Copper Amalgam Research Articles

Study of the thermal, mechanical and costrictional properties to some Foreign dental amalgams using in Iraq

In this paper, the preparation of five samples of amalgam alloy used for the restoration of teeth has been done using the amalgamation device for mixing alloys with mercury. The alloys included four high copper amalgams which are (SDI, Septalloy NG 50, YDA alloy, TG alloy) and the percentage of copper (28, 22.7 , 25, 24) % respectively, which are ready fillings. While the fifth alloy (Septalloy NG70) is for low copper amalgam with Copper ratio of 12.7%. The X-ray diffraction has been tested to study the structural properties of these samples and found for the four high-copper alloys increment in the intensity for the diffraction values of the two phases Ɛ - Cu3Sn, ƞ - Cu6Sn5 with the disappearance of the phase γ2 - Sn7Hg which decreases the intensity of this phase with copper increment, while in the low- copper alloy it shows an increase in the peaks representing the phases Ɛ - Cu3Sn, ƞ - Cu6Sn5 with an increasing proportion of copper in the amalgam, as the relationship is positive between copper increment and the tops increment of these two phases, and the relationship is inverse between the copper ratio increment in amalgams and phase γ2 where phase reacts with Eutects silver - copper component phases γ1 - Ag2Hg3, ƞ - Cu6Sn5. Also the mechanical and thermal properties has been studied for each one of five groups of amalgam alloy like compressive strength , micro hardness , thermal conductivity

Reinforcement of Endodontically Treated Teeth by Different Intraorifice Barrier Materials

Background: Fracture incidences are more common in teeth with endodontic therapy and hence endodontic therapy should aim toward the reinforcement of such teeth by placing various restorative materials. Aims: Comparative evaluation of different intraorifice barrier material on strengthening the fracture resistance of teeth requiring endodontic therapy. Methods: Sixty extracted human mandibular premolars with one root were divided into four groups (n = 15); Group 1- Light cured Glass ionomer cement, Group 2 - Nanohybrid composite (NHC), Group 3 - High copper amalgam, Group 4-Control. Decoronation of specimens was done to a standardized length of 14 mm and was instrumented up to International Organization for Standardization (ISO) #30 size master apical file. Gutta percha was used to carry out the obturation by the cold lateral compaction technique. With the exception of the control group, elimination of 3 mm obturation from the coronal portion was done and intraorifice barrier materials were placed. Universal Testing Machine was used for testing fracture resistance. Statistical Analysis: Analysis of variance was applied to analyze the data obtained and pairwise comparison was done by post hoc tukey's test (P < 0.05). Results: Better resistance to fracture incidence was seen with NHCs. Control group presented the least values. Conclusion: On placement of intraorifice barrier materials in teeth with endodontic therapy, there was a reduction in fracture incidence.

Evaluation of effect of core build-up materials on fracture resistance of endodontically treated teeth

Background: Restoration of teeth after endodontic treatment is becoming an integral part of reconstructive dentistry. Aim: The aim of this study was to evaluate the effect of different core build-up materials on fracture resistance of endodontic ally treated teeth. Materials and methods:Freshly extracted forty permanent mandibular first molars were selected. Standardized access cavities were prepared, following which mesial canals were prepared up to F2 (8%25) and distal canals up to F3 (9%30)and obturated. The coronal portion of the specimen was altered by removing the mesial wall and retaining buccal, lingual and mesial walls of 2mm and distal 5mm girth.Ten specimens each were rehabilitated with high copper amalgam, type IX GIC, posterior composite and Alkasite as core build-ups. All the specimens were finally rehabilitated with a metal crown. The specimens were tested for fracture resistance using a universal testing machine under oblique (135oto the long axis of teeth) cyclic loading. The number of cycles taken to fracture,and the fracture site was recorded.The results of mechanical cyclic loading to evaluate fracture resistance showed that compositecore endured the maximum number of cycles to fracture followed by amalgam, Alkasite and type IX GIC.To test the statistical significance inthe difference of mean value KICamong four groups, Kruskal-Wallis one-way analysis of variance was applied. Bonferroni’s multiple comparison test was performed to determine which group significantly differed from the others. Results:From the results of this study, the composite was considered to be the best core build-up material. The newer material, Alkasite can bear stress almost to that of amalgam restoration. Conclusion:This studysuggeststhat Alkasite could be used as a core material for restoring the endodontically treated teeth.

