ceramic veneers after cementation and UV aging test were evaluated. Statistical analyses were done with ANOVA and Tukey's tests and paired sample t-test (p Veneer Tr (TP = 11.15; p = 0.608), Variolink II Tr (TP = 10.98; p = 0.55), and Maxcem Clear (TP = 11.81; p = 0.702) did not affect the translucency of 1-mm-thick ceramics (TP = 11.38). The aging process affected TP values of both ceramics and cemented ceramics, as the TP values decreased after aging. Among the TP values of opaque shade resin cements, there were significant differences between the "ceramic," "ceramic + RelyX Veneer WO," "ceramic + Variolink II WO," and "ceramic + Maxcem WO" variables for both 0.5 and 1 mm thicknesses (p Veneer Tr," "ceramic + Variolink II Tr," and "ceramic + Maxcem Clear" variables at 0.5 mm thickness, and there were no significant differences between "ceramic," "ceramic + RelyX Veneer Tr," and "ceramic + Variolink II Tr" variables after aging (p > 0.05). The TP of the same color of resin cements varied related to the type or brand. Aging caused both the ceramics and cemented ceramics to become more opaque. © 2013 by the American College of Prosthodontists.

  8. 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.

  9. Effects of different application durations of scanning laser method on debonding strength of laminate veneers.

    Science.gov (United States)

    Oztoprak, Mehmet Oguz; Tozlu, Murat; Iseri, Ufuk; Ulkur, Feyza; Arun, Tulin

    2012-07-01

    Porcelain laminate veneers as esthetic and minimally invasive restorations are being used as an alternative to full veneer crowns. However, the removal of porcelain veneers that have failed may be an uncomfortable and time-consuming procedure because of the high bond strength between the porcelain laminate veneers and the tooth surface. The purpose of this study was to prepare a simple and reliable method for porcelain laminate veneer debonding by using an Er:YAG laser with the scanning method and to determine the amount of lasing time required. Eighty cylindrical specimens with a thickness of 0.7 mm and a diameter of 5 mm were fabricated from Empress II ceramic material. They were cemented on the labial surface of extracted bovine mandibular incisors using Variolink II (Ivoclar Vivadent AG, Schaan, Liechtenstein) and light cured for 40 s. The specimens were randomly divided into four groups of 20. The first group was assigned as the control group and no laser application was performed. The Er:YAG laser was applied on each specimen in the other three study groups for 3, 6, and 9 s by using the scanning method. One second after the lasing, a mechanical force was applied to remove the laminate veneers by using an Instron Universal Testing machine. Results of this study exhibited statistically significant differences between the control group and the three study groups. Intergroup comparison of shear bond strengths of the three study groups showed a statistically significant difference (p = 0.0001). This study showed that all three application times of Er-YAG laser were effective for debonding ceramic laminate veneers by softening the adhesive resin.

  10. Numeric simulation of occlusal interferences in molars restored with ultrathin occlusal veneers.

    Science.gov (United States)

    Magne, Pascal; Cheung, Raymond

    2017-01-01

    Selecting material for a minimally invasive occlusal veneer reconstruction concept requires an understanding of how stresses are distributed during functional and parafunctional forces. The purpose of this in vitro study was to investigate stress distribution in a maxillary molar restored with ultrathin occlusal veneers and subjected by an antagonistic mandibular molar to clenching and working and nonworking movements. A maxillary first molar was modeled from microcomputed tomography (micro-CT) data, using medical image processing software, stereolithography editing/optimizing software, and finite element software. Simulated ultrathin occlusal veneer materials were used. The mandibular molar antagonist was a solid nondeformable geometric entity. Loads simulated clenching, working, and nonworking movements with loading of 500 N. The values of the maximum principal stress were recorded. In the clenching load situation, maximum tensile stresses were located at the occlusal veneer (52 MPa for composite resin versus 47 MPa for ceramic). In the working movement, significant additional tensile stresses were found on the palatal root (87 MPa for composite resin and 85 MPa for ceramic). In the nonworking movement, tensile stress on the ultrathin occlusal veneer increased to 118 MPa for composite resin and 143 MPa for ceramic veneers. Tensile stress peaks shifted to the mesiobuccal root (75 MPa for composite resin and 74 MPa for ceramic). The topography of stresses generated by the various occlusal interferences were clearly identified. Significant tensile stress concentrations were found within the restoration's occlusal topography and root, with the nonworking interference being the most harmful and also the most revealing of the difference between the composite resin and ceramic ultrathin occlusal veneers. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Effect of porcelain and enamel thickness on porcelain veneer failure loads in vitro.

    Science.gov (United States)

    Ge, Chunling; Green, Chad C; Sederstrom, Dalene; McLaren, Edward A; White, Shane N

    2014-05-01

    Bonded porcelain veneers are widely used esthetic restorations. Although high success and survival rates have been reported, failures occur. Fracture is the most common failure mode. Fractures range from incomplete cracks to the catastrophic. Minimally invasive or thin partial veneers have gained popularity. The aim of this study was to measure the influences of porcelain veneer thickness and enamel substrate thickness on the loads needed to cause the initial fracture and catastrophic failure of porcelain veneers. Model discoid porcelain veneer specimens of varying thickness were bonded to the flattened facial surfaces of incisors, artificially aged, and loaded to failure with a small sphere. Individual fracture events were identified and analyzed statistically and fractographically. Fracture events included initial Hertzian cracks, intermediate radial cracks, and catastrophic gross failure. Increased porcelain, enamel, and their combined thickness had like effects in substantially raising resistance to catastrophic failure but also slightly decreased resistance to initial Hertzian cracking. Fractographic and numerical data demonstrated that porcelain and tooth enamel behaved in a remarkably similar manner. As porcelain thickness, enamel thickness, and their combined thickness increased, the loads needed to produce initial fracture and catastrophic failure rose substantially. Porcelain veneers withstood considerable damage before catastrophic failure. Increased enamel thickness, increased porcelain thickness, and increased combined enamel and porcelain thickness all profoundly raised the failure loads necessary to cause catastrophic failure. Enamel and feldspathic porcelain behaved in a like manner. Surface contact damage occurred initially. Final catastrophic failure followed flexural radial cracking. Bonded porcelain veneers were highly damage tolerant. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

  12. Influence of the veneering process on the marginal fit of zirconia fixed dental prostheses.

    Science.gov (United States)

    Kohorst, P; Brinkmann, H; Dittmer, M P; Borchers, L; Stiesch, M

    2010-04-01

    Distortions in the marginal region during manufacture are detrimental to the long-term success of fixed dental prostheses (FDPs). The aim of the present in vitro study was to evaluate changes in marginal fit because of the veneering process of four-unit FDPs made from different zirconia materials. Two groups of FDPs with 10 specimens each were machined from white body zirconia blanks (VITA In-Ceram YZ Cubes, KaVo Everest ZS-Blanks) by means of computer-aided design/computer-aided manufacturing systems and subsequently sintered to their final density. The marginal and internal gaps of the frameworks were determined using a replica technique. Afterwards, frameworks were veneered with the recommended ceramics (VITA VM9, GC Initial Zr), and fitting accuracy was evaluated again. Statistical analyses were performed by Student's t-test with the level of significance chosen at 0.05. With one framework/veneering system (Everest ZS-Blanks/Initial Zr), both marginal gap (P = 0.019) and internal gap (P = 0.001) at the premolar retainer were significantly affected by the veneering process. The resulting distortions were directed towards the lumina of the retainers and the mean values of the measured gaps decreased by about 23.8 mum (marginal gap) and 27.3 mum (internal gap). For the other system (In-Ceram YZ Cubes/VM9), no distortions because of the veneering were found. The veneering of zirconia restorations may lead to significant changes in the marginal fit, while the combination of core and veneering material used influences the resulting distortions.

  13. In vitro evaluation of fracture strength of zirconia restoration veneered with various ceramic materials

    Science.gov (United States)

    Choi, Yu-Sung; Lee, Jai-Bong; Han, Jung-Suk; Yeo, In-Sung

    2012-01-01

    PURPOSE Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques. MATERIALS AND METHODS A 1.2 mm, 360° chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely X™ Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (α=0.05). Scanning electron microscope was used to investigate the fractured interface. RESULTS Mean fracture load and standard deviation was 4263.8±1110.8 N for Group LT, 5070.8±1016.4 for Group HT and 6242.0±1759.5 N for Group ST. The values of Group ST were significantly higher than those of the other groups. CONCLUSION Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength. PMID:22977725

  14. Ruthenium isotopic evidence for an inner Solar System origin of the late veneer

    Science.gov (United States)

    Fischer-Gödde, Mario; Kleine, Thorsten

    2017-01-01

    The excess of highly siderophile elements in the Earth’s mantle is thought to reflect the addition of primitive meteoritic material after core formation ceased. This ‘late veneer’ either comprises material remaining in the terrestrial planet region after the main stages of the Earth’s accretion, or derives from more distant asteroidal or cometary sources. Distinguishing between these disparate origins is important because a late veneer consisting of carbonaceous chondrite-like asteroids or comets could be the principal source of the Earth’s volatiles and water. Until now, however, a ‘genetic’ link between the late veneer and such volatile-rich materials has not been established or ruled out. Such genetic links can be determined using ruthenium (Ru) isotopes, because the Ru in the Earth’s mantle predominantly derives from the late veneer, and because meteorites exhibit Ru isotope variations arising from the heterogeneous distribution of stellar-derived dust. Although Ru isotopic data and the correlation of Ru and molybdenum (Mo) isotope anomalies in meteorites were previously used to argue that the late veneer derives from the same type of inner Solar System material as do Earth’s main building blocks, the Ru isotopic composition of carbonaceous chondrites has not been determined sufficiently well to rule them out as a source of the late veneer. Here we show that all chondrites, including carbonaceous chondrites, have Ru isotopic compositions distinct from that of the Earth’s mantle. The Ru isotope anomalies increase from enstatite to ordinary to carbonaceous chondrites, demonstrating that material formed at greater heliocentric distance contains larger Ru isotope anomalies. Therefore, these data refute an outer Solar System origin for the late veneer and imply that the late veneer was not the primary source of volatiles and water on the Earth.

  15. Effect of light source and time on the polymerization of resin cement through ceramic veneers.

    Science.gov (United States)

    Rasetto, F H; Driscoll, C F; von Fraunhofer, J A

    2001-09-01

    The purpose of this study was to evaluate the efficiency of 3 different light sources to polymerize a light curing resin cement beneath 3 types of porcelain veneer materials. A conventional halogen light, a plasma arc light, and a high intensity halogen light were used to polymerize resin cement (Variolink II; Ivoclar North America Inc, Amherst, NY) through disks of veneer materials. Equal diameter and thickness disks of feldspathic porcelain (Ceramco II; Ceramco Inc, Burlington, NJ), pressable ceramic (IPS Empress; Ivoclar North America Inc), and aluminous porcelain (Vitadur Alpha; Vident Inc, Brea, CA) were used as an interface between the curing light tips and the light polymerized resin cement. The resin cement/veneer combinations were exposed to 4 different photopolymerization time protocols of 5 seconds, 10 seconds, 15 seconds, and 20 seconds for high intensity light units (Apollo 95E [Dental Medical Diagnostic Systems Inc, Westlake Village, CA] and Kreativ 2000 [Kreativ Inc, San Diego, CA]), and 20 seconds, 40 seconds, 60 seconds, and 80 seconds for conventional halogen light (Optilux; Demetron Research Inc, Danbury, CT). A surface hardness test (Knoop indenter) was used to determine the level of photopolymerization of the resin through the ceramic materials with each of the light sources. The data were analyzed by one-way analysis of variance and a post-hoc Scheffe test (p veneer material, and the polymerization time. For a given light and veneer material, Knoop Hardness Number increases with longer polymerization times. The Kreativ light showed statistically significant differences (p veneers in a markedly shorter time period than the conventional halogen light. However, the data in this report indicate that a minimum exposure time of 15 seconds with the Kreativ light and 10 seconds with the Apollo 95E light should be used to polymerize the Variolink II resin, regardless of the composition of the veneer. Conventional halogen lights required a

  16. Cumulative effects of successive restorative procedures on anterior crown flexure: intact versus veneered incisors.

    Science.gov (United States)

    Magne, P; Douglas, W H

    2000-01-01

    When successive restorative procedures (e.g., porcelain veneers, interdental resin composite restorations, and endodontic treatment) are carried out on the same tooth, significant effects on crown flexure can be expected. Dentin-bonded porcelain veneers (experimental group) were assessed in vitro using functional and cyclic thermal loads. They were compared to natural teeth (control group) with respect to 2 parameters: coronal flexure (investigated using experimental strain gauges) and morphology of the tooth-restoration interface (scanning electron microscopic evaluation). For both veneered and natural teeth, crown deformation was recorded at 5 sequential experimental steps: intact tooth (baseline), Class III cavities, Class III resin composite restorations, endodontic treatment, and endodontic restoration (without posts). No significant differences in crown flexure were found between natural and veneered incisors when compared across experimental steps. The main effect for experimental steps was highly significant. When averaged across all specimens (natural and veneered teeth), the endodontic treatment step resulted in the highest crown flexure (1.55x the baseline value). The unrestored Class III cavities and the endodontic restoration were next highest (1.30x and 1.28x the baseline value, respectively). The lowest crown flexures were found after restoration of the Class III cavities (1.13x the baseline value). No measurable microleakage or gaps were detected at the ceramic-resin, resin-enamel, or resin-dentin interfaces (Optibond FL, Kerr). Each subsequent reduction in tooth structure resulted in a substantial increase in crown flexibility, even after restoration. Endodontic procedures were responsible for most of the loss in crown stiffness. Extensive proximal cutting and restorations seemed to minimally affect crown flexure. Porcelain veneers showed perfect biomimetic behavior, because cumulated restoration procedures had the same effect on natural and

  17. Contrast ratio and masking ability of three ceramic veneering materials.

    Science.gov (United States)

    Shono, N N; Al Nahedh, H N A

    2012-01-01

    Porcelain veneer materials are translucent and are therefore affected by their thickness as well as the color of the underlying substructure, which limits their masking ability and compromises the esthetic result in heavily stained teeth. The purpose of this study was to compare the contrast ratio (CR) and masking ability of three different veneering ceramics with two thicknesses by measuring the color differences over white and black backgrounds. Correlations between CR and masking ability of these veneering ceramics were evaluated. A total of 30 disc-shaped specimens (12 mm diameter × 1.0 mm or 1.5 mm) were fabricated in shade A2 from three types of all-ceramic systems: IPS e.max Press (IPSe; Ivoclar Vivadent, Schaan, Liechtensein), Vita VM7 (VM7; VITA Zahnfabrik, Bad Säckingen, Germany), and Nobel Rondo Press Alumina: Solo (NRPA; Nobel Biocare, Zürich-Flughafen, Switzerland). The CR, defined as the ratio of illuminance (Y) of the test material when placed on the black background (Yb) to the illuminance of the same material when placed over a white background (Yw), was determined (CR=Yb/Yw). The color (CIE L*a*b*) and Y of each specimen were measured over standard white and black tiles using a spectrophotometer (ColorEye 7000 A, Model C6, GretagMacbeth, New Windsor, NY, USA). Masking abilities of the specimens were determined by measuring the color difference (ΔE) over white and black backgrounds. Both CR and ΔE data were analyzed using two-way analysis of variance (ANOVA). One-way ANOVA was used to compare the mean values of CR across the three materials followed by the Duncan multiple comparison test. The correlations between CR and ΔE were determined by comparing R(2) values obtained from a linear regression analysis. A Student t-test for independent samples was used to compare the mean contrast ratio and ΔE values for the two thicknesses. CR values of NRPA were significantly less than those of IPSe and VM7, and the CR of IPSe was higher than that of VM

  18. The effect of ceramic thickness and resin cement shades on the color matching of ceramic veneers in discolored teeth.

    Science.gov (United States)

    Xing, Wenzhong; Chen, Xiaodong; Ren, Dafei; Zhan, Kangru; Wang, Yining

    2017-10-01

    The objective of this study was to analyze the effects of ceramic material thickness and resin cement shade on the color matching of ceramic veneers at the gray tooth structures. Seventy-two artificial maxillary right central incisor teeth (C2 shade) were prepared according to veneer tooth preparation in practice. Ceramic materials (LT, A2 shade, IPS e.max Press) were selected to fabricate the 0.50- and 0.75-mm thick veneers at the body region. The ceramic veneer specimens were bonded to the artificial teeth by the 6 shades of resin cements (Variolink Veneer: shades of HV+3, LV-2, LV-3; and RelyX TM Veneer: shades of WO, TR, A3). A clinical spectrophotometer (Crystaleye, Olympus) was used to measure the color parameters. The color differences (ΔE values) of ceramic veneers and A2 shade tab (Vitapan Classical, Vita) and C* ab values were calculated. The results of three-way ANOVA indicated that the ΔE values of ceramic veneer and A2 shade tab were significantly different in the thickness of ceramic materials, shades of resin cements, and measuring regions (p veneers that exhibited higher ΔE values compared with veneers that were 0.75-mm thick. Tukey's HSD test showed that the average ΔE values in body region were significantly smaller than that in cervical and incisal regions. The color matching of ceramic veneers was significantly influenced not only by the ceramic thickness and the resin cement shades but also the tooth regions.

