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1
Hinman, R. W., J. A. Tesk, R. P. Whitlock, E. E. Parry, and J. S. Durkowski. "A Technique for Characterizing Casting Behavior of Dental Alloys." Journal of Dental Research 64, no. 2 (February 1985): 134–38. http://dx.doi.org/10.1177/00220345850640020801.
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MORI, Toshiko, and Farzaneh AGHAJANI. "Gypsum-bonded Investment and Dental Precision Casting (II) Investment for the Quick Casting Technique." Dental Materials Journal 22, no. 4 (2003): 521–31. http://dx.doi.org/10.4012/dmj.22.521.
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MORI, Toshiko, and Farzaneh AGHAJANI. "Gypsum-bonded Investment and Dental Precision Casting (III) Composition of Investment for the Quick Casting Technique." Dental Materials Journal 23, no. 2 (2004): 230–32. http://dx.doi.org/10.4012/dmj.23.230.
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Asgar, K. "Casting Metals in Dentistry: Past - Present - Future." Advances in Dental Research 2, no. 1 (August 1988): 33–43. http://dx.doi.org/10.1177/08959374880020011701.
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This article deals mainly with the development of dental casting techniques and formulation of the different groups of alloys used in the fabrication of ceramo-metal restorations. It is recognized that in order for the quality of dental cast restorations to be improved, having alloys with the proper composition is not enough. Biocompatibility, good mechanical and physical properties, longevity of the restoration, compatibility with porcelain, and a simple manipulative technique are as important. Researchers have contributed to different aspects of dental castings and have made cast restorations what they are today. Unfortunately, much of the original basic research has been overlooked by present investigators, who have duplicated studies conducted in the past without realizing that the study had already been performed and the research had been published. The main reason for this is that abstracts of articles published prior to 1975 are not available through a library computer-search system. To obtain copies of articles published prior to 1975, one has to search the literature to know where they were published. This article provides references for much of the past work in this area. Also, dental libraries do not carry copies of U.S. patents. This places the majority of researchers located at dental schools at a disadvantage. They are not familiar with what the patents claim, what is taught, and why certain elements are added or eliminated from alloys and investment materials. This article also provides the numbers of many U.S. patents. By having the patent number, one can obtain the text of the patent from the U.S. Patent Office in Washington, DC. Since esthetics plays an important role in today's society, emphasis will be given only to alloys designed for fabrication of ceramo-metal restorations. Many ceramo-metal alloys are available today, and they are classified differently by different individuals. In this article, classification will be based on the major components of these alloys, as well as on a chronological introduction of one group leading to the development of the next group. Based on this, one can classify these alloys into six major groups. Chemical composition, properties, and the developers of these alloys, along with their U.S. patents, are given. Recently, two types of all-ceramic restorations have been introduced. The main advantage of the all-ceramic restoration is its superior esthetic quality compared with that of ceramo-metal restorations. Their main disadvantages are low strength and ductility. Their strength, however, is sufficient for single-unit restorations, but not for bridgework. The use of titanium for dental restorations has also been studied, and it has been found to be suitable. Future Studies - Future work should be devoted to the following: (1) the development of stronger and more ductile ceramic materials: (2) further study of the promising palladium alloys from the noble metal group and titanium alloys from the base metal group; (3) the development of easier and less-time-consuming techniques for the fabrication of dental appliances; (4) the development of a powder technique rather than a cast technique for future fabrication methods; and (5) the development of new laboratory equipment, e.g., a single sintering oven capable of sintering both ceramic and metallic particles, which would be accepted if the powder technique is developed.
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Pendergrass, Paula B., Cornelia A. Reeves, and Meyer W. Belovicz. "A Technique for Vaginal Casting Utilizing Vinyl Polysiloxane Dental Impression Material." Gynecologic and Obstetric Investigation 32, no. 2 (1991): 121–22. http://dx.doi.org/10.1159/000293010.
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Haselhuhn, Klaus, Juliana Marotti, Pedro Tortamano, Claudia Weiss, Lubna Suleiman, and Stefan Wolfart. "Assessment of the Stress Transmitted to Dental Implants Connected to Screw-Retained Bars Using Different Casting Techniques." Journal of Oral Implantology 40, no. 6 (December 1, 2014): 641–48. http://dx.doi.org/10.1563/aaid-joi-d-12-00029.
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Passive fit of the prosthetic superstructure is important to avoid complications; however, evaluation of passive fit is not possible using conventional procedures. Thus, the aim of this study was to check and locate mechanical stress in bar restorations fabricated using two casting techniques. Fifteen patients received four implants in the interforaminal region of the mandible, and a bar was fabricated using either the cast-on abutment or lost-wax casting technique. The fit accuracy was checked according to the Sheffield's test criteria. Measurements were recorded on the master model with a gap-free, passive fit using foil strain gauges both before and after tightening the prosthetic screws. Data acquisition and processing was analyzed with computer software and submitted to statistical analysis (ANOVA). The greatest axial distortion was at position 42 with the cast-on abutment technique, with a mean distortion of 450 μm/m. The lowest axial distortion occurred at position 44 with the lost-wax casting technique, with a mean distortion of 100 μm/m. The minimal differences between the means of axial distortion do not indicate any significant differences between the techniques (P = 0.2076). Analysis of the sensor axial distortion in relation to the implant position produced a significant difference (P < 0.0001). Significantly higher measurements were recorded in the axial distortion analysis of the distal sensors of implants at the 34 and 44 regions than on the mesial positions at the 32 and 42 regions (P = 0.0481). The measuring technique recorded axial distortion in the implant-supported superstructures. Distortions were present at both casting techniques, with no significant difference between the sides.
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Myszka, D., and M. Skrodzki. "Comparison of Dental Prostheses Cast and Sintered by SLM from Co-Cr-Mo-W Alloy." Archives of Foundry Engineering 16, no. 4 (December 1, 2016): 201–7. http://dx.doi.org/10.1515/afe-2016-0110.
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Abstract The article presents the results of a comparative analysis of the metal substructure for dental prosthesis made from a Co-Cr-Mo-W alloy by two techniques, i.e. precision investment casting and selective laser melting (SLM). It was found that the roughness of the raw surface of the SLM sinter is higher than the roughness of the cast surface, which is compensated by the process of blast cleaning during metal preparation for the application of a layer of porcelain. Castings have a dendritic structure, while SLM sinters are characterized by a compact, fine-grain microstructure of the hardness higher by about 100 HV units. High performance and high costs of implementation the SLM technology are the cause to use it for the purpose of many dental manufacturers under outsourcing rules. The result is a reduction in manufacturing costs of the product associated with dental work time necessary to scan, designing and treatment of sinter compared with the time needed to develop a substructure in wax, absorption in the refractory mass, casting, sand blasting and finishing. As a result of market competition and low cost of materials, sinter costs decrease which brings the total costs related to the construction unit making using the traditional method of casting, at far less commitment of time and greater predictability and consistent sinter quality.
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Han, Xingting, Tomofumi Sawada, Christine Schille, Ernst Schweizer, Lutz Scheideler, Jürgen Geis-Gerstorfer, Frank Rupp, and Sebastian Spintzyk. "Comparative Analysis of Mechanical Properties and Metal-Ceramic Bond Strength of Co-Cr Dental Alloy Fabricated by Different Manufacturing Processes." Materials 11, no. 10 (September 22, 2018): 1801. http://dx.doi.org/10.3390/ma11101801.
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Cobalt-chromium (Co-Cr) alloy is a widely used base material for dental fixed prostheses. These restorations can be produced through casting technique, subtractive or additive manufacturing technologies. However, limited information is available regarding the influence of manufacturing techniques on the properties of Co-Cr alloy since most studies used different chemical compositions of Co-Cr alloy for different manufacturing methods. This study compares the mechanical properties, metal-ceramic bond strength, and microstructures of specimens produced by casting, milling, and selective laser melting (SLM) from one single Co-Cr alloy composition. The mechanical properties of the alloy were investigated by tensile and Vickers hardness tests, and metal-ceramic bond strength was determined by three-point bending. Scanning electron microscopy (SEM) with backscattered electron (BSE) images and optical microphotographs were used to analyze the surface microstructures. Compared with the casting and milling techniques, SLM Co-Cr alloy specimens indicated enhanced mechanical properties and comparable metal-ceramic bond strength. Besides, the microstructures of the SLM specimens showed finer grains with more second phase particles than the casting and milling specimens. The results of our study indicate that SLM might be superior to traditional techniques for the manufacturing of fixed dental restorations.
