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British Dental Journal Mar 1983
Topics: Chemical Phenomena; Chemistry, Physical; Dental Alloys; Dental Amalgam; Silver; Tin
PubMed: 6573884
DOI: 10.1038/sj.bdj.4805027 -
The Journal of Prosthetic Dentistry Dec 2013Previous studies have shown casting methodology to influence the as-cast properties of dental casting alloys. It is important to consider clinically important mechanical... (Comparative Study)
Comparative Study
STATEMENT OF PROBLEM
Previous studies have shown casting methodology to influence the as-cast properties of dental casting alloys. It is important to consider clinically important mechanical properties so that the influence of casting can be clarified.
PURPOSE
The purpose of this study was to evaluate how torch/centrifugal and inductively cast and vacuum-pressure casting machines may affect the castability, microhardness, chemical composition, and microstructure of 2 high noble, 1 noble, and 1 base metal dental casting alloys.
MATERIAL AND METHODS
Two commonly used methods for casting were selected for comparison: torch/centrifugal casting and inductively heated/ vacuum-pressure casting. One hundred and twenty castability patterns were fabricated and divided into 8 groups. Four groups were torch/centrifugally cast in Olympia (O), Jelenko O (JO), Genesis II (G), and Liberty (L) alloys. Similarly, 4 groups were cast in O, JO, G, and L by an inductively induction/vacuum-pressure casting machine. Each specimen was evaluated for casting completeness to determine a castability value, while porosity was determined by standard x-ray techniques. Each group was metallographically prepared for further evaluation that included chemical composition, Vickers microhardness, and grain analysis of microstructure. Two-way ANOVA was used to determine significant differences among the main effects. Statistically significant effects were examined further with the Tukey HSD procedure for multiple comparisons. Data obtained from the castability experiments were non-normal and the variances were unequal. They were analyzed statistically with the Kruskal-Wallis rank sum test. Significant results were further investigated statistically with the Steel-Dwass method for multiple comparisons (α=.05).
RESULTS
The alloy type had a significant effect on surface microhardness (P<.001). In contrast, the technique used for casting did not affect the microhardness of the test specimen (P=.465). Similarly, the interaction between the alloy and casting technique was not significant (P=.119). A high level of castability (98.5% on average) was achieved overall. The frequency of casting failures as a function of alloy type and casting method was determined. Failure was defined as a castability index score of <100%. Three of 28 possible comparisons between alloy and casting combinations were statistically significant. The results suggested that casting technique affects the castability index of alloys. Radiographic analysis detected large porosities in regions near the edge of the castability pattern and infrequently adjacent to noncast segments. All castings acquired traces of elements found in the casting crucibles. The grain size for each dental casting alloy was generally finer for specimens produced by the induction/vacuum-pressure method. The difference was substantial for JO and L.
CONCLUSIONS
This study demonstrated a relation between casting techniques and some physical properties of metal ceramic casting alloys.
Topics: Chromium Alloys; Dental Alloys; Dental Casting Investment; Dental Casting Technique; Electron Probe Microanalysis; Gold Alloys; Hardness; Hot Temperature; Humans; Materials Testing; Metallurgy; Microscopy, Electron, Scanning; Palladium; Particle Size; Platinum; Porosity; Pressure; Radiography; Spectrometry, X-Ray Emission; Surface Properties; Vacuum
PubMed: 24120072
DOI: 10.1016/j.prosdent.2013.09.001 -
Dental Materials Journal Jan 2008This study evaluated the effectiveness of a simplified silica coating method (CoJet System) on the bonding strength of resin cements to dental alloy. Bonding strength of...
This study evaluated the effectiveness of a simplified silica coating method (CoJet System) on the bonding strength of resin cements to dental alloy. Bonding strength of the specimens treated with metal primer after alumina sandblasting was compared with those treated with silica coating and silane coupling agent after alumina sandblasting. Furthermore, the influence of silane coupling agent on bonding strength was compared between one-liquid and two-liquid silane coupling agents. Measurement of shear bond strength before and after thermal cycling revealed that the group treated with silica coating in one step without alumina sandblasting yielded high bonding strength. As for the influence of silane coupling agent, treatment with two-liquid silane coupling agent achieved higher mean shear bond strength than with one-liquid silane coupling agent. Findings in this study indicated that silicatization by means of this simplified silica coating method was effective in improving the bonding strength to dental alloy.
