Wednesday, August 15, 2012

THE Twin Clasp Technique

Waxed Up Crown
Cast Clasp Replica
Having to send a patient’s partial denture to the laboratory while a crown is being fabricated to fit within the existing partial has always been a major inconvenience and disappointment to patients. Many years ago we introduced the Twin Clasp Technique to eliminate this frustrating problem. Over time this technique has proven to be quite successful. The next time a patient complains about giving up their partial denture, we encourage you to give it a try. Here is the technique:

1. Prior to tooth preparation be sure to observe the seating of the partial. Success of this technique is dependent upon a positive and accurate seat of the partial after the tooth is prepared.

2. Prepare the tooth and retract the tissue.

3. Inject heavy-bodied polyether or one-step polyvinyl around only the prepared tooth, making sure the entire margin is captured.

4. Fully seat the partial into its proper position ensuring the clasp around the prepared tooth is imbedded into the impression material. Do not allow the clasp to be totally covered - wipe off any material to expose the exterior of the clasp. The object is to register the tooth surface of the clasp, rest and minor connector. Covering the entire clasp will render this technique ineffective.

5. Allow the material to set under the clasp without occlusal contact.

6. Remove the partial and clasp impression from the mouth. The small impression will most likely be removed with the partial. Separate the impression from the partial without altering it in anyway.

7. Perform your normal C&B impression procedure without the partial in place.

8. Capture a study model impression with the partial in place.

9. Send us the clasp impression (in an old ROE crown box or baggy so it will not be lost), regular C&B impression, bite, opposing model, study model, and work authorization indicating the Twin Clasp Technique has been used.

10. At the laboratory we use the twin clasp impression to wax and cast a clasp assembly that mimics the existing partial. The new crown is fabricated to fit within the duplicate clasp.

An alternative approach, albeit inconvenient to the patient, is to send the partial to us so we may record the clasp location for you. This process requires two laboratory days.