  19. The effect of bleaching, varying the shade or thickness of composite veneers on final colour: an in vitro study.

    Science.gov (United States)

    Jarad, F D; Griffiths, C E; Jaffri, M; Adeyemi, A A; Youngson, C C

    2008-07-01

    To investigate whether bleaching prior to placement of a composite veneer had an effect on the final shade of the restoration and whether this was affected by the thickness or shade of the veneer. Twenty bovine teeth were collected, sectioned and divided into two groups. One group was the non-bleached control, while the other was the bleached group. A colour reading was recorded using a spectrophotometer. The bleached group then underwent external bleaching with 38% hydrogen peroxide and a colour reading was recorded. Each of these two groups were further sub-divided into four subgroups, on which composite veneers were placed. These subgroups were: 0.5 m thick A1, 1 m thick A1, 0.5 mm thick A4 and 1 mm thick A4 composite veneers. Colour readings were recorded after veneer placement. Statistical significance was assessed using analysis of variance. There was a difference between the colour produced for the same veneer properties, between the bleached and non-bleached groups. For a thin (0.5mm) A4 veneer bleaching produced a statistically significant difference in the amount of colour change (DeltaE) compared to veneering alone. For A1, non-bleached group there is a significant difference in the DeltaE produced by altering the thickness of the veneer. Within the limitations of this study, we can conclude that bleaching prior to placement of a thin A4 dark veneer produces a significant difference in colour change. If no bleaching is performed, altering the thickness of an A1 veneer produces a significant colour difference DeltaE. However, if bleaching is carried out there is no significant difference.

  20. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients

    Science.gov (United States)

    Aktas, Guliz; Sahin, Erdal; Vallittu, Pekka; Özcan, Mutlu; Lassila, Lippo

    2013-01-01

    This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core–veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min−1). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)−(39.7±4.7) and (27.4±5.6)−(35.9±4.7) MPa with and without colouring, respectively) (Pzirconia–veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering 1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core–veneer adhesion. Metal–ceramic adhesion was more reliable than all zirconia–veneer ceramics tested. PMID:24158142

  1. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients.

    Science.gov (United States)

    Aktas, Guliz; Sahin, Erdal; Vallittu, Pekka; Ozcan, Mutlu; Lassila, Lippo

    2013-12-01

    This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min(-1)). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)-(39.7±4.7) and (27.4±5.6)-(35.9±4.7) MPa with and without colouring, respectively) (Pveneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.

  2. Testing the Late-Veneer hypothesis with selenium isotopes

    Science.gov (United States)

    Labidi, J.; Koenig, S.; Bennett, N.; Kurzawa, T.; Aierken, E.; Shahar, A.; Schoenberg, R.

    2016-12-01

    Selenium (Se) is a siderophile element displaying an excess abundance in Earth's mantle compared to experimental predictions [1], which may be attributed to the Late-Veneer. As Se is also volatile, testing the late-veneer addition of Se can constrain the origin of other volatile elements on Earth. Here we combine high-precision Se isotope measurements of metal-silicate partitioning experiments and chondrites to assess whether planetary differentiation could leave a measurable Se isotopic signature on planetary mantles. We performed Se isotopic measurements of 5 metal-silicate partitioning experiments and 20 chondrites of all major classes. Experiments were conducted at 1 GPa and 1650 C for 1 to 4 hours using the piston-cylinder apparatus at Carnegie's Geophysical Laboratory. After wet chemistry, data were obtained on a ThermoFisher Scientific™ NeptunePlus MC-ICP-MS at the University of Tübingen with a 74Se/77Se double spike technique. δ82/76Se values are given relative to NIST SRM-3149 and the external reproducibility calculated from duplicate meteorite analyses is ≤ 0.1‰ (2 s.d.). Chondrites vary over a 0.8‰ range of δ82/76Se values. CIs and CMs show evidence for heavier 82Se/76Se ratios, likely due to mixing processes in the proto-planetary nebula. When these isotopically heavier meteorites are excluded, remaining chondrites have δ82/76Se values varying over a 0.3‰ range, within uncertainty of previous results [2]. We suggest that these chondrites may be used to estimate a δ82/76Se value of bulk planets. At the conditions of our experiments, the partition coefficients for Se log Dmetal-silicate range from 0.7±0.1 to 1.9±0.1, consistent with previous work [1]. A small but resolvable Se isotopic fractionation was observed: 82Se/76Se ratios were enriched by ≤ 0.5‰ in the silicates relative to the metals. Thus, given current uncertainties for Se isotopic measurements, marginal differences between planetary mantles and chondrites may be resolved

  3. Cervical and Incisal Marginal Discrepancy in Ceramic Laminate Veneering Materials: A SEM Analysis

    Science.gov (United States)

    Ranganathan, Hemalatha; Ganapathy, Dhanraj M.; Jain, Ashish R.

    2017-01-01

    Context: Marginal discrepancy influenced by the choice of processing material used for the ceramic laminate veneers needs to be explored further for better clinical application. Aims: This study aimed to evaluate the amount of cervical and incisal marginal discrepancy associated with different ceramic laminate veneering materials. Settings and Design: This was an experimental, single-blinded, in vitro trial. Subjects and Methods: Ten central incisors were prepared for laminate veneers with 2 mm uniform reduction and heavy chamfer finish line. Ceramic laminate veneers fabricated over the prepared teeth using four different processing materials were categorized into four groups as Group I - aluminous porcelain veneers, Group II - lithium disilicate ceramic veneers, Group III - lithium disilicate-leucite-based veneers, Group IV - zirconia-based ceramic veneers. The cervical and incisal marginal discrepancy was measured using a scanning electron microscope. Statistical Analysis Used: ANOVA and post hoc Tukey honest significant difference (HSD) tests were used for statistical analysis. Results: The cervical and incisal marginal discrepancy for four groups was Group I - 114.6 ± 4.3 μm, 132.5 ± 6.5 μm, Group II - 86.1 ± 6.3 μm, 105.4 ± 5.3 μm, Group III - 71.4 ± 4.4 μm, 91.3 ± 4.7 μm, and Group IV - 123.1 ± 4.1 μm, 142.0 ± 5.4 μm. ANOVA and post hoc Tukey HSD tests observed a statistically significant difference between the four test specimens with regard to cervical marginal discrepancy. The cervical and incisal marginal discrepancy scored F = 243.408, P veneers fabricated using leucite reinforced lithium disilicate exhibited the least marginal discrepancy followed by lithium disilicate ceramic, aluminous porcelain, and zirconia-based ceramics. The marginal discrepancy was more in the incisal region than in the cervical region in all the groups. PMID:28839415

  4. Influence of heat treatment and veneering on the storage modulus and surface of zirconia ceramic.

    Science.gov (United States)

    Siavikis, Georgius; Behr, Michael; van der Zel, Jef M; Feilzer, Albert J; Rosentritt, Martin

    2011-04-01

    Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of zirconia. Zirconia bars (Cercon, DeguDent, G; 0.5x2x20 mm) were fabricated and treated according to veneering conditions. Besides heating regimes between 680°C and 1000°C (liner bake and annealing), sandblasting (Al(2)O(3)) or steam cleaning were used. The bars were investigated after 90 days storage in water and acid. For investigating the influence of veneering, the bars were veneered in press- or layer technique. Dynamic mechanical analysis (DMA) in a three-point-bending design was performed to determine the storage modulus between 25°C and 200°C at a frequency of 1.66 Hz. All specimens were loaded on top and bottom (treatment on pressure or tensile stress side). Scanning electron microscopy (SEM) was used for evaluating the superficial changes of the zirconia surface due to treatment. Statistical analysis was performed using Mann Whitney U-test (α=0.05). Sintered zirconia provided a storage modulus E' of 215 (203/219) GPa and tan δ of 0.04 at 110°C. A 10%-decrease of E' was found up to 180°C. The superficial appearance changed due to heating regime. Sandblasting reduced E' to 213 GPa, heating influenced E' between 205 GPa (liner bake 1) and 222 GPa (dentin bake 1). Steam cleaning, annealing and storage changed E' between 4 GPa and 22 GPa, depending on the side of loading. After veneering, strong E'-reduction was found down to 84 GPa and 125 GPa. Veneering of zirconia with glass-ceramic in contrast to heat treating during veneering procedure had a strong influence on the modulus. The application of the glass-ceramic caused a stronger decrease of the storage modulus.

  5. Cervical and incisal marginal discrepancy in ceramic laminate veneering materials: A SEM analysis

    Directory of Open Access Journals (Sweden)

    Hemalatha Ranganathan

    2017-01-01

    Full Text Available Context: Marginal discrepancy influenced by the choice of processing material used for the ceramic laminate veneers needs to be explored further for better clinical application. Aims: This study aimed to evaluate the amount of cervical and incisal marginal discrepancy associated with different ceramic laminate veneering materials. Settings and Design: This was an experimental, single-blinded, in vitro trial. Subjects and Methods: Ten central incisors were prepared for laminate veneers with 2 mm uniform reduction and heavy chamfer finish line. Ceramic laminate veneers fabricated over the prepared teeth using four different processing materials were categorized into four groups as Group I - aluminous porcelain veneers, Group II - lithium disilicate ceramic veneers, Group III - lithium disilicate-leucite-based veneers, Group IV - zirconia-based ceramic veneers. The cervical and incisal marginal discrepancy was measured using a scanning electron microscope. Statistical Analysis Used: ANOVA and post hoc Tukey honest significant difference (HSD tests were used for statistical analysis. Results: The cervical and incisal marginal discrepancy for four groups was Group I - 114.6 ± 4.3 μm, 132.5 ± 6.5 μm, Group II - 86.1 ± 6.3 μm, 105.4 ± 5.3 μm, Group III - 71.4 ± 4.4 μm, 91.3 ± 4.7 μm, and Group IV - 123.1 ± 4.1 μm, 142.0 ± 5.4 μm. ANOVA and post hoc Tukey HSD tests observed a statistically significant difference between the four test specimens with regard to cervical marginal discrepancy. The cervical and incisal marginal discrepancy scored F = 243.408, P < 0.001 and F = 180.844, P < 0.001, respectively. Conclusion: This study concluded veneers fabricated using leucite reinforced lithium disilicate exhibited the least marginal discrepancy followed by lithium disilicate ceramic, aluminous porcelain, and zirconia-based ceramics. The marginal discrepancy was more in the incisal region than in the cervical region in all the groups.

  6. Influence of connector design and material composition and veneering on the stress distribution of all-ceramic fixed dental prostheses: a finite element study.

    Science.gov (United States)

    Möllers, Kristina; Pätzold, Wiebke; Parkot, Daniel; Kirsten, Armin; Güth, Jan-Frederik; Edelhoff, Daniel; Fischer, Horst

    2011-08-01

    Finite element analysis is a standard method to simulate the stress distribution in all-ceramic dental restorations in order to estimate the loading capacity of the brittle components. The hypothesis of this study was that stresses in the connector area of a veneered FDP are strongly influenced by the framework dimensions and the veneering material. Finite element analyzes of bilayered fixed dental prostheses with three different framework-designs and three different veneering materials were conducted, applying the loads onto the veneering as well as directly onto the framework. The outer shape of the veneering ceramic remained constant for all cases. The maximum first principal stresses in the framework of the fixed dental prostheses (FDP) decreased with smaller framework dimensions when the load was applied on the veneering. By applying the load directly onto the framework of the FDP without veneering a converse tendency was found. The variation of the veneering material lead to the conclusion that stresses in the framework became higher with decreasing Young's modulus of the veneer, while the stresses in the veneer increased at the same time. The veneering material plays a significant role for the failure of a FDP and cannot be neglected neither in testing nor in simulation. Thus the loading capacity of dental restorations can only be reasonably evaluated when the whole restoration is taken into account, including framework and veneering. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. In-situ evaluation of compressed brick veneer using the flatjack technique

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.R.; Gabby, B.A.

    1999-07-01

    The flatjack is a relatively nondestructive tool that allows engineers engaged in the repair and retrofit of masonry buildings (both historic and non-historic) to directly determine the in-situ state of compressive stress in masonry walls. The flatjack technique recently was used on a large modern apartment complex to quantify the compression in a brick veneer that was distressed and had questionable wind-load resistance. The compression in the veneer was due to a combination of concrete frame shrinkage and brick growth in a wall system that lacked horizontal control joints under the steel shelf angles. Although the compression caused spalling in the veneer, it also contributed beneficially to the walls' wind resistance. The amount of compression in the veneer was determined in several location throughout the height of one elevation of the building using flatjacks. The authors found that the compression in the veneer was greater than the flexural tension produced by design wind loads (including a reasonable factor of safety), but below the compressive strength of the brick masonry. This finding allowed a repair solution that was modest relative to strengthening the wall for inadequate wind resistance. Prior to employing the flatjack in the field, the authors conducted in-house research to check the accuracy and reliability of method, and develop their technique. The authors found that by altering gauge points from those locations prescribed by current ASTM standards to those recommended in recent research, greater accuracy could be obtained.

  8. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    Science.gov (United States)

    Wananuruksawong, R.; Jinawath, S.; Padipatvuthikul, P.; Wasanapiarnpong, T.

    2011-10-01

    Silicon nitride (Si3N4) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si3N4 ceramic as a dental core material. The white Si3N4 was prepared by pressureless sintering at relative low sintering temperature of 1650 °C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si3N4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si3N4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (veneer on the Si3N4 specimens, the firing was performed in electric tube furnace between 1000-1200°C. The veneered specimens fired at 1100°C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98×10-6 °C-1, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  9. Removal of fractured laminate veneers with Er:YAG laser: report of two cases.

    Science.gov (United States)

    Kursoglu, Pinar; Gursoy, Hare

    2013-01-01

    To demonstrate the efficiency of Er:YAG laser for removal of laminate veneers in case of fracture. Primary modes of failure of porcelain laminate veneers were noted to be fracture, microleakage, or debonding. One of the predisposing factors for the occurrence of fractures is heavy functional or parafunctional loading. Removal of fractured laminate veneers with Er:YAG laser is proposed as a reliable method. Two cases are presented in which fractured laminate veneers were removed with Er:YAG laser. The parameters used for removal were set at 20 Hz/320 mJ, with water irrigation for 9 sec and the chisel-type laser tip was selected (1.2×0.4 mm, rectangular shape). The pulse width was 200 ms. The laminates were removed without any damage to the underlying tissue. The new restorations were reconstructed and both patients were taken under recall program at 6-month intervals. The removal of fractured laminate veneers with Er:YAG laser could be a suitable alternative in routine clinical use.

  10. Effects of multiple firings on the mechanical properties and microstructure of veneering ceramics for zirconia frameworks.

    Science.gov (United States)

    Tang, Xuehua; Nakamura, Takashi; Usami, Hirofumi; Wakabayashi, Kazumichi; Yatani, Hirofumi

    2012-05-01

    The purpose of this study is to evaluate the effects of multiple firings on the mechanical properties and microstructure of veneering ceramics used with zirconia frameworks. Five different veneering ceramics for zirconia frameworks were used: Vintage ZR (ZR), Cerabien ZR (CZR), Vita VM9 (VM9), Cercon ceram KISS (KISS), IPS e.max ceram (e.max), and one veneering ceramic used for PFM frameworks: Vintage MP (MP). Twenty specimens were fabricated of each veneering ceramic. Ten specimens were fired twice and another ten specimens were fired ten times. Three-point flexural strength following the ISO 6872 and Vickers hardness were measured, and fracture toughness (K(IC)) was calculated. Density and porosity were determined. Specimens were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). For all materials, density increased and porosity decreased after 10 firings. Significant differences in density and porosity were observed between 2 and 10 firings, with the exception of VM9 (Pveneering ceramics for zirconia restorations. By 10 firings, the density and hardness of the veneering ceramics used with zirconia frameworks were raised, and porosity was reduced. However, no significant changes occurred in flexural strength, fracture toughness or microstructure. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Clinical longevity of ceramic laminate veneers bonded to teeth with and without existing composite restorations up to 40 months

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, Mutlu

    This study evaluated the survival rate of ceramic laminate veneers bonded to teeth with and without existing composite restorations (ECR). Twenty patients (mean age: 49.7 years) received 92 feldspathic ceramic laminate veneers (Shofu Vintage AL) on the maxillary teeth (intact teeth: n = 26; teeth

  12. Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, M.; Ozcan, Mutlu

    Objectives: This randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials. Methods: A total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in

  13. Ten-year outcome of porcelain laminate veneers placed within the general dental services in England and Wales.

    Science.gov (United States)

    Burke, F J T; Lucarotti, P S K

    2009-01-01

    It is the aim of this paper to consider the factors associated with the need for re-intervention on teeth restored with porcelain veneers. A data set was established consisting of adult patients (18 years or older) whose restoration records contained the placement of one or more porcelain laminate veneers. For each tooth treated with a porcelain veneer, the subsequent history of intervention on that tooth was consulted, and the next date of intervention, if any could be found in the extended data set, was obtained. Thus a data set was created of porcelain veneers which have been placed, with their dates of placement and their dates, if any, of re-intervention. Data for over 80,000 different adult patients were analysed, of whom 46% were male and 54% female. A total of 2562 porcelain veneer restoration occasions in 1177 patients were obtained from the data over a period of 11 years. Factors which were found to influence the survival of porcelain veneers include patient gender, patient age, changing dentist, patient's treatment need, patient charge-paying status and geographical area. While dentist factors do not appear to play a part, a variety of patient factors have been found to influence veneer survival to re-intervention. Overall, 53% of porcelain veneers in the study survived without re-intervention at 10 years.

