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Article

Electrochemical Behavior of Cobalt–Chromium Alloy Exposed to Effervescent Denture Cleansers

by
Glenda Lara Lopes Vasconcelos
1,
Carolina Alves Freiria de Oliveira
1,
Ana Paula Macedo
1,*,
Viviane de Cássia Oliveira
1,
Patrícia Almeida Curylofo
1,
Carlos Alberto Della Rovere
2,
Rodrigo Galo
1,
Bruna S. H. Tonin
3 and
Valéria Oliveira Pagnano
1
1
Department of Dental Materials and Prosthodontics, School of Dentistry of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto 14040-904, SP, Brazil
2
Department of Materials Engineering, Federal University of São Carlos, São Carlos 13565-905, SP, Brazil
3
Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-904, SP, Brazil
*
Author to whom correspondence should be addressed.
Corros. Mater. Degrad. 2025, 6(2), 23; https://doi.org/10.3390/cmd6020023
Submission received: 15 May 2025 / Revised: 3 June 2025 / Accepted: 10 June 2025 / Published: 12 June 2025
(This article belongs to the Special Issue Advances in Material Surface Corrosion and Protection)
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Abstract

:
This study demonstrates that effervescent denture cleansers can influence the electrochemical behavior of cobalt–chromium (Co-Cr) alloys, with a particular focus on their corrosion resistance. The findings underscore the importance for dental professionals of selecting cleansers compatible with Co-Cr prostheses to minimize material degradation and enhance clinical durability. Corrosion resistance was evaluated using open-circuit potential (OCP), corrosion current density (icorr), and passivation current density (ipass). Surface morphology and elemental composition were analyzed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Forty specimens (n = 5 per group) were individually immersed in one of ten test solutions: distilled water (DW), artificial saliva (AS), and eight commercial denture cleansers—Polident 3 minutes™ (P3M), Steradent™ (St), Polident for Partials™ (PP), Efferdent™ (Ef), Corega Tabs™ (CT), NitrAdine™ (Ni), Fixodent™ (Fi), and Kukident™ (Ku). Each specimen was exposed a single solution to avoid cross-contamination. Results showed St, Ef, and Ku had higher OCP values than DW and Ni (p < 0.05), indicating better corrosion resistance. AS exhibited lower OCP values compared to St (p = 0.034), Ku (p = 0.023), and P3M (p = 0.050). DW had higher icorr than PP (p = 0.030), CT (p = 0.005), and P3M (p = 0.003). For ipass, DW had lower values than Ef (p = 0.025) and Ku (p = 0.016). SEM and EDS revealed no significant surface alterations. Understanding the underlying corrosion mechanisms in different solutions provides valuable insights into optimizing material performance and ensuring durability in clinical applications. The corrosion resistance of Co-Cr depends on the stability of the passive oxide layer, which can be degraded by chloride ions, reinforced by sulfate ions, and influenced by active ingredients in denture cleansers. Overall, the Co-Cr alloy demonstrated acceptable corrosion resistance, underscoring the importance of selecting suitable cleansers for prosthesis longevity.

