[Influence of the sprue casting design on the surface porosity of the silver-palladium dental alloys].

The purpose of this work is to investigate and find out the best "design" of the casting sprues on the area and the number of the surface porosity when we cast silver-palladium dental alloys for metalloacrylics fixed partial dentures. Our observation and research have been done on 216 external surfaces from 72 M.O.D. specimens, which were casted using four different designs of casting sprues and three types of silver-palladium dental alloys (Panag, Pangold and Palliag M.). The evaluation of our findings and statistical analysis have been done. The findings of our study are the following. 1. It has been found that the "alloy" factor doesn't influence the area and the number of the surface porosity we examined, on the contrary it has been found that the "design" factor has great influence on the area and the number of the dental alloys. 2. The use of chill-sets and the securing of sprue button alloy decrease the area and the number of the surface porosity when we cast silver-palladium dental alloys. 3. The straight sprues and the placing of the specimens near the heat-center of the mold created much better conditions for decreasing the number and the area of the surface porosity than when we use the preci-roto system.