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The Journal of Prosthetic Dentistry Apr 2002The numbers and types of alloys for prosthodontic restorations have increased dramatically over the past 25 years, making selection of an alloy for a given clinical... (Review)
Review
The numbers and types of alloys for prosthodontic restorations have increased dramatically over the past 25 years, making selection of an alloy for a given clinical situation difficult. Factors such as cost, the need for better strength, and worries about alloy corrosion have pressured the alloy market to change significantly. A number of properties--including yield strength, hardness, elastic modulus, microstructural phases, grain size, corrosion performance, coefficient of thermal expansion, oxide color, and melting range--are relevant to the proper selection of an alloy for a given clinical problem. In this article, a brief historical look at prosthodontic alloys and the nomenclature for alloys is followed by a discussion of the most important physical properties of alloys for clinical practice. A summary of the types of alloys available today and their classification is then presented. Finally, speculations about future trends for alloys are made, and simple guidelines are suggested to help dentists choose appropriate alloys for their practices. This review excludes implant alloys, dental amalgam, and alloys for orthodontic and endodontic applications.
Topics: Biocompatible Materials; Color; Corrosion; Dental Alloys; Dental Bonding; Dental Restoration, Permanent; Denture, Partial; Differential Thermal Analysis; Elasticity; Hardness; Humans; Particle Size; Tensile Strength
PubMed: 12011845
DOI: 10.1067/mpr.2002.123817 -
The Journal of Prosthetic Dentistry Jun 2020Materials used for dental restorations should cause wear similar to that of natural teeth. Studies on the wear of dental alloys against monolithic zirconia are lacking.
STATEMENT OF PROBLEM
Materials used for dental restorations should cause wear similar to that of natural teeth. Studies on the wear of dental alloys against monolithic zirconia are lacking.
PURPOSE
The purpose of this in vitro study was to compare the wear of Co-Cr, gold, and Ni-Cr alloys against monolithic zirconia of different surface roughness.
MATERIAL AND METHODS
Cylindrical monolithic zirconia specimens were prepared by a sintering process. Sintered zirconia was then polished to prepare 30 zirconia substrate specimens with a smooth surface (Ra<0.1 μm) and 30 with a rough surface (3.5 μm
alloys (Co-Cr, gold, and Ni-Cr alloys) were used. Twenty cast crowns were prepared from each metal alloy in the shape of a maxillary premolar. For each alloy, 10 cast crowns were randomly selected to oppose the smooth-surface zirconia specimens and 10 to oppose the rough-surface zirconia specimens. A total of 6 wear test groups were formed. Wear tests were performed by using a mastication simulator at 240 000 mastication cycles. Wear on the antagonist specimens was measured by using a laser 3D scanner. After wear testing, antagonist and substrate specimens were inspected by using a scanning electron microscope (SEM). For statistical analysis of the data, the 2-way ANOVA and the Scheffé multiple comparison tests were used (α=.05). RESULTS
Of the 6 test groups, the gold alloy specimens opposed to rough-surface zirconia exhibited the most wear, while the Co-Cr alloy specimens opposed to smooth-surface zirconia exhibited the least wear (P<.05). Rough-surface monolithic zirconia caused significantly more wear of the metal alloy specimens than did smooth-surface monolithic zirconia (P<.01).
CONCLUSIONS
Increased surface roughness of monolithic zirconia was associated with increased wear of the opposing dental alloy. When monolithic zirconia surface roughness was increased, wear of dental alloys increased most for gold alloys, followed by Ni-Cr, and then Co-Cr alloys.
Topics: Dental Alloys; Dental Enamel; Dental Porcelain; Materials Testing; Surface Properties; Zirconium
PubMed: 31653400
DOI: 10.1016/j.prosdent.2019.06.002 -
Lasers in Medical Science Feb 2015The effects of voltage and laser beam (spot) diameter on the penetration depth during laser beam welding in a representative nickel-chromium (Ni-Cr) dental alloy were...