Graphical Abstract

1. Introduction

Cobalt–chromium (Co-Cr) alloys are widely used in high-performance applications, including dental implants and Removable Partial Dentures (RPDs), due to their exceptional corrosion resistance, robust mechanical properties, and high biocompatibility [1,2,3,4]. Co-Cr alloys spontaneously develop a thin passive film, mainly composed of chromium oxide, which serves as a protective barrier against corrosive agents [5,6]. However, exposure to harsh environments, such as the oral cavity, can compromise this film, thereby accelerating corrosion process [6].
In the oral environment, corrosion resistance is a relevant property for the biological safety and longevity of the prosthesis [7,8]. The oral cavity presents a complex and dynamic setting characterized by saliva, variable pH, and temperature changes, all of which enhance the corrosive potential and increase the susceptibility of mettalic components. This degradation may compromise mechanical integrity [9,10,11,12,13], leading to biological, functional, and esthetic complications [13,14]. Additionally, corrosion can result in the release of metal ions, potentially causing hypersensitivity reactions or adverse effects on oral tissues [6,15,16]. Therefore, the denture materials must withstand constant exposure to moisture, thermal variations, and acidic or alkaline conditions arising from food decomposition [17,18,19,20,21], to ensure long-term performance and patient safety [5,9,10,12,22,23,24].
Proper cleaning of dental prostheses is essential for maintaining oral hygiene and extending the longevity of the prosthetic rehabilitation [25,26]. Among chemical cleansers, effervescent tablets containing alkaline peroxides are often recommended as an adjunctive method to mechanical brushing for the cleaning of RPDs [25,27]. These tablets have demonstrated effective antimicrobial action both in vitro [28,29,30,31] and in vivo [32], and are efficient in removing biofilm from both acrylic and metallic surfaces [27,28,33]. Although Co-Cr alloys exhibit corrosion resistance due to their protective Cr2O3 layer, denture cleansers may compromise this barrier by dissolving the oxide or creating aggressive electrochemical conditions, leading to metal degradation and potential health risks [26,34,35,36]. This study is critical as it reveals how routine hygiene products may damage prosthetic frameworks, striking a balance between cleaning efficacy and material preservation.
While previous studies have evaluated the electrochemical properties of Co-Cr alloys in artificial saliva [21,37,38,39,40] or in association with the use of chemical products [41], there is limited research examining the structural alterations in metal alloys induced by cleansing agents. The potential impact of these products on ion release [26], surface roughness [26,29,30], mass loss [31], optical reflectance changes [34], signs of oxidation [26,35], and electrochemical behavior in the presence of effervescent tablets remain underexplored [28]. Thus, this study aimed to evaluate the effects of effervescent tablets on the surface of Co-Cr alloy, comparing these effects with those of artificial saliva and distilled water. The null hypothesis was that immersion in the tested solutions would not alter the corrosion resistance or surface characteristics of the Co-Cr alloy.

