Release Of Chromium Ions Research Articles

Exploration of Metal Ion Release from Nickel-Chromium Denture Material: The Role of Saliva pH and Immersion Duration

Nickel chromium (NiCr) is a fixed denture material. Nickel has good physical, and mechanical properties, cheap, but it has low corrosion resistance. One way to increase corrosion resistance is to modify the metal surface by silver plating using the electroplating method. This study examines the effect of saliva pH and immersion time of NiCr metal with silver plating on the release of nickel, chromium, and silver ions. Laboratory experimental studies were 27 samples of NiCr with silver plating (Ø= 10 x 10 x 2 mm) immersed in saliva and divided into 9 groups (n=3): group I (pH 5 for 5 days), group II (pH 7 for 5 days), group III (pH 9 for 5 days), group IV (pH 5 for 10 days), group V (pH 7 for 10 days), group VI (pH 9 for 10 days), group VII (pH 5 for 15 days), group VIII (pH 7 for 15 days), group IX (pH 9 for 15 days). Nickel, chromium, and silver ions release was measured using atomic absorption spectrophotometry. The data obtained were analyzed using two-way ANOVA and post hoc LSD with a 95% confidence level (α =0.05). The results showed a significant difference between salivary pH and immersion time on the ion release (p<0.05). The release of nickel and silver ions increases at acidic pH, while the release of chromium ions increases at alkaline pH. Prolonged immersion (for 15 days) in saliva increases the release of nickel and chromium ions but decreases the release of silver ions.

Investigation of Nickel and Chromium Ion Release from Simulated Fixed Orthodontic Appliances in Artificial Saliva Containing Fluoride

Fluoride is found in many oral hygiene products due to its anti-cariogenic effect. However, fluoride has a corrosive effect that begins at the time of application and continues with the fluoride remaining in the residual saliva. This study aimed to investigate the effect of different fluoride concentrations on the release of nickel and chromium ions from simulated fixed orthodontic appliances made of copper-nickel-titanium (Cu-NiTi), nickel-titanium (NiTi) and stainless steel (SS) archwires. Simulated orthodontic appliances in the experimental groups were immersed in Klimek artificial saliva containing 125, 500, or 900 ppm fluoride (NaF) for one hour and 0.1 ppm fluoride for eleven hours. The process was repeated in subsequent periods. Control groups were exposed to only Klimek artificial saliva. The amounts of nickel and chromium ions released into Klimek artificial saliva were measured using inductively coupled plasma mass spectroscopy (ICP-MS). The morphological characteristics of the archwires were examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The average roughness value of SS archwires before and after immersion was lower than that of Cu-NiTi or NiTi archwires (p<0.05). Simulated orthodontic appliances with SS archwires released more chromium ions than simulated orthodontic appliances with Cu-NiTi and NiTi archwires in experimental groups with 125 ppm fluoride (p<0.05). Simulated fixed orthodontic appliances with SS archwires released fewer nickel ions than simulated fixed orthodontic appliances with Cu-NiTi archwires in both control and experimental groups (p<0.05). Additionally, simulated fixed orthodontic appliances with SS archwires released fewer nickel ions than those with NiTi archwires in control and experimental groups with 500 ppm fluoride (p<0.05).

Release of nickel and chromium ions from stainless steel brackets as a result of long-term exposure to commonly used toothpaste

Background: Brackets in fixed orthodontic appliances are mostly made from metal or stainless steel. Maintaining oral hygiene by brushing the teeth with toothpaste during orthodontic treatment is important. One of the ingredients in toothpaste, sodium fluoride, can cause degradation of the stainless-steel surface, which has the potential to corrode or release metal elements. Purpose: the purpose of this study is to describe the Nickel and chromium ion release of stainless-steel brackets against toothpaste use in orthodontic treatment by means of narrative review. Review: The main corrosion products of stainless-steel brackets are nickel and chromium. Toothpaste detergents contain sodium lauryl sulfate, which can cause the release of nickel ions due to the presence of sodium ions, which can trigger redox reactions. In addition, the fluoride content will combine with hydrogen to produce hydrofluoric acid, which can damage the oxide layer on orthodontic wires, resulting in the release of metal ions such as nickel and chromium. The effects of the release of these ions can be carcinogenic, cause hypersensitivity reactions, and cause cytotoxicity. Corrosion causes the dissolution of filler metal, resulting in weakened bracket material and increased friction, leading to delayed tooth movement. Conclusion: Toothpaste can affect the release of nickel and chromium ions in stainless steel brackets in the presence of sodium and fluoride.