  14. SUITABILITY OF POPLAR AND BEECH LAMINAS FOR LAMINATED VENEER LUMBER MANUFACTURİNG USING MELAMINE FORMALDEHYDE ADHESIVE

    Directory of Open Access Journals (Sweden)

    İlkay Atar

    2016-12-01

    Full Text Available Laminated Veneer Lumber (LVL has been proven their usefulness and efficiency as framing members (girders, beams, joist, headers, panels, etc.in construction. Their application and manufacture is limited in Turkey. In this study, four different types of 7-layers LVLs were successfully manufactured using sawed beech (B and poplar (P veneers, and melamine formaldehyde (MF adhesive. In this work, LVLs were formed with two veneers for each surface and three veneers for core layer. Produced four different types of LVL were coded based on the type and location of the veneers. BBBBBBB, BBPPPBB, PPPPPPP and PPBBBPP were called as Group I, Group II, Group III and Group IV, respectively. As physical properties, oven dry specific gravity (SG and moisture content (MC were determined according to TS 2472 (1976a and TS 2471 (1976b standards. Mechanical properties like glueline shear strength, modulus of rupture (MOR, modulus of elasticity (MOE and compression strength (CS(parallel to grain were also determined according to EN 314-1 (2004,EN310 (1993 and TS 2595 (Anonymous 1977standards, respectively. Based on this study, the highest strength and SG values were obtained with all beech used veneers (Group I. On the other hand lowest values were recorded with all poplar veneers (Group III. It should be noted that contribution rate of beech veneers in LVL had an increase on both strength and SG values.

  15. Effect of Sandblasting on Shear Bond Strength Composite Resin Veneer

    Directory of Open Access Journals (Sweden)

    Octarina Octarina

    2013-07-01

    Full Text Available Attachment between restoration and enamel surface in indirect resin composite veneer restoration (IRCV is obtained using multi-step (MS resin cement. Recently, a one step self-adhesive dual-cured resin cement (SADRC was introduced. Objective: To determine the effect of sandblasting on shear bond strength (SBS of IRCV to enamel using MS resin cement and SADRC. Methods: Forty specimens of buccal surface of enamel human were light-cured in Solidilite chamber and were divided into two groups: IRCV without sandblasting (n=20 and with sandblasting for 10 seconds (n=20 and then bonded to enamel using MS (n=10 and SADRC (n=10, respectively. After 24h SBS of specimens were tested using a Universal Testing Machine. Data were analyzed statistically by one-way ANOVA. Results: The average SBS value of IRCV without SB and bonded with MS was 18.95+7.80MPa and MS with SB was 19.30+ SB (4.85+2.12MPa and SADRC with SB (9.57+3.45MPa(p<0.05. Conclusion: increased SBS VIRK to enamel using MS resin cement than SADRC.  

  16. Contact fatigue of veneer feldspathic porcelain on dental zirconia.

    Science.gov (United States)

    Rueda, A O; Anglada, M; Jimenez-Pique, E

    2015-03-01

    To understand the resistance to cyclic and static contact loading of feldspathic porcelain on dental zirconia (3Y-TZP), in order to understand the partial failure of porcelain (chipping or cracking). Hertzian contact techniques were used to evaluate the appearance of damage as a ring crack in terms of applied load and number of cycles in air and simulated saliva. Static contact loading showed the presence of stress corrosion cracking in the porcelain; the environmental crack growth in air was determined from the results of time to damage under static load. There was also a contribution of fatigue effects due to the interactions of the crack with the microstructure. From the obtained results, a time to failure was estimated depending on the material counterpart. Cracking can occur on porcelain coatings if the contact counterpart is teeth or porcelain in a time interval of a few years, consistent with clinical studies. Contact loading, particularly against teeth or other ceramic materials can be a significant cause of failure and chipping of feldspathic porcelain on zirconia, especially if the patient suffers from bruxism. Protection, by e.g. a guard, against repetitive contact against the porcelain can increase the lifetime of the veneer. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Cyclic testing of porcelain laminiate veneers on superficial enamel and dentin: Pressed vs. conventional layered porcelain

    Science.gov (United States)

    Tawde, Shweta

    Statement of Problem: Clinicians are inclined towards more aggressive teeth preparations to accommodate the thickness of the veneering material. The principle of conservative tooth preparation is compromised. Purpose: By using a conservative approach to treatment with porcelain veneers, long-lasting, esthetic and functional results may be achieved. Sacrificing as little tooth structure as possible and conserving the supporting tissues will facilitate prospective patients. Materials and Methods: Forty extracted human maxillary and mandibular canines were selected. The teeth were divided into one of two groups (pressable and stackable) and further subdivided according to tooth substrate (all-enamel or mixed enamel-dentin exposure). Twenty canine teeth were allotted to the pressable veneer group and 20 were allotted to the stackable veneer group. Of the 20 teeth in the pressable group, all were pressed with a lithium disilicate ceramic system (IPS e.max Press), 10 with labial tooth reduction of 0.3-0.5 mm maintaining superficial enamel (PEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (PDN). Of the 20 teeth in the stackable group, all were stacked/ layered with conventional feldspathic porcelain (Fortune; Williams/ Ivoclar); with labial veneer reduction of 0.3-0.5 mm maintaining superficial enamel (SEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (SDN). Silicon putty matrix was fabricated prior to teeth preparation to estimate the teeth reduction. The prepared facial reduction was limited to the incisal edge. No incisal or palatal/lingual reduction was performed. Impressions of the prepared teeth were taken in medium/light-bodied PVS. Master casts were made in Resin Rock. The stackable group specimens were made with fabricating refractory dies and after following the recommended steps of laboratory procedure, stackable veneers were processed. The pressable group

  18. Modified maximum tangential stress criterion for fracture behavior of zirconia/veneer interfaces.

    Science.gov (United States)

    Mirsayar, M M; Park, P

    2016-06-01

    The veneering porcelain sintered on zirconia is widely used in dental prostheses, but repeated mechanical loadings may cause a fracture such as edge chipping or delamination. In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bi-layered components subjected to mixed mode loadings, the accuracy of a new and traditional fracture criteria are investigated. A modified maximum tangential stress criterion considering the effect of T-stress and critical distance theory is introduced, and compared to three traditional fracture criteria. Comparisons to the recently published fracture test data show that the traditional fracture criteria are not able to properly predict the fracture initiation conditions in zirconia/veneer bi-material joints. The modified maximum tangential stress criterion provides more accurate predictions of the experimental results than the traditional fracture criteria. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Minimally Invasive Laminate Veneers: Clinical Aspects in Treatment Planning and Cementation Procedures

    Directory of Open Access Journals (Sweden)

    R. K. Morita

    2016-01-01

    Full Text Available When a definitive aesthetic treatment is determined, it is crucial to grant the patient’s wish with the necessary dental treatment. Thus, conservative treatments that are the solution to aesthetic problems involving morphologic modifications and provide the result that the patient expects should always be the first therapeutic option. In this context, ceramic laminate veneers, also known as “contact lens,” are capable of providing an extremely faithful reproduction of the natural teeth with great color stability and periodontal biocompatibility. Minimal or no preparation veneers are heavily advertised as the answer to our patients’ cosmetic needs, which they can be if they are used correctly in the appropriate case. This report is about ultraconservative restorations to achieve functional and aesthetic rehabilitation through treatment planning. Thus, clinicians should be aware that the preparation for laminate veneers remains within enamel, to ensure the bond strength and avoid or minimize the occurrence of postoperative sensitivity.

  20. Minimally Invasive Laminate Veneers: Clinical Aspects in Treatment Planning and Cementation Procedures

    Science.gov (United States)

    Morita, R. K.; Hayashida, M. F.; Berger, G.; Reggiani, R. D.; Betiol, E. A. G.

    2016-01-01

    When a definitive aesthetic treatment is determined, it is crucial to grant the patient's wish with the necessary dental treatment. Thus, conservative treatments that are the solution to aesthetic problems involving morphologic modifications and provide the result that the patient expects should always be the first therapeutic option. In this context, ceramic laminate veneers, also known as “contact lens,” are capable of providing an extremely faithful reproduction of the natural teeth with great color stability and periodontal biocompatibility. Minimal or no preparation veneers are heavily advertised as the answer to our patients' cosmetic needs, which they can be if they are used correctly in the appropriate case. This report is about ultraconservative restorations to achieve functional and aesthetic rehabilitation through treatment planning. Thus, clinicians should be aware that the preparation for laminate veneers remains within enamel, to ensure the bond strength and avoid or minimize the occurrence of postoperative sensitivity. PMID:28070427

  1. Providing a harmonious smile with laminate veneers for a patient with peg-shaped lateral incisors.

    Science.gov (United States)

    Alberton, Simone Beatriz; Alberton, Victória; de Carvalho, Rodrigo Varella

    2017-01-01

    The most common discrepancy concerning tooth size is the presence of peg-shaped lateral incisors, which can cause teeth with reduced size, anterior diastema, and consequently an unpleasant smile. The development of the adhesive dentistry and ceramic veneers allowed all ceramic-bonded restorations to become an esthetic and functional approach to reestablish the smile harmony. The purpose of this clinical report is to describe a conservative treatment approach to recover an esthetic disharmony caused by bilateral peg-shaped lateral incisors. A 30-year-old female patient was seeking treatment to solve an esthetic disharmony of her smile. Lithium disilicate veneers were planned and build-up with the help of diagnostic models, wax-up, mock-up, and silicone guides, to restore the morphology, size, function, and esthetic of upper lateral incisors and smile. The lithium disilicate veneers were able to provide the harmonization of the patient's smile, recovering the teeth size, shape, and anatomic characteristics.

  2. Minimally Invasive Laminate Veneers: Clinical Aspects in Treatment Planning and Cementation Procedures.

    Science.gov (United States)

    Morita, R K; Hayashida, M F; Pupo, Y M; Berger, G; Reggiani, R D; Betiol, E A G

    2016-01-01

    When a definitive aesthetic treatment is determined, it is crucial to grant the patient's wish with the necessary dental treatment. Thus, conservative treatments that are the solution to aesthetic problems involving morphologic modifications and provide the result that the patient expects should always be the first therapeutic option. In this context, ceramic laminate veneers, also known as "contact lens," are capable of providing an extremely faithful reproduction of the natural teeth with great color stability and periodontal biocompatibility. Minimal or no preparation veneers are heavily advertised as the answer to our patients' cosmetic needs, which they can be if they are used correctly in the appropriate case. This report is about ultraconservative restorations to achieve functional and aesthetic rehabilitation through treatment planning. Thus, clinicians should be aware that the preparation for laminate veneers remains within enamel, to ensure the bond strength and avoid or minimize the occurrence of postoperative sensitivity.

  3. Providing a harmonious smile with laminate veneers for a patient with peg-shaped lateral incisors

    Science.gov (United States)

    Alberton, Simone Beatriz; Alberton, Victória; de Carvalho, Rodrigo Varella

    2017-01-01

    The most common discrepancy concerning tooth size is the presence of peg-shaped lateral incisors, which can cause teeth with reduced size, anterior diastema, and consequently an unpleasant smile. The development of the adhesive dentistry and ceramic veneers allowed all ceramic-bonded restorations to become an esthetic and functional approach to reestablish the smile harmony. The purpose of this clinical report is to describe a conservative treatment approach to recover an esthetic disharmony caused by bilateral peg-shaped lateral incisors. A 30-year-old female patient was seeking treatment to solve an esthetic disharmony of her smile. Lithium disilicate veneers were planned and build-up with the help of diagnostic models, wax-up, mock-up, and silicone guides, to restore the morphology, size, function, and esthetic of upper lateral incisors and smile. The lithium disilicate veneers were able to provide the harmonization of the patient's smile, recovering the teeth size, shape, and anatomic characteristics. PMID:29279628

  4. The failure load of CAD/CAM generated zirconia and glass-ceramic laminate veneers with different preparation designs.

    Science.gov (United States)

    Alghazzawi, Tariq F; Lemons, Jack; Liu, Perng-Ru; Essig, Milton E; Janowski, Gregg M

    2012-12-01

    Fracture of feldspathic porcelain laminate veneers represents a significant mode of clinical failure. Therefore, ceramic materials that withstand a higher load to fracture, especially for patients with parafunctional habits, are needed. The purpose of this study was to examine the correlation of material (zirconia, TZP, glass-ceramic, IEC, and feldspathic porcelain, FP) design (incisal overlapped preparation, IOP, and three-quarter preparation, TQP), and fracture mode to failure load for veneers supported by composite resin abutments. A typodont tooth prepared with 2 designs (IOP, TQP) and the corresponding 2 definitive dies were used to fabricate the composite resin abutments (30 for IOP and 30 for TQP). Ten veneer specimens for each system (Y-TZP, IEC, and FP), were fabricated for each design. The veneers were cemented, invested, and tested in compression until failure by using a universal testing machine. Significant differences were evaluated by 2-factor ANOVA (α=.05). No statistical mean load difference was noted between the preparation designs for Y-TZP (IOP: 244 ±81 and TQP: 224 ±58 N), IEC (IOP: 306 ±101 and TQP: 263 ±77 N), and FP veneers (IOP: 161 ±93 and TQP: 246 ±45 N). No statistical difference in the mean load was found among the 3 veneer materials for each preparation design except between IEC (306 ±101 N) and FP (161 ±93 N) veneers for TQP. Preparation design did not influence the failure load of the veneer materials. Zirconia veneers were the least likely to fracture but the most likely to completely debond; feldspathic porcelain veneers exhibited the opposite characteristics. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  5. Spectrophotometric Study of the Effect of Luting Agents on the Resultant Shade of Ceramic Veneers: An Invitro Study.

    Science.gov (United States)

    Jankar, Ajit Suryakant; Kale, Yogesh; Pustake, Swati; Bijjaragi, Shobha; Pustake, Bhushan

    2015-09-01

    Dentistry has found practically the best available aesthetic answer, is ceramic restoration. There are various factors that contribute to the success of ceramic veneers, like colour of underlying tooth, thickness if ceramics and the type of underlying luting cement. Shade selection and matching remains still challenge, however the shade of luting agent used for cementation of veneers produces a change in resultant shade of veneers. To compare and analyze the spectrophotometric effect of opaque and transparent luting agent on resultant shade of ceramic veneers made of 2L1.5 shade (Vitapan 3D-Masters) and B2 shade (Vitapan Classic). Out of 15 ceramic veneers of 2L1.5 shade (VITAPAN 3D- Master), seven teeth cemented with opaque cement and eight teeth with transparent cement shade of dual cure resin cement (Variolink II(TM)). Out of 10 ceramic veneers of B2 shade (VITAPAN Classic), five teeth were cemented with opaque cement and other five teeth with transparent cement shade of dual cure resin cement (Variolink II(TM)). Spectrophotometric (Macbeth U.S.A.) analysis of all ceramic veneer crowns done with optiview software and readings were recorded in Commission Internationale de I' Eclairge {CIELAB} system and dE value was calculated. Statistical analysis was done by using Paired t-test. Spectrophotometric analysis of all the veneers cemented with opaque luting agent were lighter in shade due to significant change in dL value. Veneers cemented with transparent luting agent were darker in shade due to significant change in the dL value. Opaque luting agent gives lighter shade and transparent luting agent gives darker shade to ceramic veneers fabricated with 2L1.5 and B2 shades.