2. Materials and Methods

Forty metallic specimens (∅12 × 3 mm) were obtained by the lost-wax technique in a casting machine (Neutrodyn Easyti, F.Lli Manfredi, Torino, Italy), using a standardized temperature of 1380 °C and a constant torque centrifuge, to inject the Co-Cr alloy (Degudent™, Dentsply Ind. e Com. Ltd.a, São Paulo, SP, Brazil) (Table 1) into the mold (Micro Fine 1700, Talladium do Brasil, Curitiba, PR, Brazil), according to the manufacturer’s recommendation. Following the casting process, all metal specimens underwent a standardized mechanical polishing protocol to ensure consistent surface finishing. The samples were sequentially polished using silicon carbide abrasive papers (Norton Abrasives; Saint-Gobain, Vinhedo, SP, Brazil) of progressively finer grit sizes: 220 (coarse initial grinding), 400 (intermediate smoothing), 600 (fine smoothing), 1200 (pre-finishing), and, finally, 2000 grit (final finishing). Each polishing step was performed for 2 min under constant irrigation with distilled water using a rotary polishing machine (Arotec APL-4, Cotia, SP, Brazil) operating at 300 rpm with an applied pressure of 15 N. Between each grit change, specimens were ultrasonically cleaned in isopropanol for 5 min to remove residual abrasive particles and prevent cross-contamination [32]. A potable water source provided both lubrication and thermal regulation during the sample preparation process. All specimens were polished and subsequently evaluated using a surface roughness tester (Surftest SJ-201P, Mitutoyo Corporation, Japan) to standardize surface roughness within a clinically acceptable range of 0.04 to 0.06 µm [26].
The specimens were randomized (Excel; Microsoft Corp.) and distributed into 8 groups (n = 5). They were then cleaned in an ultrasonic bath (Cristófoli Equipamentos de Biossegurança Ltd.a., Campo Mourão, PR, Brazil) using isopropyl alcohol for 10 min and distilled water for 10 min [15]. The samples were thoroughly dried using hot air and then stored in a desiccator until the commencement of the testing process.
The electrochemical measurements were conducted using a potentiostat (PGP201, Radiometer Copenhagen, Denmark), with data acquisition and control managed by the Voltamaster 4 software. An electrochemical cell was composed of a 400 mL container with a side hole for sample fixation, a working electrode (WE), and an acrylic lid with 2 holes for fixing the reference (RE) and auxiliary (AE) electrodes that were used in the tests. The sample area was delineated by pressing its surface against an o-ring, which was fitted into a lateral hole, thereby exposing a defined area of 22 mm2. A saturated calomel reference electrode (SCE) (B20B110 wire; Radiometer Analytical, Loveland, CO, USA) was attached to the face of the specimen from a hole in the lid. At 25 °C, the saturated calomel electrode (SCE) exhibits a fixed potential of +0.241 V relative to the standard hydrogen electrode (SHE). Next to the SCE, in the other hole in the lid, a platinum AE with an area of approximately 1 cm2 was fixed (B35M110 wire; Radiometer Analytical, Loveland, CO, USA).
The electrolytes used were modified Fusayama’s artificial solution [15], simulating the oral environment, as well as distilled water and eight denture cleansing solutions formulated with effervescent tablets, distilled water, and artificial saliva (Table 1). The tablets were immersed in 150 mL of distilled water, heated to 37 °C using an electric heater (Fisatom Equipamentos Científicos Ltd.a, Model 752A, São Paulo, SP, Brazil), as recommended by the manufacturer, and monitored with a mercury thermometer (Premium, São Paulo, SP, Brazil). Each test specimen was immersed in a distinct, newly formulated solution. Next, the effervescent tablet was placed and left there for the pre-established 5 min period, until the tablet had finished effervescing. Then, the solution was poured into the electrochemical cell and taken to the electrochemical assay. The tests were carried out in an oven to maintain the temperature at 37 ± 2 °C. The stabilization time for open-circuit potential (OCP) measurements was set at 60 min, with data recorded every 30 s. The anodic polarization curves were obtained, and the corrosion current density (icorr) and passivation current density (ipass) were evaluated from the potential at −500 mV to 2000 mV vs. SCE at a scanning rate of 2 mV/s [15,16].
A scanning electron microscope (SEM) (FEI Inspect S 50, FEI Company, Hillsboro, Oregon, OR, USA) was employed to analyze changes on the metallic surface. Additionally, the surface composition in specific regions of interest was determined using energy-dispersive X-ray spectrometry (EDS) (FEI Inspect S 50, FEI Company, Hillsboro, Oregon, OR, USA). One specimen of each group was randomly chosen (Excel; Microsoft Corp, Redmont, WA, USA) to be analyzed by SEM and EDS after immersion in the solutions. EDS (% by mass of the chemical elements present on the metallic surface) was performed after the corrosion test. Characteristic structures were selected within the phase (A) and in the matrix of the Co-Cr alloy (B). The displayed settings (25.00 kV accelerating voltage, 10 mm WD, high vacuum) are optimized for the combined SEM-EDS analysis of Co-Cr alloys.
The data were processed and analyzed using the statistical software program IBM SPSS Statistics for Windows, version 21.0 (IBM Corp, Armonk, NY, USA). The Shapiro–Wilk test was performed to check the normality of data distribution. A one-way ANOVA test was conducted, followed by a post hoc Tukey HSD test. OCP, Kruskal–Wallis, and Dunn’s post hoc tests were used to analyze icorr and ipass data (α = 0.05 for all tests).

3. Results and Discussion

3.1. Electrochemical Behavior of Co-Cr Alloy

In this study, the null hypothesis was partially accepted as some cleansing tablet solutions significantly influenced the electrochemical behavior of the Co-Cr alloy. Kukident™, Steradent™, and Efferdent™ tablets showed the highest values for OCP, indicating their protective effect against corrosion. Furthermore, Kukident™ and Efferdent™ presented the highest values for the passivation current density (ipass), suggesting the formation of a passive layer that is less resistant to the corrosive process. In contrast, artificial saliva and distilled water provided an environment with even lower resistance to corrosion compared to the denture cleanser solutions.
The changes in potential recorded under open-circuit conditions for the Co-Cr alloy over time are illustrated in Figure 1, while the average OCP values are summarized in Table 2 and Figure 1b. For most solutions, the OCP stabilized within 45 min, with the exception of Corega Tabs™, Polident for Partials ™, Polident 3 minutes™, and NitrAdine™, which showed slower stabilization. Efferdent™ reached stabilization earlier, at 35 min (Figure 1).
The OCP results inidcated that most solutions maintained either a stable or positive electrochemical potential over time, indicating corrosion resistance for the Co-Cr alloy, except for NitrAdine™ (−105.2 mV/SCE) and distilled water (−82.1 mV/SCE). Statistically significant differences were observed in the OCP values of the Co-Cr alloy among the solutions, with NitrAdine™ and distilled water showing significantly lower potential than Efferdent™ (p = 0.002 and p = 0.009, respectively), Steradent™ (p < 0.001 and p = 0.001), and Kukident™ (p < 0.001 and p = 0.001) (Table 1 and Table 2).
The potentiodynamic polarization method, particularly OCP analysis, is one of the most commonly used electrochemical techiniques, based on oxidation-reduction reactions occurring on metallic surfaces [16,18]. Moreover, this approach assesses corrosion by analyzing the relationship between the current density per unit surface area and the applied potential [15,16]. Changes in OCP values indicate a tendency of metal corrosion on the surface when it contacts the electrolyte solution [32]. Stability or positive values mean that a stable passive layer protects the metal from corrosion [32]. Negative values indicate an unstable layer [32]. An increase in electrochemical potential during immersion can usually be attributed to the thickening of the passive film, which becomes more protective [16].