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Sharma, Abhishek, Karan Kapoor, Abhinav Chauhan, and Manisha Kanwar. "Evaluation of Various Dental Casting Alloys and Techniques-An Overview." Indian Journal of Contemporary Dentistry 2, no. 2 (2014): 67. http://dx.doi.org/10.5958/2320-5962.2014.00014.x.
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Sarna-Boś, Katarzyna, Agata Batyra, Justyna Oleszek-Listopad, Beata Piórkowska-Skrabucha, Janusz Borowicz, and Jolanta Szymańska. "A comparison of the traditional casting method and the galvanoforming technique in gold alloy prosthetic restorations." Current Issues in Pharmacy and Medical Sciences 28, no. 3 (September 1, 2015): 196–99. http://dx.doi.org/10.1515/cipms-2015-0071.
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Abstract Gold is a dental material with very good mechanical properties. It is also aesthetic and biocompatible with the tissues of the oral cavity even at 100% purity. Prosthetic restorations made of pure gold or its alloys can be practiced either through a normal casting, as well as through using the galvanoforming technique. The electrolytic method was first introduced into dentistry about 20 years ago and it allows for producing “pure” gold (which means 99.99% Au). The lack of additions of other metals improves the properties of dental prostheses, such as marginal tightness, esthetics, biocompatibility, and it helps in eliminating any allergic reactions. The literature review presented in this paper is a comparison of the traditional casting method with the newer galvanoforming technique.
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Deng, Bin, Hong Chen Liu, Yuan Fu Yi, Chen Wang, Ning Wen, and Jie Mo Tian. "Effects of Veneering Porcelain Type on Bending Strength of Dental Y-TZP/Porcelain Bilayered Structure." Advanced Materials Research 105-106 (April 2010): 524–27. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.524.
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The purpose of this study was to investigate the effect of different veneering porcelain types on the flexural strength of dental Y-TZP/porcelain layered structure. KAVO™ Everest zirconia ceramics were selected as substructure. To forming 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 porcelain was fired on the zirconia substructures either by slip-casting or pressed-on technique with or without liner coverage. Bending strength was tested according to ISO 6872 standard, and the veneered surfaces of fracture samples were analyzed by SEM. Experimental results showed that for covering KaVo™ zirconia core material, conventionally applied veneering slurry-porcelain combined with liner or wash firing has significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive.
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Bae, Soohyun, Min-Ho Hong, Hyunwoo Lee, Cheong-Hee Lee, Mihee Hong, Jaesik Lee, and Du-Hyeong Lee. "Reliability of Metal 3D Printing with Respect to the Marginal Fit of Fixed Dental Prostheses: A Systematic Review and Meta-Analysis." Materials 13, no. 21 (October 26, 2020): 4781. http://dx.doi.org/10.3390/ma13214781.
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Three-dimensional (3D) printing technologies have been widely used to manufacture crowns and frameworks for fixed dental prostheses. This systematic review and meta-analysis aimed to assess the reliability of the marginal fit of 3D-printed cobalt-chromium-based fixed dental prostheses in comparison to conventional casting methods. Articles published until 25 June 2020, reporting the marginal fit of fixed prostheses fabricated with metal 3D printing, were searched using electronic literature databases. After the screening and quality assessment, 21 eligible peer-reviewed articles were selected. Meta-analysis revealed that the marginal gap of the prostheses manufactured using 3D printing was significantly smaller compared to that manufactured using casting methods (standard mean difference (95% CI): −0.92 (−1.45, −0.38); Z = −3.37; p = 0.0008). The estimated difference between the single and multi-unit types did not differ significantly (p = 0.3573). In the subgroup analysis for the measurement methods, the tendency of marginal discrepancy between the 3D printing and casting groups was significantly different between articles that used direct observation and those that used the silicone replica technique (p < 0.001). Metal 3D printing technologies appear reliable as an alternative to casting methods in terms of the fit of the fixed dental prostheses. In order to analyze the factors influencing manufacturing and confirm the results of this review, further controlled laboratory and clinical studies are required.
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Amat, Noor Faeizah, Andanastuti Muchtar, Norziha Yahaya, Mariyam Jameelah Ghazali, and Chin Chuin Hao. "Comparison between Slip Casting and Cold Isostatic Pressing for the Fabrication of Nanostructured Zirconia." Advanced Materials Research 896 (February 2014): 335–38. http://dx.doi.org/10.4028/www.scientific.net/amr.896.335.
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Consolidation of ceramic parts may be achieved by several techniques, including the slip casting and cold isostatic pressing (CIP) methods. In the present work, the performances of the two methods are compared in the fabrication of nanostructured zirconia compacts for dental crown applications. First, a zirconia suspension suitable for slip casting was prepared. The rheological properties of the zirconia suspension were optimized by adding a dispersant agent and controlling the pH. Zirconia slurries were then slip-cast into a pellet. Second, another group of zirconia pellets were fabricated using uniaxial pressing and were then cold-isostatically pressed. Both slip-cast and CIP samples were sintered at 1300 °C with a soaking time of 2 hrs. The mechanical properties of both samples were compared. The samples prepared by slip casting were denser compared with those prepared via CIP. Slip casting technique produced samples with 98.8% of the theoretical density, which resulted in the high Vickers hardness (11.4 GPa) of the slip-cast samples. Morphological studies revealed that the microstructures of the slip cast-sample were more homogeneous and contain no porosity. The formation of such a structure is due to the enhancement of the particle packing efficiency by slip casting as well as to the removal of larger agglomerates by colloidal processing prior to casting. As a consolidation stage, slip casting appears to be more suitable than the CIP technique in preparing reliable nanostructural ceramic parts.
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Cotrut, Mihai Cosmin, Sorin Ciuca, Florin Miculescu, Iulian Vasile Antoniac, Mihai Tarcolea, and Maria Diana Vrânceanu. "The Influence of Classical and Modern Manufacturing Technologies on the Properties of Metal Dental Bridges." Key Engineering Materials 583 (September 2013): 163–68. http://dx.doi.org/10.4028/www.scientific.net/kem.583.163.
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This paper aims to characterize two dental bridges made from Co-Cr alloy, the first one obtained by the conventional method (casting) and the second one by Selective Laser Sintering technique (SLS). The elemental composition, microstructure, hardness and corrosion behavior in artificial saliva were investigated, allowing a parallel analysis of this two samples obtained with the two methods mentioned above.
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Ardelean, Lavinia, Lucien Reclaru, Cristina Bortun, and Laura Cristina Rusu. "Joint Quality Assessment of Three Different Laser Welded Dental Alloys." Solid State Phenomena 216 (August 2014): 63–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.216.63.
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The aim of this study is to assess the quality of laser welded joints, by different methods such as: scanning electronic microscopy, metallography, microhardness testing, spectrographic and radiographic analyses. The alloys assessed are a titanium-based alloy used in manufacturing prefabricated pieces for implantology, a standard AuPd alloy for the metallo-ceramic technique and a Cr-Co-Mo alloy used for manufacturing the metallic components of partial dentures. The conclusion of the testing is that laser welded joints are generally mechanically satisfactory. Laser is best suitable to weld titanium and its alloys because they have higher rates of laser beam absorption and lower thermal conductivity than other dental casting alloys.
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Borges, Silas Monteiro, Stephanie Francoi Poole, Izabela Cristina Maurício Moris, Aloísio Oro Spazzin, Adriana Cláudia Lapria Faria, and Erica Alves Gomes. "Different fabrication techniques of implant-supported prostheses." Brazilian Journal of Oral Sciences 18 (November 12, 2019): e191573. http://dx.doi.org/10.20396/bjos.v18i0.8657254.
