Research on investing methods and mold cooling methods of the self-made investment for pure titanium castings / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the influence of different investing methods and mold cooling methods on pure titanium castings invested in the self-made investment, and to provide theoretic base for the development for the investment.</p><p><b>METHODS</b>The influence of investing methods (one-step investing method and two-step investing method) on castability and crown fit of titanium castings were investigated, and the influence of cooling methods on reaction layers, mechanical properties and crown fit of titanium castings were investigated.</p><p><b>RESULTS</b>Both the investing methods exhibited good castability, but only the titanium full crowns by one-step investing method showed clinically acceptable fit. Although the quenching group showed thinner reaction layer(100 microm), lower strength and similar elongation rate, the titanium castings by bench cooling showed clinically acceptable full crown fit with 115 microm thick reaction layer as cast.</p><p><b>CONCLUSION</b>The one-step investing method and the bench cooling are recommended for the self-made investment.</p>

Effects of different polishing methods on surface roughness of pure titanium castings / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of different polishing methods on surface roughness of pure titanium castings.</p><p><b>METHODS</b>35 pure titanium castings were devided into 7 groups, used for control, mechanic polishing and electrolytic polishing, respectively. Surface roughness (Ra value) of each castings was measured with a profilometer. Surface microstructure was studied by a scaning electron microscopy, and the weight loss (Wt%) and height loss on unit area (H) before and after polishing was calculated.</p><p><b>RESULTS</b>The effects of mechanic polishing with aluminium oxide or chromium oxide were acceptable. Surface smoothness was improved with acid treatment followed by electrolytic polishing.</p><p><b>CONCLUSION</b>Aluminium oxide and chromium oxide can be used in mechanic polishing of pure titanium castings, and improvement should be made on electrolytic polishing methods.</p>