Corrosion Resistance of Cr–Co Alloys Subjected to Porcelain Firing Heat Treatment—In Vitro Study

Rylska, D.; Januszewicz, Bartłomiej; Sokołowski, G.; Sokołowski, Jerzy

doi:10.3390/pr9040636

Cited by 7 publications

(11 citation statements)

References 50 publications

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“…Similarly, after HT, there were no changes in the structure homogeneity/inhomogeneity and in the chemical composition of the superficial layers of both alloys, except for the appearance of oxygen. The present findings are supported by literature [ 45 ]. Moreover, SM-HT exhibited a more homogenous structure and chromium and oxygen distribution.…”

Section: Discussionsupporting

confidence: 93%

“…In this study, Soft Metal (MSM and sintering) exhibited a homogenous structure, on the contrary to MoguCera C (casting). Similar results were obtained by other researchers [ 34 , 38 , 39 , 44 , 45 ]. The highly inhomogeneous structure of MorguCera C resulted in an increased susceptibility to corrosion, due to a less stable passive oxide layer on the surface; as observed by other authors as well [ 16 , 46 ].…”

Section: Discussionsupporting

confidence: 92%

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Does Simulated Porcelain Firing Influence Corrosion Properties of Casted and Sintered CoCr Alloys?

2021

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The aim of the study was to evaluate how heat processing used for dental porcelain firing influences the surface properties of sintered and casted CoCr alloy. Two CoCr alloys, Soft Metal LHK (milling in soft material and sintering) and MoguCera C (casting), were used for the study. The samples were examined using SEM–EDS before and after heat treatment. Next, corrosion examinations (Ecorr, jcorr, polarization curve, Ebr) were performed. Finally, the samples were evaluated under SEM. Based on the results, the following conclusions might be drawn: 1. Thermal treatment (porcelain firing) did not cause chemical impurities formation on the surface of CoCr alloy; 2. The sintered metal exhibited significantly higher corrosion resistance than the casted one due to its homogeneity of structure and chemical composition; 3. Heat treatment (porcelain firing) decreased the resistance of casted and sintered CoCr alloy to electrochemical corrosion. The reduction in corrosion resistance was significantly higher for the casted alloy than for the sintered alloy; 4. The corrosion resistance decrease might be due to an increased thickness and heterogeneity of oxide layers on the surface (especially for the casted alloy). The development of corrosion process started in the low-density areas of the oxide layers; 5. The sintered metal seems to be a favourable framework material for porcelain fused to metal crowns.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionsupporting

confidence: 92%

Does Simulated Porcelain Firing Influence Corrosion Properties of Casted and Sintered CoCr Alloys?

2021

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“…Due to the high cost of noble metal alloys, base metal alloys, such as cobalt-chromium (Co-Cr), are more extensively used for the metal-ceramic restorations’ construction [ 26 ]. Nowadays, Co–Cr alloys are frequently utilized for dental restorations due to their good biocompatibility [ 27 ].…”

Section: Discussionmentioning

confidence: 99%

Experimental Study Regarding the Behavior at Different pH of Two Types of Co-Cr Alloys Used for Prosthetic Restorations

et al. 2021

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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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“…Recently, several research teams evaluated the physical and mechanical properties, as well as the corrosion resistance of MSM Co–Cr. Regarding the corrosion resistance, Rylska et al [ 19 ] reported that among Co–Cr alloys subjected to a porcelain firing procedure, the SLM alloy exhibited the highest corrosion resistance in 0.9 wt.% NaCl, followed by the MSM and the cast alloy. A soft-milled Co–Cr alloy showed a significantly lower Co-ion release than that of its investment cast analogue [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

“…There is limited documentation on the effect of consecutive porcelain firing cycles, such as those employed in the fabrication of metal-ceramic restorations, on the microstructure, corrosion resistance and mechanical properties of dental Co–Cr–Mo fabricated by MSM. Rylska et al [ 19 ] applied a a full porcelain firing schedule on SLM, MSM and Cast Co–Cr, and evaluated the corrosion resistance of the heat-treated alloys, as aforementioned. Önöral et al [ 15 ] conducted repeated firings on Co–Cr alloys fabricated by casting, fully sintered hard alloy milling (FHAM), presintered soft alloy milling (PSAM) and selective laser sintering (SLS); the PSAM-fabricated restorations exhibited the greatest fitting accuracy.…”

Section: Introductionmentioning

confidence: 99%

Simulating porcelain firing effect on the structure, corrosion and mechanical properties of Co–Cr–Mo dental alloy fabricated by soft milling

Lekatou,

Emmanouilidou,

Dimitriadis

et al. 2023

Odontology

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This study aims at evaluating the effect of simulating porcelain firing on the microstructure, corrosion behavior and mechanical properties of a Co–Cr–Mo alloy fabricated by Metal Soft Milling (MSM). Two groups of Co-28Cr-5Mo specimens (25 × 20 × 3 mm) were prepared by MSM: The as-sintered (AS) specimens and the post-fired (PF) specimens that were subjected to 5 simulating porcelain firing cycles without applying the ceramic mass onto their surface. Phase identification by X-ray Diffraction (XRD), microstructure examination by optical microscopy and Scanning Electron Microscopy combined with Energy-Dispersive X-ray Spectroscopy (SEM/EDX), corrosion testing by cyclic polarization and chronoamperometry in simulated body fluid (SBF), the latter test accompanied by Cr3+ and Cr6+ detection in the electrolyte through the 1.5-diphenylcarbazide (DPC) method and UV/visible spectrophotometry, and mechanical testing by micro-/nano-indentation were conducted to evaluate the effect of the post-firing cycles on the properties of Co–Cr–Mo. The results were statistically analyzed by the t test (p < 0.05: statistically significant). All specimens had a mixed γ-fcc and ε-hcp cobalt-based microstructure with a dispersion of pores filled with SiO2 and a fine M23C6 intergranular presence. PF led to an increase in the ε-Co content and slight grain coarsening. Both AS and PF alloys showed high resistance to general and localized corrosion, whereas neither Cr6+ nor Cr3+ were detected during the passivity-breakdown stage. PF improved the mechanical properties of the AS-alloy, especially the indentation modulus and true hardness (statistically significant differences: p = 0.0009 and 0.006, respectively). MSM and MSM/simulating-porcelain firing have been proven trustworthy fabrication methods of Co–Cr–Mo substrates for metal-ceramic prostheses. Moreover, the post-firing cycles improve the mechanical behavior of Co–Cr–Mo, which is vital under the dynamically changing loads in the oral cavity, whereas they do not degrade the corrosion performance.

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Corrosion Resistance of Cr–Co Alloys Subjected to Porcelain Firing Heat Treatment—In Vitro Study

Cited by 7 publications

References 50 publications

Does Simulated Porcelain Firing Influence Corrosion Properties of Casted and Sintered CoCr Alloys?

Does Simulated Porcelain Firing Influence Corrosion Properties of Casted and Sintered CoCr Alloys?

Experimental Study Regarding the Behavior at Different pH of Two Types of Co-Cr Alloys Used for Prosthetic Restorations

Simulating porcelain firing effect on the structure, corrosion and mechanical properties of Co–Cr–Mo dental alloy fabricated by soft milling

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