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Aim: This study evaluated the mechanical behavior of implant-supported crowns obtained by different fabrication technique after thermomechanical cycling. Methods: Thirty-two external hexagon dental implants were divided into four groups (n=10): CC – conventional casting with torch; EI – electromagnetic induction casting; PL – plasma casting; and CAD-CAM – milling through computer-aided design and computer-aided manufacturing. Vickers microhardness of the specimens were made before and after the thermomechanical cycling, and then subjected to fracture load. Fracture pattern was evaluated. Results: No significant difference was observed comparing the microhardness before and after thermomechanical cycling. CAD-CAM group presented significant lower microhardness than the other groups. No significant statistical difference was showed on fracture load between the groups. The CAD-CAM and PL presented lower number of failure by plastic deformation. Conclusion: The manufacturing techniques affected the mechanical behavior and the failure pattern of implant-supported crowns tested.
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Mergulhão, Marcello Vertamatti, Carlos Eduardo Podestá, and Maurício David Martins das Neves. "Mechanical Properties and Microstructural Characterization of Cobalt-Chromium (CoCr) Obtained by Casting and Selective Laser Melting (SLM)." Materials Science Forum 899 (July 2017): 534–39. http://dx.doi.org/10.4028/www.scientific.net/msf.899.534.
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The aim of this study is the consolidation of Cobalt-Chromium (CoCr) alloy powder using the additive manufacturing - selective laser melting (SLM) and the investment casting techniques. The research of this study has been applied to their biomaterial applied to development of prosthesis and dental implants. The gas atomized powder are spherical (mean diameter equal to 42,74 μm) and was analyzed by their physical and chemical properties. The microstructure of the powder and specimens was evaluated using optical microscope (OM) and scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS). The mechanical properties were evaluated of standard samples using a tensile (yield strength, maximum tensile, rupture tensile and elongation), three point bending (transverse rupture strength) and micro hardness tests. The mechanical results indicate higher values for the SLM than casting specimens. The micrographs revealed a characteristic morphology of laser been used in the SLM technique and the dendrites in the casting technique. The microstructure of samples made by SLM is thinner than the samples obtained in the cast.
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Yu, Ji-Min, Seen-Young Kang, Jun-Seok Lee, Ho-Sang Jeong, and Seung-Youl Lee. "Mechanical Properties of Dental Alloys According to Manufacturing Process." Materials 14, no. 12 (June 17, 2021): 3367. http://dx.doi.org/10.3390/ma14123367.
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The purpose of this study is to investigate the effect of the fabrication method of dental prosthesis on the mechanical properties. Casting was produced using the lost wax casting method, and milling was designed using a CAD/CAM program. The 3D printing method used the SLS technique to create a three-dimensional structure by sintering metal powder with a laser. When making the specimen, the specimen was oriented at 0, 30, 60, and 90 degrees. All test specimens complied with the requirements of the international standard ISO 22674 for dental alloys. Tensile strength was measured for yield strength, modulus of elasticity and elongation by applying a load until fracture of the specimen at a crosshead speed of 1.5 ± 0.5 mm/min (n = 6, modulus of elasticity n = 3). After the tensile test, the cross section of the fractured specimen was observed with a scanning electron microscope, and the statistics of the data were analyzed with a statistical program SPSS (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY, USA: IBM Corp.) and using Anova and multiple comparison post-tests (scheffe method). The yield strength was the highest at 1042 MPa at an angle of 0 degrees in the specimen produced by 3D printing method, and the elongation was the highest at 14% at an angle of 90 degrees in the specimen produced by 3D printing method. The modulus of elasticity was the highest at 235 GPa in the milled specimen. In particular, the 3D printing group showed a difference in yield strength and elongation according to the build direction. The introduction of various advanced technologies and digital equipment is expected to bring high prospects for the growth of the dental market.
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Denry, Isabelle L. "Recent Advances in Ceramics for Dentistry." Critical Reviews in Oral Biology & Medicine 7, no. 2 (April 1996): 134–43. http://dx.doi.org/10.1177/10454411960070020201.
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For the last ten years, the application of high-technology processes to dental ceramics allowed for the development of new materials such as heat-pressed, injection-molded, and slip-cast ceramics and glass-ceramics. The purpose of the present paper is to review advances in new materials and processes available for making all-ceramic dental restorations. Concepts on the structure and strengthening mechanisms of dental ceramics are provided. Major developments in materials for all-ceramic restorations are addressed. These advances include improved processing techniques and greater mechanical properties. An overview of the processing techniques available for all-ceramic materials is given, including sintering, casting, machining, slip-casting, and heat-pressing. The most recent ceramic materials are reviewed with respect to their principal crystalline phases, including leucite, alumina, forsterite, zirconia, mica, hydroxyapatite, lithium disilicate, sanidine, and spinel. Finally, a summary of flexural strength data available for all-ceramic materials is included.
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Savencu, Cristina, Liliana Porojan, Mihaela Bîrdeanu, Adrian Boloș, Sorin Porojan, Aurora Antoniac, and Sebastian Gradinaru. "Surface Characteristics of Base Metal Dental Alloys Processed by Alternative Procedures." Defect and Diffusion Forum 376 (July 2017): 1–11. http://dx.doi.org/10.4028/www.scientific.net/ddf.376.1.
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Technological developments in the field of based metal alloys have led to the implementation of novel manufacturing processes in dental practice. The aim of the study was to evaluate surface characteristics of Co–Cr dental alloys fabricated via conventional casting, computerized milling, selective laser sintering and selective laser melting. The morphology and the topography of the samples were investigated by SEM / EDAX (Model INSPECT S) and AFM (Model Nanosurf® EasyScan 2 Advanced Research). Depending on the nature and chemical composition of the samples the morphology is different. The microstructure of Co–Cr dental alloys depends on the manufacturing technique. Given to the differences in microstructural properties among the tested specimens, further differences in their technological achievement and clinical behavior can be anticipated.
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Barro, Óscar, Felipe Arias-González, Fernando Lusquiños, Rafael Comesaña, Jesús del Val, Antonio Riveiro, Aida Badaoui, Félix Gómez-Baño, and Juan Pou. "Effect of Four Manufacturing Techniques (Casting, Laser Directed Energy Deposition, Milling and Selective Laser Melting) on Microstructural, Mechanical and Electrochemical Properties of Co-Cr Dental Alloys, Before and After PFM Firing Process." Metals 10, no. 10 (September 27, 2020): 1291. http://dx.doi.org/10.3390/met10101291.
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The objective of this study was to compare four manufacturing processes of Co-Cr dental alloys: casting (CAST), computer aided design/computer aided manufacturing (CAD/CAM) milling (MILL), selective laser melting (SLM), and laser directed energy deposition (LDED). Comparison included microstructural, mechanical, and electrochemical analyses. Half of the samples obtained were heat treated to simulate the porcelain fused to metal (PFM) firing process, and the metal real state in an oral environment. Co-Cr dental alloys manufactured via casting, LDED, milling, and SLM techniques presented evident differences in their mechanical properties. However, their electrochemical performances were similar, with high resistance to corrosion in artificial saliva, in both aerated and deaerated media (corrosion rate under 4 microns per year). LDED and milling materials showed the highest modulus of toughness, and gave improved results in comparison with CAST and SLM techniques (p < 0.05). The LDED process could be implemented in the manufacturing of the restorative dental industry, with a high overall performance, competing directly with the best quality techniques, and reducing their disadvantages.
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Zhang, Peng, and Hong Yu Guan. "Effect of Solid Loading on Properties of All-Ceramic Crown by Gel-Casting Technique." Advanced Materials Research 833 (November 2013): 169–72. http://dx.doi.org/10.4028/www.scientific.net/amr.833.169.
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To compare the influence of porosity on bending strength, density, viscosity of slurry of dental zirconia-toughened alumina(Ce-TZP/A) ceramic by gel-casting technique. Ce-TZP/A composite ceramic powder was made from a Al2O3 of micron grade and 3Ce-ZrO2 of nanometer grade, with sintering additives of MgO and TiO2. The slurries of 5(v/v), 52%, 54%, 56% ,58% and 60% were prepared separately, and sintered at 1200°C after in situ molding using gel-casting. The properties such as bending strength, density, viscosity of slurry of specimens were measure and compared. Slurry was prepared with optimum solid content, and applied to form dental CeTZP/A basal crown on the plaster die. The marginal fitness of crowns was observed after sintered. The mean viscosity of slurry (PaS) were: 0.27±0.05, 0.31±0.1, 0.33±0.09, 0.96±0.12, 1.01±0.07, 1.21±0.02. The effect of solid loading (P=0.05) were significant. The mean bending strength (MPa) were: 43.15±0.8, 47.9±1.5, 50.09±1.7, 58.12±1.9, 39.17±1.6, 35.08±1.2. The mean toughness (MPa m^1/2) were: 17.6±0.8, 16.9±0.6, 16.1±0.5, 17.8±0.9, 18.6±0.8, 20.5±0.2. The mean density (g/cm) were: 5.32±0.9, 5.43±0.8, 6.13±0.5, 6.01±0.5, 5.13±0.3, 5.05±0.4. The specimen formed from slurry of 52(v/v) had better properties than that of others solid loading after sintered at 1150º. With the solid loading increased, the viscosity of slurry has a significantly improved.