  6. Spectrophotometric Study of the Effect of Luting Agents on the Resultant Shade of Ceramic Veneers: An Invitro Study

    Science.gov (United States)

    Kale, Yogesh; Pustake, Swati; Bijjaragi, Shobha; Pustake, Bhushan

    2015-01-01

    Introduction Dentistry has found practically the best available aesthetic answer, is ceramic restoration. There are various factors that contribute to the success of ceramic veneers, like colour of underlying tooth, thickness if ceramics and the type of underlying luting cement. Shade selection and matching remains still challenge, however the shade of luting agent used for cementation of veneers produces a change in resultant shade of veneers. Aim To compare and analyze the spectrophotometric effect of opaque and transparent luting agent on resultant shade of ceramic veneers made of 2L1.5 shade (Vitapan 3D-Masters) and B2 shade (Vitapan Classic). Materials and Methods Out of 15 ceramic veneers of 2L1.5 shade (VITAPAN 3D- Master), seven teeth cemented with opaque cement and eight teeth with transparent cement shade of dual cure resin cement (Variolink IITM). Out of 10 ceramic veneers of B2 shade (VITAPAN Classic), five teeth were cemented with opaque cement and other five teeth with transparent cement shade of dual cure resin cement (Variolink IITM). Spectrophotometric (Macbeth U.S.A.) analysis of all ceramic veneer crowns done with optiview software and readings were recorded in Commission Internationale de I’ Eclairge {CIELAB} system and dE value was calculated. Statistical Analysis Statistical analysis was done by using Paired t-test. Results Spectrophotometric analysis of all the veneers cemented with opaque luting agent were lighter in shade due to significant change in dL value. Veneers cemented with transparent luting agent were darker in shade due to significant change in the dL value. Conclusion Opaque luting agent gives lighter shade and transparent luting agent gives darker shade to ceramic veneers fabricated with 2L1.5 and B2 shades. PMID:26501014

  7. Fracture strength of veneered translucent zirconium dioxide crowns with different porcelain thicknesses

    Science.gov (United States)

    Bakitian, Fahad; Seweryniak, Przemek; Papia, Evaggelia; Larsson, Christel; Vult von Steyern, Per

    2017-01-01

    Abstract Objective: To evaluate fracture strength of veneered translucent zirconium dioxide crowns designed with different porcelain layer thicknesses. Materials and Methods: Sixty crowns, divided into six groups of 10, were used in this study. Groups were divided according to different thicknesses of porcelain veneer on translucent zirconium dioxide cores of equal thickness (0.5 mm). Porcelain thicknesses were 2.5, 2.0, 1.0, 0.8, 0.5 and 0.3 mm. Crowns were artificially aged before loaded to fracture. Determination of fracture mode was performed using light microscope. Results: Group 1.0 mm showed significantly (p ≤ .05) highest fracture loads (mean 1540 N) in comparison with groups 2.5, 2.0 and 0.3 mm (mean 851, 910 and 1202 N). There was no significant difference (p>.05) in fracture loads among groups 1.0, 0.8 and 0.5 mm (mean 1540, 1313 and 1286 N). There were significantly (p ≤ .05) more complete fractures in group 0.3 mm compared to all other groups which presented mainly cohesive fractures. Conclusions: Translucent zirconium dioxide crowns can be veneered with minimal thickness layer of 0.5 mm porcelain without showing significantly reduced fracture strength compared to traditionally veneered (1.0–2.0 mm) crowns. Fracture strength of micro-veneered crowns with a layer of porcelain (0.3 mm) is lower than that of traditionally veneered crowns but still within range of what may be considered clinically sufficient. Porcelain layers of 2.0 mm or thicker should be used where expected loads are low only. PMID:29242815

  8. How will surface treatments affect the translucency of porcelain laminate veneers?

    Science.gov (United States)

    Turgut, Sedanur; Bagis, Bora; Ayaz, Elif Aydogan; Korkmaz, Fatih Mehmet; Ulusoy, Kıvanç Utku; Bagis, Yildirim Hakan

    2014-02-01

    The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 30-µm Al2O3 [corrected]; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (α=0.05). There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values.

  9. Relative translucency of six all-ceramic systems. Part II: core and veneer materials.

    Science.gov (United States)

    Heffernan, Michael J; Aquilino, Steven A; Diaz-Arnold, Ana M; Haselton, Debra R; Stanford, Clark M; Vargas, Marcos A

    2002-07-01

    STATEMENT OF PROBLEM All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material. This study compared the translucency of 6 all-ceramic materials veneered and glazed at clinically appropriate thicknesses. Core specimens (n = 5 per group) of Empress dentin, Empress 2 dentin, In-Ceram Alumina, In-Ceram Spinell, In-Ceram Zirconia, and Procera AllCeram were fabricated as described in Part I of this study and veneered with their corresponding dentin porcelain to a final thickness of 1.47 +/- 0.01 mm. These specimens were compared with veneered Vitadur Alpha opaque dentin (as a standard), a clear glass disc (positive control), and a high-noble metal-ceramic alloy (Porc. 52 SF) veneered with Vitadur Omega dentin (negative control). Specimen reflectance was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Measurements were repeated after a glazing cycle. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white backing (Yw) to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (Pceramic systems tested when they were veneered (Pceramic systems tested. Such variability may affect their ability to match natural teeth. The glazing cycle resulted in decreased opacity for all test materials except the completely opaque In-Ceram Zirconia and metal-ceramic specimens.

  10. How will surface treatments affect the translucency of porcelain laminate veneers?

    Science.gov (United States)

    Turgut, Sedanur; Ayaz, Elif Aydogan; Korkmaz, Fatih Mehmet; Ulusoy, Kıvanç Utku; Bagis, Yildirim Hakan

    2014-01-01

    PURPOSE The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. MATERIALS AND METHODS A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 50-µm Al2O3; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (α=0.05). RESULTS There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). CONCLUSION The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values. PMID:24605200

  11. Adhesion mechanisms at the interface between Y-TZP and veneering ceramic with and without modifier.

    Science.gov (United States)

    Monaco, Carlo; Tucci, Antonella; Esposito, Leonardo; Scotti, Roberto

    2014-11-01

    This study investigated the mechanism of action at the interface between a commercially available Y-TZP and its veneering ceramic after final firing. Particular attention was paid, from a microstructural point of view, to evaluating the effects of different surface treatments carried out on the zirconia. In total, 32 specimens of presintered zirconia Y-TZP (LavaFrame, 3M ESPE, Germany) were cut with a low-speed diamond blade. The specimens were divided in two major groups, for testing after fracture or after mirror finishing, and were sintered following the manufacturer's instructions. Each major group was then randomly divided into four subgroups, according to using or not using the dedicated framework modifier, with or without a preliminary silica coating (CoJet, 3M ESPE). A suitable veneering ceramic was used for each group (Lava Ceram Overlay Porcelain, 3M ESPE). A detailed microstructural study of the interfaces of the zirconia-veneering ceramic was performed using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer to evaluate chemical variation at the interfaces. When the framework modifier was not applied on the Y-TZP surface, microdetachments, porosities, and openings in the ceramic layer were observed at the interlayers. A degree of diffusion of different elements through the interfaces from both the zirconia and veneering layers was detected. Application of the framework modifier can increase the wettability of the zirconia surfaces, allowing a continuous contact with the veneering layer. The micro-analysis performed showed the presence of a reaction area at the interface between the different materials. the increase of the wettability of the zirconia surface could improve the adhesion at interface with the veneering ceramic and reduce the clinical failure as chipping or delamination. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Influence of cooling rate on residual stress profile in veneering ceramic: measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2011-09-01

    The manufacture of dental crowns and bridges generates residual stresses within the veneering ceramic and framework during the cooling process. Residual stress is an important factor that control the mechanical behavior of restorations. Knowing the stress distribution within the veneering ceramic as a function of depth can help the understanding of failures, particularly chipping, a well-known problem with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objective of this study is to investigate the cooling rate dependence of the stress profile in veneering ceramic layered on metal and zirconia frameworks. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. The stress profile was measured in bilayered disc samples 20 mm in diameter, with a 0.7 mm thick metal or Yttria-tetragonal-zirconia-polycrystal framework and a 1.5mm thick veneering ceramic. Three different cooling procedures were investigated. The magnitude of the stresses in the surface of the veneering ceramic was found to increase with cooling rate, while the interior stresses decreased. At the surface, compressive stresses were observed in all samples. In the interior, compressive stresses were observed in metal samples and tensile in zirconia samples. Cooling rate influences the magnitude of residual stresses. These can significantly influence the mechanical behavior of metal-and zirconia-based bilayered systems. The framework material influenced the nature of the interior stresses, with zirconia samples showing a less favorable stress profile than metal. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. The color differences between different thicknesses of resin veneered over amalgam.

    Science.gov (United States)

    Al-Jazairy, Yousra Hussain; El-Hejazi, Ahmed A

    2005-11-15

    Composites and compomers are popular in dental practice. However, little is known about their esthetic appearance as veneering restorative materials over amalgam restorations. This in vitro study was designed to assess the color differences of composite and compomer restorative materials, placed in thicknesses of 1 mm and 2 mm over amalgam. Thirty six cylindrical Teflon molds were filled with amalgam (13 mm diameter, 2 mm thickness) and stored at 37 degrees C and 100% relative humidity for 7 days. Nine veneers (for each thickness of 1 and 2 mm) were fabricated from four types of tooth-colored restorative material, Dyract AP (DYR), Compoglass F (COMP), Herculite XRV (XRV), and Vitalecense (VIT), over amalgam specimens using Teflon-split molds and following the manufacturers' instructions. A spectrophotometer was used to measure the color difference DeltaE* between the two thicknesses. Color difference DeltaE* values for 1 mm thickness veneers [XRV (2.52), Comp (5.46), VIT (6.73), and DYR (6.88)] were statistically significantly higher than the 2 mm thickness [XRV (1.32), Comp (3.24), VIT (4.89), and DYR (4.83)]. Although the XRV material had the lowest DeltaE* values, no statistically significant difference was found between the two thicknesses. The color measurements at L*, a*, and b* showed most materials became darker in color at either thickness. The thicker veneer specimens were found to be closer in color to the controls than the thinner specimens. Only XRV had color differences (DeltaE*) small enough to be considered clinically acceptable (2.52 and 1.32 at 1 mm and 2 mm, respectively). In this in vitro study the color of XRV was affected the least when veneered on amalgam. Opaquers may be needed to be used with thinner veneers to minimize the effect of amalgam background.

  14. Effects of core and veneer thicknesses on the color of CAD-CAM lithium disilicate ceramics.

    Science.gov (United States)

    Kang, Wol; Park, Jong-Kyoung; Kim, So-Ri; Kim, Woong-Chul; Kim, Ji-Hwan

    2017-07-06

    The color of dental ceramics is important for achieving successful esthetic restorations. However, insufficient studies are available of the color of recently introduced computer-aided design-computer-aided manufacturing (CAD-CAM) lithium disilicate ceramics as functions of the core and veneer thicknesses. The purpose of this in vitro study was to evaluate the effects of the thickness of different core and veneer thicknesses on the color of CAD-CAM lithium disilicate ceramics. A total of 42 specimens from 2 groups of 7 ceramic cores at 3 thicknesses (0.8, 1.0, and 1.2 mm) were fabricated. The veneer was fabricated at 3 thicknesses (0.3, 0.5, and 0.7 mm). The group name was based on the name of the ceramic core (IPS e.max CAD; lithium disilicate [LD], IPS Empress CAD; leucite-reinforced glass-ceramic [LR]), and the associated number was determined by the combined thicknesses of the core and the veneer: 1=0.8+0.7; 2=1.0+0.5; and 3=1.2+0.3. The color coordinates and the color differences were calculated using a spectrophotometer. The color difference was analyzed using the CIEDE2000 chrominance and the acceptability threshold. Two-way ANOVA was used to identify the color difference based on the core/veneer thicknesses, and the Tukey honest significant differences and Games-Howell tests were conducted to verify the ΔE00 differences of the group (α=.05). In addition, regression analysis was carried out to estimate the causal relationship between the independent variables and the chrominance. At a certain thickness, the color differences of LD1, LR1, and LR2 were not clinically acceptable based on the thicknesses of the core and the veneer. Results of 2-way ANOVA demonstrated that the different thicknesses of core/veneer combination significantly affected the color difference (Pcore decreased by 0.2 mm. The color is influenced by the thicknesses of the core and the veneer. With a certain thickness, the color differences increased as the thickness of the core

  15. Influence of ceramic color and translucency on shade match of CAD/CAM porcelain veneers.

    Science.gov (United States)

    Salameh, Ziad; Tehini, Georges; Ziadeh, Norma; Ragab, Hala A; Berberi, Antoine; Aboushelib, Moustafa Nabil

    2014-01-01

    To investigate the influence of translucency of CAD/CAM ceramic milling blocks on the final color of porcelain veneer cemented using resin cement with two different opacities. A standardized incisal lap preparation was made on a maxillary right central incisor that was duplicated using composite resin material (Z250, A4, 3M ESPE). The resin dies were individually laser scanned (Bluecam, Sirona) in order to build a 3D model of the porcelain veneer on the CAD software (Cerec 3D). Three types of milling blocks were used to fabricate the required restorations: multichromatic, high translucency, and low translucency milling blocks (IPS Empress CAD, A1 Vita shade tab). The milled veneers were polished, glazed, and bonded on the resin dies using high opacity and low opacity resin cements (Panavia F2.0). A digital shade guide device (Easyshade Advance, Vita) was used to measure color parameters (CIE Lab values) at the incisal, middle, and cervical third of each cemented restoration. ΔE values of the cemented veneers were calculated against the target color (A1). Cementation of porcelain veneers resulted in significant color change of the resin die (A4) as ΔE values ranged between 8.9 and 13.7. However, the type of milling block did not have an observable effect on final color as the measured ΔE values, against original die color, were very close for the multichromatic block (ΔE = 10.7 ± 0.1), high translucency (ΔE = 9.7 ± 0.09), and low translucency blocks (ΔE = 13.4 ± 0.11). The opacity of the used resin cement did not affect the final shade match, as the observed ΔE values using either high opacity and low opacity resin cement were less than 2 for the three used ceramic blocks. The greatest color difference was observed between the incisal third of multichromatic veneers (ΔE = 8.9) and the cervical third of low translucency veneers (ΔE = 13.7), while for the rest of the test groups this shift was not clinically observable (ΔE veneers was not influenced by

  16. Using acrylic resin tooth veneers in patients with an abnormal jaw relationship: a case report.

    Science.gov (United States)

    Yang, Tsung-Chieh; Lan, Yi-Hao; Wang, Tong-Mei; Tu, Ching-Yu; Lin, Li-Deh

    2014-01-01

    This case report describes and evaluates a method of arranging artificial teeth in patients with an abnormal jaw relationship in which a wider maxillary arch opposes a narrower mandibular arch. First, the fossa of mandibular posterior teeth was positioned on the crest of the mandibular edentulous ridge. The maxillary posterior teeth were then placed palatally to maximize occlusal contacts with the opposing mandibular teeth. Finally, acrylic resin tooth veneers were attached on the buccal surface of posterior maxillary teeth to improve the arch discrepancy. This method addresses functional considerations with the inner aspect of teeth and esthetic considerations with acrylic resin tooth veneers.

  17. Esthetic improvement in the patient with one missing maxillary central incisor restored with porcelain laminate veneers

    Science.gov (United States)

    Park, Dong-Jin; Yang, Jae-Ho; Lee, Jai-Bong; Kim, Sung-Hun

    2010-01-01

    This article describes esthetic improvement in a patient with a missing maxillary left central incisor. Space analysis of the anterior dentition showed that minor tooth rearrangement was needed. Optimal space distribution for restorations was attained by orthodontic treatment. Through transforming tooth shape with porcelain laminate veneers, the maxillary left lateral incisor was transformed into central incisor and the maxillary left canine into a lateral incisor. The maxillary right central incisor was also restored for esthetic improvement. In a case of changing a tooth shape with porcelain laminate veneers, pre-treatment evaluation, space analysis and diagnostic wax-up are important factors. PMID:21165273

  18. Analyzing the effect of ion exchange on flexural strength of cermaco II and colorlogic veneer porcelains

    Directory of Open Access Journals (Sweden)

    N. Rashidan

    1998-04-01

    Full Text Available   The major foible of dental ceramics is their brittle nature. Therefore, the producers of these materials have focused on the “strength” issue. A method of increasing strength is ion exchange on porcelain surface which leads to formation of a compressive crust that opposing forces should overcome before developing a crack. In current study, ion exchange in two types of porcelain, Ceramco II which is used in PFM restorations and Colorloic veneer which is used for laminates, veneers, inlays and onlays, are evaluated. Additionally, laminate porcelains, etching effect on strength of porcelain and interaction of acid etching and ion exchange have been studied.

  19. A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers.

    Science.gov (United States)

    Durán Ojeda, Gerardo; Henríquez Gutiérrez, Ismael; Guzmán Marusic, Álvaro; Báez Rosales, Abelardo; Tisi Lanchares, José Pablo

    2017-01-01

    The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein) which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein) through the layering technique.

  20. A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers

    Directory of Open Access Journals (Sweden)

    Gerardo Durán Ojeda

    2017-01-01

    Full Text Available The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein through the layering technique.

