Bite registration and mounting casts

[Faux]

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I was practicing using some PVS material on my typodont for bite registration and using that to mount casts.


Every-time i mount them and the stone sets, i remove the registration and theres always a gap in occlusion. Why is that? Do I need to raise the pin before i start putting mounting stone to adjust for the bite registration thickness?

 

[free99]

This was a problem I had in preclinic too. Bite registration should only be used when you can't accurately hand articulate the casts. If you do need to use pvs bite registration, trim it so that there is no bulk or excess on the edges. Wax rims in edentulous areas with notches help to lock everything together, too.

 

[Faux]

This was a problem I had in preclinic too. Bite registration should only be used when you can't accurately hand articulate the casts. If you do need to use pvs bite registration, trim it so that there is no bulk or excess on the edges. Wax rims in edentulous areas with notches help to lock everything together, too.

how do you know if you trimmed enough before having to redo it again? and why is it different in clinic than pre-clinic?

 

[CDT13]

Trim it down so that all you have left are just the very cusp tips.


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[THS]

Definitely trim the PVS. It's a much higher "resolution" material than the alginate used to for the casts you're mounting. So the cusp tips will be sharper and the grooves will be deeper in the PVS than they are on the cast, so the teeth on the cast cannot fully seat into the PVS unless it is thoroughly trimmed.

I like to use Aluwax, I find that it has low enough detail that casts can fully seat into the bite record without any trimming.

And when hand articulation isn't possible, such as a partially edentulous patient with only first premolar occlusion, I will place a "log" of fast setting putty (such as Genie Putty) along the edentulous ridge and have them close. Then you not only have a good inter-arch record you can use to mount, but you can also shove a perio probe through the putty at to measure the restorative space.

As for mounting, I would make sure you mount one cast at a time, keep the casts fully articulated with rubber bands, and take into account any properties of the stone you are working with. Plaster tends to expand a little more than mounting stone, so keep the articulator closed with rubber bands while the stone is setting as well.