dental materials 25 ( 2 0 0 9 ) 1096–1103 available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/dema The influence of the pure metal components of four different casting alloys on the electrochemical properties of the alloys Süleyman H. Tuna a,∗ , Nuran Özc ¸ic ¸ek Pekmez b , Filiz Keyf c , Fulya Canlı b a Department of Prosthodontics, Faculty of Dentistry, Suleyman Demirel University, Isparta, Turkey b Department of Chemistry, Faculty of Science, Hacettepe University, Ankara, Turkey c Department of Prosthodontics, Faculty of Dentistry, Hacettepe University, Ankara, Turkey article info Article history: Received 6 May 2008 Received in revised form 28 December 2008 Accepted 10 February 2009 Keywords: Noble alloys Base alloys Pure metals Electrochemical properties Corrosion Ion release Potentiodynamic polarization test abstract Objectives. The aim of this study was to investigate the influence of the pure metal compo- nents of the four different casting alloys on the corrosion behaviors of these alloys tested. Methods. Potentiodynamic polarization tests were carried out on four different types of cast- ing alloys and their pure metals at 37 ◦ C in an artificial saliva solution. The ions released from the alloys into the solutions during the polarization test were also determined quantitatively using inductively coupled plasma-mass spectrometry (ICP-MS). Results. Ni–Cr (M1) and Co–Cr (M2) alloys had a more homogenous structure than palladium based (M3) and gold based (M4) alloys in terms of the pitting potentials of the casting alloys and those of the pure metals composing the alloys. The total ion concentration released from M3 and M4 was less than from M1 and M2. This may be because M3 and M4 alloys contained noble metals. It was also found that the noble metals in the M3 and M4 samples decreased the current density in the anodic branch of the potentiodynamic polarization curves. In other words, noble metals contributed positively to dental materials. Significance. Corrosion resistance of the casting alloys can be affected by the pure metals they are composed of. Au and Pd based noble alloys dissolved less than Ni–Cr and Co–Cr based alloys. © 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. 1. Introduction Metals have been used as substitute materials for missing tooth tissues for thousands of years [1]. Using pure metals including gold solely for restorations, such as crowns and bridges, results in lack of resistance. Thus, alloys produced by mixing certain proportions of metals are necessary to obtain better physical qualities, biocompatibility and corro- sion resistance [2]. The major factors affecting alloy selection are economics, physical properties, casting technique, bio- compatibility and corrosion [3]. The corrosion of the metallic ∗ Corresponding author at: Suleyman Demirel Üniversitesi, Dis ¸ Hekimli ˘ gi Fakültesi, Isparta, Turkey. Tel.: +90 246 2113273; fax: +90 246 2370607. E-mail address: shakan@dishek.sdu.edu.tr (S.H. Tuna). materials in the oral cavity results in the deterioration of restorations, both mechanically and esthetically. More importantly, corrosion products may have adverse local and systemic effects on biological structures [4–9]. The amount of metal ions released depends on the nature and strength of the metal–oxide bond, structure, role of alloying element, composition and thickness of oxide films [10]. Gold alloys are used as a prosthesis material. Pd alloys may be preferred as an alternative to gold alloys when econom- ically compared but the corrosion resistance of Pd alloys is lower than that of Au alloys [2]. Today Ni alloys are often used 0109-5641/$ – see front matter © 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2009.02.013