High-copper Amalgam Research Articles

Dental restorative materials and halitosis: a preliminary in-vitro study

Despite the widespread use of dental restorative materials, little information exists in the literature regarding their potential impact on bad breath. This in vitro study aims to fill this gap by investigating the influence of different restorative materials on the release of hydrogen sulfide (H2S). Thirteen diverse dental restorative materials, including composites, flowable composites, glass ionomer restorative materials, high-copper amalgam, and CAD–CAM blocks, were examined. Cellulose Sponge models were used as negative and positive control. All samples were prepared with a diameter of 5 mm and a height of 2 mm. Except for the negative control group, all samples were embedded into Allium cepa L., and the emitted H2S was measured using the Wintact W8802 hydrogen sulfide monitor. Surface roughness’s effect on emission was explored by roughening the surfaces of CAD–CAM material samples, and gas emission was measured again. The data were statistically analyzed using the Kruskal–Wallis test and DSCF pairwise comparison tests. Fiber-reinforced flowable composite (EverX Flow), amalgam (Nova 70-caps), and certain composite materials (IPS Empress Direct, Tetric Evoceram, Admira Fusion X-tra) released higher H2S concentrations compared to the negative control. The H2S release period lasted longer in the same materials mentioned above, along with G-aenial Universal Injectable. Indirectly used materials, such as GC Cerasmart, Vita Enamic, and Vita YZ HT, demonstrated significantly lower emissions compared to other direct restoratives. Importantly, the surface roughness of indirect materials did not significantly affect peak H2S concentrations or release times. The study reveals variations in H2S release among restorative materials, suggesting potential advantages of indirect restorative materials in reducing H2S-induced halitosis. This comprehensive understanding of the relationship between restorative materials and halitosis can empower both dental professionals and patients to make well-informed treatment choices. Notably, there is evidence supporting the enhanced performance of indirect restorative materials for individuals affected by halitosis.

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.

Improvement of corrosion resistance and dimensional change of the high copper dental amalgam by Al2O3 additions.

the main goal of this present investigation is to study the effect of the (Al2O3) addition on corrosion resistance and dimensional change of the high copper dental amalgam. One alloy has been prepared via casting composed of silver (47%), tin (30%), copper (22%), and zinc (1%). (Al2O3) addition is added in distinct percentages of the (0.5, 1, 1.5, 2) wt.%. Specimens were prepared according to ADA specification No. 1. The specimens have been stored at 37±1 C° using a chamber prepared for this purpose. corrosion resistance improved with addition from 0.5% to 2% (Al2O3) and observed that dimensional change of amalgam improved after (Al2O3) additions.

Effect of Copper Content Addition to Dental Amalgam Properties

A set of high-copper amalgam alloys have been prepared based on the change in the ratio of copper to silver using elemental components of high purity 99.9%. The amalgamation processes were done by mixing alloy powders with mercury at a fixed ratio. Structural properties were studied using X-ray diffraction and Optical Microscopy. Also, microhardness, and compressive strength were used to study some other important mechanical properties. The prepared amalgams were compared with well-known commercial amalgams; ANA 2000 and Standalloy F. The results of X-ray diffraction showed several prime phases in alloys and amalgams whose proportions and distribution depended on the copper content in the alloy. The results of mechanical test measurements showed a linear increase in the mechanical properties with increasing copper content in the amalgams. The results were similar to the measured values of the commercial amalgam.

Dosimetric evaluation of the effect of dental restorative materials in head and neck radiotherapy.

The aim of our study is to assess the dose enhancement from scattered radiation due to dental restorative materials used for occlusal and mesio-occlusal-distal (MOD) cavity filling during simulated head and neck radiotherapy. We have studied the dose enhancement ratio (DER) of conventional amalgam, high-copper amalgam, and resin composite dental restorative materials at cadaver mandible teeth using 2 therapeutic photon energies of 1.25 MeV (Co-60 gamma ray) and 6 MV (Linac X-ray) for irradiation. DER values at buccal position for Co-60 and 6 MV X-ray were 1.250 ± 0.013 and 1.151 ± 0.012, respectively. For dental cavity fillings, DER values for 6 MV X-ray were 1.065 ± 0.021, 1.100 ± 0.014, and 1.162 ± 0.016 for resin composite filling, low-copper amalgam filling, and high-copper amalgam filling, respectively. Our results revealed that DER regarding irradiation energy was minimum for 6 MV X-rays. With respect to dental restorative filling material, DER was minimum for resin composite filling. Regarding the cavity type, our results with standard deviation (SD) calculations revealed that DER was slightly but not significantly different for both Co-60 gamma ray (1.25 MeV) and 6 MV X-ray energies for both occlusal and MOD cavities. Our dosimetric results for a single beam geometry suggest that, among the three types of filling, resin composite filling is an ideal restorative filling material with minimal morbidity-inducing radiation dose enhancement that may result in increased osteoradionecrosis and secondary caries risk. There is a need for further dosimetric studies with actual clinical beam arrangements.

