A comparison of three techniques for fabricating metal molds

Investigation on the dimensional accuracy and techniques variability of metal molds and refractory casts for the construction of maxillofacial external prostheses have resulted in the following conclusions. 1. A relative comparison of the box-pour, open-cast, and wax-sprue techniques for constructing metal molds for external prostheses showed the open-cast technique to be the most accurate and easiest techniques. 2. The wax-sprue technique was the most complex and consumed maximum time and materials. This technique also offered the greatest possibility for introducing errors and obtaining inconsistent results because of multiple steps. 3. For all techniques the positive metal molds always demonstrated a poorer fit in comparison to the negative metal molds. The positive metal molds were larger castings. 4. Most metal molds were significantly larger than the standard brass die in length and width dimensions. 5. A direct comparison of a theoretic calculation and experimental measurements for dimensional accuracy shows the construction of metal molds to be very dependent on the manipulation of materials and reproducibility of methods.