Clasp Categories: Suprabulge and Infrabulge
Posted on 11/30/2011
We will begin now to outline various clasp designs utilized as retainers and part of the elements of the "clasp assembly". The design of clasps can be broadly broken down into two distinct categories:
1. Suprabulge
2. Infrabulge
Suprabulge refers to clasps that original from the occlusal direction (at or above the height of contour) angling towards the gingiva. Usually, the suprabulge clasp originates from a rest, a guide plate or a minor connector. The clasp will contact the tooth at an available undercut.
Examples of suprabulge clasps are:
1. Circumferential clasp
2. Embrasure Clasp (aka butterfly clasp)
3. Ring Clasp
4. Half-and-Half Clasp
5. Reverse Action (Hairpin) Clasp
6. Extended Arm Clasp
The infrabulge clasp refers to clasp originating from the gingival direction (typically from the denture base) and contacting the tooth at an available undercut.
Examples of the infrabulge clasp are:
1. I Bar
2. Y Bar
3. T Bar
It should be noted that above terminology is based off of 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. Many clasp designs have alternative names that refer to the same design. There is really no correct or incorrect naming convention so long as both the doctor and lab technician understand the design. Diagrams are often helpful to avoid misunderstandings.
1. Suprabulge
2. Infrabulge
Suprabulge refers to clasps that original from the occlusal direction (at or above the height of contour) angling towards the gingiva. Usually, the suprabulge clasp originates from a rest, a guide plate or a minor connector. The clasp will contact the tooth at an available undercut.
Examples of suprabulge clasps are:
1. Circumferential clasp
2. Embrasure Clasp (aka butterfly clasp)
3. Ring Clasp
4. Half-and-Half Clasp
5. Reverse Action (Hairpin) Clasp
6. Extended Arm Clasp
The infrabulge clasp refers to clasp originating from the gingival direction (typically from the denture base) and contacting the tooth at an available undercut.
Examples of the infrabulge clasp are:
1. I Bar
2. Y Bar
3. T Bar
It should be noted that above terminology is based off of 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. Many clasp designs have alternative names that refer to the same design. There is really no correct or incorrect naming convention so long as both the doctor and lab technician understand the design. Diagrams are often helpful to avoid misunderstandings.
