Half and Half Clasp
Posted on 12/07/2011
As noted in yesterday's blog, there are specific situations where the typical circumferential clasp is contraindicated due to the inclination of the abutment. The ring clasp was an example of a modified circumferential clasp for inclined molars.
When a pre-molar is inclined lingually and there is a lingual undercut adjacent to edentulous space, it is difficult to use a standard circumferential clasp. The "half and half" clasp was designed to address this specific situation. Here are the elements of the half and half clasp design:
1. Guide Plate
2. Buccal circumferential arm originating from the guide plate
3. Lingual circumferential arm originating from a minor connector
4. One or two occlusal rest seats
The advantages of the half and half clasp are that it provides for excellent support of the premolar. The disadvantage is that it covers a great deal of tooth structure which can lean to caries.
Here is a picture of a half and half clasp
*Picture and portions of the text adapted from An Atlas of Removable Partial denture Design by Dr. Russell J. Stratton and Dr. Frank J. Wiebelt published by Quintessence Publishing Co., Inc. in 1988. Page. 61. Additional resource: www.medkaau.com/album/download.php?image_id=434.
When a pre-molar is inclined lingually and there is a lingual undercut adjacent to edentulous space, it is difficult to use a standard circumferential clasp. The "half and half" clasp was designed to address this specific situation. Here are the elements of the half and half clasp design:
1. Guide Plate
2. Buccal circumferential arm originating from the guide plate
3. Lingual circumferential arm originating from a minor connector
4. One or two occlusal rest seats
The advantages of the half and half clasp are that it provides for excellent support of the premolar. The disadvantage is that it covers a great deal of tooth structure which can lean to caries.
Here is a picture of a half and half clasp
*Picture and portions of the text adapted from An Atlas of Removable Partial denture Design by Dr. Russell J. Stratton and Dr. Frank J. Wiebelt published by Quintessence Publishing Co., Inc. in 1988. Page. 61. Additional resource: www.medkaau.com/album/download.php?image_id=434.
