Open-cast technique for metal molds used in constructing facial prostheses

A new (open-cast) technique for the fabrication of metal molds has been presented. Its simplicity relies on the use of gummed asbestos tape as a boxing agent for the investment models. This technique has the following advantages over the "lost wax" technique: (1) it requires approximately one-quarter the amount of investment material, (2) it eliminates the use of investing rings or wax patterns, (3) it eliminates the boil-out step for the wax pattern and reduces the total time required to make a metal mold, and (4) it affords a high degree of visibility. The only disadvantage is that the larger prostheses require large amounts of Lino-type metal which is very heavy. However, this has not restricted the use of this technique since these metals cast well and can be easily placed in large ovens. This technique, because of its advantages, offers more efficient use of laboratory time and personnel.