|dc.description.abstract||In 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 in vivo performance studies if patients' safety is to be guaranteed. At the time of the present 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 cobalt-chromium 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±0.1oC for 1, 4, 7, 14, 21, 28, 35 and 42 days. The analytes were verified 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. In addition, surprisingly, electrobrightened samples released fewer metal ions than polished samples. RM as-received heat-treated specimens released more metal ions than the non-heat treated as-received samples. The performance of the RM alloy has been largely linked to the manufacturing technique. Further studies are recommended.||en_US