UCLA abutments are stock parts and are made of a gold/palladium alloy interface with a plastic chimney. They can be used to make traditional screw-retained PFM (porcelain fused to metal) or FCG (full cast gold) crowns as well as custom abutments.
Even though they are stock parts, they are often regarded as custom abutments since they aren’t prosthetically useful until they are customized by the lab.
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Making a Screw Retained Crown
To make a screw retained crown, wax is added directly to the plastic chimney of the UCLA abutment to create the desired crown or coping shape. That waxup, along with the metal base, is invested and cast into a high noble metal alloy. For PFM crowns, the porcelain is then stacked and fired directly to the UCLA abutment.
Wax is applied directly to the plastic chimney and both are invested and cast.
Making Custom Abutments
Making custom abutments with UCLA abutments works the same way except that the waxup will be in an ideal abutment shape that will then be cast and used for a cement retained crown.
UCLA can be used to make custom abutments.
This was the only technique for fabricating custom abutments before CAD/CAM abutments became available. These days we only use this technique when a CAD/CAM abutment is not available.
Engaging and Non-Engaging Styles
UCLA Abutments come in both engaging and non-engaging styles. The engaging style has anti-rotational features at the interface and is used for making screw retained crowns and custom abutments. The non-engaging style has no anti-rotational features at the interface and is only used for making screw retained bridges.