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Lapcevic, Ana R., Danimir P. Jevremovic, Tatjana M. Puskar, Robert J. Williams, and Dominic Eggbeer. "Comparative analysis of structure and hardness of cast and direct metal laser sintering produced Co-Cr alloys used for dental devices." Rapid Prototyping Journal 22, no. 1 (January 18, 2016): 144–51. http://dx.doi.org/10.1108/rpj-04-2014-0051.
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Purpose – The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM samples) and additive direct metal laser sintering technology (DMLS samples), and to compare the results. Design/methodology/approach – CCM samples were made in a conventional casting machine, using remanium 800+ Co-Cr dental alloy (Dentaurum, Ispringen, Germany). DMLS samples were fabricated out of EOS CC SP2 Co-Cr alloy (EOS, GmbH, Munich, Germany) using DMLS technology. Samples for structural analysis were plate-shaped (10 × 10 × 1.5 mm3) and for the hardness test were prismatic-shaped (55 × 10.2 × 11.2 mm3). Structure was analysed via an inverting microscope and colour metallography method. Findings – CCM samples have a dense, irregular dendritic mesh, which is typical for the metallic phase of the Co-Cr dental alloy. DMLS alloy has a more homogenous and more compact structure, compared to CCM. Metals, the alloy basis consists of, form semilunar stratified layers, which are characteristic for the additive manufacturing (AM) technique. Hardness values of DMLS (mean value was 439.84 HV10) were found to be higher than those of CCM (mean value was 373.76 HV10). Originality/value – There are several reports about possible use of AM technologies for manufacturing dental devices, and investigation of mechanical properties and biocompatibility behaviour of AM-produced dental alloys. Microstructure of Co-Cr alloy made with DMLS technology has been introduced for the first time in the present paper.
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Saláta, József. "A fogászati kerámiaanyagok fejlődésének történeti áttekintése." Kaleidoscope history 11, no. 22 (2021): 284–93. http://dx.doi.org/10.17107/kh.2021.22.284-293.
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Initially, ceramics - mostly burnt clay - were used to manufacture container pottery. The first porcelain objects reached Europe out of China in the Medieval Ages. The technique of their manufacturing was a mystery for many hundred years, yet Germans succeeded first to produce fine European porcelain at the beginning of the 18th century. Its elegance and hardness woke the dentists’ interest too thus Frenchmen created the first porcelain dentures in the second half of the 18th century. Since then, there has been an increasing demand for esthetic fixed implant dentures instead of removable ones. The development of ceramic materials resulted in better mechanical and optical properties, thus the first fixed porcelain inlays and jacket crowns were introduced already in 1889. The addition of leucite filler crystals to porcelain in the 20th century increased the thermal expansion of the ceramic. It could be fired on common dental casting alloys, so the first porcelain-fused-to-metal (PFM) crown was created in 1962. Several new techniques were developed from the middle of the 1980s to the end of the 1990s to deal with initial shrinkage and achieve better properties. Beyond casting, pressing, and CAD/CAM technology, additive manufacturing opened new perspectives in dentistry several years ago in processing dental ceramics.
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Loch, Joanna, Alicja Łukaszczyk, Joanna Augustyn-Pieniążek, and Halina Krawiec. "Electrochemical Behaviour of Co-Cr and Ni-Cr Dental Alloys." Solid State Phenomena 227 (January 2015): 451–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.451.
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The purpose of this paper was to study the corrosion resistance of Co-Cr and Ni-Cr dental alloys in simulated artificial saliva by means of electrochemical techniques. Co and Ni based alloys are widely used in dental skeletal structures and orthopedic implants such as screws, pins and plater. And recently they have been applied for making stents. The advantages of these alloys include low cost of casting, matching thermal expansion coefficient with the ceramics of metal-ceramic restorations, and acceptable mechanical and tribological properties in vivo. The microstructure of investigated alloys were studied by using optical microscopic observation, X-ray diffraction measurements and Scanning Electron Microscope with X-ray microanalyzer. The mechanical properties were characterized by microhardness tests.
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Can, Gülşen, Gül Akpınar, and Ahmet Aydın. "The Release of Elements from Dental Casting Alloy into Cell-Culture Medium and Artificial Saliva." European Journal of Dentistry 01, no. 02 (April 2007): 086–90. http://dx.doi.org/10.1055/s-0039-1698319.
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ABSTRACTObjectives: The biocompatibility of dental casting alloys is a critical issue because these alloys are in long-term intimate contact with oral tissues. Since the biocompatibility of alloys is not completely known; the release of elements from the alloys has been studied. The aim of this study was to compare the elemental release from dental casting alloy during exposure to artificial saliva and cell-culture medium.Materials and Methods: Twenty specimens made from Ni-Cr alloy were provided in the form of 5 mm diameter discs, 2 mm in thickness with a 7 mm stem attached to one face to facilitate handling. Ten of twenty samples were polished separately using a conventional technique. The remaining ten samples were left sandblasted with 50 μm Al203. Ten samples (5 polished, 5 sandblasted) were separately placed into cell-culture wells with Dulbecco’s Modified Eagle’s Medium. The other ten samples were placed separately into cell-culture wells with artificial saliva. The samples were subjected in contact with these medium for 30 days. These medium were collected every 7 days. The cell-culture medium and artificial saliva without alloy samples were subjected to elemental analyses as a control. At the end of the exposure time, Atomic Absorption Spectrometry (AAS) was used to determine the release of elements from the alloys into all collected medium. Statistical analyses were assessed with two-way ANOVAResults: In general, the elemental release occurred with in all medium. The elemental releases of sandblasted alloys were higher than polished alloys. Artificial saliva was found to cause more release from the samples. In both media, Ni released from polished and sandblasted alloys were higher than Cr and Mo.The results suggest that the release of elements from the alloys might have correlated with the environments and the surface of dental alloy. (Eur J Dent 2007;2:86-90)
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Uriciuc, Willi Andrei, Horatiu Vermesan, Ancuta Elena Tiuc, Aranka Ilea, Adina Bianca Bosca, and Catalin Ovidiu Popa. "Casting over Metal Method Used in Manufacturing Hybrid Cobalt-Chromium Dental Prosthetic Frameworks Assembles." Materials 14, no. 3 (January 23, 2021): 539. http://dx.doi.org/10.3390/ma14030539.
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Cobalt–chromium (Co–Cr) alloys are the most widely used materials for removable and fixed dental prosthetic frameworks. The fitting accuracy between these components in dental prosthetic frameworks assembles (DPFAs) is largely influenced by the manufacturing method. This study presents a novel manufacturing method that combined two common techniques for obtaining one single framework: casting of Co–Cr inserts on top of parts previously manufactured by selective laser melting (SLM) of Co–Cr powder (CoM). Horizontal (n = 4) and vertical (n = 3) surfaces were microscopically analyzed (n = 770 count sum). The results revealed a high precision of the process and high fitting accuracy between the hybrid frameworks. The average distance measured between the frameworks in joined position was 41.08 ± 7.56 µm. In conclusion, the manufacturing of Co–Cr alloys DPFA using the CoM method reduced the deformation of hybrid frameworks and improved the joining accuracy between them.
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Qasim, Tarek, Yeo Khee Wee, Wei Lun Cai, and Xiao Zhi Hu. "Contact Damage of Curved Multi-Layered Ceramics: Prepared by Slip Casting Technique." Key Engineering Materials 417-418 (October 2009): 461–64. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.461.
