A study of the flexibility of wrought wire clasps

Abstract

T he 18-gauge platinum-gold-palladium (PGP) wrought wire clasp arm is often used as a direct retainer for distal-extension removable partial dentures instead of a cast chromium-cobalt clasp arm, when the retentive undercut is on the mesial-buccal part of the abutment tooth. The wrought wire clasp arm can flex in any direction so that stresses caused by movement of the removable partial denture are dissipated. This helps to protect the abutment tooth from harmful forces. The 18-gauge PGP clasp wire has a fusing temperature sufficiently high that it can be safely cast against by gold and some chromium-cobalt alloys and soldered without changing its physical properties. An 18-gauge clasp wire is thick enough to resist breakage and allow tapering for additional flexibility.’ However, clinical observations of some wrought wire clasps on removable partial dentures constructed at the School of Dentistry, University of Washington, have indicated that these clasps may be less flexible than expected. Several reports in the dental literature have documented similar findings.