How to Make a Partial Index of a Clasp Assembly

by technical advisor Tony Megale, CDT

Watch O’Brien technical advisor and CDT Tony Megale give step by step instructions on making an index of a partial clasp assembly.

Step by step

Patients with partials are often reluctant to give up their partials for any significant amount of time. Partial clasp indexes are a way to replicate the clasping arm of their partial for use in crown fabrication. They’re easy to make and they give the lab the information they need without the patient giving up their teeth. In this video, Tony will walk through the steps necessary to quickly and easily create a partial index for your patient’s case.

Transcript

Hi, this is Tony with O’Brien Dental Lab.

What I want to talk to you about today Is making a partial index. It’s for the patient who has anterior teeth, doesn’t want to give their partial while the fabrication of the crown is going on.

So, what we have to do on our end is make an index of the buckle and lingual and occlusal rest and guide plane areas so that we have all the information we need to fabricate the crown for you.

If the index is made after the preparation is complete, this technique can be used for conventional type clasping arms and occlusal rest. We do not recommend this for precision type attachments because of the technical aspect of these attachments in relationship with the partial and the crown.

First thing you want to do is, after you do the preparation is, place the partial back in the patient’s mouth making sure that you have proper clearance on the occlusal, buckle, and lingual of the preparation for the fabrication of the crown.

The next thing you want to do is you want to remove the partial from the patient’s mouth after verifying that you have the proper clearance. Then, take a standard polyvinyl impression of the preparation. Once you’ve taken your standard impression of the preparation area, then what we want to do is get things cleaned up. And then prepare to take the impression of the partial over the preparation, making the actual index. So the next step is we’re going to take the polyvinyl material we’re going to inject it over the preparation what we’re going to do.

We’re going to build a cone up that is about the same size of the original tooth or slightly larger. Then you want to take the partial place it back into the patient’s mouth and have the patient lightly load it.
The reason you want to do this is so that you know the positioning of the partial is correct with the occlusion and the patient is closing properly.

Once the polyvinyl material sets up, then remove the partial from the patient’s mouth. What’s going to happen is this index or the polyvinyl is going to come out with the partial.
At that point, take a surgical blade and place it on the buccal clasp and slide that surgical blade along that buckle clasp removing any material that has overlaid that buckle clasp. Then move to the lingual bracing arm. Take the surgical blade, do the same thing, repeat that step. Remove anything that’s covered that bracing arm on the outside surface.

Then, look at your occlusal rest. If your occlusal will rest isn’t clearly visible, take that surgical blade and lightly or carefully remove that material so it’s clearly visible. At that point, you can take the index and pop it out of the partial. Be careful not to do any damage to the underside of this index, because when we get this to the laboratory, we need to be able to place it back on the preparation exactly as you have taken the impression from the mouth. When sending the index to the lab, please put it in the container and clearly mark it as a partial index. And also, please add that to your Rx, that you are sending a partial index.

I hope this has been helpful. In the future, if you have any questions about this technique or anything I can do for you, please don’t hesitate to call me at the laboratory. Call Tony.

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