Argen Milled Abutments not Matching .stl

[lcsmith0000]

Has anyone been having any issues of late with Argen custom abutments not matching the design files? We design using split files. We have had a run in the last month where all of our abutments are coming back either too tall(mostly too tall by .5mm )or too short and even canted to the side. It's driving me crazy and of course the company line is its me and not their milling. We have verified using the correct scan bodies and the order forms properly filled in. We placed the abutments we received in the scanner and lined them up with the design file and they do not match. We are at a loss. OEM abuts come back fine from Nobel and Straumann, just the Argen abuts that have gone off the rails.

 

[lcsmith0000]

Here's an example. Argen milled this one 4 times and was different every time. The last two tries are shown here. The first five frames show the design, then a merge of received abut with the design, the abut alone and then the abut shown from the facial to show height difference. The last frame shows the one that was canted. The Argen technical rep and I lined up the top as the crown fit the top but would not go down on the model with the abutment placed.
The result shows the bottom below the margin is out of line. All of the ones we have had problems with have been distorted in the portion below the margin being either too long in most cases or too short in another.

 

[doug]

What did Argen say about the problem?

 

[KingGhidorah]

Not with abutments, but with gold yes. The problem just started recently, last gold case we sent to them came back completely different dimensions. I scanned it in and compared to the STL sent over and it was nowhere near close. The margins and internals were good, but everything else was distorted. We sent it back so they could redo it and it came back the same way a second time.

 

[lcsmith0000]

Not with abutments, but with gold yes. The problem just started recently, last gold case we sent to them came back completely different dimensions. I scanned it in and compared to the STL sent over and it was nowhere near close. The margins and internals were good, but everything else was distorted. We sent it back so they could redo it and it came back the same way a second time.

We have had a few gold crowns come back undermilled too on occasion, but usually come back fine when resubmitted. These abutments have been driving me nuts. Had a 5unit bridge over 4 abutments that rocked on the abuts that was the beginning of our noticing the abutments were not coming back as designed. I resubmitted the same files and when they came back, the bridge fit. We had 6 different cases that the abutments all came back too tall after that and subsequent re-submissions were no better.

 

[lcsmith0000]

What did Argen say about the problem?

They never have given me a solid answer. Everyone to whom I talked were totally at a loss for a cause. I suggested it was probably in the calibration of the mills but eventually they came back and said there were 4 different mills used in these cases. They downloaded the latest DME, but that didn't help as the case in the above screen grabs was done in both the old DME and the new.
As far as the cases, most were scanned with NT trading scanbodies but one of the cases was an I/O scan using ELOS scan bodies.

 

[Cleo]

I bet they have a larger bur placed in the wrong order in the machine. I have had that problem with my own mill and that is what it looks like. The machine thinks it is milling with a 1mm bur but a 2mm has been placed in by accident. You get a wierd overmill. The looks can be a little different depending on where in the process the burs get mixed up.

 

[tuyere]

If you have a decent scanner, scan their unmodified milled parts and use QC comparative software like GOM suite to compare their milled parts to the original STL you provided them. That will give you very detailed and unambiguous information about where the error lies, and how it's manifesting. The anatomy of the error is often clear enough with this technique to pinpoint where the issue is occurring in the process; i.e., a part that's evenly larger or smaller than the original mesh indicates a scaling issue, with a printed model or from a bad shrink factor for zirconia milling; too much material removed on the sides of a cavity but accuracy on the 'roof/floor' of the cavity (blanking on the anatomical terms today) indicates spindle runout, with spindle/collet/tool issues making the tool wobble slightly and cut a wider effective diameter than it should be; etc etc.