discrepency of io scan vs physical model/desktop scan

[Slimboyphat]

Merging 2 scans together: 1 scan is from physical model scanned with medit t710 desktop. other is full arch IO scan of adjusted 4-13 temps by doc with 3shape.

I'm seeing discrepencies on 6-11 anterior margin alignment. doc didn't do full preps so the unprepped linguals of the anterior and untouched molars is what I use for exocad alignment.

It almost seems the anterior 6 being stretched to far buccally(.3mm) when comparing lingual margins and buccal gingiva. if I was to resize io temp scan to fit more accurately over anteriors preps then ruggae and posterior molars don't match well.

One thing that pops into mind is I don't believe the die stone/water was measured so I'm going to pour up new model and compare. But what's the general consensus on io scans vs physical model/desktop scan accuracy? is there often distortion on full arch io scan with a new 3shape scanner?

 

[Sda36]

Merging 2 scans together: 1 scan is from physical model scanned with medit t710 desktop. other is full arch IO scan of adjusted 4-13 temps by doc with 3shape.

I'm seeing discrepencies on 6-11 anterior margin alignment. doc didn't do full preps so the unprepped linguals of the anterior and untouched molars is what I use for exocad alignment.

It almost seems the anterior 6 being stretched to far buccally(.3mm) when comparing lingual margins and buccal gingiva. if I was to resize io temp scan to fit more accurately over anteriors preps then ruggae and posterior molars don't match well.

One thing that pops into mind is I don't believe the die stone/water was measured so I'm going to pour up new model and compare. But what's the general consensus on io scans vs physical model/desktop scan accuracy? is there often distortion on full arch io scan with a new 3shape scanner?

Is it possible the impression wasn't timed and removed to early? This stretches the impression and then it fully sets in the condition leaving you with longer yet narrower preps. Nothing fits correctly. Another nightmare is if the impression is compressed,cyo much seating pressure in the mouth and it springs back after removal. Have experienced both.

 

[rkm rdt]

Since when is a photocopy of a photocopy of a photocopy more accurate than the original?

 

[Car 54]

@Slimboyphat I really don't think the water and die stone ratios could affect things that much, unless it was so extreme. I haven't measured that since they invented rope. I did it once or twice, saw and felt what it looked like in the mixing bowl, and have done it that way for years....wait for it, wait for it, the purists that will hammer me for not doing it every time according to the IFU

I also agree with @Sda36 for it to be that distorted, would have to have been how the impression was taken in the mouth.

Here is a post regarding discrepancies. I did find out from my account on Monday that the bridge we remade to the impression (scanned impression pour up in 3Shape),fit perfectly, no adjustments at all.

Primescan

One of my Doctors started using Primescan. She wants to send me the cases but the only way she knows is through the Portal. She sends a lot of cases every month so If I have to purchase the Sofware license I will, but before going that route, is there and easily and cheaper solution to get those...

dentallabnetwork.com

 

[Contraluz]

I have yet to see perfectly matching scans...

 

[CoolHandLuke]

It almost seems the anterior 6 being stretched to far buccally(.3mm)

this is due to the method of scan being used.

if you don't follow the recommended procedure for scanning, you end up with misaligned data and wrong proportions

naturally the method describes the accuracy

this lady describes the rocking of anterior for 3 shape

this man describes the same motion for medit

if the scan user simply swept along the facial without the anterior rocking, then its no wonder the data was poorly aligned.

 

[mmbh]

There Definitely needs to be more scan training for the offices. Majority of our digital bites are off some.

 

[rkm rdt]

FYI. Training the dental office to scan is a huge money maker. I always say “while the other lab rep is sitting in the waiting room, I’m standing chairside “.