RPA clasp design for distal-extension removable partial dentures.

The RPA design has been discussed as an alternative to the RPI design. With its mesial rest and special retentive arm design, it gives essentially the same kind of tooth release that the RPI clasp provides. In addition, there are some advantages over the RPI design. The circumferential-type retentive arm is easier to grasp for removal of the prosthesis. The clasp is simple in design with few variations among patients and thus can be easily and consistently fabricated by dental laboratories. But most important, the circumferential retentive arm avoids the tissue problems around abutment teeth and allows the RPA clasp to be used in many situations where the RPI clasp is contraindicated.