Copper Amalgam Working Electrode for Voltammetric Determination of Selenite

Selenium is one of the heavy metal pollutants in the aquatic environment. Selenite is a form of inorganic selenium, which is very poisonous to living things. Therefore, we need a method that selectively identify selenite to determine its concentration in water. In this study, a square wave stripping voltammetry was used to measure selenite concentration using copper amalgam working electrode. The optimum measurement parameters were obtained at a deposition potential of –450 mV and a deposition time of 800 seconds. This analysis method had good precision with a relative standard deviation (% RSD) of 4.89%. Linear calibration curves are shown in the range 0.03 mM – 0.10 mM with R2 of 0.988 and in the range of 0.10 mM – 0.70 mM with R2 of 0.995 and a detection limit of 9.0 µM. The standard selenite solution was measured with a recovery percentage of 96.67%. The same solution was measured using the HG-AAS method and the recovery percentage was 96.35%. Statistical tests using the t-test showed that the two results did not have a significant difference with a 95% confidence limit. Thus, the voltammetry method using copper amalgam working electrode can be used as an alternative method for determining selenite, as it is cheaper and simpler than the HG-AAS method.

Light irradiation inhibits mercury adsorption by mineral sulfide sorbent

An applicable way of mineral sulfide based remediators such as copper sulfide (CuS) for effective abatement of elemental mercury (Hg0) from coal-fired flue gas is to inject them prior to electrostatic precipitators (ESPs), in which light irradiation widely exists because of the corona discharge. A systematical investigation of Hg0 removal by CuS sorbent under light irradiation was conducted for the first time. The results show that light irradiation significantly inhibited the Hg0 removal efficiency of the CuS sorbent. The normalized Hg0 concentration at the reactor outlet even quickly increased from 0 to 0.45 once a lamp was turned on. Light irradiation excited a transfer of electrons on the Cu-terminated sites from inner Cu 3d orbit to outer Cu 4s orbit, and hence inhibited the formation of copper amalgam, which was supposed to be a key step in Hg0 immobilization by the CuS sorbent. Moreover, light irradiation accelerated the decomposition of copper amalgam to Hg0 which re-emitted to the gas flow. With these novel insights into the role of light irradiation concerning Hg0 removal over mineral sulfides, this work can provide guidance for selecting and adopting proper mineral sulfides in real-world coal combustion conditions to replace traditional activated carbons.

Complex formation between copper(II) and arginine in two ionic media and in a large range of reagent concentration

Arginine and copper(II) play an important role in human physiology. Arginine is a precursor of NO which is a vasodilator and the right quantity of copper(II), bound to several amino acids, is necessary for the human body. The complex formation between copper(II) and arginine is studied at 25 °C and in two different ionic media: 1.00 mol dm−3 NaClO4 and 1.00 mol dm−3 NaCl. The investigation is carried out potentiometrically, by employing in 1.00 mol dm−3 NaClO4 cells involving glass and copper amalgam electrodes. In 1.00 mol dm−3 NaCl, only the glass electrode can be used. In both ionic media, the adoption of the constant ionic medium allows to extend the investigation to a large range of reagent concentration. Experimental data can be explained by assuming the formation of mononuclear complexes in copper(II). In 1.00 mol dm−3 NaClO4, complexes with the participation of hydrogen ions are assumed. The presence of the main complex in a large hydrogen ion concentration is supported also by spectrophotometric measurements.

Preparation of copper amalgam (CuHg) as working electrode for analysis of selenium

Selenium is an essential trace element for human. Beside the range of concentration, the beneficial and toxic effects of selenium are also depending on which chemical form it takes. In nature or environment and some organisms, selenium is present both in organic and inorganic forms where some studies revealed that inorganic species especially selenite are more toxic than the organics matter. Various methods are used to analyse selenium, but it is usually to determine the total selenium, not designed for field applications, requires several preparation steps prior to actual determination, and needs a lot of chemicals. These problems can be solved by voltammetry methods by using dropping or film mercury as a working electrode. The nature of poisonous mercury becomes a limitation in the use of this working electrode. A copper amalgam (CuHg) as working electrodes was successfully prepared for the analysis of selenium. CuHg working electrode was made in a simple way, namely by deposition of copper (Cu) on the surface of Cu wire with potential and at certain time, then dipped into a solution of saturated mercury salt to form the amalgam. Cyclic voltammetry was used to investigate the electrochemical properties of selenium with 0.1 M HCl as a supporting electrolyte. Cyclic voltammetry technique was conducted on the working potential range of - 300 mV (Ei) to -800 mV (Ef). Profiles of cyclic voltammogram were influenced by the scan rate applied. In addition, SEM images showed that the adsorption of selenium occurred on the surface of CuHg working electrode.

