In vitro' tensile tests and corrosion analyses of a rapid manufacture-produced cobalt-chromium alloy compared to cast cobalt-chromium alloys (original) (raw)

Dedication: This research project is dedicated to all who have supported the development of dentaltechnology in Ghana. il ABSTRACT ln this age of technological advancement in dentistry, the traditional method of manufacturing removable partial denture frameworks could be supplemented with rapid manufactured (RM) denture frameworks when the technology is fully developed. The RM technology has the potential to provide a better corrosion resistance, accuracy, high strength and density, reduce time and labour and eventually provide low cost restorations compared to the traditional 'lost wax technique' which is considered laborious and time consuming. However, fundamental independent tests including tensile and corrosion tests must be completed to move current researches from a proof of concept stage towards rn vivo pertormance studies if patients' safety is to be guaranteed. At the time of the presenl in vitro study, no published literature was found to have made a comparison between cast and RM dental alloys to investigate their tensile and corrosion properties. Test specimens and procedures used in this project were in accordance with BS EN ISO 22674:2006 for dental metallic restorations' During the corrosion test, electrobrightened and highly polished samples of an RM cobalt-chromium alloy were compared with those manufactured with a cast cobalt-chromium alloy. An RM as-received heat and non-heat treated cobaltchromium samples were also compared. The samples were immersed in artificial saliva (0.1M saline lactic acid) with pH 2.3+0.1 at a temperature of 37+0.1'C for 1 , 4, 7, 14, 21, 28, 35 and 42 days. The analytes were verif ied qualitatively for cobalt, chromium and molybdenum and quantitatively for released metal ions using an atomic absorption spectrometer. Results from the tests showed that the RM alloy had better ductility, modulus of elasticity, resilience, toughness and corrosion resistant properties. ln addition, surprisingly, electrobrightened samples released fewer metal ions than polished samples. RM as-received heattreated specimens released more metal ions than the non-heat treated as-received samples. The pedormance of the RM alloy has been largely linked to the manufacturing technique. Futther studies are recommended.