The Applied Basic Research On Surface Finishing And Coloring For Cast Titanium Denture Frameworks

With advances in dental titanium casting technique and the significant increase of application of cast titanium restorations in prosthodontics, the study on the techniques of surface treatment of titanium castings have become ever important in resent years. In order to improve the methods of surface treatment of titanium castings frameworks efficiently, the chemical polishing, electrochemical polishing and anodization of titanium castings were studied in this paper, which will enhance the qualities and esthetics of titanium dentures.Part 1: The chemical polishing of titanium castings1. The study on technique of chemical polishing of the titanium castings and the surface properties of titanium castings polished chemically.To investigate the effect of chemically polishing times on the capability and performance of chemically polished titanium castings. The of casting titanium testpieces were immersed in the solution mixed by hydrofluoric acid and nitric acid in the ratio of 1 to 7 in volume for different immersing times. The meltages, the surface roughness, lightness, microhardness and metallographical structures of surface reacted layers were examined. The results showed that the meltages and lightness were increased and the surface roughness and the microhardness were decreased when the immersing time increased. The thickness of the surface reacted layers was becoming thinner while the immersing time increased. After immersed in the chemical polishing bath, structures surface reacted layers of the samples were dissolved away, and the surface microhardness was close to that of inner matrix. Meanwhile the surface roughness was decrease to 60% of the non-immersed testpieces, and the lightness of the chemically polished samples was improved significantly. Although the prolonging the immersing time, the surface roughnesses decreased more largely, the meltages were increased more largely as well, which resulted in impaired the fitness of titanium denture framework. So considering the application in clinic, and according to metallographical structures of surface of the chemically polishing casting testpieces, the best and suitable immersing time is 120s, during which the accuracy could be maintained. The chemical polishing bath did not...