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The Angle Orthodontist 1997Treatment of horizontal and vertical tooth discrepancies requires wires of low stiffness to produce forces as the teeth are leveled and aligned. In this investigation,... (Comparative Study)
Comparative Study
Treatment of horizontal and vertical tooth discrepancies requires wires of low stiffness to produce forces as the teeth are leveled and aligned. In this investigation, the stiffness characteristics of several solid and multistrand nickel-titanium and stainless steel orthodontic wires were determined at selected clinically relevant deflections. Twenty specimens of 24 different wires were tested in both three-point and three-bracket bending modes. The unloading force deflection plot of each wire was described by a polynomial regression from which wire stiffnesses were obtained by mathematical differentiation. Graphs of the functional relationship between stiffness and deflection are presented. The results of this investigation show that wire stiffness can be altered not only by changing the size, but also by varying the number of strands and the alloy composition. An equally important finding was the dependence of stiffness on deflection for most of the wires measured. Comparisons were also made between the stiffness values obtained in three-point bending and the three-bracket bending systems.
Topics: Dental Alloys; Dental Stress Analysis; Elasticity; Humans; Materials Testing; Models, Theoretical; Nickel; Orthodontic Brackets; Orthodontic Wires; Pliability; Regression Analysis; Stainless Steel; Stress, Mechanical; Surface Properties; Titanium; Tooth Movement Techniques
PubMed: 9188965
DOI: 10.1043/0003-3219(1997)067<0209:SDBOSO>2.3.CO;2 -
The Angle Orthodontist Nov 2014To analyze the effect of various coating formulations on the mechanical and corrosion properties of nickel-titanium (NiTi) orthodontic wires.
OBJECTIVE
To analyze the effect of various coating formulations on the mechanical and corrosion properties of nickel-titanium (NiTi) orthodontic wires.
MATERIALS AND METHODS
Uncoated, rhodium-coated, and nitrified NiTi wires were observed with a three-point-bend test, surface roughness (Ra) measurement, scanning electron microscopy, energy dispersive spectroscopy, and electrochemical testing (open circuit potential, electrochemical impedance spectroscopy, and cyclic polarization scan). Differences in the properties of tested wire types were analyzed with analysis of variance and Tukey post hoc test.
RESULTS
Uncoated and nitrified NiTi wires showed similar mechanical and anticorrosive properties, while rhodium-coated NiTi wires showed the highest Ra and significantly higher modulus of elasticity, yield strength, and delivery of forces during loading but not in unloading. Rhodium-coated NiTi wires also had the highest corrosion current density and corrosion potential, lowest impedance modulus, and two time constants on Bode plot, one related to the Rh/Au coating and the other to underlying NiTi.
CONCLUSION
Working properties of NiTi wires were unaffected by various coatings in unloading. Nitrification improved corrosion resistance. Rhodium coating reduced corrosion resistance and pronounced susceptibility to pitting corrosion in artificial saliva because of galvanic coupling between the noble coating and the base alloy.
Topics: Coated Materials, Biocompatible; Corrosion; Dental Alloys; Dielectric Spectroscopy; Elastic Modulus; Electrolysis; Gold; Humans; Materials Testing; Microscopy, Electron, Scanning; Nickel; Orthodontic Wires; Pliability; Polarography; Rhodium; Saliva, Artificial; Spectrometry, X-Ray Emission; Stress, Mechanical; Surface Properties; Titanium
PubMed: 24654939
DOI: 10.2319/090413-651.1 -
Wiadomosci Lekarskie (Warsaw, Poland :... 2021The aim: To carry out a comparative assessment of metal alloys for the manufacture of metal-ceramic constructions of dentures by determining the indicator of their...
OBJECTIVE
The aim: To carry out a comparative assessment of metal alloys for the manufacture of metal-ceramic constructions of dentures by determining the indicator of their histotoxicity.
PATIENTS AND METHODS
Materials and methods: To identify the effect of metal alloys on cobalt and nickel bases on the tissue of organism, we carried out an experimental-morphological study of standard samples of metal alloys "Shot-alloy", "Remanium-2000", "Cerium", "Dent-NCB", "Cellite-N".
RESULTS
Results: A careful histological analysis of the capsules formed around the metal alloy samples during two periods of the experiment showed that the healing time of the subcutaneous tissue was not the same. The most complete healing, that is, the formation of mature fibrous connective tissue, occurred during the implantation of the cobaltbased alloy "Remanium-2000" and the capsule formed at the end of the experiment around the implanted sample from the "Shot-alloy" alloy, and during the implantation of the "Cerium" alloy, healing the wound surface and the formation of a connective tissue capsule occurs fully than in previous cases.