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Contact damage of curved multi-layered systems, consisting of a brittle zirconia (3Y-TZP)/Alumina (Al2O3) coating – prepared by slip casting – on a compliant polymeric substrate from indentation by a hard tungsten carbide sphere is investigated. The essence of this study is to compare the structural performance of layered ceramics, and monolithic ceramic in the brittle coating and compliant substrate of dental crown-like systems. The specimens are loaded at the axis of symmetry. The failure evolution to initiate cracking and final failure patterns in curved multi-layered specimens are compared to those of the single layer specimens of the same thickness and the same study are conducted again with the flat specimens. The onset of fracture is observed in situ using a video camera. It is demonstrated that in all specimens, cone cracking occurs prior to radial cracking, with the latter being defined as the primary mode of catastrophic failure. The multi-layered ZTA (Zirconia Toughened Alumina) specimens prepared by slip casting possessed a distinct final failure pattern in comparison with a single layer specimen. The results of this study provide useful guidelines for building brittle multi-layered coating systems with the functionally graded feature, and complex shapes with geometrical uniformity.
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Amat, Noor Faeizah, Andanastuti Muchtar, Norziha Yahaya, and Mariyam Jameelah Ghazali. "Effect of Dispersant Agent Amount in Colloidal Processing of Zirconia Dental Ceramic." Advanced Materials Research 622-623 (December 2012): 215–19. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.215.
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The effects of a polyelectrolyte dispersant agent, polyethyleneimine (PEI), on the rheology of zirconia 3Y-TZP suspensions and the densification characteristics of sintered zirconia were investigated. The colloidal processing technique was used to minimize the agglomeration of nanoparticles during the fabrication of the samples. Five batches of 10% zirconia suspensions containing different amounts of PEI at 0.3, 0.4, 0.5, 0.6, and 0.7 wt% were prepared. The rheological properties of the zirconia suspensions were determined using a rotational viscometer. The optimum amount of PEI that can maximize powders dispersion was determined. The green samples were then prepared using the slip casting process. The samples were densely sintered at a final sintering temperature of 1300 °C. The result revealed that the zirconia suspension with 0.5 wt% PEI was the most optimum amount to obtain a well-dispersed suspension. The sintered density of zirconia 3Y-TZP reached its maximum by adding 0.5 wt% PEI.
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Jackson, Brian J. "The Use of Laser-welded Titanium Framework Technology: A Case Report for the Totally Edentulous Patient." Journal of Oral Implantology 31, no. 6 (December 1, 2005): 294–300. http://dx.doi.org/10.1563/779.1.
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Abstract Laser-welded technology has become a viable alternative to the conventional lost wax-casting technique in the field of implant dentistry. Studies have demonstrated the predictable nature of laser-welded titanium frameworks for endosseous implants in the partial and totally edentulous patient. A standardized impression and fabrication procedure is required for an accurate and predictable superstructure. More long-term studies are needed for more widespread acceptance and usage by dental practitioners.
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Naumovski, Borjan, and Biljana Kapushevska. "Dimensional Stability and Accuracy of Silicone – Based Impression Materials Using Different Impression Techniques – A Literature Review." PRILOZI 38, no. 2 (September 1, 2017): 131–38. http://dx.doi.org/10.1515/prilozi-2017-0031.
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Abstract A quality-made dental impression is a prerequisite for successful fixed-prosthodontic fabrication and is directly dependent on the dimensional stability, accuracy and flexibility of the elastomeric impression materials, as well as on the appropriately used impression techniques. The purpose of this paper is to provide a literature review of relevant scientific papers which discuss the use of various silicone impression materials, different impression techniques and to evaluate their impact on the dimensional stability and accuracy of the obtained impressions. Scientific papers and studies were selected according to the materials used, the sample size, impression technique, storage time, type of measurements and use of spacer for the period between 2002 and 2016. In the reviewed literature several factors that influence the dimensional stability and accuracy of silicone impression molds, including the choice of the type of viscosity, impression material thickness, impression technique, retention of the impression material on the tray, storage time before the casting, number of castings, hydrophilicity of the material, release of byproducts, contraction after polymerization, thermal contraction and incomplete elastic recovery were presented. The literature review confirmed the lack of standardization of methodologies applied in the research and their great diversity. All findings point to the superiority of the addition silicone compared to the condensation silicone.
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Wahjuni, Sri, and Sefy Ayu Mandanie. "Fabrication of Combined Prosthesis With Castable Extracoronal Attachments (Laboratory Procedure)." Journal Of Vocational Health Studies 1, no. 2 (November 14, 2017): 75. http://dx.doi.org/10.20473/jvhs.v1.i2.2017.75-81.
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Background : Nows a days has developed many kind of dentures to improve the functionality, comfort aesthetics. Stability, retention and its aesthetic can be improved by attachments. With many kind design assortment of dentures so need a different technique with the existing design. Purpose : The aim of this study is to know the danture manufacturing process in combination with Castable protesa Extracoronal Attachments labolatory procedure. Review: Fixed dentures are each bonded teeth protesa, inserted mechanically and support by teeth or dental implant abutment or that provide the main support for the dental protesa. A partial denture is a spin-off protesa that replaces one or more missing teeth, on the maxillary or mandibullary and can be opened by patients without the supervision of a dentist. Extracoronal attachment is an attachment that is part of the male and female part are almost entirely outside the contours of the Crown of the tooth. Conclusion: the initial stages are making of coping use wax pattern and inserted the female, the casting of metal, porcelain applications, making the wax pattern of the metal frame work, the casting of metal, inserted male, making a removable dentures.
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Łukaszczyk, A., and J. Augustyn-PieniąŻek. "Corrosion Resistance of Co-Cr-Mo Alloy Used in Dentistry." Archives of Metallurgy and Materials 60, no. 1 (April 1, 2015): 523–28. http://dx.doi.org/10.1515/amm-2015-0084.
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Abstract The presented paper studies the effect of the casting technology on the corrosion resistance of Co-Cr-Mo alloy. The investigations were conducted on a commercial alloy with the brand name ARGELOY N.P SPECIAL (Co-Cr-Mo) produced by Argen as well as the same alloy melted and cast by the lost wax casting method performed by a dental technician. The corrosion behavior of the dental alloys in an artificial saliva was studied with the use of the following electrochemical techniques: open circuit potential and voltammetry. After the electrochemical tests, studies of the surface of the examined alloys were performed by means of a scanning electron microscope with an X-ray microanalyzer. The results of the electrochemical studies show that the dependence of the corrosion resistance on the microstructure associated with the recasting process is marginal. The results of the electrochemical studies of the considered alloy clearly point to their good corrosion resistance in the discussed environment.
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Kiliçarslan, Mehmet Ali, Pelin Özkan, Bülent Uludag, and Emre Mumcu. "Comparison of Internal Fit between Implant Abutments and Cast Metal Crowns vs Laser-sintered Crowns." Journal of Contemporary Dental Practice 15, no. 4 (2014): 428–32. http://dx.doi.org/10.5005/jp-journals-10024-1557.
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ABSTRACT Aim A common problem related to cemented single crowns is the internal misfit, which may cause inadequate retention, especially when seated on the implant abutment. The aim of this study was to compare the internal fit of Co-Cr crowns using a traditional lost-wax casting technique from laser-sintered Co-Cr alloy crowns. Materials and methods Twelve metallic crowns per each technique were fabricated. The effect of the thickness of cement, originated internal gap was evaluated. Crowns were cemented on the implant abutments with resin cement, and the internal fit of crowns was measured at five areas with an optical microscope. The data were analyzed, and the means were compared with a t-test (p<0.05). Results The internal gap width measurements for the lasersintered group (min. 52.19 ± 11.61 µm and max. 140.01 ± 31.84 µm) indicated the presence of a significantly closed internal gap compared to the crowns obtained through the lost wax method (min. 65.50 ± 9.54 µm and max. 313.46 ± 48.12 µm). Conclusion The fit of the metal crown likely varies with the fabrication technique. The use of techniques that enable the adjustment of crown parameters, such as the laser sintering technique, maintains the desired fit between casting and implant abutments. Clinical significance This study investigated which technique affects the internal fit of cemented implant-supported crowns, comparing the use of lost wax casting and laser-sintered metal dental alloys. The results of this study indicate that the use of laser-sintered crowns can improve for crown accuracy. How to cite this article Kiliçarslan MA, Özkan P, Uludag B, Mumcu E. Comparison of Internal Fit between Implant Abutments and Cast Metal Crowns vs Laser-sintered Crowns. J Contemp Dent Pract 2014;15(4):428-432.