The effects of voltage and laser beam (spot) diameter on the penetration depth during laser beam welding in a representative nickel-chromium (Ni-Cr) dental alloy were the subject of this study. The cast alloy specimens were butted against each other and laser welded at their interface using various voltages (160-390 V) and spot diameters (0.2-1.8 mm) and a constant pulse duration of 10 ms. After welding, the laser beam penetration depths in the alloy were measured. The results were plotted and were statistically analyzed with a two-way ANOVA, employing voltage and spot diameter as the discriminating variables and using Holm-Sidak post hoc method (a = 0.05). The maximum penetration depth was 4.7 mm. The penetration depth increased as the spot diameter decreased at a fixed voltage and increased as the voltage increased at a fixed spot diameter. Varying the parameters of voltage and laser spot diameter significantly affected the depth of penetration of the dental cast Ni-Cr alloy. The penetration depth of laser-welded Ni-Cr dental alloys can be accurately adjusted based on the aforementioned results, leading to successfully joined/repaired dental restorations, saving manufacturing time, reducing final cost, and enhancing the longevity of dental prostheses.
Topics: Chromium Alloys; Dental Alloys; Dental Casting Technique; Dental Soldering; Lasers, Solid-State; Welding
PubMed: 24326743
DOI: 10.1007/s10103-013-1502-3 -
Dental Materials : Official Publication... Sep 1999The objective was to examine in vitro the galvanic interaction between titanium and a high-copper dental amalgam or a gallium-based direct filling alloy at different...
OBJECTIVES
The objective was to examine in vitro the galvanic interaction between titanium and a high-copper dental amalgam or a gallium-based direct filling alloy at different area ratios, and to relate the observed interactions to the electrochemical characteristics of the alloys.
METHODS
The tested materials were cast titanium, a single-composition, spherical high-copper amalgam, and a gallium-based direct filling alloy. Polarization curves were recorded. The galvanic couples were prepared at Ti/filling alloy ratios of 1:1, 2:1, 4:1 and 6:1. The couples were exposed to synthetic saliva at 37 degrees C and the galvanic currents and potentials were measured as a function of time. The results were analyzed by ANOVA and Tukey tests (p < or = 0.05).
RESULTS
Freshly abraded titanium initially was anodic to both the amalgam and the gallium alloy, but the polarity reversed after a period of exposure. The galvanic potential and current density increased with the increasing Ti/alloy area ratio. The potential increase was smaller and the current increase larger for the Ga alloy than for the amalgam. The difference was consistent with the polarization characteristics. The galvanic current density was of the order of 10(-8) A/cm2 for the Ti/amalgam couple, and 10(-7) to 10(-6) A/cm2 for the Ti/gallium alloy couple.
SIGNIFICANCE
The results show that the galvanic interaction between titanium and direct filling alloys is small. High copper dental amalgams should suffer little galvanic corrosion when in contact with Ti. For gallium direct filling alloys, the galvanic interaction may be more detrimental because of the inherently lower corrosion resistance.
Topics: Analysis of Variance; Corrosion; Dental Alloys; Dental Amalgam; Electrogalvanism, Intraoral; Electrolysis; Gallium; Materials Testing; Statistics, Nonparametric; Titanium
PubMed: 10863427
DOI: 10.1016/s0109-5641(99)00051-2 -
The Chinese Journal of Dental Research Dec 2000To reveal the potential of the new titanium alloy as dental prosthodontic materials.
OBJECTIVE
To reveal the potential of the new titanium alloy as dental prosthodontic materials.
METHODS
Dental castings of TAMZ alloy were investigated in the casting machine specially designed for titanium. A mesh pattern was used to count the castability value. The mechanical properties were measured by means of a universal testing machine. Optical micrography was done on the exposed cross-section of TAMZ alloy casting. From the surface to the inner part the Knoop hardness in reacted layer of TAMZ alloy casting was measured. The structure and elemental analyses of the reacted layer were made by SEM and element line scanning observation.
RESULTS
The castability value (Cv = 98%) and the tensile test (sigma b = 850 Mpa, sigma 0.2 = 575 Mpa, delta = 7.33%) data were collected. The castings microstructure showed main alpha phase and small beta phase. Knoop hardness in the surface reacted layer was greater than that in the inner part. From the SEM and element line scanning observation, there are three different layers in the surface reacted layer of the TAMZ alloy castings, and higher level of element of O, Al, Si and Zr were found in the reacted layer while the Si permeated deeper than others.
CONCLUSION
TAMZ alloy can be accepted as a material for dental alloy in prosthodontics.
