Clasp Assemblies
Posted on 11/23/2011
As outlined in the previous blog post, there are four elements of clasp assembly. We will now discuss the purpose of each element and explain how they provide for mechanical retention.
1. Rests
The purpose of rests is to prohibit movement of the prosthesis in a gingival direction. This is important as it prevents the framework from placing too much pressure on the gingiva which could lead to gingival resorption.
2. Retentive Arms
The retentive arm combined with the reciprocating element, restrict horizontal movement of the appliance. The retentive arm will typically emerge from the buccal side and restrict movement in that direction. It will utilize the natural or prepared undercuts in the tooth. More discussion of the retentive arm will follow when we discuss various clasp options.
3. Reciprocating or bracing element
The reciprocating or bracing element of the clasp assembly is designed to restrict movement in the horizontal direction - together with the retentive arm. Typically, the bracing arm will restrict horizontal movement in the lingual direction. In addition, the reciprocating element will offset the forces placed by the retentive arm during insertion and removal of the prosthesis.
4. Minor connector/s
Minor connectors are elements which connect the major connector to the various clasp assemblies including the rests, clasps and bracing arms. As such, they provide the necessary attachment to create the retentive assembly.
*Portions of this post were adapted from the book: Atlas of Removable Partial denture Design by Dr. Russell J. Stratton and Dr. Frank J. Wiebelt published by Quintessence Publishing Co., Inc. in 1988.
1. Rests
The purpose of rests is to prohibit movement of the prosthesis in a gingival direction. This is important as it prevents the framework from placing too much pressure on the gingiva which could lead to gingival resorption.
2. Retentive Arms
The retentive arm combined with the reciprocating element, restrict horizontal movement of the appliance. The retentive arm will typically emerge from the buccal side and restrict movement in that direction. It will utilize the natural or prepared undercuts in the tooth. More discussion of the retentive arm will follow when we discuss various clasp options.
3. Reciprocating or bracing element
The reciprocating or bracing element of the clasp assembly is designed to restrict movement in the horizontal direction - together with the retentive arm. Typically, the bracing arm will restrict horizontal movement in the lingual direction. In addition, the reciprocating element will offset the forces placed by the retentive arm during insertion and removal of the prosthesis.
4. Minor connector/s
Minor connectors are elements which connect the major connector to the various clasp assemblies including the rests, clasps and bracing arms. As such, they provide the necessary attachment to create the retentive assembly.
*Portions of this post were adapted from the book: Atlas of Removable Partial denture Design by Dr. Russell J. Stratton and Dr. Frank J. Wiebelt published by Quintessence Publishing Co., Inc. in 1988.