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Izadi, Alireza, Fariborz Vafaee, Arash Shishehian, Ghodratollah Roshanaei, and Behzad Fathi Afkari. "Evaluation of dimensional accuracy of dental bridges manufactured with conventional casting technique and CAD/CAM system with Ceramill Sintron blocks using CMM." Journal of Dental Research, Dental Clinics, Dental Prospects 12, no. 4 (December 19, 2018): 264–71. http://dx.doi.org/10.15171/joddd.2018.041.
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Background. Recently, non-presintered chromium-cobalt (Cr-Co) blocks with the commercial name of Ceramill Sintron were introduced to the market. However, comprehensive studies on the dimensional accuracy and fit of multi-unit frameworks made of these blocks using the coordinate measuring machine (CMM) are lacking. This study aimed to assess and compare the dimensional changes and fit of conventional casting and milled frameworks using Ceramill Sintron. Methods. A metal model was designed and scanned and 5-unit frameworks were fabricated using two techniques: (I) the conventional casting method (n=20): the wax model was designed, milled in the CAD/CAM machine, flasked and invested; (II) the milling method using Ceramill Sintron blocks (n=20): the wax patterns of group 1 were used; Ceramill Sintron blocks were milled and sintered. Measurements were made on the original reference model and the fabricated frameworks using the CMM in all the three spatial dimensions, and dimensional changes were recorded in a checklist. Data were analyzed with descriptive statistics, and the two groups were compared using one-way ANOVA and Tukey test (α=0.05). Results. The fabricated frameworks in both groups showed significant dimensional changes in all the three dimensions. Comparison of dimensional changes between the two groups revealed no significant differences (P>0.05) except for transverse changes (arch) that were significantly greater in Ceramill Sintron frameworks (P<0.05). Conclusion. The two manufacturing processes were the same regarding dimensional changes and the magnitude of marginal gaps and both processes resulted in significant dimensional changes in frameworks. Ceramill Sintron frameworks showed significantly greater transverse changes than the conventional frameworks.
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Stamenkovic, Dejan, Kosovka Obradovic-Djuricic, Rebeka Rudolf, Rajko Bobovnik, and Dragoslav Stamenkovic. "Selective laser melting and sintering technique of the cobalt-chromium dental alloy." Srpski arhiv za celokupno lekarstvo 147, no. 11-12 (2019): 664–69. http://dx.doi.org/10.2298/sarh190706112s.
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Introduction/Objective. The objective of this paper is to describe the microstructure and mechanical properties of sintered Co-Cr alloy and to emphasize its advantages and disadvantages with respect to the microstructure and mechanical properties of cast Co-Cr alloy. Methods. Base Co-Cr alloy, EOSint M EOS Co-Cr SP2 (EOS GmbH, Munch, Germany), was used for the purpose of this research as the base material for sintering metal structures of metal-ceramic restorations. Metal sintering was conducted by using EOSint M 280 device of German origin in a stream of neutral gas ? argon. After that, the alloy was heated over a period of 20 minutes at the temperature of 800?C. The chemical composition of the alloy was determined by energy dispersive spectroscopy. Microstructure of the tested alloy samples was examined under an optical metallographic and scanning electron microscope. Physical and mechanical properties were measured in a universal testing machine. The samples were prepared according to the standard ISO 527-1:1993. Results. Chemical composition of the sintered Co-Cr alloy, determined by applying energy dispersive spectroscopy, indicated the same qualitative but different quantitative composition compared to cast Co-Cr alloys. The microstructure of the sintered Co-Cr alloy is lamellar in nature, with two dominant phases: ?-Co and/or ?-Cr (fcc ? face-centered cubic) and ?-Co (hcp ? hexagonal close-packed). Mechanical properties of the Co-Cr alloy obtained by applying selective laser melting technology compared to the cast Co-Cr alloy are superior or approximately the same. Conclusion. Selective laser melting of the Co-Cr alloy is a good example of new technologies based on digitization. Together with other digitized procedures, this technology is an introduction to a new era in dentistry popularly called Dentistry 4.0. The advantages of the selective laser melting technology with respect to the conventional technology of casting Co-Cr alloy metal structures are precise metal structure fitting and eco-friendly technology.
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Savencu, Cristina Elena, Sorin Porojan, and Liliana Porojan. "Analysis of Internal and Marginal fit of Metal-ceramic Crowns During Processing, Using Conventional and Digitized Technologies." Revista de Chimie 69, no. 7 (August 15, 2018): 1699–701. http://dx.doi.org/10.37358/rc.18.7.6398.
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Copings accuracy is an important factor for long-term clinical success of ceramic fused to metal dental restorations. The purpose of the study was to investigate marginal and internal fit of metal-ceramic crowns during processing, using conventional and digitized technologies. Metal copings were produced by Digital light Processing (DLP), invested and casted. Ceramic veneers were overpressed. Internal and marginal fit was measured using silicon replica technique for patterns, casted frameworks and final ceramic fused to metal crowns. Best adaptation was found in resin-pattern group, with small increasing of gap after casting and after ceramic pressing.
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Hong, Joon-Ki, Seong-Kyun Kim, Seong-Joo Heo, and Jai-Young Koak. "Mechanical Properties and Metal-Ceramic Bond Strength of Co-Cr Alloy Manufactured by Selective Laser Melting." Materials 13, no. 24 (December 16, 2020): 5745. http://dx.doi.org/10.3390/ma13245745.
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Cobalt–chromium (Co-Cr) metal is one of the widely used biomaterials in the fabrication of dental prosthesis. The purpose of this study was to investigate whether there are differences in the properties of metals and bond strength with ceramics depending on the manufacturing methods of Co-Cr alloy. Co-Cr alloy specimens were prepared in three different ways: casting, milling, and selective laser melting (SLM). The mechanical properties (elastic modulus, yield strength, and flexural strength) of the alloys were investigated by flexure method in three-point bending mode, and microstructures of the specimens were analyzed. After application of the veneering ceramic through the three-point bending test, bond strength of the Metal-Ceramic was investigated. The cracked surfaces were observed by means of energy dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM) with backscattered electron (BSE) images. In mechanical properties, the elastic modulus was highest for the casting group, and the yield strength and flexural strength were lowest for the milling group. The SLM group showed finer homogeneous crystalline-microstructure, and a layered structure was observed at the fractured surface. After the ceramic bond strength test, all groups showed a mixed failure pattern. The casting group showed the highest bond strengths, whereas there was no significant difference between the other two groups. However, all groups have met the standard of bond strength according to international standards organization (ISO) with the appropriate passing rate. The results of this study indicate that the SLM manufacturing method may have the potential to replace traditional techniques for fabricating dental prosthesis.
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Potran, Michal, Branko Strbac, Tatjana Puskar, Miodrag Hadzistevic, Janko Hodolic, and Branka Trifkovic. "Measurement of the accuracy of dental working casts using a coordinate measuring machine." Vojnosanitetski pregled 73, no. 10 (2016): 895–903. http://dx.doi.org/10.2298/vsp150105089p.
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Background/Aim: Dental impressions present a negative imprint of intraoral tissues of a patient which is, by pouring in gypsum, transferred extraorally on the working cast. Casting an accurate and precise working cast presents the first and very important step, since each of the following stages contributes to the overall error of the production process, which can lead to inadequately fitting dental restorations. The aim of this study was to promote and test a new model and technique for in vitro evaluation of the dental impression accuracy, as well as to asses the dimensional stability of impression material depending on the material bulk, and its effect on the accuracy of working casts. Methods. Impressions were made by the monophasic technique using the experimental master model. Custom trays with spacing of 1, 2 and 3 mm were constructed by rapid prototyping. The overall of 10 impressions were made with each custom tray. Working casts were made with gypsum type IV. Measurement of working casts was done 24 h later using a co-ordinate measuring machine. Results. The obtained results show that the working casts of all the three custom trays were in most cases significantly different in the transversal and sagittal planes in relation to the master model. The height of abutments was mainly unaffected. The degree of convergence showed certain significance in all the three custom trays, most pronounced in the tray with 3 mm spacing. Conclusion. The impression material bulk of 1?3 mm could provide accurate working casts when using the monophasic impression technique. The increase of the distance between abutment teeth influences the accuracy of working casts depending on the material bulk.