Effects of air abrasive polishing on chromium ion release from different metal self-ligating orthodontic brackets

Treatment with fixed orthodontic appliances compromises the oral hygiene and increases the risk of plaque related disorders and dental staining in addition to corrosion and corrosion byproduct: ions. The aims this study was assessment the effects of air polishing on Chromium ion (Cr) release from stainless steel self-ligating brackets.
 one hundred and sixty self-ligating stainless-steel brackets of four brands Damon® Q™ (Damon® Q™, Ormco, Orange, CA, USA), Discovery® SL 2.0 (Dentaraum, Ispringen, Germany), Leone® F1000 (SLB; F1000, Leone SpA, Sesto Florentino, Florentino, Italy) and Lotus Plus® (Lotus plus, Orthotechnology co., Brazil) were exposed to different time of air abrasion polishing (0, 5, 10, 20 seconds) then immersed in artificial saliva with pH value 6.75 and incubated at 37°C for 28 days. Cr ion release was assessed using atomic absorption spectrophotometer at 7, 14 and 28 days and accumulative effect was calculated. Scanning electron microscope (SEM) were used to assess the surface changes and microtopography after polishing for randomly selected sample. Analysis of variance test (ANOVA), and Tukey’s (HSD) test were used to identify the significant difference among the studied groups where the level of significance set as P ≤ 0.05.
 The results revealed that all brands showed significant increase in Cr ion release concomitant with an increase in the polishing time. Damon® Q™ show the greatest amount of Cr ion release
 Conclusion: The air polishing procedure enhanced the amount of Cr ion release to a subtoxic level and could be used in adult patients using 5 sec. recommended time of polishing with prolonged intervals between the visits.

Nickel and Chromium Ion Release from Orthodontic Wires Subjected to Various Drinks and Distilled Water.

Objectives: The aim of this in vitro study was to assess the quantity of nickel and chromium ions released from orthodontic wires when subjected to various beverage solutions and distilled water. Materials and Methods: Orthodontic appliances composed of five brackets, one band and 0.016-inch stainless steel and nickel titanium wires were immersed in Coke, tea, coffee and distilled water. The samples were incubated at 37°C for 1 hour, 6 hours, 24 hours, and one week. There was a total of 120 appliances divided into 24 groups (n=5 in each group). Atomic absorption spectroscopy was used to examine the amount of released ions. Two-way and one-way ANOVA followed by Tukey test were used for statistical analysis and P<0.05 was considered significant. Results: The release of nickel ions from both wires was highest in Coke and lowest in distilled water at all time points. Coffee and tea demonstrated values in-between these two limits. Similarly, chromium ion release from both wires was highest in Coke at all time-points compared to all other solutions (P<0.05). None of the other tested drinks showed significant differences in chromium ion release compared to distilled water. Conclusion: Restricting the intake of acidic drinks, particularly carbonated beverages like Coke, plays a critical role in safeguarding orthodontic wire components. Educating patients and providing dietary guidelines are essential for maximizing treatment effectiveness. Further research is required to investigate additional factors impacting ion release and devising methods to mitigate potential harm.

Effect of Lactobacillus casei shirota strain probiotic beverage on the release of chromium ions in stainless steel brackets

AbstractIntroduction: Stainless steel brackets are often used in orthodontic treatment. Chromium is one of the stainless steel bracket elements that increases corrosion resistance. Chromium ions release can cause allergic reactions. Acidic pH due to food and drink consumed can cause corrosion and release of ions. One of the most widely consumed acidic pH drinks is the Lactobacillus casei shirota strain probiotic because it provides health benefits. The purpose of this study was to determine the effect of the Lactobacillus casei shirota strain probiotic beverage on the release of chromium ions in stainless steel brackets. Methods: Laboratory experimental research with post-test only control group design. The number of samples is 10 for 2 groups. The bracket was immersed in artificial saliva as the control group and the probiotic drink Lactobacillus casei shirota strain as the treatment group. After 18 hours and 15 minutes of immersion in an incubator at 37°C, the immersion solutions were tested using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) to determine the release of chromium ions. The results of the study were analyzed using independent t-test. Results: The average chromium ion release in the control group was 7.63 ppm while the treatment group was 7.87 ppm. The results of independent t-test showed a significant difference (p&lt;0.05). Conclusion: The release of chromium ions of stainless steel bracket immersed in probiotic beverage Lactobacillus casei shirota strain was significantly greater than that of immersion in artificial saliva. The value of chromium ion release obtained was still below the average daily intake of chromium.