3.2. Corrosion Resistance and Longevity

Regarding corrosion rates (icorr), the results obtained show a significant difference among the effervescent tablets (Table 2 and Figure 1b). Artificial saliva showed higher values than Polident 3 minutes™ (p = 0.023) and Corega Tabs™ (p = 0.035). Furthermore, Polident for Partials™ (p = 0.030), Corega Tabs™ (p = 0.005), and Polident 3 minutes™ (p = 0.003) exhibited lower values than distilled water. For the analysis of the corrosion resistance of the Co-Cr alloy, the potentiodynamic polarization curves of Polident 3 minutes™, Corega Tabs™, Polident for Partials™, and NitrAdine™ provided less corrosion, that is, they were responsible for the formation of a lower corrosion current (icorr) than Steradent™ and Efferdent™. For ipass, significant differences were found among the groups, in which distilled water presented a higher current than Efferdent™ (p = 0.025) and Kukident™ (p = 0.0176) (Table 2 and Figure 1b).
The potentiodynamic curve is the graphical representation of the variation in current density as a function of the potential applied to an electrode [33]. Potentiodynamic curves can show corrosion potential (icorr), passive range, and passivation current density (ipass) [34]. According to Clear (1989) [33], corrosion current density (icorr) provides information about the relation between corrosion current and the probability of occurrence of corrosion, which indicates that a corrosion current density more significant than 27 mA/cm2 corresponds to a service life of less than 2 years, while values between 2.7 and 27 mA/cm2 suggest a service life of 2 to 10 years. When the current density is below 2.7 mA/cm2, the material shows improved resistance, lasting approximately 10 to 15 years, and for values below 0.5 mA/cm2, the corrosion rate is negligible, ensuring excellent durability and minimal material degradation [34]. The icorr values indicate that the corrosion rate with Corega Tabs™ (0.2 µA/cm2), Polident 3 minute™ (0.2 µA/cm2), and Polident for Partials™ (0.3 µA/cm2) was negligible in time. On the other hand, the value of artificial saliva (38.6 µA/cm2) suggests that corrosion may occur within less than 2 years. This fact serves as a warning to RPD users regarding the longevity of the metal framework in their prostheses.
For ipass, significant differences were found among the groups, in which distilled water presented higher current than Efferdent™ (p = 0.025) and Kukident™ (p = 0.016) (Table 2 and Figure 1b). Considering the ipass values, the higher ipass value indicates the slower formation speed of the passivating layer [35]. In this study, the numbers show a slight variation in negative values (−8 to −5.5 µA/cm2), with statistical differences between Kukident™ and Efferdent™ compared to distilled water, indicating that the Co-Cr alloy exhibited satisfactory corrosion resistance under water compared to these three denture tablets.
There are studies in the literature that have investigated the electrochemical behavior of Co-Cr alloys in artificial saliva [4,7,11,16,18]. Raimundo et al. (2015) [18] observed that disinfection with peracetic acid at concentrations of 0.2% and 2% did not cause corrosion in samples made with CP-Ti-4 [18]. On the other hand, Galo et al. (2014) [16] evaluated the corrosive behavior in artificial saliva for two alloys (Co–Cr–Mo and Ni–Cr–4Ti) cast under two different conditions, argon atmosphere casting and oxygen–gas flame centrifugal casting, observing enhanced resistance in the cobalt–chromium alloy [16]. Few studies have verified the effects of cleansing solutions on the metallic framework of the prosthesis [17,21,22,25,26,28,33,34,39]. Felipucci et al. (2011b) [21,22] also evaluated the action of the citric acid-based cleansing tablet (NitrAdine Medical Interporous™). They observed suggestive points of oxidation on the surface of the Co-Cr alloy [22]. There are also reports of ion release [18,28].
Existing evidence indicates that NitrAdine™ does not induce significant changes in the surface roughness of cobalt–chromium (Co-Cr) alloys [26]. However, previously, its use was recommended daily, and later, it was recommended twice a week, which may have minimized the adverse effects on the surface of the Co-Cr metallic framework [26,28]. Pupim et al. (2022) [37] evaluated the electrochemical behavior of a Co-Cr alloy after immersion in a solution with an alkaline peroxide-based effervescent tablet (Corega Tabs™). They reported no damage to the Co-Cr alloy [37]. In addition, the authors noted that Co-Cr exhibited a lower tendency to develop a corrosive process with Corega Tabs™ compared to the distilled water solution (control).