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Kim, Hae Ri, Young Kyung Kim, Jun Sik Son, Bong Ki Min, Kyo-Han Kim, and Tae-Yub Kwon. "Comparison of in vitro biocompatibility of a Co–Cr dental alloy produced by new milling/post-sintering or traditional casting technique." Materials Letters 178 (September 2016): 300–303. http://dx.doi.org/10.1016/j.matlet.2016.05.053.
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Pompa, Giorgio, Stefano Di Carlo, Francesca De Angelis, Maria Paola Cristalli, and Susanna Annibali. "Comparison of Conventional Methods and Laser-Assisted Rapid Prototyping for Manufacturing Fixed Dental Prostheses: An In Vitro Study." BioMed Research International 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/318097.
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This study assessed whether there are differences in marginal fit between laser-fusion and conventional techniques to produce fixed dental prostheses (FDPs). A master steel die with 2 abutments was produced to receive a posterior 4-unit FDPs and single copings. These experimental models were divided into three groups (n=20/group) manufactured: group 1, Ni-Cr alloy, with a lost-wax casting technique; group 2, Co-Cr alloy, with selective laser melting (SLM); and group 3, yttria-tetragonal zirconia polycrystal (Y-TZP), with a milling system. All specimens were cut along the longitudinal axis and their adaptation was measured at the marginal and shoulder areas on the right and left sides of each abutment. Measurements were made using a stereomicroscope (×60 magnification) and a scanning electron microscope (×800 magnification). The data were analyzed using one-way analysis of variance and the Bonferroni post hoc test, with a significance cutoff of 5%. Significant differences (P<0.05) were observed between group 3 and the other groups. The marginal opening was smallest with Co-Cr alloy substructures, while the shoulder opening was smallest with Ni-Cr alloy substructures. Within the limitations of this study, the marginal fit of an FDP is better with rapid prototyping (RP) via SLM than conventional manufacturing systems.
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Dzhendov, Dzh, Iv Katreva, and Ts Dikova. "Prosthetic treatment protocol with fixed dental constructions made on 3D printed cast patterns." Archives of Materials Science and Engineering 1, no. 90 (March 1, 2018): 33–40. http://dx.doi.org/10.5604/01.3001.0012.0611.
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Purpose: of the present paper is to develop prosthetic treatment protocol for fixed partial dentures made of 3D printed cast patterns. Design/methodology/approach: The clinical and laboratory protocols for manufacturing of fixed prosthetic constructions upon 3D cast patterns are developed on the basis of the literature review and our previous experimental investigations. Comparison between the conventional technique and innovative approach is made. Findings: The terms "semi-digital treatment plan" and "fully digital treatment plan" are defined according to the way of obtaining data for the virtual 3D model and the production method of the fixed prostheses. A classification of treatment protocols with non-removable partial dentures produced by additive technology is developed. Protocols for "semi" and "fully" digitized treatment plans with fixed partial dentures made by casting with 3D printed models are created. Research limitations/implications: Implementation of the fully digitized protocol for manufacturing of fixed prosthetic constructions via 3D printed prototypes requires specific equipment in the dental office and dental technician laboratory – intraoral scanner and CAD/ CAM system with 3D printing machine. Practical implications: Establishing of systematic clinical and laboratory protocols helps dental specialists to implement the innovative working approach in their practice with no risk of neglecting or omitting of some important procedures which increases the quality and long lasting effect of the dental constructions. Originality/value: Following the developed protocols reduces the role of the subjective factor in production technology of fixed prosthetic constructions while saving labour and time.
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Pretti, Mariana, Edson Hilgert, Marco Antônio Bottino, and Rander Pereira Avelar. "Evaluation of the shear bond strength of the union between two CoCr-alloys and a dental ceramic." Journal of Applied Oral Science 12, no. 4 (December 2004): 280–84. http://dx.doi.org/10.1590/s1678-77572004000400005.
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INTRODUCTION: Based on the importance of the integrity of the metal/ceramic interface, the purpose of this work was to evaluate the shear bond strength of the metal-ceramic union of two Co-Cr alloys (Wirobond C, Bego; Remanium 2000, Dentaurum) combined with Omega 900 ceramic (Vita Zahnfabrik). MATERIAL AND METHOD: Eleven cylindrical matrixes were made for each alloy, and the metallic portion was obtained with the lost wax casting technique with standardized waxing of 4mm of height and of 4mm of diameter. The ceramic was applied according to the manufacturer's recommendations with the aid of a teflon matrix that allowed its dimension to be standardized in the same size as the metallic portion. The specimens were submitted to the shear bond test in an universal testing machine (EMIC), with the aid of a device developed for such intention, and constant speed of 0.5mm/min. RESULTS AND CONCLUSIONS: The mean resistance was 48.387MPa for Wirobond C alloy, with standard deviation of 17.718, and 55.956MPa for Remanium 2000, with standard deviation of 17.198. No statistically significant difference was observed between the shear strength of the two metal-ceramic alloys.
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André Rocha Pimenta, Marilia Garcia Diniz, Sidnei Paciornik, Carlos Antonio Freire Sampaio, Mauro Sayão de Miranda, and José Maria Paolucci-Pimenta. "Mechanical and microstructural properties of a nickel-chromium alloy after casting process." RSBO 9, no. 1 (March 29, 2013): 17–24. http://dx.doi.org/10.21726/rsbo.v9i1.960.
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There is a growing concern on the development of adequate materials to interact with the human body. Several researches have been conducted on the development of biomaterials for dental applications. Objective: This study aimed to determine the microstructural and mechanical properties of a nickel- based alloy, after the casting process. Material and methods: The alloy was melted through lost wax technique and centrifugation, by using blowtorch with liquefied petroleum gas. To evaluate the mechanical properties, tensile bond strength and microhardness tests were performed. The microstructural characterization was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Statistical analyses were performed on microhardness results, through Student t test. A program for digital image processing was used to determine the percentage of the existing phases. Results and conclusion: The tensile strength was higher than that reported by the manufacturer, 559.39±25.63MPa versus 306 MPa, respectively. However, the yield strength was slightly lower, 218.71±29.75 MPa versus 258 MPa, reported by the manufacturer. The microhardness tests showed about 70 HV, far above the value informed by the manufacturer (21 HV). It can be affirmed with 95% confidence interval that the casting process did not alter the material’s hardness. The alloy’s microstructure is formed by a matrix with dendritic aspect and gray color and a second white interdendritic phase with equally distributed precipitates as well as porosities. EDS tests showed that the matrix is rich in nickel and chromium, the interdendritic second phase is rich in molybdenum and the precipitates in titanium or silicon. The matrix represents 86% of the area and the second phase 12%.
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Rivera-Muñoz, Eric M., Rodrigo Velázquez-Castillo, and P. Muñoz-Alvarez. "Mechanical Characterization of Hydroxyapatite-Based, Organic-Inorganic Composites." Materials Science Forum 539-543 (March 2007): 583–88. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.583.
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Hydroxyapatite-based materials have been used for dental and biomedical applications. Newly developed synthesis techniques give cause to a broad field in the study of these materials and industry demands products with better properties day by day. The purpose of the present work was to evaluate the mechanical properties of hydroxyapatite-based (HAp-based), organic-inorganic composites. HAp-based, organic-inorganic composites were obtained by modified gel casting process and organic molecules in a gelatin solution. HAp samples of different sizes and shapes were obtained with controlled micro and macro porosity and then were immersed into several gelatin solutions with different concentrations. X-ray powder Diffraction (XRD), Infra Red (IR) Spectroscopy and Scanning Electron Microscopy (SEM) techniques were used to analyze samples before and after gel casting process in order to assure that chemical and physical properties remains the same after this process. IR Spectroscopy and SEM techniques were used to characterize samples after the introduction of organic phase in order to analyze the final morphology of samples. Mechanical characterization was made in compression mode to samples without and with different concentrations of organic phase in order to establish the optimum conditions in which the highest compressive strength and Young’s modulus is reached.
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Montanini, Roberto, Michele Scafidi, Giorgio Staiti, Antonia Marcianò, Leonardo D’Acquisto, and Giacomo Oteri. "Misfit evaluation of dental implant-supported metal frameworks manufactured with different techniques: Photoelastic and strain gauge measurements." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 230, no. 12 (November 11, 2016): 1106–16. http://dx.doi.org/10.1177/0954411916676192.