Analysis of Cypermethrin Using an Electrode Solid Copper Amalgams Developed as a Working Electrode in Differential Pulse Voltammetry Compared with Gas Chromatography Methods

Analysis of Cypermethrin Using an Electrode Solid Copper Amalgams Developed as a Working Electrode in Differential Pulse Voltammetry Compared with Gas Chromatography Methods

Experimental proof of applicability of alternative sort of plating of contemporary copper forgeries with use of mercury

Abstract Practical applicability of alternative sort of coating of contemporary copper forgeries with use of mercury only (i.e. without use of another metal such as silver or tin) has been experimentally definitely proven. This undescribed way of amalgamation coating is based on simple dipping of a cleaned copper flan in mercury. In few hours, a stable silvery layer of the copper amalgam covers the copper surface. This kind of plating was most likely used by forgers in process of plating of the copper forgeries copying parvi of Wenceslas II at the beginning of the 14th century.

Increased mercury emissions from modern dental amalgams

All types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor than the low copper amalgams used before the 1970s. High copper amalgams has been developed with focus on mechanical strength and corrosion resistance, but has been sub-optimized in other aspects, resulting in increased instability and higher emission of mercury vapor. This has not been presented to policy makers and scientists. Both low and high copper amalgams undergo a transformation process for several years after placement, resulting in a substantial reduction in mercury content, but there exist no limit for maximum allowed emission of mercury from dental amalgams. These modern high copper amalgams are nowadays totally dominating the European, US and other markets, resulting in significant emissions of mercury, not considered when judging their suitability for dental restoration.

Residual Effects from Occupational Mercury Exposure Include a Proposed Mercury Tremor Biomarker or “Fingerprint”

The study investigated residual effects of high levels of occupational mercury exposure, 30 years after a cohort of women worked in public service dentistry. They had all used copper amalgam in a pellet form that required heating and handling, and silver amalgam before the encapsulated form was available. Mercury handling practices changed in the mid-1970 when the workforce was urine tested and mercury poisoning became apparent. The aim was to compare control group and exposed group scores on tasks from a neurobehavioural test battery; plus survey results from a composite health, work history and environmental influences survey. The findings showed that the exposed and control groups were equivalent not only on those variables that one would want to be matched (age, alcohol consumption), but also on many of the cognitive and psychomotor test scores. The present paper focuses on psychomotor skill and tremor patterns. Tremor patterns were seen as generating new evidence of long term effects of the historic mercury insult. Data also suggest that there may be a distinctive mercury “fingerprint”, in samples of sinusoidal waveforms that may have potential as a non-invasive sub-clinical biomarker for adverse effects of mercury exposure, in screening or workplace monitoring.

Composite Replacement of Amalgam Restoration Versus Freshly Cut Dentin: An In Vitro Microleakage Comparison.

The aim of this study was to evaluate the microleakage of the composite restorations when bonded to tooth structure previously restored with amalgam material compared with that of freshly cut dentin. Thirty intact, extracted intact human molars were mounted in autopolymerizing acrylic resin. Class II box preparations were prepared on the occluso-proximal surfaces of each tooth (4-mm bucco-lingual width and 2-mm mesio-distal depth) with the gingival cavosurface margin 1 mm above the CEJ. Each cavity was then restored using high copper amalgam restoration (Disperalloy, Dentsply) and then thermocycled for 10,000 thermal cycles. Twenty-five of the amalgam restorations were then carefully removed and replaced with Filtek Supreme Ultra Universal (3M ESPE); the remaining five were used for scanning electron microscopy and energy dispersive x-ray spectroscopy analysis. A preparation of the same dimensions was performed on the opposite surface of the tooth and restored with composite resin and thermocycled for 5000 thermal cycles. Twenty samples were randomly selected for dye penetration testing using silver nitrate staining to detect the microleakage. The specimens were analyzed with a stereomicroscope at a magnification of 20×. All of the measurements were done in micrometers; two readings were taken for each cavity at the occlusal and proximal margins. Two measurements were taken using a 0-3 scale and the percentage measurements. Corrosion products were not detected in either group (fresh cut dentin and teeth previously restored with amalgam). No statistically significant difference was found between the microleakage of the two groups using a 0-3 scale at the occlusal margins (McNemar test, p=0.727) or proximal margins (Wilcoxon signed-rank test, p=0.174). No significance difference was found between the two groups using the percentage measurements and a Wilcoxon signed-rank test at either the occlusal (p=0.675) or proximal (p=0.513) margins. However, marginal microleakage was statistically significant between the proximal and occlusal margins (p<0.001). Within the limitations of this in vitro study, no significant difference was found between the microleakage of nondiscolored dentin in teeth that were previously restored with amalgam compared with freshly cut dentin. However, marginal microleakage in the proximal surface was higher than that in the occlusal surface.