Comparison of nickel and chromium ion release using four different commercially available mouthwashes on orthodontic brackets and wires: An In vitro study

Comparison of nickel and chromium ion release using four different commercially available mouthwashes on orthodontic brackets and wires: An In vitro study

Nickel and chromium ion release from coated and uncoated orthodontic archwires under different pH levels and exposure times

ObjectivesThe purpose of this study was to determine and compare nickel and chromium ion release from traditional stainless steel and nickel titanium wires and newer esthetic archwires under different pH conditions, for different time intervals. MethodsTen pieces of 10-mm segments of five different orthodontic archwires were submerged in buffer solutions of pH 4.0, 5.5, and 7.0, for 4 and 13 weeks. The sample solutions were analyzed using ICP-MS. First, the results were analyzed by three-way ANOVA to determine any significant differences in metal concentration (ppb) between the different groups. Then, a post-hoc multiple pairwise comparison by Tukey's Studentized Range (HSD) Test was conducted to further compare the different materials and pH conditions. ResultsFor nickel, uncoated NiTi had the highest nickel ion release (ppb), while AO Iconix had the lowest average nickel ion release, with a significant difference (p < 0.0001). The average nickel release increased with time and decreased with pH. For chromium, materials with uncoated stainless steel had the highest average chromium ion release, whereas AO Iconix had the lowest average chromium ion release, with a statistically significant difference (p < 0.0001). Chromium ion release increased with time and decreased with pH. ConclusionsThere were significant differences in metal ion release between different pH conditions, materials, and time points. The metal ion release increased with increase in time and decrease in pH. Overall, the coated archwires showed less metal ion release than the uncoated wires.

Study of the rheological properties and solution microstructure of progressively cross‐linked aqueous gels

AbstractA stepwise cross‐linking polyacrylamide hydrogel was prepared using the laboratory homemade stepwise crosslinker PVC‐PP‐Cr and partially hydrolyzed polyacrylamide. The microstructure was investigated by using the scanning electron microscope and dynamic light scattering. The results show that the system has a controllable cross‐linking time of 4 ~ 6 h, good heat resistance, and maximum gel strength of &gt;300,000 mPa.S. In terms of viscoelastic behavior, a stepwise cross‐linking process between crosslinker and hydrolyzed polyacrylamide (HPAM) is presented, and the viscoelasticity is increased step by step. During the stepwise cross‐linking process, the dendritic structure, network structure and lamellar structure to a stable spatial network structure is obtained. Here, the cross‐linked structure between polymer molecular chains is formed after addition of the crosslinker, which increases the steric hindrance of macromolecular chains and further enhances the stability of the system. With the gradual release of chromium ions from the PVC‐PP‐Cr stepwise crosslinker, the gel system is formed continuously. When intermolecular friction stopped increasing, intermolecular entanglement and interaction are enhanced, and elasticity is also increased.

Metal ions release in saliva from Fixed Orthodontic appliances: A Systematic Review

Standard Orthodontic intervention, involves the use of brackets, bands and arch wires. Brackets used in orthodontic treatment provide the means to transfer force to the teeth using the arch wire. Biodegradation of different types orthodontic brackets might lead to metal ion release . Nickel (Ni) and chromium (Cr) containing alloys are present in the manufacture of most of the orthodontic appliances.Increae of nickel and/or chromium ion release could result in heath hazardous effects Analysis of released metal ions was performed through mass spectroscopy, atomic absorption spectroscopy. The aim of this study is to systematically assess the release of metal ions with fixed orthodontic appliances using ceramic brackets. Electronic searches will be performed in two databases (PubMed, Cochrane). The PubMed, identified 29 studies, 4 of which met the inclusion criteria. In conclusion, Although these studies are limited and very few, this systematic review can state that the release of metal ions in patients with fixed orthodontic appliances is in measurable amounts that are considered to be safe. In addition there are no difference in the release of salivary ions regardless of the bracket type used.