Topics: Aluminum; Chemical Phenomena; Chemistry, Physical; Dental Alloys; Dental Casting Investment; Dental Casting Technique; Dental Prosthesis; Dental Stress Analysis; Elasticity; Hardness; Humans; Materials Testing; Microscopy, Electron, Scanning; Molybdenum; Oxygen; Silicon; Surface Properties; Tensile Strength; Titanium; Zirconium
PubMed: 11314090
DOI: No ID Found -
Journal of Ayub Medical College,... 2017Re-use of dental casting alloy is a routine practice, which is carried out with the motive to conserve resources. There have been studies on the re-use of alloys but a...
BACKGROUND
Re-use of dental casting alloy is a routine practice, which is carried out with the motive to conserve resources. There have been studies on the re-use of alloys but a controversy exists as to the proportioning ratio of fresh to used alloy and the number of time an alloy can be recast. The objective of the study was to measure the effect of addition of 50% by weight used alloy to the fresh Cobalt-Chromium alloy on the castability.
METHODS
In the present in-vitro experimental study A total of 20 specimens were cast by flame centrifuge, using modified Whitlock's method. The total sample size was divided into four groups of five specimens each. Group 1 was the control group with 100% fresh alloy cast once. In group 2, 3 and 4, a 50% by weight cut off of previous castings were mixed to the fresh alloy. The reused alloy for the group 2 and 3 was further aged or exposed to flame casting separately. The number of completely cast segments were counted and castability value was calculated according to the Whitlock's formula.
RESULTS
There was no significant difference of castability value among the entire tested group (p=0.085).
CONCLUSIONS
Within the limitations of the present study, it is recommended that commercial Co-Cr-Mo alloy can be re-used six times without affecting its castability, when 50% fresh alloy is added on each re-use.
Topics: Chromium Alloys; Dental Alloys; Equipment Reuse; Materials Testing
PubMed: 28718246
DOI: No ID Found -
Acta of Bioengineering and Biomechanics 2017The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment.
PURPOSE
The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment.
METHODS
The alloy surface undergone chemical passivation treatment in four different media. Corrosion studies were carried out by means of electrochemical methods in saline solution. Corrosion effects were determined using SEM.
RESULTS
The greatest increase in the alloy polarization resistance was observed for passive layer produced in Na2SO4 solution with graphite. The same layer caused the highest increase in corrosion current. Generally speaking, the alloy passivation in Na2SO4 solution with graphite caused a substantial improvement of the corrosion resistance. The sample after passivation in Na2SO4 solution without graphite, contrary to others, lost its protective properties along with successive anodic polarization cycles. The alloy passivation in Na3PO4 solution with graphite was the only one that caused a decrease in the alloy corrosion properties. The SEM studies of all samples after chemical passivation revealed no pit corrosion - in contrast to the sample without any modification.
CONCLUSIONS
Every successive polarization cycle in anodic direction of pure Wirobond C® alloy enhances corrosion resistance shifting corrosion potential in the positive direction and decreasing corrosion current value. The chemical passivation in solutions with low pH values decreases susceptibility to electrochemical corrosion of Co-Cr dental alloy. The best protection against corrosion was obtained after chemical passivation of Wirobond C® in Na2SO4 solution with graphite. Passivation with Na2SO4 in solution of high pH does not cause an increase in corrosion resistance of WIROBOND C. Passivation process increases alloy resistance to pit corrosion.
Topics: Chromium Alloys; Coated Materials, Biocompatible; Corrosion; Dental Alloys; Dental Materials; Electroplating; Graphite; Hydrogen-Ion Concentration; Materials Testing; Sodium Chloride; Sulfates; Surface Properties
PubMed: 28869626
DOI: No ID Found -
BioMed Research International 2020The purpose of this study was to evaluate the effect of recycling on the properties of interface between 2 dental alloys and their corresponding porcelains.
PURPOSE
The purpose of this study was to evaluate the effect of recycling on the properties of interface between 2 dental alloys and their corresponding porcelains.
