METALS FOR PARTIAL DENTURE BASES

Partial denture bases are often constructed from metallic materials because of the greater strength and rigidity of metals compared with polymeric substances such as polymethylmeth‐acrylate. The primary choice of metal for this purpose has been gold and gold alloys. More recently other systems such as the stainless steels and cobalt‐chromium alloys have been used. Whilst yellow gold, i.e. alloys containing at least 60% gold, has near‐ideal physical properties, it has one major disadvantage in being very costly. A further criticism, although infrequently raised, is the colour, which some patients find too obtrusive. The cost of the base alloy can be reduced by alloying gold with palladium and silver to produce the so‐called white golds. These materials are some 50% lower in cost than yellow gold, are grey in colour but have rather inferior mechanical properties. This is clearly shown by Table 1.