A comparative study of the corrosion and ion release behaviour of chromium oxide coatings exposed to saline, Ringer’s and Hank’s physiological solutions

Chromium oxide coatings deposited on stainless steel substrates by RF reactive magnetron sputtering were tested for their corrosion and ion release behaviour in three physiological solutions. The Raman investigations showed that the coatings were predominantly Cr2O3. The coatings tested in Ringer’s and Hank’s solutions possess lower defect densities, better corrosion resistance, and lower ion release when compared to those tested in saline solution. The overall minimal chromium ion release from these samples suggests that the coatings have the potential to be used as an implantable coating for orthopaedic implant applications where material degradation and ion release remains a major concern.

Cobalt and Chromium Ion Release in Metal-on-Polyethylene and Ceramic-on-Polyethylene THA: A Simulator Study With Cellular and Microbiological Correlations

BackgroundThe aims of this study were to determine the levels of cobalt (Co) and chromium (Cr) ions generated in simulators from metal-on-polyethylene (MoP) and ceramic-on-polyethylene (CoP) constructs. Furthermore, we aimed to investigate the cytotoxic effect of these ion levels on native tissues and their potential to modify periprosthetic joint infection risk. MethodsWe used in vitro culture of human adipose-derived mesenchymal stem cells (AMSCs) and Staphylococcus epidermidis cultures, respectively. Ten hip simulator constructs (5 MoP and 5 CoP) were assembled and run for 1,000,000 cycles in bovine serum and evaluated for CoCr concentration. Cytotoxicity and growth impact on AMSCs and S. epidermidis was compared between CoCr and inert silicon dioxide. ResultsAfter 1,000,000 cycles, mean MoP and CoP Co concentration was 2264 and 0.6 ng/mL, respectively (P < .001). Mean MoP and CoP Cr concentration was 217 and 4.3 ng/mL, respectively (P < .001). Mean MoP Co:Cr ratio was 10:1. Co ions were significantly more toxic to human AMSCs than control silicon dioxide in a dose-response manner (P < .001). S. epidermidis growth was not significantly impacted by Co concentrations observed in the simulators. ConclusionMoP constructs built in ideal conditions generated substantial CoCr debris, highlighting a baseline risk with these implants that may be exacerbated by host factors or imperfect surgical technique. Evaluation of impact on AMSCs suggests that debris levels produced under simulator conditions can be cytotoxic. In addition, these concentrations did not potentiate or inhibit S. epidermidis growth, suggesting that elevated periprosthetic joint infection rates with adverse local tissue reaction are related to other factors potentially associated with tissue necrosis.

Nickel and chromium ion release from stainless steel bracket on immersion various types of mouthwashes

The stainless steel bracket is widely used in orthodontics because of its mechanical properties, strength, and good biocompatibility. However, under certain conditions, it can be susceptible to corrosion. Studies have reported that the release of nickel and chromium ions because of corrosion can cause allergic reactions in some individuals and are mutagenic. The condition of the oral environment can lead to corrosion, and one factor that can alter the oral environment is mouthwash. The aim of this study was to measure the nickel and chromium ions released from stainless steel brackets when immersed in mouthwash and aquadest. The objects consisted of four groups of 17 maxillary premolar brackets with .022 slots. Each group was immersed in a different mouthwash and aquadest and incubated at 37 °C for 30 days. After 30 days of immersion, the released ions were measured using the ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). For statistical analysis, both the Kruskal-Wallis and Mann-Whitney tests were used. The results showed differences among the four groups in the nickel ions released (p < 0.05) and the chromium ions released (p < 0.5). In conclusion, the ions released as a result of mouthwash immersion have a small value that is below the limit of daily intake recommended by the World Health Organization.

Chromium oxide coatings with the potential for eliminating the risk of chromium ion release in orthopaedic implants.

Chromium oxide coatings prepared by radiofrequency reactive magnetron sputtering on stainless steel substrates were exposed to Ringer's physiological solution and tested for their electrochemical corrosion stability using an open circuit potential measurement, potentiodynamic polarization, electrochemical impedance spectroscopy and Mott–Schottky analysis. The coatings were found to be predominantly Cr2O3, based on the observation of the dominance of and Eg symmetric modes in our Raman spectroscopic investigation and the Eu vibrational modes in our Fourier transform infrared spectroscopic measurements on the coatings. We investigated for the presence of chromium ions in Ringer's solution after all of the above electrochemical tests using atomic absorption spectroscopy, without finding a trace of chromium ions at the ppm level for coatings tested under open circuit and at the lower potentials implants are likely to experience in the human body. The coatings were further exposed to Ringer's solution for one month and tested for adhesion strength changes, and we found that they retained substantial adhesion to the substrates. We expect this finding to be significant for future orthopaedic implants where chromium ion release is still a major challenge.