  1. A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers

    Science.gov (United States)

    Henríquez Gutiérrez, Ismael; Guzmán Marusic, Álvaro; Báez Rosales, Abelardo; Tisi Lanchares, José Pablo

    2017-01-01

    The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein) which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein) through the layering technique. PMID:28884029

  2. Esthetic restorations of maxillary anterior teeth with orthodontic treatment and porcelain laminate veneers: a case report

    Science.gov (United States)

    Moon, Ji-Eun; Kim, Sung-Hun; Han, Jung-Suk; Yang, Jae-Ho

    2010-01-01

    If orthodontists and restorative dentists establish the interdisciplinary approach to esthetic dentistry, the esthetic and functional outcome of their combined efforts will be greatly enhanced. This article describes satisfying esthetic results obtained by the distribution of space for restoration by orthodontic treatment and porcelain laminate veneers in uneven space between maxillary anterior teeth. It is proposed that the use of orthodontic treatment for re-distribution of the space and the use of porcelain laminate veneers to alter crown anatomy provide maximum esthetic and functional correction for patients with irregular interdental spacing. PMID:21165191

  3. Esthetic Rehabilitation with Direct Composite Veneering: A Report of 2 Cases

    Directory of Open Access Journals (Sweden)

    Kyatham Sowmya

    2017-01-01

    Full Text Available Esthetic or cosmetic dentistry is one of the main areas of dental practice. Increasing demand of patients for esthetics has resulted in the development of several techniques for restoring the anterior teeth. Composite resin restorations have become an integral part of contemporary restorative dentistry and can be called “star of minimal invasion” due to its conservative concepts. The direct composite veneering allows restoring the tooth in a natural way and preservation of sound tooth structure when compared to indirect restorations. This article presents two case reports of esthetic rehabilitation of anterior teeth using direct composite veneering with two-year follow-up with acceptable outcome.

  4. Esthetic Rehabilitation with Direct Composite Veneering: A Report of 2 Cases.

    Science.gov (United States)

    Sowmya, Kyatham; Dwijendra, K S; Pranitha, V; Roy, Konda Karthik

    2017-01-01

    Esthetic or cosmetic dentistry is one of the main areas of dental practice. Increasing demand of patients for esthetics has resulted in the development of several techniques for restoring the anterior teeth. Composite resin restorations have become an integral part of contemporary restorative dentistry and can be called "star of minimal invasion" due to its conservative concepts. The direct composite veneering allows restoring the tooth in a natural way and preservation of sound tooth structure when compared to indirect restorations. This article presents two case reports of esthetic rehabilitation of anterior teeth using direct composite veneering with two-year follow-up with acceptable outcome.

  5. Esthetic and functional rehabilitation of crowded mandibular anterior teeth using ceramic veneers: a case report.

    Science.gov (United States)

    de Andrade, Oswaldo Scopin; Ferreira, Luiz Alves; Hirata, Ronaldo; Rodrigues, Flavia Pires; D'Alpino, Paulo Henrique Perlatti; Di Hipolito, Vinicius

    2012-09-01

    The use of ceramic veneers to restore crowded teeth in the maxilla has been widely discussed in the literature. However, the use of this technique in the mandible has received little attention. Therefore, this case report describes the treatment of crowded mandibular anterior teeth using ceramic veneers. The primary treatment challenge in this region is the reduced tooth structure available for rehabilitation. Proper communication between the clinician and dental technician is required to achieve clinical success. This article presents a straightforward treatment plan and restorative technique that includes both the clinical and laboratory sequences necessary for predictable and stable postoperative outcomes.

  6. Primary forest products industry and timber use, Minnesota, 1973.

    Science.gov (United States)

    James E. Blyth; Steven Wilhelm; Jerold T. Hahn

    1979-01-01

    Discusses recent Minnesota forest industry trends; timber removals for industrial roundwood in 1973; production and receipts in 1973 of pulpwood, saw logs, and other industrial roundwood products. Shows trends in pulpwood and veneer log production and compares saw log production in 1960 and 1973. Discusses primary wood-using mill residue and its disposition.

  7. Evaluation of shear bond strength between zirconia core and ceramic veneers fabricated by pressing and layering techniques: In vitro study.

    Science.gov (United States)

    Subash, M; Vijitha, D; Deb, Saikat; Satish, A; Mahendirakumar, N

    2015-08-01

    Although ceramic veneered on to zirconia core have been in use for quite some time, information regarding the comparative evaluation of the Shear bond strength of Pressable & Layered ceramic veneered on to zirconia core is limited. To evaluate the shear bond strength of zirconia core and ceramic veneer fabricated by two different techniques, Layering (Noritake CZR) and Pressing (Noritake, CZR Press). 20 samples of zirconia blocks were fabricated and the samples were divided into group A & B. Group A - Ceramic Veneered over zirconia core by pressing using Noritake CZR Press. Group B - Ceramic Veneered over zirconia core by layering using Noritake CZR. The veneered specimens were mounted on to the center of a PVC tube using self-cure acrylic resin leaving 3 mm of the veneered surface exposed as cantilever. Using a Universal testing machine the blocks were loaded up to failure. The results were tabulated by using independent samples t-test. The mean shear bond strength for Pressed specimens was 12.458 ± 1.63(S.D) MPa and for layered specimens was 8.458 ± 0.845(S.D) MPa. Pressed specimens performed significantly better than the layered specimen with a P value 0.001. Clinicians and dental laboratory technicians should consider the use of pressed ceramics as an alternative to traditional layering procedures to reduce the chances of chipping or de-lamination of ceramics.

  8. Fracture resistance and marginal discrepancy of porcelain laminate veneers influenced by preparation design and restorative material in vitro.

    Science.gov (United States)

    Lin, Tai-Min; Liu, Perng-Ru; Ramp, Lance C; Essig, Milton E; Givan, Daniel A; Pan, Yu-Hwa

    2012-03-01

    The purpose of this investigation is to evaluate marginal discrepancy and fracture resistance of two veneering materials using two preparation designs. Two veneer preparation designs (full and traditional) were restored with leucite-reinforced ceramic (ProCAD, Ivoclar Vivadent, Amherst, NY) milled by CAD/CAM (Cerec 3D milling system, Serona Dental Systems), and conventional sintered feldspathic porcelain (Noritake Super Porcelain EX3, Noritake Dental Supply Co). Forty-eight specimens were analysed with a sample size of n=12 per group. The thickness of each veneer was measured on four specific surfaces. Marginal discrepancy was evaluated with a replica technique and cross-sectional view using a digital microscope. The fracture resistance of veneers cemented on standardised composite resin dies was evaluated using a universal testing machine. Results were analysed with ANOVA, Tukey-Kramer post hoc testing, and linear regression. The results of this investigation revealed no correlation between the thickness and marginal discrepancy of the veneers. The full preparation design with ProCAD and the traditional preparation design with feldspathic porcelain manifested smaller gap. Fracture resistance was decreased for the full preparation design with feldspathic porcelain. In terms of marginal discrepancy and fracture resistance, the most favourable combination was a traditional veneer preparation design with conventional sintered feldspathic porcelain. For the full veneer preparation, a stronger ceramic material such as ProCAD is suggested. Published by Elsevier Ltd.

  9. Influence of abutment type and esthetic veneering on preload maintenance of abutment screw of implant-supported crowns.

    Science.gov (United States)

    Delben, Juliana Aparecida; Barão, Valentim Adelino Ricardo; Dos Santos, Paulo Henrique; Assunção, Wirley Gonçalves

    2014-02-01

    The effect of veneering materials on screw joint stability remains inconclusive. Thus, this study evaluated the preload maintenance of abutment screws of single crowns fabricated with different abutments and veneering materials. Sixty crowns were divided into five groups (n = 12): UCLA abutment in gold alloy with ceramic (group GC) and resin (group GR) veneering, UCLA abutment in titanium with ceramic (group TiC) and resin (group TiR) veneering, and zirconia abutment with ceramic veneering (group ZiC). Abutment screws made of gold were used with a 35 Ncm insertion torque. Detorque measurements were obtained initially and after mechanical cycling. Data were analyzed by ANOVA and Fisher's exact test at a significance level of 5%. For the initial detorque means (in Ncm), group TiC (21.4 ± 1.78) exhibited statistically lower torque maintenance than groups GC (23.9 ± 0.91), GR (24.1 ± 1.34), and TiR (23.2 ± 1.33) (p veneering material. More irregular surfaces in the hexagon area of the castable abutments were observed. The superiority of any veneering material concerning preload maintenance was not established. © 2013 by the American College of Prosthodontists.

  10. [Effect of ceramic thickness and resin cement shades on final color of heat-pressed ceramic veneers].

    Science.gov (United States)

    Ren, D F; Zhan, K R; Chen, X D; Xing, W Z

    2017-02-09

    Objective: To analyze the effect of ceramic materials thickness and resin cement shades on the final color of ceramic veneers in the discolored teeth, and to investigate the color agreement of try-in pastes to the corresponding resin cements. Methods: Sixty artificial maxillary central incisor teeth (C2 shade) were used to simulate the natural discolored teeth and prepared according to veneer tooth preparation protocol. Veneers of different thickness in the body region (0.50 and 0.75 mm) were fabricated using ceramic materials (LT A2 shade, IPS e.max Press). The ceramic veneer specimens were bonded to the artificial teeth using the 6 shades of resin cements (Variolink Veneer: shades of LV-3, LV-2, HV+3; RelyX™ Veneer: shades of TR, A3, WO) ( n= 5). A clinical spectrophotometer was used to measure the color parameters of ceramic veneers at the cervical, body and incisal regions. Color changes of veneers before and after cementation were calculated and registered as ΔE1, and the changes between try-in paste and the corresponding resin cements were registered as ΔE2. Results: Three-way ANOVA indicated that ΔE1 and ΔE2 values were significantly affected by the ceramic thickness, resin cement shades and measuring regions ( Pveneers were cemented with resin cements in shades of HV+3 and WO. The ΔE2 values of six shades ranged from 0.60-2.56. The shades of HV+3, WO and A3 resin cements were more than 1.60. Conclusions: Different thickness of ceramic materials, resin cement shades and measuring regions could affect the final color of ceramic veneers. The color differences of some resin cements and corresponding try-in pastes might be observed in clinical practice.

  11. Veneered anatomically designed zirconia FDPs resulting from digital intraoral scans: Preliminary results of a prospective clinical study.

    Science.gov (United States)

    Selz, Christian F; Bogler, Jan; Vach, Kirstin; Strub, Joerg R; Guess, Petra C

    2015-12-01

    The aim of this prospective clinical study was to evaluate the clinical performance of veneered anatomically designed zirconia fixed dental prostheses (FDPs) resulting from intraoral digital impressions. 24 patients requiring treatment were provided with all-ceramic FDPs. Intraoral scans (iTero) were performed and veneered anatomically designed CAD/CAM-zirconia FDPs (Zerion/VitaVM9) were fabricated. A feldspar veneering ceramic following a slow cooling firing protocol was applied. A self-curing resin based luting material was used for adhesive cementation. Clinical evaluations were performed at baseline and 6, 12, and 18 months recalls according to the modified USPHS-criteria. Intraoral digital surface scans (iTero) were performed at each recall examination and were digitally superimposed (Geomagic) to evaluate potential veneer cohesive fractures. Kaplan-Meier survival analysis comprised secondary caries, clinically unacceptable fractures, root canal treatment and debonding. Kaplan-Meier success rate included restorations with minimal crevices, tolerable color deviations and clinically acceptable fractures. Data were statistically analyzed. The Kaplan-Meier survival rate and success rate of the FDPs were 100% and 91.7%, respectively. Clinically acceptable veneer cohesive fractures and crevices at the restoration margin were observed in two patients. These shallow veneer fractures were only detected by overlapping baseline and recall scans. Ceramic surface roughness increased significantly over time (pVeneered zirconia FDPs fabricated from digital intraoral scans showed a favorable clinical performance over an observation period of 18 months. Anatomical zirconia core design and slow cooling firing protocol of the veneering ceramic reduced the incidence of chip fractures to a level that could not be detected clinically. The digital workflow on the basis of intraoral digital impressions resulted in clinically satisfying outcomes for veneered zirconia FDPs. Copyright

  12. 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.

  13. Fracture of porcelain-veneered gold-alloy and zirconia molar crowns using a modified test set-up

    Science.gov (United States)

    Larsson, Christel; Drazic, Marko; Nilsson, Eddie; Vult von Steyern, Per

    2015-01-01

    Abstract Objective: The main aim of this study was to compare fracture load and fracture mode of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and metal-ceramic (MC) molar crowns using a modified test set-up to produce fractures similar to those seen in vivo, i.e. fractures of the veneering material rather than complete fractures. Materials and methods: 13 high-noble-alloy MC and 13 Y-TZP molar crowns veneered with porcelain were manufactured. The crowns were artificially aged before final load to fracture. Load was applied using a 7 mm diameter steel ball exerting force on the cusps with stresses directed toward the core-veneer interface. Fracture surface analysis was performed using light- and scanning electron microscopy. Results: The test design produced fractures of the veneering material rather than complete fractures. MC crowns withstood significantly (p > 0.001) higher loads (mean 2155 N) than Y-TZP (mean 1505 N) crowns, yet both endure loads sufficient for predictable clinical use. Fracture mode differed between MC and Y-TZP. MC crowns exhibited fractures involving the core-veneer interface but without core exposure. One Y-TZP crown suffered a complete fracture, all others except one displayed fractures of the veneering material involving the core-veneer interface with core exposure. Conclusions: The test set-up produces fractures similar to those found in vivo and may be useful to evaluate the core-veneer interface of different material systems, both metals and ceramics. The study confirms suggestions from previous studies of a weaker core-veneer bond for Y-TZP compared to MC crowns. PMID:28642899

  14. Fracture of porcelain-veneered gold-alloy and zirconia molar crowns using a modified test set-up

    Directory of Open Access Journals (Sweden)

    Christel Larsson

    2015-01-01

    Full Text Available Objective: The main aim of this study was to compare fracture load and fracture mode of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP and metal-ceramic (MC molar crowns using a modified test set-up to produce fractures similar to those seen in vivo, i.e. fractures of the veneering material rather than complete fractures. Materials and methods: 13 high-noble-alloy MC and 13 Y-TZP molar crowns veneered with porcelain were manufactured. The crowns were artificially aged before final load to fracture. Load was applied using a 7 mm diameter steel ball exerting force on the cusps with stresses directed toward the core-veneer interface. Fracture surface analysis was performed using light- and scanning electron microscopy. Results: The test design produced fractures of the veneering material rather than complete fractures. MC crowns withstood significantly (p > 0.001 higher loads (mean 2155 N than Y-TZP (mean 1505 N crowns, yet both endure loads sufficient for predictable clinical use. Fracture mode differed between MC and Y-TZP. MC crowns exhibited fractures involving the core-veneer interface but without core exposure. One Y-TZP crown suffered a complete fracture, all others except one displayed fractures of the veneering material involving the core-veneer interface with core exposure. Conclusions: The test set-up produces fractures similar to those found in vivo and may be useful to evaluate the core-veneer interface of different material systems, both metals and ceramics. The study confirms suggestions from previous studies of a weaker core-veneer bond for Y-TZP compared to MC crowns.

  15. Influence of thermal expansion mismatch on residual stress profile in veneering ceramic layered on zirconia: Measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Najjar, Achref; Jakubowicz-Kohen, Boris D; Sadoun, Michaël J

    2015-09-01

    Mismatch in thermal expansion coefficient between core and veneering ceramic (Δα=αcore-αveneer, ppm/°C) is reported as a crucial parameter influencing veneer fractures with Yttria-tetragonal-zirconia-polycrystal (Y-TZP) prostheses, which still constitutes a misunderstood problem. However, the common positive Δα concept remains empirical. The objective of this study is to investigate the Δα dependence of residual stress profiles in veneering ceramic layered on Y-TZP frameworks. The stress profile was measured with the hole-drilling method in bilayered disc samples of 20mm diameter with a 0.7mm thick Y-TZP framework and a 1.5mm thick veneer layer. 3 commercial and 4 experimental veneering ceramics (n=3 per group) were used to obtain different Δα varying from -1.3ppm/°C to +3.2ppm/°C, which were determined by dilatometric analyses. Veneer fractures were observed in samples with Δα≥+2.3 or ≤-0.3ppm/°C. Residual stress profiles measured in other groups showed compressive stresses in the surface, these stresses decreasing with depth and then becoming more compressive again near the interface. Small Δα variations were shown to induce significant changes in residual stress profiles. Compressive stress near the framework was found to decrease inversely to Δα. Veneer CTE close to Y-TZP (+0.2ppm/°C Δα) gived the most favorable stress profile. Yet, near the framework, Δα-induced residual stress varied inversely to predictions. This could be explained by the hypothesis of structural changes occurrence within the Y-TZP surface. Consequently, the optimum Δα value cannot be determined before understanding Y-TZP's particular behavior when veneered. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Contribution factor of wood properties of three poplar clones to strength of laminated veneer lumber

    Science.gov (United States)

    Fucheng Bao; Feng Fu; Elvin Choong; Chung-Yun Hse

    2001-01-01

    The term "Contribution Factor" (c.) was introduced in this paper to indicate the contribution ratio of solid wood properties to laminated veneer lumber (LVL) strength. Three poplar (Populus sp.) clones were studied, and the results showed that poplar with good solid wood properties has high Contribution Factor. The average Contribution...

