EVALUATION OF CORROSION RESISTANCE OF GOLD-PALLADIUM,SILVER- PALLADIUM, NICKEL-CHROMIUM AND NICKELCHROMIUM-TITANIUM DENTAL ALLOYS IN SYNTHETIC SALIVA

摘要

Dental casting alloys have played a major role in the restorative process for almost 75 years.rnGold-based alloys were used almost exclusively, but because of their high cost they began tornbe replaced by alternative base metals-alloys.rnIn this work, the corrosion resistance of dental alloys of gold-palladium, silver-palladium,rnnickel-chromium and nickel-chromium-titanium in synthetic saliva was evaluated usingrntechniques such as potentials corrosion measurements, anodic polarisation curves, time versusrncurrent curves, impedance measurements, and superficial characterisation technical usingrnscanning electron microscopy and EDS analyses. The results of this study revealed that thernsilver-palladium and nickel-chromium alloys demonstrate good corrosion resistance, but, notrntoo high as the gold-palladium corrosion resistance.rnOn the other hand, the titanium additions in the nickel-chromium alloy increase the corrosionrnsusceptibility of this alloy, in special to localised corrosion. Localised corrosion occurred atrnlower potentials in the titanium containing alloys in both conditions investigation, afterrncasting and as rolled. Scanning electron microscopy and EDS analyses show that micrornstructural heterogeneity introduced by the titanium addition were probably responsible for thernslightly lower localised corrosion resistance exhibited by this alloy.