3.3. Surface and Microstructural Analyses

Before the potentiodynamic polarization tests, no significant alterations were identified in the evaluated samples through SEM, and all exhibited a heterogeneous microstructure inherent to the casting process, even before immersion in the cleaning solutions (Figure 2). After the tests, it was possible to verify the topographic contrast of the metallic surface, suggesting that the effervescent tablets and artificial saliva provided evidence of the microstructure, allowing for the observation of the phase and matrix of the Co-Cr alloy (Figure 3). These surface characteristics are particularly relevant, as they demonstrate that microstructural heterogeneity in cast alloys creates localized galvanic couples that dramatically alter electrolyte interaction kinetics [1,20].
Based on the elemental composition obtained through EDS analysis (Table 3), it was observed that, during the study of the corrosion process, elements from the effervescent tablets, specially K and Na from the Corega Tabs™ and Na from Kukident™, were detected on the surface of the Co-Cr alloy. This suggests possible chemical interactions or adsorption of these elements onto the alloy surface. In both the phase and matrix regions of the alloy, there was a lower amount of Co before corrosion, except for Fixodent, which presented similar surfaces before and after the corrosion. Furthermore, an increase in C and O on the surface of the samples after the corrosion test was verified for all solutions.
SEM and EDS analyses revealed no detrimental effects of the denture tablets on the Co-Cr alloy. Through the EDS (Table 3), it is possible to visualize the chemical interaction among the elements of the Co-Cr alloy (Co, Cr, Mo, C, Si, Mn, O) with the elements from the effervescent tablets, such as calcium and sodium, probably due to the formation of a passivation layer during corrosion tests. The tests revealed the microstructure of the Co-Cr alloy, showing its phase and matrix, characteristics of cast alloys [1], due to the effects of effervescent tablets and artificial saliva (Figure 3). This can affect the corrosion process, as surface conditions (such as cracks and porosities) may accelerate the surface attack [36].
It was observed that the tablets that caused greater oxygen disclosure in region A, Polident for Partials™, Corega Tabs™, and Efferdent™, also considerably increased the Cr concentration, likely due to the formation of Cr oxide on the surface of the Co-Cr alloy [7,20,41]. This can result in lower ipass values, indicating better corrosion resistance. In region B, Polident 3 minutes™ and Corega™ promoted a significant increase in oxygen. Corega Tabs™ showed evidence of sodium and potassium, and with Kukident™, the presence of sodium on the surface of the alloy was identified. It was observed that the Co concentration decreased with the effervescent tablets, both in regions A and B, likely due to the coating of the surface with Cr oxides and consequent Co masking on the surface of the Co-Cr alloy [7,20,41].
Furthermore, understanding the potential release of alloy constituents into the oral environment is critical, as these constituents may adversely affect systemic health [38]. While combined mechanical–chemical cleaning demonstrated superior efficacy through synergistic tribocorrosion effects [22,40], this study exclusively evaluated chemical methods. Notably, the in vitro model presents key limitations like the absence of dynamic oral conditions (e.g., pH fluctuations, thermal cycling, salivary flow); the lack of mechanical stimuli (e.g., mastication-induced tribological forces, which accelerate wear–corrosion interactions); and the simplified exclusion of biofilm, a clinically ubiquitous factor that modulates surface degradation kinetics [3,8,9,10,11]. These experimental conditions may not fully represent the complex chemo-mechanical synergies encountered in clinical settings.
These findings aimed to elucidate the effect of denture cleansers on the Co-Cr surfaces, filling a gap in the RPD hygiene protocol. Future research with RPD users and these cleansing products, whether or not associated with the mechanical method, should be encouraged to clarify and make their use a viable alternative, especially for elderly individuals or those who are physically unable to clean their prostheses solely by the mechanical method properly.