Evaluation of Nickel and Chromium Ion Release from Stainless Steel, HANT and NiTi Arch Wires in Two 28-day Time Spans

Background: Stainless steel and Nickel Chromium alloys show special mechanical features, which has made them the most common materials for fabrication of orthodontic arch wires. Objectives: The aim of this study was to evaluate the effect of length of immersion and type of arch wire on release of nickel and chromium ions from fixed orthodontic appliances. Materials and Methods: 15 simulated half-arch maxillary fixed orthodontic appliances were divided into 3 groups according to the types of arch wires. Each sample was individually immersed in 50 ml of distilled water and incubated at 37oC for 28 days. Afterwards, solutions were sent to laboratory for investigation of the released ions and the samples were incubated for another 28 days in new distilled water. After each 28-day time span, the concentrations of nickel and chromium were measured using an atomic absorption spectrophotometer. T-test was used for statistical analysis and P < 0.05 were considered statistically significant. Results: Stainless steel arch wires released the greatest amount of nickel and chromium ions at both 28 days periods. The lowest amount of nickel and chromium in both time spans was released from NiTi and HANT arch wires, respectively Nickel ion release decreased overtime while the chromium release increased. Conclusions: The amounts of released nickel and chromium ions from fixed orthodontic appliances from all three types of evaluated arch wires were below the daily dietary intake of these ions and do not bring about biological concerns.

Http://www.omicsgroup.org/journals/polyolefin-from-commodity-to-specialty-2169-0022-1000e111.php?aid=47818

Generally, the combination use of difference metals occurs galvanic corrosion. Therefore, the combination use of SUS316L (SUS) and Ti-6Al-4V(Ti64) is supposed to be prohibited in human body. However, there are necessary cases of the combination use in clinical orthopedics. In order to investigate the in-vivo galvanic corrosion, the plates and screws made of SUS and Ti64 were implanted into the proximal tibia of the rabbits for 52 weeks. The plate and screws were implanted in 4 different combinations of pairing up in different metals and identical metals. By means of X-ray follow-up and Contact Micro Radiography (CMR), new bone formation around the implants was investigated. And cytopathological observation was performed on the surrounding tissue. Regarding to the implants, microscopic observation was performed on the removed implants surface. Furthermore, metal element analysis was carried out to investigate chromium ion release as a sign of the galvanic corrosion. In X-ray follow-up and CMR, the bone tissue under the plates became thin and porous like as concellous bone in all the combinations, which is supposedly due to the stress shielding and the disturbance of periosteal blood flow by the implantation. In the surrounding soft tissue and bone tissue, no remarkable findings were obtained in the cytopathological observation. Regarding to microscopic observation of the implants, short striations with metallic luster in SUS implants, and short striations with metallic luster or dark brown color in Ti64 implant were confirmed. However these are supposedly caused by the scratching or frictional damage during the screw fixation. In metal element analysis, the Cr element elution was confirmed around the SUS plates. However, there is no significant difference between SUS screw (identical metals) and Ti64 screw (different metals). As the results, the in-vivo galvanic corrosion and related changes were not confirmed in all investigations at 52 weeks.

Metal Ion Release From Ni-Cr Alloy with Different Artificial Saliva Acidities

AIMS: evaluate the effects of changes in salivary pH on ion release from the Ni – Cr alloy at different time and calculate the amount of nickel, chromium ions released from these alloyes.MATERIALS AND METHODS: Fourty eight specimens of Ni-Cr alloy were divided, four specimens immersed in each of four types of artificial saliva at different pH (7 as control,6,5 and 2.5), in three storage periods (12, 24 and 36days). All test tubes were incubated at 37°C. After the immersion time was finished the quantities of metallic ions released for Ni and Cr were measured for each test solutions after 12, 24and 36days of immersion by atomic absorption spectroscopy. RESULTS: The results of Nickel and Chromium ion release showed a statistically significant difference at p≤0.05 between three immersion solutions after (12, 24, 36) days, artificial saliva (pH2.5) showed higher rate of Ni and Cr release than artificial saliva (pH 7as control ,6,5) after various immersion times. It should mention the nickel ion release has been found to be more than chromium ion release. CONCLUSIONS: There is an evidence that the Ni and Cr ions release from Ni-Cr alloy at the presence of different acidity of artificial saliva. Chromium and nickel ion release in small amount in artificial saliva with pH(6,5), while in pH 2.5 release in large amount after (12, 24, 36) days of immersion. Nickel exhibited the highest level of ion release than Cr