Topics: Aluminum Oxide; Carbon Compounds, Inorganic; Coated Materials, Biocompatible; Dental Alloys; Dental Bonding; Dental Etching; Dental Materials; Dental Polishing; Electron Probe Microanalysis; Humans; Materials Testing; Resin Cements; Shear Strength; Silanes; Silicon Compounds; Silicon Dioxide; Stress, Mechanical; Surface Properties; Temperature; Time Factors
PubMed: 18309607
DOI: 10.4012/dmj.27.16 -
Dental Materials : Official Publication... Nov 2007The purpose of this study was to establish a method to compare and classify dental alloys in relation to their resistance to corrosion. (Comparative Study)
Comparative Study
OBJECTIVES
The purpose of this study was to establish a method to compare and classify dental alloys in relation to their resistance to corrosion.
METHODS
Alloy samples and pure metal samples were prepared and tested in chemical and electrochemical corrosion according to ISO 10271. For electrochemical test, the rest potential versus time and a potentiodynamic scan were recorded. After chemical corrosion test, the ions released were analyzed by ICP (induced coupled plasma) spectroscopy.
RESULTS
High gold alloys had a similar polarization curve than gold. The same effect was observed for Pd-base alloys, their curves were similar to the one of palladium. The ions released during chemical corrosion were non-precious metallic ions. Thereby Ni-Cr alloys were found to release the most ions. Au-Pt alloys showed the highest release of ions compared with other precious alloys but low compared with Ni-Cr. Electrochemical corrosion was more aggressive than chemical corrosion and every type of elements was etched, the higher the precious metal content, the higher the resistance to corrosion of the alloy.
DISCUSSION
Using the recorded data, a classification system for electrochemical corrosion was developed and discussed to judge the results. Hereby were gold and zinc used as reference materials. The applied classification system defines five classes and it is proposed that alloys of class V are not acceptable. For chemical corrosion resistance, three classes were distinguished according to the quantity of metallic ions released and it is proposed that class III (100-1000 microg/cm(2)week) is not acceptable. Palladium and Pd-base alloys showed a higher electrochemical and chemical corrosion resistance than gold.
Topics: Corrosion; Dental Alloys; Electrochemistry
PubMed: 17466365
DOI: 10.1016/j.dental.2006.11.030 -
Shika Zairyo, Kikai = Journal of the... Nov 1990The goal of this study was to test the influence of the type and oxidation treatment of dental casting alloys on the tensile bond strength of luting cements. Also, the... (Comparative Study)
Comparative Study
The goal of this study was to test the influence of the type and oxidation treatment of dental casting alloys on the tensile bond strength of luting cements. Also, the influence of film thickness of luting cements on the tensile bond strength of different dental casting alloys was examined. Four different luting cements (zinc phosphate, polycarboxylate, glass ionomer and adhesive resin cements) and four different dental casting alloys (Au-Ag-Cu, Ag-Pd, hardened Ag-Pd and Ni-Cr alloys) were used. Cylindrical alloy rods for the tensile bond strength test were casted, and then, top surfaces of the rods were cemented with each luting cement to the bottom surfaces of other rods, using the film thickness adjustment apparatus. The film thickness of luting cement was adjusted to 20, 30, 50, 75 or 100 microns. The tensile bond strengths of each cement to different casting alloys at each film thickness were measured one day after the rods had been cemented. The tensile bond strength of the zinc phosphate cement could not be determined in this study due to the separation of the alloy rods cemented with the zinc phosphate cement in water before the tensile test. The tensile bond strength to the adhesive resin cement to any alloy showed the greatest strength; however, that of the glass ionomer cement to any alloy was the lowest strength among the cements examined. The Ni-Cr alloy had the highest bond strength of any luting cement, compared to other alloys. The tensile bond strengths of luting cements significantly decreased with the increase in film thickness of cement layer. The adhesive resin cement had the greatest bond strength, and the glass ionomer cement was the lowest bond strength at any film thickness. The oxidation treatment significantly increased the bond strength of the adhesive resin cement to both Au-Ag-Cu and Ag-Pd alloys. The tensile bond strength of the adhesive resin cement was most dependent upon the film thickness of cement layer, and that of the polycarboxylate cement was least dependent upon the film thickness of cement layer among the cements examined. In addition, the oxidation treatment for precious alloys could be a factor contributing to the increase in the bond strength of the adhesive resin cement.