CONCLUSION
Conclusions: The analysis of the performed experiment testifies in favor of the point of view that the speed and quality of healing of damaged subcutaneous tissue upon the introduction of implanted research alloys depend largely on the individual chemical components that make up the alloys, or on their combination.
Topics: Ceramics; Chromium Alloys; Humans; Materials Testing; Metal Ceramic Alloys
PubMed: 34725283
DOI: No ID Found -
Indian Journal of Dental Research :... 2012The final esthetic outcome of a metal-ceramic restoration is influenced by several factors including the type of the underlying metal as well as the brand of the ceramic. (Comparative Study)
Comparative Study
BACKGROUND
The final esthetic outcome of a metal-ceramic restoration is influenced by several factors including the type of the underlying metal as well as the brand of the ceramic.
SETTINGS AND DESIGN
An in vitro study.
AIMS
The purpose of the in vitro study was to investigate the influence of four types of metal-ceramic alloys and two porcelain systems on the color co-ordinates of the metal-ceramic complex. It also aimed at establishing a color index which correlated the color of the metal-ceramic combination to the yellow-blue axis.
MATERIALS AND METHODS
Twenty-four disc-shaped metal specimens of 12 mm × 1 mm were cast from base metal alloys, nickel-chromium (Ni-Cr) (Wiron 99), cobalt-chromium (Co-Cr) (Wirobond C), a palladium (Pd)-rich noble metal alloy (Spartan Plus), and a high noble gold (Au) alloy (Pontostar). These discs were covered with two commercially available feldspathic porcelains (Vita Omega and Shofu Vintage) of A3 shade to a total thickness of 1.2 mm. Each group had six specimens, of which three were coated with Vita Omega and the remaining with Shofu Vintage. Opaque and dentin layers were applied to a standardized thickness of 0.2 mm ± 0.05 mm and 1 mm ± 0.05 mm, respectively onto the metal surface after air abrasion with 50 μm alumina particles. The reflectance spectra were measured with a spectrophotometer and data were recorded in L*, a* and b* coordinates in the CIE Lab Color Order System.
STATISTICAL ANALYSIS
Analysis of variance (ANOVA) and path analysis were the statistical tools employed to analyze the data. A critical difference (CD) value was calculated for each color co-ordinate to make comparisons between each metal-ceramic combination. A color index for each metal-ceramic complex was also calculated from the color co-ordinates obtained.
RESULTS
ANOVA revealed that significant differences existed between the metal-porcelain combination at 0.01 ( P < 0.01) level. The L* value was significantly higher for Au and Co-Cr alloys with Vita Omega porcelain. The a* value was highest for Ni-Cr alloy when combined with Shofu Vintage ceramic. The b* value of Au alloy with Vita Omega porcelain was significantly higher than any other metal-ceramic combination. The color co-ordinates of Pd alloy with both porcelain systems did not show any significant differences. Gold alloy with Vita Omega showed the highest color index value.
CONCLUSION
The variations in metal-ceramic alloy and porcelain can influence the shade of a metal-ceramic restoration. Color index value was the highest for gold alloy.
