How to fabricate a new crown that fits an existing RPD
... without forcing the patient to surrender the partial.
by Nelson Gendusa, DDS
When a tooth abutting a partial denture requires crowning, the dentist traditionally picks up the prosthesis in a full-arch transfer impression and sends it to the laboratory. This allows the technician to use the clasps as a guide when creating the crown contour. For most patients, going dentureless (even for a few days) is unpleasant. Without the prosthesis, mastication may be difficult. If the RPD includes anterior teeth, the patient may spend the period between appointments hiding from the world in mortified seclusion. The following technique uses a Blu Mousse Super-Fast index to register the clasp-tooth-relationship. This allows the technician or dentist to create an accurate template of the clasp. As a result, the patient never has to surrender the prosthesis. Incidentally, we didn’t dream up this technique ourselves. It was contributed by Dr. Allen L. Weiner (Medfield, MA) who also sent the clinical photos.
How to make a clasp/tooth index using Blu-Mousse® Super fast material.
1. Prepare the tooth for a crown as usual and take the working impression using whatever technique and materials you prefer.
2. Insert the RPD in the mouth and assure that it is properly positioned.
3. Inject Blu-Mousse Super-Fast over the preparation. Continue expressing material the until the clasps and occlusal rests are completely covered. Because Blu-Mousse has the fluffy consistency of whipped-cream, it will not flow. Therefore, there is no need to use a confining tray.
4. After 30 seconds later remove the RPD with the Blu-Mousse blob attached. (Notice the impression of the preparation.)
5. Using a blade, carefully trim away the Blu-Mousse until the outer surfaces of the clasp are exposed then return to patient after temporization procedure is complete.