[Comparison of investment expansion methods aspect of porosity]

Currently, the use of non-precious metal alloys in fixed prosthetic restorations has warranted review of the work done sofar using precious metal alloys. One of the parameters exhibiting the success of castings done using non-precious metal alloys is porosity, which is evaluated through such methods as rod forms, waxing heat, to investing and other castability methods. The porosity ratios of cats similarly done employing different investment expansion methods have been evaluated. While there is no statistical difference due to different methods, the hygroscopic expansion method noted successful results.