Topics: Aluminum Oxide; Aluminum Silicates; Chromium Alloys; Color; Dental Etching; Dental Porcelain; Gold Alloys; Hot Temperature; Humans; Materials Testing; Metal Ceramic Alloys; Palladium; Potassium Compounds; Prosthesis Coloring; Spectrophotometry, Ultraviolet; Surface Properties
PubMed: 23649078
DOI: 10.4103/0970-9290.111279 -
Dental Materials : Official Publication... Jan 1992Previous studies have utilized in vitro alloy cytotoxicity tests to evaluate dental casting alloys. The purposes of this study were to: (1) evaluate the precision of the... (Comparative Study)
Comparative Study
Previous studies have utilized in vitro alloy cytotoxicity tests to evaluate dental casting alloys. The purposes of this study were to: (1) evaluate the precision of the optical density and visual tests previously used, (2) evaluate a new test measuring absorbance of solubilized formazan dyes, and (3) test the correlation between these tests for cytotoxicity. Balb/c 3T3 cells were plated in 24-well culture trays at 25,000 cells/cm2 around ten types of dental casting alloys (six samples/alloy) and incubated for 72 h. Cells were histochemically stained with MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide)/succinate for 2 h, then fixed, washed, and dried. Toxicity was measured by optical densitometer (OD) scanning, visual assessment, and 560-nm absorbance of DMSO-solubilized dyes. Measurements of rings of inhibition were not used, because they did not provide precise data, and correlated poorly with the other methods. The results were analyzed by ANOVA, Tukey intervals, and coefficients of variation (CV's). MTT required shorter incubation times for adequate staining, allowed for solubilization of the monolayers, and was less expensive than NBT (2,2'-di-p-nitro-phenyl-5,5'-diphenyl-3,3'-dimethoxy-[3,3'-dimethoxy-4,4 '-biphenylene] ditetrazolium chloride). Results showed that all three methods ranked alloy toxicities similarly (p = 0.05). The solubilization method was most discriminating due to lower CV's. Correlation between densitometer and solubilization methods was excellent (R2 = 0.96). Between-experiment CV's were generally less than 20%, and often less than 10%. Between-sample CV's were generally less than 20%.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Analysis of Variance; Cells, Cultured; Densitometry; Dental Alloys; Materials Testing; Reproducibility of Results; Spectrophotometry
PubMed: 1521687
DOI: 10.1016/0109-5641(92)90056-i -
Clinical Oral Investigations May 2022To analyse the sliding resistance of a modern 3D-printed polymer bracket combined with different archwire types and to compare the results with conventionally used...
OBJECTIVES
To analyse the sliding resistance of a modern 3D-printed polymer bracket combined with different archwire types and to compare the results with conventionally used polymeric, ceramic and metal brackets. It was of further interest which bracket-archwire combination could be best qualified for clinical use.
MATERIALS AND METHODS
The sliding behaviour was tested using an orthodontic measurement and simulation system (OMSS) for the use of two bracket types of the polymer, ceramic and metal group in combination with a 0.016 inch × 0.022 inch and 0.017 inch × 0.025 inch archwire of nickel-titanium (NiTi), titanium-molybdenum alloy (TMA) and stainless steel. Six bracket types were combined with six different archwire types and compared to each other.
RESULTS
The sliding resistance showed significant differences between various the bracket-archwire complexes. The combination of 3D-printed polymer brackets with both steel archwire cross-sections showed the least values of sliding resistance (average 23-29%), while the combination of ceramic brackets with TMA archwires presented the highest (average 47%).
CONCLUSIONS
The present study could show that modern 3D-printed bracket materials can have similar or even better mechanical properties than conventional ones regarding sliding resistance. Although the combination of bracket and archwire material is decisive for low sliding resistance values, the selection of the bracket material seems to have a greater influence than the selection of the archwire material or its cross section.
CLINICAL RELEVANCE
It might be possible in future to combine aesthetic and biomechanical requirements for aesthetic brackets by using 3D-printing technology.
Topics: Dental Alloys; Dental Stress Analysis; Esthetics, Dental; Friction; Materials Testing; Orthodontic Appliance Design; Orthodontic Brackets; Orthodontic Wires; Polymers; Printing, Three-Dimensional; Stainless Steel; Surface Properties; Titanium
PubMed: 35092503
DOI: 10.1007/s00784-022-04373-5 -
The Angle Orthodontist May 2014To investigate the microstructure, hardness, and electrochemical behavior of four contemporary Ag-based soldering alloys used for manufacturing orthodontic appliances.
OBJECTIVE
To investigate the microstructure, hardness, and electrochemical behavior of four contemporary Ag-based soldering alloys used for manufacturing orthodontic appliances.
MATERIALS AND METHODS
The Ag-based alloys tested were Dentaurum Universal Silver Solder (DEN), Orthodontic Solders (LEO), Ortho Dental Universal Solder (NOB), and Silver Solder (ORT). Five disk-shaped specimens were produced for each alloy, and after metallographic preparation their microstructural features, elemental composition, and hardness were determined by scanning electron microscopy with energy-dispersive X-ray (EDX) microanalysis, X-ray diffraction (XRD) analysis, and Vickers hardness testing. The electrochemical properties were evaluated by anodic potentiodynamic scanning in 0.9% NaCl and Ringer's solutions. Hardness, corrosion current (Icorr), and corrosion potential (Ecorr) were statistically analyzed by one-way analysis of variance and Tukey test (α=.05).
