Centrifugally casting metal dental restorations - using preheated lost wax mould hardened at high temp

摘要

In the prodn. of dental restorations by centrifugally casting a Cr-Co and/or Ni alloy into a mould formed by mounting a wax pattern on a support pin in a metal ring lined with a cushioning or elastic material, casting moulding material around the pattern, drying the mould, melting out the wax and hardening the mould, the improvement is that the mould is hardened at 700-950 degrees C for 20-150 mins. and the mould temp. is 100-500 degrees C before centrifugal casting. Hardening of the mould in the above temp. range ensures that combustible and volatile cpds. in the cushioning material and moulding material are driven off. Use of a hot mould reduces the formation of cracks by thermal shock. The castings produced have accurate dimensions and good surface finish.