  17. ESTIMATING THE SIZE OF LATE VENEER IMPACTORS FROM IMPACT-INDUCED MIXING ON MERCURY

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Valentin, E. G.; Barr, A. C., E-mail: rivera-valentin@brown.edu [Department of Geological Sciences, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912 (United States)

    2014-02-10

    Late accretion of a ''veneer'' of compositionally diverse planetesimals may introduce chemical heterogeneity in the mantles of the terrestrial planets. The size of the late veneer objects is an important control on the angular momenta, eccentricities, and inclinations of the terrestrial planets, but current estimates range from meter-scale bodies to objects with diameters of thousands of kilometers. We use a three-dimensional global Monte Carlo model of impact cratering, excavation, and ejecta blanket formation to show that evidence of mantle heterogeneity can be preserved within ejecta blankets of mantle-exhuming impacts on terrestrial planets. Compositionally distinct provinces implanted at the time of the late veneer are most likely to be preserved in bodies whose subsequent geodynamical evolution is limited. Mercury may have avoided intensive mixing by solid-state convection during much of its history. Its subsequent bombardment may have then excavated evidence of primordial mantle heterogeneity introduced by the late veneer. Simple geometric arguments can predict the amount of mantle material in the ejecta blanket of mantle-exhuming impacts, and deviations in composition relative to geometric predictions can constrain the length-scale of chemical heterogeneities in the subsurface. A marked change in the relationship between mantle and ejecta composition occurs when chemically distinct provinces are ∼250 km in diameter; thus, evidence of bombardment by thousand-kilometer-sized objects should be readily apparent from the variation in compositions of ejecta blankets in Mercury's ancient cratered terrains.

  18. Retention of veneered stainless steel crowns on replicated typodont primary incisors: an in vitro study.

    Science.gov (United States)

    Guelmann, Marcio; Gehring, Daren F; Turner, Clara

    2003-01-01

    The purpose of this in vitro study was to determine the effect of crimping and cementation on retention of veneered stainless steel crowns. One hundred twenty crowns, 90 from 3 commercially available brands of veneered stainless steel crowns (Dura Crown, Kinder Krown, and NuSmile Primary Crown) and 30 (plain) Unitek stainless steel crowns were assessed for retention. An orthodontic wire was soldered perpendicular to the incisal edge of the crowns; the crowns were fitted to acrylic replicas of ideal crown preparations and were divided equally into 3 test groups: group 1--crowns were crimped only (no cement used); group 2--crowns were cemented only; and group 3--crowns were crimped and cemented to the acrylic replicas. An Instron machine recorded the amount of force necessary to dislodge the crowns and the results were statistically analyzed using 2-way ANOVA and Tukey honestly significant difference (HSD) test. Group 3 was statistically more retentive than groups 1 and 2. Group 2 was statistically more retentive than group 1 (P crowns were statistically more retentive than the veneered crowns (P crowns showed statistically less retention values than all other crowns (P crowns showed statistically better retention rates than all other brands (P crowns with veneer facings were significantly more retentive than the nonveneered ones when cement and crimping were combined.

  19. The Use of Pre-Fabricated Composite Veneers to Enhance Esthetics

    Directory of Open Access Journals (Sweden)

    Panteqi Stela

    2017-11-01

    Full Text Available Background: This article is focused on the use of polymerized, prefabricated nano-hybrid-composite veneers to close diastema and to regain a vitality appearance of non vital discolored teeth. Case Reports: A 24-year old patient presented herself with a major complaint about the discoloration of her maxillary central incisors. The prefabricated composite veneers were recommended as the perfect solution in this case. Tooth shape and size was evaluated with the contour guide. Two pre-fabricated composite veneers size “M” were trimmed and cemented with the same hybrid composite resin that they were made from. A 28 year-old patient presented herself with a major complaint about her diastema. Her maxillary frontal teeth were intact. It was decided to use two veneers; size “L” and shade A2/B2 and Enamel Universal were chosen. Identical steps were followed as in clinical case 2. Conclusion: This new technique of treatment resulted to be an affordable way to regain esthetics. It is a one session treatment and requires no lab sessions, which makes it very comfortable for both dentist and patients. As with all new techniques, there is still a lot to be done, to confirm its effectiveness as a long term solution in esthetic dentistry.

  20. Color management of porcelain veneers: influence of dentin and resin cement colors

    NARCIS (Netherlands)

    Dozic, A.; Tsagkari, M.; Khashayar, G.; Aboushelib, M.

    2010-01-01

    Objective: Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence

  1. Influence of crystal structure on debonding failure of zirconia veneered restorations.

    Science.gov (United States)

    Aboushelib, Moustafa N; Wang, Hang

    2013-07-01

    Delamination of porcelain from intact zirconia framework was recently reported as the most common failure mode of these restorations. The aim of this study was to investigate the influence of different laboratory surface treatments on crystals structure and fracture strength of zirconia veneered restorations. Zirconia discs received airborne particle abrasion with either 50 or 120μm alumina particles then half of the specimens were annealed to remove surface pre-stresses, while assintered discs served as a control. Crystal structure of each group was evaluated using X-ray diffraction analysis (XRD). The discs were then veneered with porcelain and biaxially loaded to fracture with the veneer surface in tension (α=0.05). Regarding debonding failure, 50μm particle abrasion significantly increased biaxial flexure strength compared to as-sintered specimens. On the contrary 120μm particle abrasion resulted in significant reduction in flexure strength and was associated with higher percent of monoclinic phase (7%). However for both types of particle sizes, annealing reduced initial failure load as it led to complete reverse transformation of the monoclinic phase which was associated with zirconia grain pull-out at the critical crack location. Paying attention to the surface treatment of zirconia before veneering could reduce chances of delamination and significantly improve the strength of the bilayered restorations. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. 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.

  3. Esthetic Rehabilitation of Anterior Teeth with Porcelain Laminates and Sectional Veneers

    NARCIS (Netherlands)

    Gresnigt, Marco; Ozcan, Mutlu

    2011-01-01

    Full-coverage bonded porcelain restorations offer predictable treatment options in dentistry, but a certain amount of tooth material must be removed to allow space for the required thickness of the restorative material. Laminate veneers and inlays are considered minimally invasive, but they also

  4. The papillary veneers concept: an option for solving compromised dental situations.

    Science.gov (United States)

    Viana, Pedro Couto; Correia, André; Kovacs, Zsolt

    2012-12-01

    Rehabilitating anterior edentulous areas can be a challenge for clinicians when there is a loss of hard and soft tissues. The authors present an innovative approach to manage these cases. Case 1 involved a patient with a dental implant placed in the position of tooth no. 7 and a loss of soft tissues in the proximal areas. The authors bonded veneers to teeth nos. 6 and 8 and placed a screw-retained implant crown in the position of tooth no. 7. All of the prosthetic components had gingiva-shade and crown ceramics. Case 2 involved a patient with a dental implant in the position of tooth no. 10 and loss of soft tissues. The authors bonded papillary veneers to teeth nos. 9 and 11 and placed a screw-retained zirconia anatomical abutment prepared for a ceramic veneer with gingiva-shade ceramics in the cervical area. The prosthetic option of papillary veneers helps in the restoration of lost soft tissue and can mimic natural appearance in a predictable and stable way.

  5. Chipping behaviour of all-ceramic crowns with zirconia framework and CAD/CAM manufactured veneer

    National Research Council Canada - National Science Library

    Schmitter, M; Mueller, D; Rues, S

    2012-01-01

    .... 32 identical, anatoform zirconia (Sirona inCoris ZI, mono L F1) frameworks (thickness 0.6mm) were constructed (Sirona inLab 3.80). Afterwards, 16 crowns were completed using a CAD/CAM manufactured lithium disilicate ceramic veneer...

  6. Effect of Thermal Treatment of Veneer on Formaldehyde Emission of Poplar Plywood

    Directory of Open Access Journals (Sweden)

    Takato Nakano

    2013-01-01

    Full Text Available A large amount of poplar plywood is now being imported into Japan from China, and as a result, formaldehyde emitted from this plywood represents an undesirable chemical that must be controlled using a chemical catching agent. The aim of this study is to find an approach to reduce the formaldehyde emission of poplar plywood using thermal treatment without employing any chemicals. The experimental results obtained show that heating veneer sheets in the temperature range of 150 °C to 170 °C effectively reduced the formaldehyde emission of plywood, without diminishing the mechanical properties of the veneer. By applying Langmuir’s theory and Hailwood-Horrobin theory to the adsorption isotherm obtained in this study, the relationship between the formaldehyde emission of plywood and the adsorption properties of veneer as a material is discussed. When veneer sheets were heated in the temperature range of 150 °C to 170 °C, the amount of hydrated water (monomolecular layer decreased slightly and that of dissolved water (polymolecular layer did not change. It is hypothesized that the formaldehyde emission of plywood is related to the condition of the adsorption site of the wood.

  7. Veneers, rinds, and fracture fills: Relatively late alteration of sedimentary rocks at Meridiani Planum, Mars

    Science.gov (United States)

    Knoll, A.H.; Jolliff, B.L.; Farrand, W. H.; Bell, J.F.; Clark, B. C.; Gellert, Ralf; Golombek, M.P.; Grotzinger, J.P.; Herkenhoff, K. E.; Johson, J.R.; McLennam, S.M.; Morris, Robert; Squyres, S. W.; Sullivan, R.; Tosca, N.J.; Yen, A.; Learner, Z.

    2008-01-01

    Veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at Meridiani Planum, Mars. The chemistry of submillimeter thick, buff-colored veneers reflects multiple processes at work since the establishment of the current plains surface. Veneer composition is dominated by the mixing of silicate-rich dust and sulfate-rich outcrop surface, but it has also been influenced by mineral precipitation, including NaCl, and possibly by limited physical or chemical weathering of sulfate minerals. Competing processes of chemical alteration (perhaps mediated by thin films of water or water vapor beneath blanketing soils) and sandblasting of exposed outcrop surfaces determine the current distribution of veneers. Dark-toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture, halite precipitation, and possible minor sulfate removal. Cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact. These appear to reflect limited groundwater activity along the margins of fractures, cementing mechanically introduced fill derived principally from outcrop rocks. The limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping Meridiani strata were exposed on the plains surface. Copyright 2008 by the American Geophysical Union.

  8. Structural Performance of COM-Ply Studs Made with Hardwood Veneers

    Science.gov (United States)

    Robert H. McAlister

    1979-01-01

    COM-PLY 2 x 4 studs made with veneers of yellow-poplar, sweetgum, and white oak were tested for strength and stiffness, nail-holding properties, modulus of elasticity of component parts, static bending, and compression parallel and perpendicular to the grain. All tests were conducted according to performance standards for composite studs used in exterior walls or ASTM...

  9. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains

    Science.gov (United States)

    Min, Jie; Zhang, Qianqian; Qiu, Xiaoli; Zhu, Minhao; Yu, Haiyang; Gao, Shanshan

    2015-01-01

    Objectives The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains. Methods Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated. Results The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes. Significance Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings. PMID:26368532

  10. Effects of ageing on surface textures of veneering ceramics for zirconia frameworks.

    Science.gov (United States)

    Tang, Xuehua; Tan, Zhenquan; Nakamura, Takashi; Yatani, Hirofumi

    2012-11-01

    To evaluate the effects of ageing on surface textures of veneering ceramics for zirconia frameworks. Five different veneering ceramics for zirconia frameworks, Vintage ZR (ZR), Cerabien ZR (CZR), VitaVM9 (VM9), Cercon ceram KISS (KISS), and IPS e.max ceram (e.max), and one veneering ceramic with metal frameworks, Vintage MP (MP), were evaluated. Twenty specimens were fabricated from each veneering ceramic. All specimens were divided into two groups, one of which was subjected to accelerated ageing. The other was used as the control. Accelerated ageing was performed on the distilled water for 5h at 200°C and 2 atm. Surface textures were examined using laser profilometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Compared to unaged specimens, surface roughness parameters (Ra, Rp, Rv) of all aged specimens except e.max were significantly greater (P=0.000). Compared to the unaged specimens, sodium and potassium on the surfaces of all the aged specimens significantly decreased (Pveneering ceramics were changed by the accelerated ageing test. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Shear bond strength of veneering ceramic to coping materials with different pre-surface treatments.

    Science.gov (United States)

    Tarib, Natasya Ahmad; Anuar, Norsamihah; Ahmad, Marlynda

    2016-10-01

    Pre-surface treatments of coping materials have been recommended to enhance the bonding to the veneering ceramic. Little is known on the effect on shear bond strength, particularly with new coping material. The aim of this study was to investigate the shear bond strength of veneering ceramic to three coping materials: i) metal alloy (MA), ii) zirconia oxide (ZO), and iii) lithium disilicate (LD) after various pre-surface treatments. Thirty-two (n = 32) discs were prepared for each coping material. Four pre-surface treatments were prepared for each sub-group (n = 8); a) no treatment or control (C), b) sandblast (SB), c) acid etch (AE), and d) sandblast and acid etch (SBAE). Veneering ceramics were applied to all discs. Shear bond strength was measured with a universal testing machine. Data were analyzed with two-way ANOVA and Tukey's multiple comparisons tests. Mean shear bond strengths were obtained for MA (19.00 ± 6.39 MPa), ZO (24.45 ± 5.14 MPa) and LD (13.62 ± 5.12 MPa). There were statistically significant differences in types of coping material and various pre-surface treatments ( P veneering ceramic to zirconia oxide was higher than metal alloy and lithium disilicate. The highest shear bond strengths were obtained in sandblast and acid etch treatment for zirconia oxide and lithium disilicate groups, and in acid etch treatment for metal alloy group.

  12. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains.

    Directory of Open Access Journals (Sweden)

    Jie Min

    Full Text Available The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains.Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated.The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes.Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings.

  13. [Effect of different surface treatments on the shear bond of zirconia substructure and veneering ceramic].

    Science.gov (United States)

    Zhong, Qun; Peng, Yan; Wu, Xue-ying; Weng, Jia-wei

    2014-06-01

    To investigate the effect of different surface treatments on the shear bond strength of zirconia substructure and veneering ceramic. Kavo zirconia specimens were divided into 4 groups (each group contains 8 specimens) according to different surface treatments: Group A was pigmented by dipping presintered blocks in the coloring solution VITA LL5, and not treated with abrasion after firing; Group B was pigmented with the same solution and then dealt with abrasion; Group C was not treated by any methods and Group D was only dealt with abrasion. All the veneering ceramics were fired on the zirconia substructure by slip-casting technique and the shear bond strength of zirconia substructure and veneering ceramic were tested. The data was analyzed statistically with SPSS 10.0 software package. The shear bond strength of the abrasive-treated groups (group B and group D) was significantly higher than the other two groups, but no significant difference was found between pigmented-treated groups (group A and group C) and non-pigmented-treated groups (group B and group D). Abrasion can increase the shear bond between Kavo zirconia substructure and veneering ceramics while pigmentation has no significant effect on the bonding strength.

  14. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains.

    Science.gov (United States)

    Min, Jie; Zhang, Qianqian; Qiu, Xiaoli; Zhu, Minhao; Yu, Haiyang; Gao, Shanshan

    2015-01-01

    The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains. Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated. The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes. Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings.

  15. Effect of core design and veneering technique on damage and reliability of Y-TZP-supported crowns.

    Science.gov (United States)

    Guess, Petra C; Bonfante, Estevam A; Silva, Nelson R F A; Coelho, Paulo G; Thompson, Van P

    2013-03-01

    To evaluate the effect of framework design modification and veneering techniques in fatigue reliability and failure modes of veneered Yttria-Stabilized Tetragonal Zirconia Polycrystals (Y-TZP) crowns. A CAD-based mandibular molar crown preparation served as a master die. Y-TZP crown cores (VITA-In-Ceram-YZ, Vita-Zahnfabrik, Bad Säckingen, Germany) in conventional (0.5mm uniform thickness) or anatomically designed fashion (cusp support) were porcelain veneered with either hand-layer (VM9) or pressed (PM9) techniques. Crowns (n=84) were cemented on 30 days aged dentin-like composite dies with resin cement. Crowns were subjected to single load to fracture (n=3 each group) and mouth-motion step-stress fatigue (n=18) by sliding a WC indenter (r=3.18 mm) 0.7 mm buccally on the inner incline surface of the mesio-lingual cusp. Stress-level curves (use level probability lognormal) and reliability (with 2-sided 90% confidence bounds, CB) for completion of a mission of 50.000 cycles at 200 N load were calculated. Fractographic analyses were performed under light-polarized and scanning electron microscopes. Higher reliability for hand-layer veneered conventional core (0.99, CB 0.98-1) was found compared to its counterpart press-veneered (0.50 CB 0.33-65). Framework design modification significantly increased reliability for both veneering techniques (PM9 [0.98 CB 0.87-0.99], VM9 [1.00 CB 0.99-1]) and resulted in reduced veneer porcelain fracture sizes. Main fracture mode observed was veneer porcelain chipping, regardless of framework design and veneering technique. Hand-layer porcelain veneered on conventional core designs presented higher reliability than press-veneered with similar core designs. Anatomic core design modification significantly increased the reliability and resulted in reduced chip size of either veneering techniques. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. [Preliminary clinical evaluation of the esthetic effect of deep discolored anterior teeth restored with zirconia veneers].

