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  • Characterisation of a new dental alloy with high Au content [Elektronski vir]
    Rudolf, Rebeka ...
    The basis for developing a new dental alloy with high Au content is appropriate chemical composition and manufacturing technology. The demands which have to be met when developing a new dental alloy ... are linked with fulfilling the necessary requirements for making the alloy suitable for use inmetal-ceramic restorations. Due to the stress generated by masticatory forces, alloys for dental restorations must have corresponding mechanical properties (yield strength, tensile strength, and elongation), hardness, the coefficient of thermal expansion (CTE), and biocompatibility. Namely dental alloy placed in an oral cavity reacts with the environment and deteriorates. This new Au dental alloy with high Au content is based on the ternary system of Au-Pt-Zn with a nominal composition of 88.5Au-8.7Pt-1.5Zn-0.5In-0.4Ir-0.3Rh. Both the hardness and tensile strength of the as-cast alloy can be significantly improved by proper heat treatment. Strengthening could be attributed to the alloying elements and precipitation of new fine particles during heat treatment, which further block any moving dislocations. The dental alloy was melted and cast in a vacuum-induction melting furnace in Zlatarna Celje. Casting was followed with subsequent thermo-mechanical treatment (procedures of profile and polish milling, thermaltreatment) and cutting-off strips to form a regular shape. The heat treatments of Au alloy samples were carried out in a tube furnace under different temperatures, and over different times. Testing of the new Au dentalalloy included examining the initial cast, and the different heat- treated conditions of the Au alloy. Measurements of hardness were done according to standard 6507-1:1998, and static tensile testing was performed for determining the mechanical properties. The optical properties of Au-dental alloy were investigated by means of spectro-photometric colourimetry. Spectral reflectance data from the mirror-polished flat samples of initial Au dental alloy were collected under the CIE standard illuminant D65. Finally the test of cytotoxicity of new Au based dental alloys using standard in vitro assays for testing the biocompatibility with establishing new, more sensitive, in vitro tests on cell lines was done. According to the results of our research we can conclude that new dental alloy from Zlatarna Celje satisfied all requested standards regarding mechanical properties, hardness and CTE: Rp0.=550 [N/mm2], Rm =610 [N/mm2], A= 9%, 180 HV and CTE (25-600°C) about 14,45*10-6K-1. This new Au dental alloy has a yellow tinge incomparison to conventional Au-Pt-Zn alloys and did not show cytotoxicity when using standard short-term in-vitro assays on an L929 cell.
    Vir: Zbornik referatov [Elektronski vir] = Conference proceedings (Str. 1-12)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2007
    Jezik - angleški
    COBISS.SI-ID - 11649046

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