Effect of Reinforcement on the Fracture Resistance of Endodontically Treated Molars by Various Bonded Restorations-An In Vitro Study

Abstract Objective: To compare and evaluate the fracture resistance of endodontically treated molars reinforced with various bonded restorations and to study the type of fractures in various restorations. Methods: Forty extracted mandibular molars were endodontically treated. MOD (Mesio-Occluso-Distal) cavities were prepared and Mesio-Buccal cusp was reduced in all to provide cuspal coverage. All the teeth were then divided into 4 groups. The cavities in group 1(control) were filled with high copper amalgam. Group 2 was restored with direct resin composite. In group 3 after the priming and bonding procedures as in group 2, cavity surfaces were coated with flowable resin composite. Before curing a piece of polyethylene ribbon fiber was cut and coated with adhesive resin and was embedded inside the flowable composite. The resin composite was cured with visible light cure (VLC) gun. For group 4, restorations were done according to the recommendations provided by the manufacturers of SR Adoro (Ivoclar-Vivadent, Schaan, Liechtenstein) composite material. Compressive fracture strength test was performed after at least 24 hours of the fabrication of the specimens, by application of compressive loading in a Universal testing machine, applied on the occlusal aspect of each specimen with a steel bar. The mean loads necessary to fracture were recorded in Newton and the results were statistically analyzed. Results: Group 4 (indirect composite inlay) had the greater fracture resistance and group 1(Amalgam) had the poorest. Difference between group 1 and 3, group 1 and 4, group 2 and 4 were statistically significant. No statistically significant difference was found between group 1 and 2, group 2 and 3, group 3 and 4. Predominant type of fracture in group 1 and 3 was fracture of tooth below cemento enamel junction at tooth restoration interface without mesio buccal cusp involvement. In group 2 and 4, predominant fractures were of tooth below cemento enamel junction through center of restoration without mesio–buccal cusp involvement.

Comparative study of mechanical properties of direct core build-up materials.

Background and Objectives:The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement.Materials and Methods:All the materials were manipulated according to the manufacturer's recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done.Results:Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus.Conclusions:Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success.

Evaluation of corrosion products in dentin after removal of old amalgams with and without roughing

Background & Objectives: To evaluate of corrosion products in dentin after removal of old Amalgams with and without roughness Materials and Method: Twenty Class II cavities were prepared on extracted premolars then Randomly were divided into four groups according to how they were restored. Group 1 : Light-cured packable composite to establish a microleakage baseline; Group 2: A high copper Amalgam; then stored in 37 ° C normal saline for 6 months to create amalgam corrosion products. Group 3: Identical to Group 2, but later the amalgam was replaced with composite leaving the cavity walls intact. Group 4: Identical to Group 3 except the cavity walls were extended 0.5 mm after amalgam removal prior to insertion of the composite. There are 5 specimens in each four groups for EDX analysis.Evaluation of EDX analysis was descriptive. Results : Corrosion products were detected in Groups 1,2,3 but were not detected in Group 4 . Conclusions : After amalgam removal, roughing dentinal walls could remove the corrosion products penetrating it. Keywords : Corrosion, High copper Amalgam, Dentin, surface roughing

Application of hanging copper amalgam drop electrode for voltammetric determination of selenium content in fruiting bodies of selected mushrooms

A high-sensitivity method based on the CSV with the differential pulse step performed at the hanging copper amalgam drop electrode (HCADE) has been applied for selenium trace determination in selected mushrooms. The HCADE is characterised by simple handling, regeneration facility as well as very good repeatability and reproducibility of the surface. For synthetic solution LOD of Se(IV) as low as 0.25 nM (0.02 μg · kg−1) at preconcentration time (120 s) could be obtained with RSD = 2.3% (n = 5). The accuracy of the method was validated by analysis of certified reference materials (BCR 185R). Fruiting body caps of 12 selected macrofungi species from Basidiomycetes have been investigated. The selenium content determined in the dry matter of mushroom samples was equal to 0.49 ‒ 11.7 mg · kg−1. The highest concentration of selenium was found in Boletus edulis and the lowest one in Laetiporus sulphureus on-plant growing pathogen.