RESULTS
EDX analysis showed that all materials belong to the Ag-Zn-Cu ternary system. Three different mean atomic contrast phases were identified for LEO and ORT and two for DEN and NOB. According to XRD analysis, all materials consisted of Ag-rich and Cu-rich face-centered cubic phases. Hardness testing classified the materials in descending order as follows: DEN, 155±3; NOB, 149±3; ORT, 141±4; and LEO, 136±8. Significant differences were found for Icorr of NOB in Ringer's solution and Ecorr of DEN in 0.9% NaCl solution.
CONCLUSION
Ag-based soldering alloys demonstrate great diversity in their elemental composition, phase size and distribution, hardness, and electrochemical properties. These differences may anticipate variations in their clinical performance.
Topics: Copper; Corrosion; Dental Alloys; Dental Soldering; Electrochemistry; Electron Probe Microanalysis; Hardness; Humans; Materials Testing; Metallurgy; Microscopy, Electron, Scanning; Orthodontic Appliances; Potentiometry; Silver; Spectrometry, X-Ray Emission; Transition Temperature; X-Ray Diffraction; Zinc
PubMed: 24199746
DOI: 10.2319/073013-569.1 -
Magnetic Resonance in Medical Sciences... 2016We examined safety issues related to the presence of various metallic dental materials in magnetic resonance (MR) imaging at 7 tesla. (Comparative Study)
Comparative Study
PURPOSE
We examined safety issues related to the presence of various metallic dental materials in magnetic resonance (MR) imaging at 7 tesla.
METHODS
A 7T MR imaging scanner was used to examine 18 kinds of materials, including 8 metals used in dental restorations, 6 osseointegrated dental implants, 2 abutments for dental implants, and 2 magnetic attachment keepers. We assessed translational attraction forces between the static magnetic field and materials via deflection angles read on a tailor-made instrument and compared with those at 3T. Heating effects from radiofrequency during image acquisitions using 6 different sequences were examined by measuring associated temperature changes in agarose-gel phantoms with a fiber-optic thermometer.
RESULTS
Deflection angles of the metallic dental materials were significantly larger at 7T than 3T. Among full metal crowns (FMCs), deflection angles were 18.0° for cobalt-chromium (Co-Cr) alloys, 13.5° for nickel-chromium (Ni-Cr) alloys, and 0° for other materials. Deflection angles of the dental implants and abutments were minimal, ranging from 5.0 to 6.5°, whereas the magnetic attachment keepers were strongly attracted to the field, having deflection angles of 90° or more. Increases in temperature of the FMCs were significant but less than 1°C in every sequence. The dental implant of 50-mm length showed significant but mild temperature increases (up to 1.5°C) when compared with other dental implants and abutments, particularly on sequences with high specific absorption rate values.
CONCLUSION
Although most metallic dental materials showed no apparent translational attraction or heating at 7T, substantial attraction forces on the magnetic attachment keepers suggested potential risks to patients and research participants undergoing MR imaging examinations.
Topics: Chromium Alloys; Crowns; Dental Abutments; Dental Alloys; Dental Implants; Dental Materials; Dental Prosthesis Design; Gold Alloys; Hot Temperature; Humans; Magnetic Fields; Magnetic Resonance Imaging; Magnets; Metals; Optical Fibers; Palladium; Phantoms, Imaging; Radio Waves; Safety; Silver; Thermometers
PubMed: 25994037
DOI: 10.2463/mrms.2014-0122 -
Journal of Applied Biomaterials &... Jan 2018The 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...
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.
Topics: Chromium Alloys; Cobalt; Corrosion; Dental Alloys; Humans; Hydrogen-Ion Concentration; Nickel; Saliva
PubMed: 29076515
DOI: 10.5301/jabfm.5000383 -
Journal of Applied Oral Science :... 2009Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the... (Comparative Study)
Comparative Study
UNLABELLED
Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed.
OBJECTIVE
The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system.
MATERIAL AND METHODS
Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37 degrees C and thermocycling (37 degrees C/5 degrees C/37 degrees C/55 degrees C/37 degrees C). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (alpha=0.05).
RESULTS
The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05) extract decreased cell number and viability when the alloy was subjected to thermocycling.
CONCLUSION
Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.
Topics: Alloys; Aluminum Oxide; Biocompatible Materials; Carbon Compounds, Inorganic; Cell Count; Cell Line, Tumor; Cell Survival; Chromium Alloys; Dental Alloys; Dental Casting Investment; Dental Casting Technique; Dental Etching; Dental Materials; Dental Polishing; Diamond; Humans; Materials Testing; Saliva, Artificial; Silicon Compounds; Silicon Dioxide; Temperature; Titanium
PubMed: 19936519
DOI: 10.1590/s1678-77572009000500013