Metal ion release: also a concern for ceramic-on-ceramic couplings?

BIOLOX delta is the newest ceramic composite material of the BIOLOX family and its use in hip devices represents a good alternative to Metal-on-Metal or Metal-on-Polyethylene coupling. Some Metal-on-Metal hip devices have shown chromium and cobalt release, which promoted toxic effects. Furthermore, the ceramic composite contains trivalent chromium, even if strongly bound to the alumina lattice. The present study is aimed at detecting any 'in vivo' release of chromium ions from BIOLOX delta bearings in the blood, erythrocytes and urine of patients. Twenty patients implanted with total hip arthroplasty (THA) with BIOLOX delta-BIOLOX delta couplings and 21 subjects with no implanted prostheses were studied. Inductively coupled plasma mass spectrometry equipped with dynamic reaction cell was used for analysis. In the THA group the Cr ions values were; in blood mean 0.21 µg/l (±0.09), in serum 0.21 µg/l (±0.12), in normalized erythrocytes 0.13 µg/l (±0.09), in normalized urine 0.12 µg/g creatinine (±0.13). In the control group the Cr ions values were; in blood mean 0.22 µg/l (st dev 0.14), in serum 0.17 µg/l (±0.08), in normalized erythrocytes 0.13 µg/l (±0.11), in normalized urine 0.07 µg/g creatinine (±0.08). The Lab reference values were 0.1-5.0 µg/l for blood, 0.1-0.5 µg/l for serum, 0.14-4.58 µg/l for normalised erythrocytes and 0.05-2.2 µg/l for urine. All samples in both groups resulted in chromium levels within the normal reference range and the safety of BIOLOX delta ceramics, in terms of chromium ions release, has been demonstrated.

Study Of Release Of Nickel And Chromium Ions From Different Brands Of Stainless Steel Brackets”-An Invitro Study

Background and objectives: The aim of the study was to investigate the nickel and chromium ion release from the different brands of stainless steel brackets in to the normal saline. Materials and Methods: Five full set of Dentaurum,3M and Koden brackets were immersed in sterile plastic tube and marked A,B,C respectively, containing 50ml of Normal saline and maintained at 37°c for 3 weeks. The processing was done by using 0.5ml of saliva that was transferred to a 2ml plastic test tube with a micropipette. The chemical analysis for Ni and Cr is performed with an Atomic Absorption Spectrometer. The concentration of Ni and Cr are expressed in micrograms per litre.This process was done by 1st,7th,14th and 21st day. The values are analyzed. Results: The nickel and chromium release of Koden brackets is high. The least release of nickel and chromium is observed in Dentaurum brackets. The chromium release is insignificant within the groups but it significant in duration of days. The nickel release is significant within the groups but it is insignificant in duration of days. Interpretation and Conclusion: Nickel and chromium release from different company brackets are not uniform, it varies. Koden brackets show more amount of nickel release, Dentaurum brackets show least amount of Nickel release.

Metal Ion Levels in Total Hip Arthroplasty Versus Hip Resurfacing

Recent studies suggest that the tapered interface between stem and femoral head may be a substantial source of cobalt and chromium ion release after metal-on-metal (MOM) total hip arthroplasty (THA). This study compared patient ion levels after MOM hip resurfacing (HR) and MOM THA performed with identical acetabular components. 110 HRs were compared with 22 THAs. All had well-oriented components, unilateral implants, and serum ion studies beyond one year post-operatively. The HR group’s median cobalt value was 1.11μg/L vs. 2.86μg/L for the THA patients. The HR group’s median chromium value was 1.49μg/L vs. 2.94μg/L for THA. Significantly higher THA ion levels suggest a source of ions other than the MOM bearing itself.