    Science.gov (United States)

    Zhou, T F; Wang, X Z; Liu, J Y; Sun, Q; Wang, X K

    2016-12-18

    To observe the esthetic effect of deep discolored anterior teeth restored by zirconia veneers. Small defected deep discolored anterior teeth with complete root canal therapy were restored by zirconia veneers (n=15). The same name teeth on the other side of the same dental arch were chosen as control teeth. The color difference values ΔE of the neck 1/3, the middle 1/3 and the incisor 1/3 between the deep discolored tooth and the normal control tooth before and after therapy were measured to evaluate the esthetic effect of zirconia veneer restoration. At the same time, the marginal fit of zirconia veneers was checked by the standard of United States Public Health Service (USPHS). The integrity of the veneers was also examined. On the labial side, fibers color difference values ΔE of the neck 1/3, the middle 1/3 and the incisor 1/3 between deep discolored teeth and normal control teeth were measured by the electronic colorimeter, which were 24.92±3.00,26.64±4.00 and 21.94±3.31 respectively. All the values were above 4.0, which were considered unacceptable in clinic. After restoration by zirconia veneers, the color difference values ΔE of the middle 1/3 and the incisor 1/3 between the restored and control teeth were 1.82±0.17 and 1.84±0.21. Both values were less than 2.0, which indicated both good color matching. The color difference value ΔE of the neck 1/3 was 3.92±0.48, which was less than 4.0 and could be accepted in clinic. The statistical analysis of the colors of the teeth before and after restoration compared with the control teeth was done by Paired t test. The t values in the neck 1/3, the middle 1/3 and the incisor 1/3 were 30.37, 21.56, 23.37 respectively. In the three group, all the Pveneers were broken or detached in the period of observation. Zirconia veneers can be a good method to restore deep discolored anterior teeth. However, it should be used cautiously when the patient's esthetic expectation was too high.

  17. Shear bond strength of veneering ceramic to zirconia core after different surface treatments.

    Science.gov (United States)

    Kirmali, Omer; Akin, Hakan; Ozdemir, Ali Kemal

    2013-06-01

    The aim of this study was to evaluate the effect of different surface treatments: sandblasting, liners, and different laser irradiations on shear bond strength (SBS) of pre-sintered zirconia to veneer ceramic. The SBS between veneering porcelain and zirconium oxide (ZrO2) substructure was weak. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to veneering porcelain. There is no study that evaluated the bond strength between veneering porcelain and the different surface treatments on pre-sintered ZrO2 substructure. Two hundred specimens with 7 mm diameter and 3 mm height pre-sintered zirconia blocks were fabricated. Specimens were randomly divided into 10 groups (n=20) according to surface treatments applied. Group C, untreated (Control); Group E, erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiated; Group N, neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiated; Group SB, sandblasted; Group L, liner applied; Group NL, Nd:YAG laser irradiated+liner applied; Group EL, Er:YAG laser irradiated+liner applied; Group SN, sandblasted+Nd:YAG laser irradiated; Group SE, sandblasted+Er:YAG laser irradiated; and Group SL, sandblasted+liner applied. The disks were then veneered with veneering porcelain. Before the experiment, specimens were steeped in 37°C distilled water for 24 h. All specimens were thermocycled for 5000 cycles between 5°C and 55°C with a 30 sec dwell time. Shear bond strength test was performed at a crosshead speed of 1 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Surface treatments significantly changing the topography of the yttrium-stabilized tetragonal zirconia (Y-TZP) ceramic according to scanning electron microscopic (SEM) images. The highest mean bond strength value was obtained in Group SE, and the lowest bond strength value was observed in NL group. Bond strength values of the other groups were similar to each other. This

  18. Influence of activation mode of resin cement on the shade of porcelain veneers.

    Science.gov (United States)

    Magalhães, Ana Paula Rodrigues; Cardoso, Paula de Carvalho; de Souza, João Batista; Fonseca, Rodrigo Borges; Pires-de-Souza, Fernanda de Carvalho Panzeri; Lopez, Lawrence Gonzaga

    2014-06-01

    The aim of this study was to evaluate the influence of resin luting cement's activation mode in the final shade of porcelain veneers after accelerated artificial aging (AAA). Porcelain veneers (IPS Empress Esthetic) were produced using a standardized shade (ET1) and thickness (0.6 mm). Twenty bovine teeth were collected, prepared, and divided into two groups: group I (n = 10)-light-cured group, only base paste was applied to the veneers; group II (n = 10)-dual-cured group, in which the same base paste used in group I and a transparent catalyst were proportionally mixed for 20 seconds and then applied to the veneers. The specimens were light-cured for 60 seconds each and were next subjected to AAA. They were submitted to color readings with a spectrophotometer in three instances: in the tooth surface (only the substrate), after the cementation and polymerization of the veneers, and after the AAA. The values of L*, a*, and b* were obtained and the total color change was calculated (∆E*). Values obtained were subjected to statistical analysis, with a significance of 0.05. There were no significant differences between dual- and light-cured modes considering ∆E*, L*, a*, and b* values obtained after aging (p > 0.05). Within the dual-cured mode there were no significant differences in ∆E*, L*, a*, and b* values (p > 0.05). No relevant differences were found between the two activation modes in color change. When submitted to aging, dual- and light-cured modes of the resin cement showed visually perceptible (∆E* > 1.0) color changes; however, within the threshold of clinical acceptance (∆E* > 3.3). © 2013 by the American College of Prosthodontists.

  19. Characterization of residual stresses in zirconia veneered bilayers assessed via sharp and blunt indentation.

    Science.gov (United States)

    Wendler, Michael; Belli, Renan; Petschelt, Anselm; Lohbauer, Ulrich

    2015-08-01

    The present study evaluated the effect of the coefficient of thermal expansion (CTE) mismatch and the cooling protocol on the distribution of residual stresses and crack propagation in veneered zirconia bilayers. Ceramic discs with two different CTEs (Vita VM9 and Lava Ceram) were fired onto zirconia plates and cooled following a slow (0.5°C/s) or a fast (45°C/s) cooling protocol. The residual stress distribution throughout the veneer thickness was assessed by means of depth-wise Vickers indentation after sequentially sectioning the bilayers parallel compared to normal to the interface. A mathematical solution for the residual stress distribution was used as reference. Additionally, Hertzian cone crack propagation in the veneers was induced by cyclic contact loading and measured at different number of cycles to estimate the crack growth rate. The higher CTE mismatch of the VM9 group generated an important stress gradient with high compressive residual stresses near the interface, hindering the crack propagation. The low CTE mismatch group (Lava Ceram) developed only a slight stress gradient and higher cone crack growth rates. No differences were observed between the two cooling protocols applied regarding stress magnitude and crack propagation behavior. The CTE mismatch has a predominant role in the generation of residual stress gradients within the veneer, which directly influences contact-induced crack propagation. Based on the results, the cooling protocol had no significant effect on the residual stress distribution in zirconia-veneer bilayers. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Effect of various veneering techniques on mechanical strength of computer-controlled zirconia framework designs.

    Science.gov (United States)

    Kanat, Burcu; Cömlekoğlu, Erhan M; Dündar-Çömlekoğlu, Mine; Hakan Sen, Bilge; Ozcan, Mutlu; Ali Güngör, Mehmet

    2014-08-01

    The objectives of this study were to evaluate the fracture resistance (FR), flexural strength (FS), and shear bond strength (SBS) of zirconia framework material veneered with different methods and to assess the stress distributions using finite element analysis (FEA). Zirconia frameworks fabricated in the forms of crowns for FR, bars for FS, and disks for SBS (N = 90, n = 10) were veneered with either (a) file splitting (CAD-on) (CD), (b) layering (L), or (c) overpressing (P) methods. For crown specimens, stainless steel dies (N = 30; 1 mm chamfer) were scanned using the labside contrast spray. A bilayered design was produced for CD, whereas a reduced design (1 mm) was used for L and P to support the veneer by computer-aided design and manufacturing. For bar (1.5 × 5 × 25 mm(3) ) and disk (2.5 mm diameter, 2.5 mm height) specimens, zirconia blocks were sectioned under water cooling with a low-speed diamond saw and sintered. To prepare the suprastructures in the appropriate shapes for the three mechanical tests, nano-fluorapatite ceramic was layered and fired for L, fluorapatite-ceramic was pressed for P, and the milled lithium-disilicate ceramics were fused with zirconia by a thixotropic glass ceramic for CD and then sintered for crystallization of veneering ceramic. Crowns were then cemented to the metal dies. All specimens were stored at 37°C, 100% humidity for 48 hours. Mechanical tests were performed, and data were statistically analyzed (ANOVA, Tukey's, α = 0.05). Stereomicroscopy and scanning electron microscopy (SEM) were used to evaluate the failure modes and surface structure. FEA modeling of the crowns was obtained. Mean FR values (N ± SD) of CD (4408 ± 608) and L (4323 ± 462) were higher than P (2507 ± 594) (p veneering ceramic on zirconia with a reduced framework design may reduce ceramic chipping. © 2014 by the American College of Prosthodontists.

  1. Performance of Monolithic and Veneered Zirconia Crowns After Endodontic Treatment and Different Repair Strategies.

    Science.gov (United States)

    Scioscia, A; Helfers, A; Soliman, S; Krastl, G; Zitzmann, N U

    2018-01-16

    To investigate failure loads of monolithic and veneered all-ceramic crowns after root canal treatment and to analyze marginal integrity of repair fillings. Seventy-two human molars were restored with monolithic (Zr-All) or veneered (Zr-Ven) zirconia crowns. Molars were assigned to six groups (n=12 per group) depending on restoration material, access type (no access cavity [control] or endodontic treatment [test]), and type of filling (one-step [1-st] or two-step [2-st]). For type of filling, molars were treated using a self-etch universal adhesive and cavities were either filled with layered composite (1-st) or filled until the crown material was reached, which was additionally conditioned and then filled (2-st). Scanning electron microscopic analysis of the restoration margins was performed before and after thermomechanical loading (TML), and the percentage of continuous margins was assessed. Crowns were then loaded to failure. Preparation of the access cavity required more time in monolithic (445 s) than in veneered crowns (342 s). Loads to failure were higher in control groups (Zr-All: 5814 N; Zr-Ven: 2133 N) and higher in monolithic test (2985 N) than in veneered test crowns (889 N). In monolithic crowns, 1-st had lower fracture loads than 2-st fillings (2149 N vs 3821 N). Continuous margins of 66% to 71% were achieved, which deteriorated after TML by 39% to 40% in Zr-All, by 34% in Zr-Ven-1-st, and by 24% in Zr-Ven-2-st. Endodontic access and adhesive restorations resulted in reduced fracture load in monolithic and veneered zirconia crowns. Two-step fillings provided higher fracture loads in Zr-All and better marginal quality in Zr-Ven crowns.

  2. Marginal integrity of two zirconia-based crowns before and after porcelain veneering

    Directory of Open Access Journals (Sweden)

    Sakineh Nikzad

    2013-04-01

    Full Text Available Background and Aims: The marginal integrity of fixed restorations always is a major matter of concern for dental clinicians. Any cause of distortion, including veneering processes, in the marginal integrity is supposed to be detrimental for long-term success of fixed dental prostheses. The aim of this in vitro study was to compare the marginal adaptation of two different full ceramic restoration systems (Zirkouzahu&Cercon and possible changes in marginal integrity following the multiple veneering process. Materials and Methods: Twelve all-ceramic crowns in the form of coping were fabricated on a pre-made standard metal die with finish line of shoulder preparation from two commercial systems: Cercon® and Zirkonzahn®. The specimens were not cemented. The Crown/Die discrepancy were measured by means of a precise stereo microscope (accuracy±0.1 μm, at various points (n=12 selected along circumferential margin of the restorations. Same procedure was accomplished after applying the veneering porcelain. The mean gap dimensions were calculated and data were analyzed by multivariate (b test. Results: Mean marginal gap dimensions before and after veneering porcelain firing cycles, for Cercon® were (59.67±13.46 µm and (63.75±14.16 µm and for Zirkonzahn® were (65.81±24.37 µm and (64.74±21.94 µm, respectively. Hotelling trace Multivariate(b test method showed that the rate of mismatching marginal integrity in two groups (Cercon® and Zirkonzahn® had no significant difference before and after porcelain firing (P>0.05. Conclusion: Within the limitation of this study, the marginal integrity of both systems were seems to be within the clinically acceptable standard dimension, i.e. 120μm.The marginal gap of both all-ceramic systems were not affected by veneering porcelain firing cycles.

  3. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    Energy Technology Data Exchange (ETDEWEB)

    Wananuruksawong, R; Jinawath, S; Wasanapiarnpong, T [Research Unit of Advanced Ceramic, Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok (Thailand); Padipatvuthikul, P, E-mail: raayaa_chula@hotmail.com [Faculty of Dentistry, Srinakharinwirot University, Bangkok (Thailand)

    2011-10-29

    Silicon nitride (Si{sub 3}N{sub 4}) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si{sub 3}N{sub 4} ceramic as a dental core material. The white Si{sub 3}N{sub 4} was prepared by pressureless sintering at relative low sintering temperature of 1650 deg. C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si{sub 3}N{sub 4} ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si{sub 3}N{sub 4} specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (<150 micrometer, Pyrex) with 5 wt% of zirconia powder (3 wt% Y{sub 2}O{sub 3} - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si{sub 3}N{sub 4} specimens, the firing was performed in electric tube furnace between 1000-1200 deg. C. The veneered specimens fired at 1100 deg. C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98x10{sup -6} deg. C{sup -1}, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  4. Porcelain bonding to titanium with two veneering principles and two firing temperatures.

    Science.gov (United States)

    Haag, Per; Andersson, Martin; Nilner, Krister

    2013-01-01

    Dental literature, as well as dental laboratories, has described problems with ceramic veneering of titanium, while clinical and in vitro studies have reported good results. The objective of this study was to investigate the effect of firing temperature, thermo cycling, and veneering methods on bond strength between porcelain and titanium. Eighty titanium specimens were prepared with one of two methods: a bonding agent firing or an oxidation firing. During veneering, half of the specimens in each group were fired at 30 degrees C above and half at the manufacturer's recommended temperature. In the bonding agent group and in the oxidation group, half of each firing group was thermocycled. Bond strength was calculated in a three-point bending test. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses of the titanium and the porcelain fracture surfaces of one specimen from each subgroup was used in order to study the composition of the interface between titanium and porcelain surfaces after fracture. No significant difference in bond strength was found when firing at a higher temperature compared with firing at the recommended temperature. An oxidation firing before veneering yielded significantly higher bond strength in a three-point bending test than when firing with a bonding agent. SEM and EDS analyses indicated a higher frequency of titanium oxide fractures in the oxidation than in the bonding agent group.The main finding is that firing at 30 degrees C above the recommended temperature does not significantly affect bond strength between titanium and porcelain. SEM and EDS analysis indicate that fractures occur in the titanium oxide layer by oxidation firing and in the interface between titanium oxide layer and veneering material by bonding agent firing.This finding might indicate that three- point bending test is not a relevant method for determining bond strength in this case, since the firing methods might influence the

  5. Fracture Load Before and After Veneering Zirconia Posterior Fixed Dental Prostheses.

    Science.gov (United States)

    Rodríguez, Verónica; Castillo-Oyagüe, Raquel; López-Suárez, Carlos; Gonzalo, Esther; Peláez, Jesús; Suárez-García, María-Jesús

    2016-10-01

    To evaluate the fracture load of 3-unit zirconia-based posterior fixed dental prostheses (FDPs) before and after veneering the frameworks. Forty standardized stainless-steel master dies were fabricated (height: 5 mm, convergence: 6º, chamfer: 1 mm) and randomly screwed in pairs onto metal bases. The bases were randomly divided into two groups (n = 20 each) according to the zirconia CAD/CAM system used for constructing 3-unit structures for FDPs: group 1 (L): Lava All-ceramic, group 2 (Z): IPS e.max ZirCAD. Half of the zirconia structures per group were randomly selected and veneered, while the remaining half was left unveneered. The specimens were luted in standard fashion onto the stainless steel master dies using conventional glass ionomer cement. All specimens were tested for fracture load (FL). Specimens were subjected to a three-point bending test until fracture by applying an axial compressive load at the central fossa of the pontics with a universal testing machine at a 0.5 mm/min crosshead speed. Wilcoxon's rank-sum test and Weibull statistics were used for statistical analysis (α = 0.05). L structures recorded significantly higher values of load to fracture than the Z group both before and after veneering. Within each ceramic group, no differences were found between unveneered and veneered frameworks. Although further studies are necessary to corroborate these findings, both zirconia systems could be recommended for restoring posterior teeth on the basis of the fracture load values recorded in this experiment (>1000 N). The veneering procedure did not affect the overall load to fracture in any group. © 2015 by the American College of Prosthodontists.

  6. Asteroid bombardment and the core of Theia as possible sources for the Earth's late veneer component

    Science.gov (United States)

    Sleep, Norman H.

