Setting reactions in dental amalgam. Part 1. Phases and microstructures between one hour and one week

Determination and Calculations of Mercury Vapor Concentration and Energy Released from Freshly Condensed Dental Amalgams Having Various Copper Percentages within the Alloy

Dental amalgam is an alloy consisting of a mixture of fine metallic powder of silver, tin, zinc, copper, and a trace amount of palladium in combination with about fifty percent elemental mercury that forms a matrix phase. Dental amalgams consisting of a high-copper content are the most common types of alloys currently utilized for the restoration of decayed, broken, and fractured posterior human teeth. The present research objective was primarily to improve the material properties by determining and analyzing the amount of mercury vapor released from dental amalgam received from eight different commercial brands. The mechanical hardness of the alloys was found to increase with an increase in copper content in the amalgam. The effect of copper addition on material aging was also studied. During the release of mercury vapor, the corresponding energies associated with the release of mercury vapor from each sample were determined for each successive measurement. The results indicated that increasing the copper content of the amalgam counters the release of mercury vapor from posterior teeth and improves the hardness properties.

Modeling the annealing and thermal stability of silver dental amalgam

Effect of heat treatment on the structure and thermal properties of silver-copper dental amalgam (Ag-Cu/Hg) was investigated by means of Monte Carlo (MC) simulation. Simulated pair correlation functions in the framework of MC algorithm form the basis for a diverse analysis of the amalgam annealed up to 2893 K. As heat treatment increases, structural properties remain essentially unchanged up to 1093 K, beyond which, the properties are deteriorated. Phase separation in the context of homo-coordination and segregation of Ag-Cu alloy is characterized as the annealing of amalgam alloy is proceeded. Thus, the amalgam alloy could also maintain a microstructural phase and a structural strength around this temperature, consistent with the annealing reported experimentally. These findings provide insights into amalgam industrial technology, setting amalgamation process, Hg release in dental clinics, and basic information appreciated in the dentistry industry and partnership in forensic science. Graphical abstract Thermal stability of the homogeneous amalgam (Ag-Cu/Hg) is studied up to 2893 K where a phase separation and structural alteration is noted above 1093 and Hg phase segregates into a domain different from Ag-Cu alloy domain.

Antibacterial properties of metal and metalloid ions in chronic periodontitis and peri-implantitis therapy

Periodontal diseases like periodontitis and peri-implantitis have been linked with Gram-negative anaerobes. The incorporation of various chemotherapeutic agents, including metal ions, into several materials and devices has been extensively studied against periodontal bacteria, and materials doped with metal ions have been proposed for the treatment of periodontal and peri-implant diseases. The aim of this review is to discuss the effectiveness of materials doped with metal and metalloid ions already used in the treatment of periodontal diseases, as well as the potential use of alternative materials that are currently available for other applications but have been proved to be cytotoxic to the specific periodontal pathogens. The sources of this review included English articles using Google Scholar™, ScienceDirect, Scopus and PubMed. Search terms included the combinations of the descriptors "disease", "ionic species" and "bacterium". Articles that discuss the biocidal properties of materials doped with metal and metalloid ions against the specific periodontal bacteria were included. The articles were independently extracted by two authors using predefined data fields. The evaluation of resources was based on the quality of the content and the relevance to the topic, which was evaluated by the ionic species and the bacteria used in the study, while the final application was not considered as relevant. The present review summarizes the extensive previous and current research efforts concerning the use of metal ions in periodontal diseases therapy, while it points out the challenges and opportunities lying ahead.

Morphology and electrochemical behavior of Ag-Cu nanoparticle-doped amalgams

The aim of this study was to introduce Ag-Cu phase nanopowder as an additive to improve the corrosion behavior of dental amalgams. A novel Ag-Cu nanopowder was synthesized by the precipitation method. An amalgam alloy powder (World-Cap) was added and mixed with 5 wt.% and 10 wt.% of Ag-Cu nanopowders, respectively, to form experimental amalgam alloy powders. The original alloy powder was used as a control. Alloy powders were examined using X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy and electron probe microanalysis. Amalgam disk specimens of metallurgically prepared were tested in 0.9% NaCl solution using electrochemical methods. The changes in the corrosion potential and anodic polarization characteristics were determined. Corrosion potential data were analyzed statistically (n=3, analysis of variance, Tukey's test, p<0.05). The diameters of lamellar structure Ag-Cu nanoparticles were measured to be approximately 30 nm. The composition of the Ag-Cu nanoparticles determined by TEM-energy-dispersive spectroscopy was 56.28 at.% Ag-43.72 at.% Cu. A light-shaded phase was found mixing with dark Cu-Sn reaction particles in the reaction zones of Ag-Cu nanoparticle-doped amalgams. The Ag-Cu nanoparticle-doped amalgams exhibited zero current potentials more positive than the control (p<0.05) and no current peak was observed at -325mV that related to Ag-Hg phase and Cu6Sn5 phase in anodic polarization curves. The results indicated that the corrosion resistance of high-copper single-composition amalgam could be improved by Ag-Cu nanoparticle-doping.

Initial mercury evaporation from experimental Ag–Sn–Cu amalgams containing Pd

This study examined the Hg evaporation during setting from experimental Ag-Sn-Cu alloy powders with and without Pd. Four series of alloy powders were fabricated to examine the effect on the Hg evaporation of the alloy compositions (all percentages in this report are weight percents): Pd (0-1.5), Cu (9.0-14.0), Ag (57.0-63.7), and Sn (24.9-29.5). These variations in composition produced alloy powders with gamma-Ag3Sn to beta-AgSn ratios varying from 0.0 to 23.9. The total amounts of Hg released from 10 min after trituration were measured from cylindrical specimens (4 x 8mm; n = 4 ) at 37 degrees C using a Hg vapor analyzer. The results were compared to those from commercial alloys (one high-Cu and one low-Cu alloy). All amalgams made from alloys containing 1.5% Pd exhibited lower Hg vapor release than any other amalgams, with the exception of the low-Cu amalgam. The results clearly showed that the alloy formulation affected the mercury evaporation behavior during setting of the resultant amalgams. A small addition of Pd to the alloy can produce amalgams with 50-60% less Hg vapor release during setting than a leading commercial high-Cu amalgam, Tytin.

Dental materials: 1996 literature review

This critical review of the published literature on dental materials for the year 1996 has been compiled by the Dental Materials Panel of the UK. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, resin-bonded bridges and ceramo-metallic restorations, ceramics, denture base resins and soft lining materials, impression materials, implants materials, orthodontic materials, biomechanics and image processing, resin composites and casting investment materials and waxes). Three hundred and thirteen articles have been reviewed.