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Tribological properties of nickel-based dental alloys DOI:10.15199/28.2018.5.5

  1. INTRODUCTION Metal alloys are still one of the most important biomaterial groups dedicated to dental reconstruction [1, 2]. The use of metal alloys in dental prosthetics is associated with their good mechanical properties, biocompatibility, high corrosion resistance and good casting properties. The most popular dental alloys are alloys based on nickel, titanium and cobalt [1, 3÷9], of which it is performed permanent dentures-bridges, crowns and implants veneered with polymer, composite or ceramic [9÷16]. To make molds for dental castings, the technology of lost wax is mainly used, while the mold pouring process is carried out using the centrifugal casting method [17, 18]. This technique of manufacturing dental prostheses allows to obtain very high surface smoothness and excellent dimensional-shape accuracy. Moulding compounds used to mold are characterized by very high resistance to high temperature and low thermal expansion. In order to reproduce the dental reconstructions shape, casting waxes with small shrinkage and high stiffness are used, which prevents accidental distortions of modelled shapes and guarantees small dimensional deviations of the castings. Moulds for dental casts are performed of flowable self-hardening masses in metal and silicon rings. These rings protect the moulds from thermal and mechanical cracks that may arise during the annealing and cooling of moulds and by pouring under centrifugal pressure [19÷21]. In addition to the technological aspects of moulding and pouring processes, the quality of prosthetic castings depends on the properties of dental alloys. The technological and physical properties of alloys determine exploitation capabilities of casted prostheses, their dimensional stability and their matching. For these reasons, these alloys should have a sufficiently high hardness, abrasion resistance and strength, as well as good castability, low solidification shrinkage, low tendency to gas adso[...]

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