4. Conclusions

Under the experimental conditions of this study, the conclusions that can be drawn are as follows:
  • NitrAdine™ and distilled water demonstrated significantly lower open-circuit potentials calues compared to EfferdentTM, Kukident™, and Steradent™, indicating a greater susceptibility of the Co-Cr alloy to corrosion.
  • Artificial saliva promoted the higher corrosive behavior of the Co-Cr alloy, showing higher current density than the other solutions.
  • Polident 3 minutes™, Polident for PartialsTM, and Corega TabsTM exhibited lower values of current density and indicated a lower tendency for Co-Cr alloy corrosion over time.
  • SEM and EDS analyses showed no adverse effects on the Co-Cr alloy with the denture tablets.

Author Contributions

All authors contributed to the conception and design of the study. G.L.L.V. and C.A.F.d.O. contributed equally to this paper A.P.M., G.L.L.V., P.A.C., V.d.C.O., C.A.F.d.O. and C.A.D.R. performed material preparation, data collection, and analysis. R.G. carried out the methodology. B.S.H.T. wrote the first draft of the manuscript and performed the final reviewing. All authors provided comments on previous versions of the manuscript. C.A.F.d.O. performed writing, review, and editing. V.O.P. provided supervision. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001.

Data Availability Statement

This work is part of the doctoral thesis of Glenda Lara Lopes Vasconcelos—School of Dentistry of Ribeirao Preto—USP. doi: 10.11606/T.58.2019.tde-08082018-111912.

Conflicts of Interest

The authors declare no potential conflicts of interest concerning the research, authorship, and/or publication of this article.