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This study aims to compare in-vitro the fitting accuracy of implant-supported metal frameworks used for full-arch orthodontic restoration. The hypotheses tested were as follows: (1) for a fixed implant morphology, strains developed within the framework depend on how the framework had been fabricated and (2) stresses transferred to the implant–bone interface are related to the amount of framework misfit. Metal frameworks were fabricated using four different manufacturing techniques: conventional lost-wax casting, resin cement luting, electrospark erosion, and computer-aided design/computer-aided manufacturing milling. Each framework was instrumented with three strain gauges to measure strains developed because of prosthetic misfit, while quantitative photoelastic analysis was used to assess the effect of misfit at the implant–resin interface. All the tested frameworks presented stress polarization around the fixtures. After screw tightening, significantly greater strains were observed in the lost-wax superstructure, while the lowest strains were observed in the luted framework, demonstrating consistent adaptation and passive fitting. No significant difference in stress distribution and marginal fit was found for bars fabricated by either computer-aided design/computer-aided manufacturing or spark erosion. This study suggested that, in spite of known limitations of in-vitro testing, direct luting of mesostructures and abutments should be the first clinical option for the treatment of complete edentulism, ensuring consistent passive fitting and effective cost–benefit ratio.
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Bechir, Farah, Simona Maria Bataga, Elena Ungureanu, Diana Maria Vranceanu, Mariana Pacurar, Edwin Sever Bechir, and Cosmin Mihai Cotrut. "Experimental Study Regarding the Behavior at Different pH of Two Types of Co-Cr Alloys Used for Prosthetic Restorations." Materials 14, no. 16 (August 17, 2021): 4635. http://dx.doi.org/10.3390/ma14164635.
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Cobalt-chromium (Co-Cr) alloys are widely utilized in dentistry. The salivary pH is a significant factor, which affects the characteristics and the behavior of dental alloys through corrosion. This study aimed to evaluate the corrosion behavior in artificial saliva with different pH values (3, 5.7, and 7.6) of two commercial Co-Cr dental alloys manufactured by casting and by milling. Corrosion resistance was determined by the polarization resistance technique, and the tests were carried out at 37 ± 1 °C, in Carter Brugirard artificial saliva. After the electrochemical parameters, it can be stated that the cast Co-Cr alloy has the lowest corrosion current density, the highest polarization resistance, and the lowest speed of corrosion in artificial saliva with pH = 7.6. In the case of milled Co-Cr alloy, the same behavior was observed, but in artificial saliva with pH = 5.7, it recorded the most electropositive values of open circuit potential and corrosion potential. Although both cast and milled Co-Cr alloys presented a poorer corrosion resistance in artificial saliva with a more acidic pH value, the milled Co-Cr alloy had better corrosion behavior, making this alloy a better option for the prosthetic treatment of patients suffering from GERD.
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Sprio, Simone, Elisabetta Campodoni, Monica Sandri, Lorenzo Preti, Tobias Keppler, Frank Müller, Nicola Pugno, and Anna Tampieri. "A Graded Multifunctional Hybrid Scaffold with Superparamagnetic Ability for Periodontal Regeneration." International Journal of Molecular Sciences 19, no. 11 (November 15, 2018): 3604. http://dx.doi.org/10.3390/ijms19113604.
Full textAbstract:
The regeneration of dental tissues is a still an unmet clinical need; in fact, no therapies have been completely successful in regenerating dental tissue complexes such as periodontium, which is also due to the lack of scaffolds that are able to guide and direct cell fate towards the reconstruction of different mineralized and non-mineralized dental tissues. In this respect, the present work develops a novel multifunctional hybrid scaffold recapitulating the different features of alveolar bone, periodontal ligament, and cementum by integrating the biomineralization process, and tape casting and electrospinning techniques. The scaffold is endowed with a superparamagnetic ability, thanks to the use of a biocompatible, bioactive superparamagnetic apatite phase, as a mineral component that is able to promote osteogenesis and to be activated by remote magnetic signals. The periodontal scaffold was obtained by engineering three different layers, recapitulating the relevant compositional and microstructural features of the target tissues, into a monolithic multifunctional graded device. Physico-chemical, morphological, and ultrastructural analyses, in association with preliminary in vitro investigations carried out with mesenchymal stem cells, confirm that the final scaffold exhibits a good mimicry of the periodontal tissue complex, with excellent cytocompatibility and cell viability, making it very promising for regenerative applications in dentistry.
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Mercieca, Sven, Malcolm Caligari Conti, Joseph Buhagiar, and Josette Camilleri. "Assessment of corrosion resistance of cast cobalt- and nickel-chromium dental alloys in acidic environments." Journal of Applied Biomaterials & Functional Materials 16, no. 1 (October 26, 2017): 47–54. http://dx.doi.org/10.5301/jabfm.5000383.
Full textAbstract:
Background: The aim of this study was to compare the degradation resistance of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys used as a base material for partial dentures in contact with saliva. Methods: Wiron® 99 and Wironit Extra-Hard® were selected as representative casting alloys for Ni-Cr and Co-Cr alloys, respectively. The alloys were tested in contact with deionized water, artificial saliva and acidified artificial saliva. Material characterization was performed by X-ray diffractometry (XRD) and microhardness and nanohardness testing. The corrosion properties of the materials were then analyzed using open circuit potential analysis and potentiodynamic analysis. Alloy leaching in solution was assessed by inductively coupled plasma mass spectrometry techniques. Results: Co-Cr alloy was more stable than the Ni-Cr alloy in all solutions tested. Leaching of nickel and corrosion attack was higher in Ni-Cr alloy in artificial saliva compared with the acidified saliva. The corrosion resistance of the Co-Cr alloy was seen to be superior to that of the Ni-Cr alloy, with the former exhibiting a lower corrosion current in all test solutions. Microstructural topographical changes were observed for Ni-Cr alloy in contact with artificial saliva. The Ni-Cr alloy exhibited microstructural changes and lower corrosion resistance in artificial saliva. The acidic changes did not enhance the alloy degradation. Conclusions: Ni-Cr alloys are unstable in solution and leach nickel. Co-Cr alloys should be preferred for clinical use.
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Kumar, Manjit, Abhishek Gupta, and Vandana Chabhra. "Comparative Evaluation of Tensile Bond Strength of Nickel-Chromium Alloy to Dental Enamel Using Different Resin Cements – An In Vitro Study." Dental Journal of Advance Studies 04, no. 03 (December 2016): 170–76. http://dx.doi.org/10.1055/s-0038-1672065.
Full textAbstract:
Abstract Aim: The aim of this study was to evaluate and compare the tensile bond strength of nickel-chromium alloy to dental enamel by using four different resin cements. Materials and Methods: 40 extracted central incisor teeth embedded in acrylic blocks were flattened not to expose dentin. Wax rectangular blocks of 5 mm length, 5 mm width and 1 mm height with a loop were invested and casted using Nickel-Chromium alloy by conventional induction casting method and sandblasted. Then casted rectangular blocks and 40 tooth embedded acrylic samples were divided into four groups (10 each) and cemented to tooth enamel following manufacturer's instructions as; GroupAcemented using RelyX U200, Group B cemented using Smartcem 2, Group C cemented using Multilink Speed and Group D cemented using Multilink N and then stored in artificial saliva for 24 hours. The direct pull tensile test was carried out on Universal Testing Machine at cross head speed of 0.5mm/min. Results: One way ANOVA showed a highly statistically significant (p<.01) difference between all the four resin cements. Post Hoc Tests- Multiple comparisons showed highly statistically significant (p< 0.01) difference between RelyX U200: Multilink N, Smartcem 2: Multilink Speed, Smartcem 2: Multilink N, Multilink Speed: Multilink N. Difference between RelyX U200 : Smartcem 2 and RelyX U200 : Multilink Speed was statistically significant(p< 0.05). Conclusion: Self etch resin cement (Multilink N) showed maximum mean tensile bond strength as compared to self-adhesive resin cements (Smartcem 2, RelyX U200 and Multilink Speed). Clinically the greatest advantage of self-adhesive cements is the easy and fast application technique. But this time saving technique is not as effective as self-etch resin luting agents. The presumed benefit of saving time with self-adhesive luting agents may only be realized at the expense of compromising bond strength.