Chapter 3. Direct Retainers – Clasp Assemblies

The component of a removable partial denture that engages the abutment teeth to provide retention and resist deleterious forces is referred to as a direct retainer.

Direct retainers are broadly classified into two main groups as intracoronal (within the crown) and extracoronal (outside the crown) retainers, depending on whether they are located within or outside the contours of the clinical crown.

Clasps, which are designed based on the principle of a metal’s resistance to deformation, are the most commonly used type of extracoronal direct retainers.

Clasps are classified in various ways: according to fabrication types—cast clasps, wrought wire clasps, and combination clasp (retentive arm is made from wrought wire); and according to approaching type—occlusally approaching (circumferential clasps) and gingivally approaching (bar-type clasps).