MATERIALS AND METHODS
Noble alloy (Pd-Cu-Ga) and high-noble alloy (Au-Pt) were used in this study. Metal matrices (cylinders 4 mm × 4 mm with pedestal 5 mm × 1 mm) were prepared by arc melting in argon after recasting 1-3 times. Corresponding porcelain with overall dimensions of 4 mm × 2 mm was veneered on each metal cylinder. There were 22 specimens in each alloy group. Specifically, two specimens of each group were chosen randomly for interfacial morphology and diffusion analyses by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The remaining 20 specimens were divided into 2 groups with or without thermal cycling. The bond strength was evaluated by shear test, and the data were analyzed by two-way analysis of variance (ANOVA). The failure mode of shear test specimen was observed with a stereoscopic microscopy and subjected to the exact probability test ( = 0.05).
RESULTS
According to the results from SEM, no obvious difference was observed in the interfacial morphology of both Pd-Cu-Ga and Au-Pt alloys among different recasting specimens. EDS analysis revealed that no significant difference was found in the width of elemental diffusion among 2 test alloys after recycling 1-3 times. Notably, in Pd-Cu-Ga alloy groups, the peak of Ga in thrice recasting was lower than those in first and second recastings. And there was no significant difference ( > 0.05) in the metal-ceramic shear bond strength of Pd-Cu-Ga and Au-Pt alloys after recycling 1-3 times, with or without thermal cycling. The results of failure modes observed on specimens were not affected by the recycling and thermal cycling in the 2 tested alloys.
CONCLUSIONS
Within the limitations of this study, the Pd-Cu-Ga and Au-Pt alloys can be recycled 2 times without significant changes on the properties of metal-ceramic interface, with or without thermal cycling.
Topics: Ceramics; Chromium Alloys; Dental Alloys; Dental Porcelain; Materials Testing; Metal Ceramic Alloys; Microscopy, Electron, Scanning; Recycling; Shear Strength; Surface Properties
PubMed: 32337242
DOI: 10.1155/2020/3529781 -
British Dental Journal Mar 1992The quality of construction of fixed bridge prostheses directly affects their long-term survival. The cost, alloy composition and marginal fit of bridges made by 30...
The quality of construction of fixed bridge prostheses directly affects their long-term survival. The cost, alloy composition and marginal fit of bridges made by 30 commercial dental laboratories is assessed. Duplicate models of a three unit bridge preparation were sent to 30 different laboratories, as if required for a patient receiving treatment under the General Dental Service. Material was sent via general dental practitioners, requesting metal-ceramic bridges made from 45% Au alloy, precious metal or non-precious metal. Proximal contacts were overbuilt at 65% of sites and pontic tissue contacts were excessive in all but one bridge. Eight laboratories did not use alloys corresponding to the request made. The mean marginal gaps of non-precious metal bridges (145 microns) were significantly greater than those for 45% gold alloy (106 microns). Marginal fit was poor and a number of factors have been observed, with other postulated, which may have contributed to this problem.
Topics: Ceramics; Dental Alloys; Dental Casting Technique; Denture, Partial, Fixed; Gold Alloys; Humans; Laboratories, Dental; Models, Dental; Palladium; Quality of Health Care; United Kingdom
PubMed: 1543635
DOI: 10.1038/sj.bdj.4807820 -
Brazilian Dental Journal 2016In order to evaluate its application as a dental prosthesis material, a CoCrW alloy was subjected to in vitro cytotoxicity test, surface characterization and...
In order to evaluate its application as a dental prosthesis material, a CoCrW alloy was subjected to in vitro cytotoxicity test, surface characterization and electrochemical studies performed in artificial saliva and 0.15 mol.L-1 NaCl medium. The used techniques were: anodic polarization curves, chronoamperometric measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) analysis and X-ray photoelectron spectroscopy (XPS). Cytotoxicity test was also performed. The electrochemical behavior of CoCrW alloy was compared in both studied media, from corrosion potential (Ecorr) to a 600 mV anodic overvoltage. From the electrochemical measurements it was observed that the CoCrW alloy in both media presents only generalized corrosion. SEM and EDS analysis showed that the alloy presents carbide niobium and silicon and manganese oxides as nonmetallic inclusions. XPS results indicated that cobalt does not significantly contribute to the passivating film formation. Cytotoxicity test showed no cytotoxic character of CoCrW alloy. These results suggest that the CoCrW alloy can be used as biomaterial to be applied as prosthesis in dental implants.
Topics: Dental Alloys; In Vitro Techniques; Saliva, Artificial; Surface Properties
PubMed: 27058381
DOI: 10.1590/0103-6440201300513