Corrosion of galvanic pairs of Co-Cr alloys with high-copper silver amalgam using Mansfeld formulas

ABSTRACT In the restoration of lost or damaged dental pieces, different alloys are frequently used, leaving the mouth exposed to electrical currents that circulate through saliva and dental fluids. In the present work, electrochemical methods are used to determine the corrosion rate of galvanic pairs of a high copper silver amalgam with Co-Cr dental alloys in artificial saliva. It is observed that when the difference in corrosion potentials of dissimilar alloys are small (less than 100 mVecs), Evans diagrams do not give good results, so the Mansfeld correction formulas must be used. Thus, it is found that the most resistant to corrosion is the pair formed between the amalgam and the bulk Co-Cr alloy (PG1,3) and that the corrosion products released in greater quantity to the electrolyte are those that contain ions of Co, Cr, Ag, Sr and Cu.

高銅型アマルガムと可視光線重合型コンポジットレジンの圧縮試験時の AE 特性について

Differences in environmental strength of high-copper amalgams and photo-cured composite resins for posterior after storage in deionized water at 37 degrees C for 1 year were evaluated by examining compressive strength and acoustic emission (AE) characteristics. The results were as follows: Microfailure in amalgams and composite resins was detected from the onset of stress and their microfailures toward catastrophic failure occurred at 70 to 90% of their ultimate strength. One-year compressive strength for amalgam decreased to 80 to 98% of its 24-hour compressive strength and that for composite resin to 65 to 75%.

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.

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 Magnetic Resonance Applications on Dental Amalgam Phase Changes

Aim: The aim of this study was to examine the potential for low- versus high-field strength magnetic resonance applications to effect phase changes in high-copper dental amalgam as detected by X-ray diffraction (XRD) analysis. Materials and Methods: Disk-shaped samples (5 x 1 mm2) of amalgam filling were prepared (n = 90) and were thermocycled for 1000 cycles. The samples were then divided into three groups that were exposed to a 0.2 tesla or a 1.5 tesla magnetic field, or received no magnetic field exposure as a control. The samples were subsequently examined by XRD for phase determination 1, 7, and 30 days later. Results: The relationships between the gama, gama1, and eta phases, as well as the mercury peak intensities, were statistically analyzed using analysis of variance and the Kruskal Wallis test. No statistically significant differences were observed (p > 0.05). There were also no significant time-dependent differences observed between the gama, gama1, and eta phases, or in the mercury peak intensities, of the groups, according to the Friedman test (p > 0.05). Conclusion: The results of this study indicate that exposure to a magnetic field via magnetic resonance imaging does not affect the structure of dental amalgam. Keywords: Dental amalgam, magnetic resonance imaging, x-ray diffraction.

Orthodontic bonding to high-copper amalgam with different adhesive cements

Objective: The aim of this study was to compare the shear bond strengths of metal brackets bonded by four different adhesive cements to high-copper amalgam surfaces. Materials and Methods: A commonly used dental amalgam (nongamma 2, lathe-cut, high-copper alloy) (Cavex Avalloy, Cavex) was triturated according to the manufacturers' directions, and then condensed into a cylindrical (diameter: 8 mm, depth: 2 mm) undercut cavity prepared in auto polymerized acrylic resin. Exposed surfaces of 100 specimens were polished with 400, 600, 800, and 1200 grit paper and cleaned for 10 min under running tap water, air-dried, sandblasted for 3 s with 50-micron aluminum oxide abrasive, and coated with alloy primer (Alloy PrimerTM, Kuraray). Lower incisors metal brackets were bonded to prepared surfaces with an orthodontic composite Transbond XT (3M) (control) and four adhesive cements: C and B Metabond (Parkell), Panavia F 2.0 (Kuraray), Resinomer (Bisco), and Bis Cem (Bisco). After 24 h, all samples were tested for shear bond strength with the universal test machine. The data were calculated as MPa and statistically analyzed. Results: Statistically bond strengths of Panavia F 2.0 and C and B Metabond were higher than the bond strengths of Bis Cem and Resinomer (P 0.05). Conclusion: Bonding the brackets to sand blasted and alloy primer coated amalgam surfaces can be achieved by traditional orthodontic composites (Transbond XT). Panavia F 2.0 and C and B Metabond adhesive cements may improve bonding to high-copper amalgam.

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

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.

Shear bond strength, failure modes, and confocal microscopy of bonded amalgam restorations

This study evaluated the shear bond strength, failure modes, and confocal microscopy of two different amalgam alloy restorations lined with five adhesive systems. Two regular-set high-copper dental amalgam alloys, Amalcap Plus and Valiant Ph.D, and five commercially available adhesive systems were selected. One hundred and twenty freshly-extracted human third molars were used for the study. The results were statistically evaluated using two-factor analysis of variance (ANOVA). The shear bond strength (SBS) of amalgam to dentin was significantly affected by both the adhesive (p<0.0001) and amalgam alloy (p<0.0002). Regarding mode of failure (MF), among samples restored with Valiant Ph.D, 31 of 50 exhibited adhesive failure, and 19 displayed mixed failure. Laser optical microscopy (OM) of the bonded interface revealed the presence of a good hybrid layer was evident in all experimental groups. Higher bond strengths were measured for four of the five adhesives when used in combination with the spherical alloy.