Retrofitting a Crown to an Existing Partial Denture

I first posted this “article” on Dentaltown back in 2007.  A friend just reminded me about it, so I thought I’d re-post it here.

We all know what a pain this can be – fitting a new crown to an existing partial denture.  I learned this technique from the Parkell advertorial “magazine” they send out.  I changed it up a bit.  I’ve been using it for years, and it works very well in my hands.  Unfortunately, I didn’t take any photos of the clinical aspect of making the special impression for the clasp duplication.  But, I’ll try to describe…

Prep the tooth.

Make the normal impression for the crown.

THEN… Squirt a blob of Blu Mousse over the prepped tooth and seat the partial denture.  Quickly, with your finger, wipe away the excess Blu Mousse such that you can see the occlusal rest and clasps shining through the Blu Mousse.  Let the BM set.

Remove the partial (BM comes with it).  Carefully trim away any excess BM with a bard parker blade and tease the impression out from under the RPD.  Set this BM impression of the clasps and rest aside, and send your case to the lab to pour the models.  Have them return the models and this is where the photos below pick up

Cut an index groove in the edentulous area of the model.

Seat your BM clasp impression on the die. (Lingual view.)

I have colored in the clasp and rest areas with a pen for easier viewing

Facial view.

I blocked out the saw cut area with some paper towel.

Then I used Luxatemp and flowed a blob over the index previously cut in the edentulous area as our “base.”  Then flowed it up the distal guide plane, onto the occlusal rest, and into the clasp areas.

Note that it is a bit “over-built,” to strengthen the “clasps.”  Luxatemp is a bit brittle.  We’re primarily interested in the internal aspect of the clasps and rest for the purposes of building up the crown contours.

Luxatemp “clasp assembly” with Blu-Mousse removed and reseated on model.

I sent these photos to the lab to make sure they understood what to do with this silly piece of plastic.

The index groove in the edentulous area makes precise orientation and placement of the “jig” easy.

Send case back to lab.

Final result.  I didn’t touch the crown.  I didn’t touch the clasps.

This is how it came back from the lab.

Awesome!

Not a bad fit, eh?

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