    2016-07-01

    The silicate Earth contains Pt-group elements in roughly chondritic relative ratios, but with absolute concentrations veneer implies addition of chondrite-like material with 0.3-0.7% mass of the Earth's mantle or an equivalent planet-wide thickness of 5-20 km. The veneer thickness, 200-300 m, within the lunar crust and mantle is much less. One hypothesis is that the terrestrial veneer arrived after the moon-forming impact within a few large asteroids that happened to miss the smaller Moon. Alternatively, most of terrestrial veneer came from the core of the moon-forming impactor, Theia. The Moon then likely contains iron from Theia's core. Mass balances lend plausibility. The lunar core mass is ˜1.6 × 1021 kg and the excess FeO component in the lunar mantle is 1.3-3.5 × 1021 kg as Fe, totaling 3-5 × 1021 kg or a few percent of Theia's core. This mass is comparable to the excess Fe of 2.3-10 × 1021 kg in the Earth's mantle inferred from the veneer component. Chemically in this hypothesis, Fe metal from Theia's core entered the Moon-forming disk. H2O and Fe2O3 in the disk oxidized part of the Fe, leaving the lunar mantle near a Fe-FeO buffer. The remaining iron metal condensed, gathered Pt-group elements eventually into the lunar core. The silicate Moon is strongly depleted in Pt-group elements. In contrast, the Earth's mantle contained excess oxidants, H2O and Fe2O3, which quantitatively oxidized the admixed Fe from Theia's core, retaining Pt-group elements. In this hypothesis, asteroid impacts were relatively benign with ˜1 terrestrial event that left only thermophile survivors.

  7. [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).

  8. Endo-restorative treatment of a severly discolored upper incisor: resolution of the "aesthetic" problem through Componeer veneering System

    National Research Council Canada - National Science Library

    Migliau, Guido; Besharat, Laith Konstantinos; Sofan, Afrah Ali Abdullah; Sofan, Eshrak Ali Abdullah; Romeo, Umberto

    2015-01-01

    .... The aim of the study is to evaluate clinically the effectiveness of a direct composite veneering system in resolving aesthetic problem of an upper incisor with a multidisciplinary treatment approach...

  9. Effects of a convenient silica-coating treatment on shear bond strengths of porcelain veneers on zirconia-based ceramics.

    Science.gov (United States)

    Oguri, Takuya; Tamaki, Yukimichi; Hotta, Yasuhiro; Miyazaki, Takashi

    2012-01-01

    Porcelain veneering of zirconia is necessary, but chipping of the veneer may cause clinical problems. We investigated the effects of silica coating to improve the bond strength between porcelain veneers and zirconia-based ceramics. The ceramics tested were zirconia/alumina nanocomposites stabilized with ceria. Three surface treatments, grinding with a carborundum point (CA), sandblasting with alumina (SB), and Silano-Pen treatment (SP), were performed. Untreated specimens (NT) were examined as a control. The surface roughnesses and contact angles after treatment were measured. Shear bond tests were conducted, and the average strengths were calculated. EPMA was used for elemental identifications and surface observations. The bond strengths with SP were 20.00±3.43MPa and were significantly larger than that (15.35±3.12 MPa) of NT (pzirconia and a porcelain veneer.

  10. Fabrication of lithium silicate ceramic veneers with a CAD/CAM approach: a clinical report of cleidocranial dysplasia.

    Science.gov (United States)

    da Cunha, Leonardo Fernandes; Mukai, Eduardo; Hamerschmitt, Raphael Meneghetti; Correr, Gisele Maria

    2015-05-01

    The fabrication of minimally invasive ceramic veneers remains a challenge for dental restorations involving computer-aided design and computer-aided manufacturing (CAD/CAM). The application of an appropriate CAD/CAM protocol and correlation mode not only simplifies the fabrication of ceramic veneers but also improves the resulting esthetics. Ceramic veneers can restore tooth abnormalities caused by disorders such as cleidocranial dysplasia, enamel hypoplasia, or supernumerary teeth. This report illustrates the fabrication of dental veneers with a new lithium silicate ceramic and the CAD/CAM technique in a patient with cleidocranial dysplasia. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Comminution process to produce engineered wood particles of uniform size and shape with disrupted grain structure from veneer

    Science.gov (United States)

    Dooley, James H; Lanning, David N

    2013-07-30

    Comminution process of wood veneer to produce wood particles, by feeding wood veneer in a direction of travel substantially normal to grain through a counter rotating pair of intermeshing arrays of cutting discs arrayed axially perpendicular to the direction of veneer travel, wherein the cutting discs have a uniform thickness (Td), to produce wood particles characterized by a length dimension (L) substantially equal to the Td and aligned substantially parallel to grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) substantially equal to the veneer thickness (Tv) and aligned normal to W and L, wherein the W.times.H dimensions define a pair of substantially parallel end surfaces with end checking between crosscut fibers.

  12. Evaluation of the optical properties of CAD-CAM generated yttria-stabilized zirconia and glass-ceramic laminate veneers.

    Science.gov (United States)

    Alghazzawi, Tariq F; Lemons, Jack; Liu, Perng-Ru; Essig, Milton E; Janowski, Gregg M

    2012-05-01

    When feldspathic porcelain (FP) laminate veneers are used to mask tooth discoloration that extends into the dentin, significant tooth reduction is needed to provide space for the opaque layer and optimize the bonding of the restoration. The purpose of this study was to investigate the color effect of trial insertion paste (TP), composite resin abutment (CRA), and veneer regions on the optical properties of feldspathic porcelain (FP), yttria-stabilized zirconia (Y-TZP), and IPS e.max CAD HT (IEC) veneers. A melamine tooth was prepared for a laminate veneer on a model, and a definitive cast was made. The definitive die was scanned by using the TurboDent System (TDS), then 30 CRA were machined and 10 veneers were fabricated for each ceramic material (FP, Y-TZP, IEC). The optical properties of different veneer materials, CRA (A(1), A(2), A(3)) and TP (bleach XL, opaque white, transparent, and yellow) were evaluated in the cervical, body, and incisal regions with a spectrophotometer. Results were analyzed by using 1-way ANOVA (.05). The color difference for all the veneers was affected by TP and CRA colors in different regions. The mean values for the Y-TZP veneer color coordinates (L*: 74 ±0.34, a*: 0.09 ±0.20, and b*: 17.43 ±0.44) were significantly different (Pveneers (L*: 70.15 ±0.23, a*: -0.69 ±0.073, and b*:11.48 ±0.30) and FP veneers (L*: 70.00 ±0.86, a*: - 0.28 ±0.203, and b*: 13.86 ±1.08). There was no difference between IEC for L* and FP. Significant difference was detected (Pveneer materials for a* and b*. The TP color affected the color difference for all veneer materials except the Y-TZP, while there was no effect on the CRA color. The magnitude of color coordinates changed as a function of TP color and veneer material. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  13. Fire resistance of engineered wood rim board products.

    Science.gov (United States)

    Robert H. White

    2003-01-01

    Engineered wood products, such as oriented strandboard, laminated veneer lumber, and other composite wood products, are being used more often in construction. This includes use as rim boards, which are the components around the perimeter of a floor assembly. This situation has increased the need for information about the fire resistance of these products. In this study...

  14. Effect on in vitro fracture resistance of the technique used to attach lithium disilicate ceramic veneer to zirconia frameworks.

    Science.gov (United States)

    Schmitter, M; Schweiger, M; Mueller, D; Rues, S

    2014-02-01

    This in vitro study should assess the fracture resistance of veneered zirconia-based crowns with either luted or fused veneer. Thirty-two identical zirconia frameworks (IPS e.max ZirCAD; Ivoclar/Vivadent), were constructed (inLab 3.80; Sirona Dental Systems). All frameworks were veneered with CAD/CAM-fabricated lithium disilicate ceramic (IPS e.max CAD; Ivoclar/Vivadent). For half the crowns (n=16) the veneer was luted to the framework (Multilink Implant; Ivoclar/Vivadent); for the other it was fused (IPS e.max Crystall./Connect; Ivoclar/Vivadent). Half of the specimens were then loaded until failure without artificial aging; the other half underwent artificial aging before assessment of the ultimate load. To compare the two techniques further, finite element analysis (FEA) and fractographic assessment using SEM and EDX analysis were conducted. Statistical assessment was performed by use of non-parametric tests. Initial fracture forces were higher in the fusion group (mean: 1388±190 N versus 1211±158 N). All specimens were insensitive to artificial aging. FEA showed that tensile stresses in the veneer at the frame-veneer interface were much higher for crowns with luted veneer; this may be the reason for their lower fracture resistance. Fractographic analysis revealed that both fused and luted specimens had cohesive and adhesive fracture patterns which resulted in partial delamination of the veneer. Fused crowns are superior to luted crowns. Comparison of fracture resistance with the maximum loads which may occur clinically (Fmax=600 N on one tooth) suggests both techniques might be used clinically, however. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Clinical evaluation on porcelain laminate veneers bonded with light-cured composite: results up to 7 years.

    Science.gov (United States)

    D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; D'Amario, Maurizio

    2012-08-01

    The purpose of this study was to evaluate the clinical performance of laminate porcelain veneers bonded with a light-cured composite. Thirty patients were restored with 119 porcelain laminate veneers. The veneers were studied for an observation time of 7 years. Marginal adaptation, marginal discoloration, secondary caries, color match, and anatomic form were clinically examined following modified United States Public Health Service (USPHS) criteria. Each restoration was also examined for cracks, fractures, and debonding. Pulp vitality was verified. In addition, plaque and gingival indexes and increase in gingival recession were recorded. Survival rate evaluating absolute failures and success rate describing relative failures were statistically determined, using both restoration and patient-related analyses. On the basis of the criteria used, most of the veneers rated Alfa. After 7 years, the results of the clinical investigation regarding marginal adaptation and marginal discoloration revealed only 2.5% and 4.2% Bravo ratings, respectively, among the 119 initially placed veneers. Using the restoration as the statistical unit, the survival rate was 97.5%, with a high estimated success probability of 0.843 after 7 years. Using the patient as the statistical unit, the survival rate was 90.0% and the estimated success probability after 7 years was 0.824. Gingival response to the veneers was all in the satisfactory range. Porcelain laminate veneers offer a predictable and successful treatment modality giving a maximum preservation of sound tooth. The preparation, cementation, and finishing procedures adopted are considered key factors for the long-term success and aesthetical result of the veneer restorations.

  16. Change of the properties of plywood during the thermomodification of veneer and the polarization of the glue

    Science.gov (United States)

    Zamilova, A. F.; Galikhanov, M. F.; Safin, R. R.; Ziatdinov, R. R.; Mikryukova, Y. K.

    2017-09-01

    The article presents the results of experiments on the influence of preliminary thermal treatment of veneer and the effect of the constant electric field (during the preparation of plywood) on the moisture-resistance and adhesive properties of birch plywood. It was found that the thermomodification of veneer and polarization in the process of plywood preparation can significantly improve the properties of plywood, namely, to reduce moisture resistance and increase the strength of plywood material.

  17. Effect of different surface pretreatments and adhesives on the load-bearing capacity of veneered 3-unit PEEK FDPs.

    Science.gov (United States)

    Stawarczyk, Bogna; Thrun, Hadelinde; Eichberger, Marlis; Roos, Malgorzata; Edelhoff, Daniel; Schweiger, Josef; Schmidlin, Patrick R

    2015-11-01

    Polyetheretherketone (PEEK) can be used as a framework material for fixed dental prostheses (FDPs). However, information about the fracture load of veneered PEEK FDPs is still scarce. The purpose of this in vitro study was to investigate the influence of different PEEK surface pretreatments and adhesive systems on the fracture load of 2 differently veneered FDPs. Four hundred eighty anatomically shaped 3-unit PEEK frameworks were milled, airborne-particle abraded with 50 μm alumina powder, and divided into 4 groups according to the following surface pretreatment (n=120): plasma treatment, etching with either sulfuric acid or piranha solution, and no further treatment. All groups were then allocated to 4 conditioning groups: visio.link, Ambarino P60, Signum PEEK Bond, or no conditioning. They were veneered with Signum Composite (n=15) or Signum Ceramis (n=15). Upon completion, the FDPs were thermally aged, and fracture loads and failure types were determined. Statistical analysis was performed with 3/2/1-way ANOVA with the post hoc Tukey HSD test (α=.05). The highest fracture loads were achieved without treatment in combination with visio.link (737 ±138 N). The lowest values were obtained after piranha acid etching and conditioning with visio.link (277 ±71 N); both groups were veneered with Signum Composite. The results, however, indicated no clear influence of either pretreatment or conditioning. With few exceptions, FDPs veneered with Signum Composite showed higher fracture load values compared to Signum Ceramis. After thermocycling, all FDPs showed cracks in the veneering composite resin material in the pontic region, regardless of the PEEK pretreatment or the adhesive system used. After loading, no fractures of the PEEK frameworks were evident in any FDPs, but chipping of the veneering material was observed. With respect to the fracture types after thermocycling, pretreatment, conditioning, or veneering resin cement did not affect the fracture results

  18. Degree of conversion of a resin cement light-cured through ceramic veneers of different thicknesses and types.

    Science.gov (United States)

    Runnacles, Patrício; Correr, Gisele Maria; Baratto Filho, Flares; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

    2014-01-01

    During the cementation of ceramic veneers the polymerization of resin cements may be jeopardized if the ceramics attenuate the irradiance of the light-curing device. The aim of this study was to evaluate the effect of different types and thicknesses of ceramic veneers on the degree of conversion of a light-cured resin-based cement (RelyX Veneer). The cement was light-cured after interposing ceramic veneers [IPS InLine, IPS Empress Esthetic, IPS e.max LT (low translucency) and IPS e.max HT (high translucency) - Ivoclar Vivadent] of four thicknesses (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm). As control, the cement was light-cured without interposition of ceramics. The degree of conversion was evaluated by FTIR spectroscopy (n=5). Data were analyzed with one-way ANOVA and Tukey's test (α=0.05). Significant differences were observed among groups (p0.05). Among 1.5-mm-thick veneers, IPS e.max LT was the only one that showed different results from the control (pveneers were able to produce cements with degrees of conversion similar to the control (p>0.05). The degree of conversion of the evaluated light-cured resin cement depends on the thickness and type of ceramics employed when veneers thicker than 1.5 mm are cemented.

  19. [Effects of three types of veneering porcelain on bending strength of KAVO(TM) Y-TZP/porcelain bilayered structure].

    Science.gov (United States)

    Ma, Ting-ting; Yi, Yuan-fu; Shao, Long-quan; Tian, Jie-mo; Hou, Kang-lin; Zhang, Wei-wei; Wen, Ning; Deng, Bin

    2010-10-01

    To investigate the effect of three types of veneering porcelain on the bending strength of KAVO Y-TZP/porcelain layered structure. KAVO zirconia ceramics were used as the substructure. To form Y-TZP/porcelain bilayered structure, a leucite-based veneering porcelain was fired on the zirconia substructures by slip-casting technique with dentin washbake, and two nano-fluorapatite-based veneering porcelains were fired on the zirconia substructures by either slip-casting or pressed-on technique with or without liner coverage. The bending strength was tested according to ISO 6872 standard, and the veneered surfaces of the fracture samples were analyzed by scanning electron microscopy (SEM). For covering KAVO zirconia core material, the conventional veneering slurry-porcelain combined with liner or wash firing had significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive failure. Thin layer sintering using washbake program or liner on KAVO zirconia surface increases the surface wettability, and this procedure may be indispensable when veneering on the surface of dental zirconia.

  20. The effect of veneering on the marginal fit of CAD/CAM-generated, copy-milled, and cast metal copings.

    Science.gov (United States)

    Ates, Sabit Melih; Yesil Duymus, Zeynep; Caglar, Ipek; Hologlu, Bilal

    2017-11-01

    This in vitro study investigated the marginal fit of metal and zirconia copings before and after veneering on dies with shoulder/chamfer (s/c) finish lines. Using CAD/CAM, ten (n = 10) each s/c zirconia (NZ) copings and ten (n = 10) each s/c metal (MM) copings were generated. As controls, ten (n = 10) each s/c zirconia copings were copy-milled (ZZ) and ten (n = 10) each s/c metal copings were cast (CC). The vertical marginal discrepancy of the copings was measured at 20 predefined spots of the circular shoulder and chamfer finish lines in microns (μm) before and after a first and a second veneering firing using a stereomicroscope at ×40 magnification. Data were statistically analyzed, and the comparisons of CAD/CAM-milled (NZ, MM), copy-milled (ZZ), and cast (CC) copings before and after veneering were made at a significance level of p veneering firing (40 ± 8/42 ± 7). MM copings showed gap values similar to NZ. Second firings did not significantly increase gaps in all groups except ZZ2 of chamfer finish line. Veneering increased the marginal gap width of copings. Within the limits of this in vitro study, aesthetic ceramic veneering of CAD/CAM-generated copings caused a statistically significant but tolerable loss of marginal fit precision.