Topics: Adhesiveness; Chromium Alloys; Dental Alloys; Dental Bonding; Dental Cements; Gold Alloys; Surface Properties; Tensile Strength
PubMed: 2135542
DOI: No ID Found -
Operative Dentistry 1981
Topics: Dental Alloys; Dental Amalgam; Dental Instruments; Mercury
PubMed: 6941226
DOI: No ID Found -
Australian Dental Journal Jun 1980A Ni-Cr based crown and bridge alloy has been successfully stir-cast into small investment mould spaces using a modified induction melting and casting machine....
A Ni-Cr based crown and bridge alloy has been successfully stir-cast into small investment mould spaces using a modified induction melting and casting machine. Stir-casting produced substantial improvements to the mechanical properties of the cast alloy. A model for the development of the stir-cast microstructure is described and the clinical significance of the improvements in the alloy's properties is discussed.
Topics: Chemical Phenomena; Chemistry; Chemistry, Physical; Chromium; Dental Alloys; Metallurgy; Nickel; Stress, Mechanical; Surface Properties; Thermodynamics
PubMed: 6932192
DOI: 10.1111/j.1834-7819.1980.tb03701.x -
Australian Dental Journal Feb 1988
Topics: Australia; Dental Alloys; Dental Amalgam
PubMed: 3165620
DOI: 10.1111/j.1834-7819.1988.tb00632.x -
Journal of the Mechanical Behavior of... Sep 2012The purpose of this study was to evaluate the shear bond strength between CoCrMo dental alloy and porcelain restorations by application of different metal-ceramic...
OBJECTIVES
The purpose of this study was to evaluate the shear bond strength between CoCrMo dental alloy and porcelain restorations by application of different metal-ceramic transitional interfaces aiming at improvement of the bond strength and fracture tolerances.
METHODS
Several metal-ceramic specimens with different composite interlayers were produced. The interlayers consisted of metal/ceramic composites with different metal volume fractions (20 M; 40 M; 60 M; 80 M). The metal-ceramic bond strength as well as the fracture strength of the composites and monolithic base materials were assessed by the means of a shear test performed in a universal test machine. The interfaces of fractured and untested specimens were examined by the means of optical microscopy. The microstructures of monolithic base materials were analyzed using SEM/EDS. The elastic and inelastic properties of the homogeneous compositions were additionally evaluated using dynamic mechanical analysis.
RESULTS
The bond strength results obtained for metal-ceramic gradated specimens were the highest (261±38 MPa) for 40 vol% metal in the interlayer [40 M] vs. 109±27 MPa for a direct metal-ceramic joint. The Young's moduli and the fracture resistance of the composites revealed an increasing trend for increasing metal contents.
SIGNIFICANCE
This study shows that a graded transition between metal and ceramic, provided by a metal/ceramic composite interlayer, is regarded for an increase by 2.5 times in the bond strength between the two materials relative to conventional sharp transitions. The elastic modulus of the composites used as interlayers might be very reasonably approximated by a micromechanical model.
Topics: Chromium; Cobalt; Dental Alloys; Dental Porcelain; Dental Restoration Repair; Materials Testing; Mechanical Phenomena; Molybdenum
PubMed: 22922337
DOI: 10.1016/j.jmbbm.2012.04.019 -
Materials Science & Engineering. C,... Apr 2016The rolling rate (r) dependence of textures was investigated in the Ti-26Nb-3Al (mol%) alloy to reveal the conditions required to form the {001}<110> recrystallization...
The rolling rate (r) dependence of textures was investigated in the Ti-26Nb-3Al (mol%) alloy to reveal the conditions required to form the {001}<110> recrystallization texture, which is a desirable orientation for the β-titanium shape memory alloy. {001}<110> was the dominant cold-rolling texture when r=90% and it was transferred to the recrystallization texture without forming {112}<110>, which is detrimental for the isotropic mechanical properties of the rolled sheet. A further increase in r resulted in the formation of {112}<110> in both rolling and recrystallization textures. Therefore, r should be controlled to form only the {001}<110> rolling texture, because the {112}<110> texture can overwhelm the {001}<110> texture during recrystallization.
Topics: Dental Alloys
PubMed: 26838877
DOI: 10.1016/j.msec.2015.12.086