Removable Partial Dentures with cast metal frameworks are probably one of the oldest forms of dentistry. Originally, the frameworks were made out of wrought (hammered) silver. One of the most famous American dentists was Paul Revere who was a silversmith when he wasn’t fighting redcoats.
This type of partial denture offers numerous advantages. The frameworks are cast to fit the teeth. Since they sit on the teeth, as well as being attached to them, they are extremely stable and retentive. The teeth have been altered slightly beforehand in order that the partial denture can rest upon them without interfering with the way the patient bites the teeth together.
The metal framework does not contact the gums. Thus, as the gums resorb, this type of partial does not sink with them and rarely requires relines. Because the teeth are altered by the dentist beforehand, there are fewer limitations in the placement of clasps, and they are less likely to be seen than the wrought wire clasps of the treatment partial. Modern frameworks are cast from an extremely strong alloy called chrome cobalt which can be cast very thin and are much less likely to break than the all plastic variety. They are also much less noticeable to the tongue.
The largest single advantage that cast metal framework partial dentures have is that sore spots are almost never an issue since neither the framework, nor the plastic extensions contact the soft oral tissues with any force! Patients who exhibit the symptoms of TMJ, or who are known bruxers are much better off with cast metal partials than with flexible framework partials.