Categories of Retention
Posted on 11/18/2011
RPD Framework retention can be broadly categorized into three types:
1. Phenomenal Retention: retention provided by adhesion, cohesion or other natural phenomena.
2. Frictional Retention: retention derived from contact surfaces such as guide plates to guide planes.
3. Mechanical retention: retention provided by clasps (direct retainers).
Phenomenal Retention
In order to understand the phenomenal retention, it is appropriate that we define the terms:
Adhesion refers to the retention from dissimilar molecules.
Cohesion refers to the retention created from similar molecules.
Both adhesion and cohesion (including interfacial surface retention) are phenomena that are exhibited when appliances are placed in the mouth and due to the naturally wet environment from the mucosa. Both adhesion and cohesion are directly proportional to the area covered and as such a palatal plate will create more retention than an A-P bar.
*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 and the website: Wikipedia http://en.wikipedia.org/wiki/Surface_tension
1. Phenomenal Retention: retention provided by adhesion, cohesion or other natural phenomena.
2. Frictional Retention: retention derived from contact surfaces such as guide plates to guide planes.
3. Mechanical retention: retention provided by clasps (direct retainers).
Phenomenal Retention
In order to understand the phenomenal retention, it is appropriate that we define the terms:
Adhesion refers to the retention from dissimilar molecules.
Cohesion refers to the retention created from similar molecules.
Both adhesion and cohesion (including interfacial surface retention) are phenomena that are exhibited when appliances are placed in the mouth and due to the naturally wet environment from the mucosa. Both adhesion and cohesion are directly proportional to the area covered and as such a palatal plate will create more retention than an A-P bar.
*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 and the website: Wikipedia http://en.wikipedia.org/wiki/Surface_tension
RPD Framework, retention, adhesion, cohesion, frictional forces, mechanical retention, dental lab tech, dentist
- Wikipedia Surface Tension : http://en.wikipedia.org/wiki/Surface_tension
