Rest Options for RPD Frameworks
Posted on 10/25/2011
There are three main categories of rest designs for RPD frameworks:
1. Occlusal Rests
2. Cingulum (Lingual) Rests
3. Incisal Rests
1. Occlusal Rests
The occlusal rest is an extension of the minor connector that is designed into an occlusal recess prepared by the doctor. The rest must form an angle of less than 90 degrees with the minor connector. The purpose of the angle is to avoid horizontal stress to the abutment and ensure seating into the prepared recess. Occlusal rests are design on posterior teeth only and typically sit on either the mesial occlusal or distal occlusal surface.
2. Cingulum Rest
The cingulum rest is an extension of the framework that sits on the lingual surface of an anterior tooth - primarily designed for canines, although it is possible to create a cingulum rest on lateral or centrals. A vertical stop is essential, and if not possible to create in the prepared tooth, a restoration such as a crown with a built in rest seat is fabricated.
3. Incisal Rest
The incisal rest is an extension of the RPD framework that sits on the incisal edge to provide support for the framework. Although not nearly as common as occlusal rests or cingulum rests, incisal rests are viable option when cingulum rests are contraindicated. An example is lower anterior teeth where there is insufficient space for a cingulum rest. The major disadvantage of the incisal rest is aesthetics. Additionally, the use of the incisal rest is not possible on the maxillary due to interference with incisal edges of the mandibular anterior teeth.
*This post was 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. Pages 20-23
1. Occlusal Rests
2. Cingulum (Lingual) Rests
3. Incisal Rests
1. Occlusal Rests
The occlusal rest is an extension of the minor connector that is designed into an occlusal recess prepared by the doctor. The rest must form an angle of less than 90 degrees with the minor connector. The purpose of the angle is to avoid horizontal stress to the abutment and ensure seating into the prepared recess. Occlusal rests are design on posterior teeth only and typically sit on either the mesial occlusal or distal occlusal surface.
2. Cingulum Rest
The cingulum rest is an extension of the framework that sits on the lingual surface of an anterior tooth - primarily designed for canines, although it is possible to create a cingulum rest on lateral or centrals. A vertical stop is essential, and if not possible to create in the prepared tooth, a restoration such as a crown with a built in rest seat is fabricated.
3. Incisal Rest
The incisal rest is an extension of the RPD framework that sits on the incisal edge to provide support for the framework. Although not nearly as common as occlusal rests or cingulum rests, incisal rests are viable option when cingulum rests are contraindicated. An example is lower anterior teeth where there is insufficient space for a cingulum rest. The major disadvantage of the incisal rest is aesthetics. Additionally, the use of the incisal rest is not possible on the maxillary due to interference with incisal edges of the mandibular anterior teeth.
*This post was 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. Pages 20-23