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Cmd 06 00023 g001
Figure 1. (a) Mean potential of open-circuit effervescent tablets (OCP). (b) Potential dynamic polarization curve. DW—distilled water; AS—artificial saliva; P3M—Polident 3 minutes™; PP—Polident for Partials™; CT—Corega Tabs™; ST—Steradent™; KU—Kukident™; EF—Efferdent™; Fi—Fixodent™; Ni—NitrAdine™.
Figure 1. (a) Mean potential of open-circuit effervescent tablets (OCP). (b) Potential dynamic polarization curve. DW—distilled water; AS—artificial saliva; P3M—Polident 3 minutes™; PP—Polident for Partials™; CT—Corega Tabs™; ST—Steradent™; KU—Kukident™; EF—Efferdent™; Fi—Fixodent™; Ni—NitrAdine™.
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Figure 2. The electron micrograph obtained by EDT (backscattered electron) in the SEM of the Co-Cr dental alloy before the corrosion test: A represents the phase and B represents the matrix of Co-Cr alloy. Arrows: micro-bubbles resulting from the casting process.
Figure 2. The electron micrograph obtained by EDT (backscattered electron) in the SEM of the Co-Cr dental alloy before the corrosion test: A represents the phase and B represents the matrix of Co-Cr alloy. Arrows: micro-bubbles resulting from the casting process.
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Figure 3. Electromicrographs obtained by EDT in SEM after the corrosion test in the following solutions: (a) distilled water; (b) artificial saliva; (c) Polident 3 minutes™; (d) Polident for Partials™; (e) Corega Tabs™; (f) Steradent™; (g) Kukident™; (h) Efferdent™; (i) Fixodent™; (j) NitrAdine™.
Figure 3. Electromicrographs obtained by EDT in SEM after the corrosion test in the following solutions: (a) distilled water; (b) artificial saliva; (c) Polident 3 minutes™; (d) Polident for Partials™; (e) Corega Tabs™; (f) Steradent™; (g) Kukident™; (h) Efferdent™; (i) Fixodent™; (j) NitrAdine™.
Cmd 06 00023 g003
Table 1. Co-Cr alloy and solutions’ composition.
Table 1. Co-Cr alloy and solutions’ composition.
Trade MarkCompositionManufacturer
Distilled WaterH2ON/A
Artificial SalivaNaCl (400 mg/L), KCl (400 mg/L), CaCl2.H2O (795 mg/L),
NaH2PO4.H2O (690 mg/L), NaS.9H2O (5 mg/L), and urea (1000 mg/L)
(Sigma Chemical Company, St. Louis, MO, USA)		Modified Fusayama’s
artificial saliva (AS) [15]
Degudent™Cobalt (Co) (64.8%), Chromium (Cr) (28.5%),
Silicon (Si) (0.5%), Molybdenum (Mo) (5.3%),
Manganese (Mn) (0.5%), and Carbon (C) (0.4%)		Dentsply Ind.e Com. Ltd.a,
São Paulo, Brazil
Polident 3 Minutes™Sodium bicarbonate, citric acid, sodium carbonate,
potassium monopersulfate, sodium perborate, sodium benzoate, PEG-180, EDTA, sodium lauryl sulfoacetate		GlaxoSmithKline, Philadelphia, PA, USA
Polident for Partials™Sodium bicarbonate, citric acid, potassium monopersulfate, sodium carbonate, sodium percarbonate, EDTA, sodium benzoate, sodium lauryl sulfoacetate
Corega Tabs™Sodium bicarbonate, citric acid, sodium perborate monohydrate, potassium peroxymonosulfate, sodium benzoate, sodium lauryl sulfoacetateReckitt Benckiser Healthcare,
United Kingdom
Steradent™Sodium bicarbonate, potassium caroate, citric acid,
sodium carbonate peroxide, sodium sulfate, sodium carbonate, PEG-15, malic acid, sodium, dodecylbenzenesulfonate, EDTA
Kukident™ Sodium sulfate, sodium bicarbonate, citric acid, sodium carbonate, sodium perborate, sulfamic acid, potassium monopersulfate, sodium carbonate peroxide, EDTA, sodium lauryl sulfoacetate, sorbitolPrestige Brands, Inc.
North Broadway Irvington, NY, USA
Efferdent™Ingredients not published by the company
Fixodent™Potassium monopersulfate, sodium bicarbonate, EDTA, citric acid, sodium lauryl sulfate, lactose monohydrate, sodium bicarbonate, sodium perborate, sorbitolProcter & Gamble, Cincinnati,
OH, USA
NitrAdine™Citric acid, sodium lauryl sulfate, lactose monohydrate,
sodium bicarbonate, sodium chloride, hydrogen potassium monopersulfate, sodium carbonate, peppermint flavoring, PVP		BonifAG, Vaduz,
Liechtenstein
Table 2. OCP, icorr, and ipass sample mean (95% confidence interval of mean) of effervescent tablets and statistical comparisons.
Table 2. OCP, icorr, and ipass sample mean (95% confidence interval of mean) of effervescent tablets and statistical comparisons.
SolutionsOCP * (mV/SCE *)icorr * (µA/cm2)ipass * (µA/cm2)
Distilled Water−82 (−149; −15) a20.6 (8.2; 33.0) ab−8.0 (−9.4; −6.7) a
Artificial Saliva−25 (−136; 86) ab38.6 (−2; 79.4) a−6.9 (−7.6; −6.1) ab
Polident 3 Minutes™−11 (−187; 166) ab0.2 (0.1; 0.3) c−5.7 (−6.6; −4.8) ab
Polident for Partials™−5 (−111; 101) ab0.3 (0.1; 0.5) bc−5.7 (−6.3; −5.0) ab
Corega Tabs™40 (26; 106) ab0.2 (0.2; 0.3) c−7.6 (−9.2; −6.0) ab
Steradent™172 (141; 203) b3.8 (0.6; 6.9) abc−5.7 (−6.3; −5.0) ab
Kukident™179 (114; 245) b1.9 (0.9; 2.8) abc−5,5 (−6.0; −5.0) b
Efferdent™139 (107; 171) b3.9 (1.7; 6.1) abc−5.5 (−6.2; −4.9) b
Fixodent™8 (−162; 178) ab2.1 (0.3; 4.0) abc−5.8 (−6.3; −5.3) ab
NitrAdine™−105 (−223, 13) a0.6 (0.1; 1.0) abc−6.5 (−7.6; −5.3) ab
abc Equal letters indicate statistical similarity between groups (p > 0.05). * OCP: open-circuit potential; icorr: corrosion current density; ipass: passivation current density; SCE: saturated calomel electrode.
Table 3. Analysis (% by mass) of chemical elements after immersion in cleansing solutions.
Table 3. Analysis (% by mass) of chemical elements after immersion in cleansing solutions.
Solution
WCDWASP3MPPCTSTKUEFFiNi
Phase of Co-Cr alloyC3.333.454.715.996.874.666.319.735.415.669.04
O 5.868.639.7511.158.388.6310.164.717.40
Na 0.040.07
Mg 0.070.03
P 0.230.42
Cl 0.010.11
Si1.44 1.831.581.711.671.531.721.472.26
Mo16.37 16.7315.5116.0316.0014.0915.9114.1014.34
Ca 0.050.18
Cr39.9130.1929.5842.7341.0041.1440.7938.5242.9436.0835.82
Co38.9566.0159.0624.0925.2925.3126.8427.5023.8737.9831.15
Matrix of Co-Cr alloyC2.12 2.935.364.644.364.994.063.965.1412.83
O3.47 0.0014.808.7119.549.918.959.605.429.62
Na 0.04 1.55 0.76
Mg 0.050.02
P 0.250.30
Cl 0.040.07
Si0.97 1.191.271.441.211.211.180.951.25
Mo4.04 3.125.092.853.654.804.043.614.68
Ca 0.051.51
K 0.40
Cr26.6731.1430.0725.1027.0026.1225.2926.8125.5025.1123.64
Co63.1568.4766.5750.4353.2843.7454.9553.4255.7359.7847.99
WC—without immersion; DW—distilled water; AS—artificial saliva; P3M—Polident 3 minutes™; PP—Polident for Partials™; CT—Corega Tabs™; ST—Steradent™; KU—Kukident™; EF—Efferdent™; Fi—Fixodent™; Ni—NitrAdine™. C (carbon), O (oxygen), Na (sodium), Mg (magnesium), P (phosphorus), Cl (chlorine), Si (silicon), Mo (molybdenum), Ca (calcium), K (potassium), Cr (chromium), and Co (cobalt).
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MDPI and ACS Style

