clasp assembly
The combination of a retentive clasp arm, reciprocal arm, and rest that engages a natural tooth to retain and stabilise a removable partial denture.
Full Definition
A clasp assembly is the primary retentive mechanism of a cast removable partial denture, consisting of at least one retentive arm that engages an undercut on the abutment tooth, a reciprocal arm that opposes lateral forces, and an occlusal or cingulum rest that prevents vertical displacement. The design of the clasp assembly—whether circumferential (Aker's), bar (RPI, RPA), or combination—is determined during the surveying and design phase. In laboratory prescriptions, the technician must follow the prescribed clasp type and location exactly. Misidentification of clasp types in documentation can lead to incorrect fabrication and subsequent retention failure. Editors should be familiar with named clasp designs to avoid conflating design terminology.
Usage
Usage note: The word 'clasp' alone is informal; laboratory reports should specify the full clasp assembly design type (e.g., 'circumferential clasp assembly on tooth 14').
In Context
- "An RPI clasp assembly was specified on the mesially tilted lower molar to minimise torquing forces." — Laboratory design prescription
- "The retentive arm of the clasp assembly was adjusted to engage the 0.25 mm undercut." — Fitting report