Forensic or archaeological issue: is chemical analysis of dental restorations helpful in assessing time since death and identification of skeletonized human remains?

In 2011, small mass grave with completely skeletonized remains was discovered in Belgrade suburb. An eyewitness claimed that skeletons belonged to German soldiers killed in WWII. Anthropologists were engaged to investigate whether the skeletal remains correspond to the indicated German group or represent more recent case requiring court trial. Numerous dental restorations were noticed. Owing to the fact that different dental materials were used in dental practice at certain times, the aim of this study was to explore whether analysis of dental restorations could help in identification and estimation of time since death. Inductively coupled plasma optical emission spectrometry revealed that dental fillings corresponded to copper amalgam, conventional silver amalgam, silicophosphate cement, and zinc phosphate cement. Chemical results combined with anthropological and historical facts suggest that the individuals lived before the 1960s in country with well-developed dental service at that time. Therefore, chemical analysis of dental fillings was useful to distinguish between skeletal remains that are too old to be of forensic interest and the remains relevant to legal investigations.

High Copper Amalgam Alloys in Dentistry

Amalgam Restoration is an example of the material giving its name to the process. Amalgam fillings are made up of mercury, powdered silver and tin. They are mixed and packed into cavities in teeth where it hardens slowly and replaces the missing tooth substance. The high copper have become material of choice as compared to low copper alloys nowadays because of their improved mechanical properties, corrosion resistance, better marginal integrity and improved performance in clinical trial. The high copper amalgam was used as a restorative material. The application of high copper amalgam was found to be much more useful than low copper amalgam. High copper had much more strength, corrosion resistance, durability and resistance to tarnish as compared to low copper amalgams. No marked expansion or condensation was noted in the amalgam restoration after its setting after 24 hrs. By using the high copper alloy, the chances of creep were also minimized in the restored tooth. No discomfort or any kind of odd sensation in the tooth was noted after few days of amalgam restoration in the tooth.

Effect of tooth whitening on dental restorative materials

ObjectiveTo evaluate the effects of tooth whitening with 10% carbamide peroxide on the surface ultramorphology of three dental restorative materials. Materials and methodsThree materials were tested: (1) a reinforced zinc oxide-eugenol cement (IRM® Powder Zinc Oxide Eugenol, Dentsply, Konstanz, Germany), (2) a high copper amalgam with spherical particles (Ventura Finest®, Madespa SA, Toledo, Spain) and (3) a nanohybrid composite (EvoCeram Tetric®, Ivoclar Vivadent AG, Schaan, Liechtenstein). 6 specimens of each material (N=18) were inserted into silicone molds with circular cavities of 10mm×2mm. 3 specimens of each material were randomly assigned into the whitening or control groups. In the whitening group, the specimens were exposed to a 10% carbamide peroxide gel (Opalescence® PF 10%, Ultradent, South Jordan, UT, USA) for 14 consecutive days, 6h per day. In the control group, the specimens were exposed to distilled water. After 14 days stored at 37°C, all specimens were analyzed by scanning electron microscopy. ResultsThe specimens exposed to carbamide peroxide revealed an irregular surface, with cracks and pores. Specimens from all control groups showed a smooth surface. ConclusionThe 10% carbamide peroxide gel may cause changes in surface ultramorphology of the materials tested: reinforced zinc oxide-eugenol cement, amalgam and composite.

CORROSION OF AMALGAMS IN ORAL CAVITY

This paper is a study of the effect of natural saliva (oral cavity) and a fluoride mouthwash on dentalamalgams .Two types electrodes were made the first was of a high copper amalgam while the second wasmade from a low copper amalgam. They were immersed in two types of electrolytes for twelve hours and the whole galvanic cell was connected to a computer via a potentiosat. Their corrosion currents, corrosionvoltage and corrosion resistance was recorded and compared to find which medium that is usually has themost severe effect on the amalgams corrosion.