Pitting of Teeth When Shell-Blasting

[drm313mac]

An issue we are having here, and am wondering if we are alone in this:

When removing stone after processing, using the Trinco @ 60 psi (natural walnut shells),Heraeus Kulzer Mondial-i teeth are losing their outer layer. of course, we are trying not to directly hit the teeth, but sometimes this is unavoidable. They now appear dull, in some cases like decalcified teeth.

We are not having this issue with 2- or 3-layered teeth, nor with 5-layered Unidesa Odident teeth.

Reducing pressure results in more time needed to remove stone.

Any suggestions? Is this something we are doing wrong, or is this an issue with Mondial-I teeth (a weaker 4th layer),or is this an issue with many of the better teeth?

 

[AJEL]

Dave have you tried a blend of Walnut &Pecan ground shells (I use 4 bar)? I use this for Vinyl cases. Unfortunately I cannot read the label & forgot where I obtained them, A auto supply house in WI 100# has lasted me several years and I still have quite a bit to go.

 

[drm313mac]

4-bar is just over 58 psi, so that should not be the issue, as we are running 60 psi.

No, the only thing I have ever used is walnut shells. I will look into this.

Has anyone ever had bad batches of teeth? Too soft? I am awaiting a reply from my Heraeus Kulzer rep, Chris Ove, on this issue.

IF I do have to change teeth, your recommendations for a higher-end line that is not too expensive, has great anatomy and esthetics, and is ultra-durable, AND (preferably) acrylic? I have been getting the Mondial-i from Nowak @ $52 / arch. Unidesa Odident are ~$65 @ Uhler, Merz Artegral are about the same, and I refuse to do business w/ Dentsply. Mondials are more difficult to get balanced occlusion, but I like their anatomy.

 

[TomZ]

How often do you replace the blasting media?
Powdered plaster and stone concentrations mixed with your shells can increase the abrasive properties of the shells.

 

[Tayebdental]

Or the denture teeth material used is made of soft acrylic!. Why not soak the denture in plaster removing agent and ultrasonic for 10 minutes.

This is happening because the shell pits are harder than the tooth material and worsen with higher psi.

 

[drm313mac]

Tom,

With that in mind, I did an experiment. I took a denture made with the lower cost Yamahachi teeth, as well as another with Unidesa Ortolux Top teeth, and blasted for 5 seconds @ 90 degrees from ~ 1 cm, and no damage whatsoever. This same test destroyed the Mondial-i teeth.

To answer your question, we replaced about a month ago. The handpiece clogged with stone particles, and so we had no choice but to replace everything.

Also, to an extent this is the fault of my lab tech. In dental school, I was taught NEVER to directly blast the teeth, else the glaze may be removed. Some teeth were destroyed, while others not, and so I must assume perhaps either the batch was bad, or the glaze was damaged when grinding the teeth prior to mounting.

What is your recommendation for teeth? That is, great esthetics and anatomy, mid- to higher-grade teeth, VERY durable, in this general price range? Is there such a beast? Uhler sells the Unidesa Odident 5-layer @ $65/arch, Hi-Tec the Merz Artegral for the same. Unidesa only ships teeth once per month, so if I need something NOW and not in stock; too bad. Hi-Tec is the only dealer for Merz. Other options? Am I going to be stuck with either a softer Mondial-i vs Dentsply?
And I prefer acrylic teeth, as they bond better w/o a binder than composite teeth, and to date we have only done one porcelain case.

 

[drm313mac]

Or the denture teeth material used is made of soft acrylic!. Why not soak the denture in plaster removing agent and ultrasonic for 10 minutes.

This is happening because the shell pits are harder than the tooth material and worsen with higher psi.

I have never tried that. We will soak in something + ultrasonic, especially the higher-end dentures.

AND I discovered today the tech who invested this case forgot to coat the teeth prior to investing.

 

[lcmlabforum]

I don't think that Ivoclar is that expensive, esp. if you do not need the Chromoscop line. The Blueline is DCL and very
reasonably priced. I usually use the Postaris because I like the Chromoscop and they cost the most. I really think
they are very durable without being brittle.
I would not use the 4 layer or PE for the same reason you have problem with (softer - not DCL).
LCM