Vasconcelos, G.L.L.; Freiria de Oliveira, C.A.; Macedo, A.P.; Oliveira, V.d.C.; Curylofo, P.A.; Rovere, C.A.D.; Galo, R.; Tonin, B.S.H.; Pagnano, V.O. Electrochemical Behavior of Cobalt–Chromium Alloy Exposed to Effervescent Denture Cleansers. Corros. Mater. Degrad. 2025, 6, 23. https://doi.org/10.3390/cmd6020023

AMA Style

Vasconcelos GLL, Freiria de Oliveira CA, Macedo AP, Oliveira VdC, Curylofo PA, Rovere CAD, Galo R, Tonin BSH, Pagnano VO. Electrochemical Behavior of Cobalt–Chromium Alloy Exposed to Effervescent Denture Cleansers. Corrosion and Materials Degradation. 2025; 6(2):23. https://doi.org/10.3390/cmd6020023

Chicago/Turabian Style

Vasconcelos, Glenda Lara Lopes, Carolina Alves Freiria de Oliveira, Ana Paula Macedo, Viviane de Cássia Oliveira, Patrícia Almeida Curylofo, Carlos Alberto Della Rovere, Rodrigo Galo, Bruna S. H. Tonin, and Valéria Oliveira Pagnano. 2025. "Electrochemical Behavior of Cobalt–Chromium Alloy Exposed to Effervescent Denture Cleansers" Corrosion and Materials Degradation 6, no. 2: 23. https://doi.org/10.3390/cmd6020023

APA Style

Vasconcelos, G. L. L., Freiria de Oliveira, C. A., Macedo, A. P., Oliveira, V. d. C., Curylofo, P. A., Rovere, C. A. D., Galo, R., Tonin, B. S. H., & Pagnano, V. O. (2025). Electrochemical Behavior of Cobalt–Chromium Alloy Exposed to Effervescent Denture Cleansers. Corrosion and Materials Degradation, 6(2), 23. https://doi.org/10.3390/cmd6020023

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