Introduction Recently, titanium and its alloys have been widely used in restorative surgery as dental and orthopedic prostheses, pacemakers, heart valves, etc. The success of titanium materials in these applications is due to their excellent mechanical properties, good resistance to corrosion in biological fluids and very low toxicity for the organism. However, its high melting temperature (1700 C) and extreme difficulty in casting hinder the use of pure titanium in prosthetic dentistry. The high chemical reactivity of Ti towards oxygen at elevated temperatures rendered the casting operation very difficult and necessitated special melting procedures, mold material, and equipment to prevent metal contamination. Since the reactivity of molten Ti towards oxygen is a direct function of temperature, casts problems could be alleviated if useful Ti-alloys, with a significantly lower casting temperature (1100 C) were available. Chern and his group found that adding Cu or Co at < 30 weight % lowered the melting point of Ti, and maintained superior passive properties. Al-Jabab developed six different new low melting ternary alloys, xTi-yAg- zCu (x=50 or 60, y=40 to 10, z=10 to 30), and found that 60TiyAgzCu alloys had excellent castability, 1 2 0 3 4 0 3 5 Corrosion behavior of new titanium alloy for dental implant applications Abdullah M. Al-Mayouf*, PhD Amal A. Al-Swayih , MSc Norah A Al-Mobarak , PhD Abed S. Al-Jabab , PhD F F G This study presents the corrosion behavior of a low melting point Titanium alloy, which contains 30% weight copper and 10% weight silver (TCA). The study was carried out in naturally aerated artificial saliva using different methods: open-circuit potential, linear polarization, potentiodynamic scan and electrochemical impedance spectroscopy. In addition, the behavior of pure Titanium (Ti) and Ti6Al4V (TVA) were also studied for comparison. Titanium and its alloys exhibited spontaneous and immediate passivity as a result of oxide film formation. The interpretation of electrochemical impedance spectroscopy (EIS) results was based upon a two-layer model of the oxide film, which consists of a thin barrier-type inner layer and a porous outer layer. The potentiodynamic curves had an extremely low passivation current density and an excellent corrosion resistance. The long-term results indicated that the film oxide was very stable up to 15 days. It was concluded from this study that TCA alloy has a good corrosion resistance comparable to that of TAV alloy, but less than that of Ti corrosion resistance. chemical and acceptable mechanical properties that gave them a great potential for future use as dental alloys. Among them, 60Ti10Ag30Cu showed a very good electrochemical behavior and cation release better than pure Ti, that makes it very interesting to investigate. This paper presents an electrochemical study regarding the behavior of Ti30Cu10Ag, Ti and Ti6Al4V in artificial saliva under simulated physiological conditions. Electrochemical measurements were made at 37 C using a cell containing naturally aerated artificial saliva as electrolyte with the composition shown Table 1. The working electrode was pure Titanium (Ti), Ti6Al4V (TAV) alloy or Ti30Cu10Ag (TCA) alloy, and the composition, melting point and supplier of these electrodes are summarized in Table 2. The reference electrode is a saturated calomel electrode (SCE), and all potentials are referred to this electrode. A large-area platinum electrode was used as the counter electrode. The specimen was connected to a copper wire and then imbedded into an epoxy resin. Before measurements were taken, electrode was polished with emery paper, then washed thoroughly with doubly distilled water. Finally the electrodes were cleaned ultrasonically for 10 minutes in ethanol. Then it is immersed in the test solution and polarized cathodically at 1000 mV relative to open circuit potential for 5 minutes. All electrochemical measurements were carried out on a GILL AC* (ACM Instruments, Cumbria England, Experimental 0 6 Received 2 September 2001; Revised 16 January 2002; Accepted 26 January 2002 * Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh,11451, Saudi Arabia Girls' College of Education at Riyadh, Scientific Departments, P.O. Box 27104, Riyadh,11417, Saudi Arabia College of Dentistry, Department of Restorative Dental Science, King Saud University, P.O. Box 90573, Riyadh,11632, Saudi Arabia F G Saudi Dental Journal, Vol. 14, No. 3, September - December 2002 Address reprint requests to: Dr. Abdullah M. Al-Mayouf E-mail: amayouf@ksu.edu.sa 118