Is it true?

[prestige.dental]

is it a true statement that PVS impression full arch cast is more accurate than virtual cast on screen made by 50k trios scanner

 

[CoolHandLuke]

depends on the mouth. does not depend on the impression system.

a poorly prepared very wet mouth when scanned presents an error factor for the stitching process.

likewise the absence of retraction cord.

a poorly taken impression with pulls everywhere also presents an error factor.

what IOS does more than anything is improve CONSISTENCY instead of accuracy.

i.e. the scans will be error free more times than pvs. granted there will be some cases that present problems to scan. this is a test of how good the dentist is, not how accurate the machine can be. if you are constantly restoring mesial margins 5-8mm below gumline, its going to be difficult for any system - digital or no - to capture correctly.

so it depends on the mouth.

 

[Sevan P]

Open tray is the only way one of my docs does his prettau style bridges. I would think with the way Digital is going it would be better and more accurate, but not a lot of people have the balls to attempt it.

 

[prestige.dental]

what is the reason ZZ has nothing to do with IOS.
coz lot of work flows are through trios /omnicam

 

[CoolHandLuke]

what is the reason ZZ has nothing to do with IOS.
coz lot of work flows are through trios /omnicam

the same reason Wacom does not also make a Photoshop program to compete with photoshop; that wouldn't be good business.

to maintain open architecture (makes all kinds of cases able to be manufactured) and tight focus on quality of the product.

ZZ make several mills and scanners and sell them all seperately because they know not everyone can buy both and maybe several people already have one or the other. the scanner and mill are items that have been around the manufacturing world for a long time now. IOS has not. ZZ might get into IOS but that does mean getting even more invested in equipment manufacturing for a negligible market.

 

[grantoz]

i work with zz and do many cases that are sirona and 3 shape scans you just need the stl software for both.Its a fact of life, zz are also doing a lot of development in this area watch this space.

 

[Yourgoes]

Accuracy wise, both systems have pros and cons. The one major con of IOS is crossarch distortion.

Look at what most people are using full arch IOS data for... mostly clear aligners that are flexible (aka forgiving) to inaccuracies around cross arch deviations.

This is something I've suffered personally with. Sometimes it would work, sometimes it wouldn't... no knowing until if fit....... or didn't .

As Luke said, the issue is with the stitching algorithms. In any one single region, the accuracy is very good on high end IOS (around 9um I believe on Trios3),so great for quadrant dentistry. IOS has no bubbles/pulls/tears and doesn't face the compounding inaccuracies that come from going from taking PVS impressions to pouring in stone to scanning the model. So there are inherent advantages in the simplicity of the IOS workflow (besides speed/efficiency).

BUT, IOS is technique sensitive and issues like excessive saliva, soft tissue management and/or scan path strategy can corrupt the fidelity of your larger files. As the span becomes longer, cross arch accuracy starts to suffer...

PVS still wins in the full arch category despite its inherent short comings (based on my experiences). That being said, the more divergent the angles between two or more implants, the more likely even your PVS impression will not be perfectly accurate. Perfectly parallel artifacts in an open tray is where PVS impressions excel (again based on my experiences).

3shape presented workflows in Chicago using IOS for full arch, like cast partials... We'll see... I went from believer to skeptic... so they have to win me back.

I've been playing with hybrid files using the best of both worlds, works really well....but quite time consuming.

 

[rkm rdt]

Perhaps the solution involves the use of a cbct scan.

I know that tissue mapping has been shown on TSC.

 

[prestige.dental]

Accuracy wise, both systems have pros and cons. The one major con of IOS is crossarch distortion.

Look at what most people are using full arch IOS data for... mostly clear aligners that are flexible (aka forgiving) to inaccuracies around cross arch deviations.

This is something I've suffered personally with. Sometimes it would work, sometimes it wouldn't... no knowing until if fit....... or didn't .

As Luke said, the issue is with the stitching algorithms. In any one single region, the accuracy is very good on high end IOS (around 9um I believe on Trios3),so great for quadrant dentistry. IOS has no bubbles/pulls/tears and doesn't face the compounding inaccuracies that come from going from taking PVS impressions to pouring in stone to scanning the model. So there are inherent advantages in the simplicity of the IOS workflow (besides speed/efficiency).

BUT, IOS is technique sensitive and issues like excessive saliva, soft tissue management and/or scan path strategy can corrupt the fidelity of your larger files. As the span becomes longer, cross arch accuracy starts to suffer...

PVS still wins in the full arch category despite its inherent short comings (based on my experiences). That being said, the more divergent the angles between two or more implants, the more likely even your PVS impression will not be perfectly accurate. Perfectly parallel artifacts in an open tray is where PVS impressions excel (again based on my experiences).

3shape presented workflows in Chicago using IOS for full arch, like cast partials... We'll see... I went from believer to skeptic... so they have to win me back.

I've been playing with hybrid files using the best of both worlds, works really well....but quite time consuming.

Well said

I noticed that glide well uses 3shape scanners for every thing except for bars. They use imetric for bars.

What special about imetric

 

[zero_zero]

Well said

I noticed that glide well uses 3shape scanners for every thing except for bars. They use imetric for bars.

What special about imetric

Imetric is one of the most accurate scanners out there...

Sent from my SM-G900W8 using Tapatalk

 

[rkm rdt]

Imetric is one of the most accurate scanners out there...

Sent from my SM-G900W8 using Tapatalk

And the door must be big enough for the pt's head.

 

[lcmlabforum]

This is in the FWIW department here.
Went to Straumann open house at the expanded milling facilities in Arlington Texas and shown impressive
set up there.
What was interesting was even with all the scan accuracy, etc from a cast submitted, they have
a special room that has a sort of coordinate measuring machine to physically measure the cast.
The reason I was given was because they see errors in the casts often enough, that they
will compare the scanned imaged with known dimensions for the implant parts and that station
allows for some sort of adjustments before milling their full arch frameworks in metal.
So take that for what is is worth - maybe the analog casts will always have error, and
need digital to correct, or scanning alone without comparing with a know library, is not
accurate enough for fabricate a full arch prosthesis.
And the specialist I spoke to said for now, 3Shape has about the most accurate outcome
in the market from what they can see.
Then I went to the Bullard Memorial lecture at Baylor (Annual prosthodontic lecture) and
the speaker from Harvard (Dr. German Galluci) believes in the iTero more than the 3Shape.
He routinely use the intra-oral scans for his full arch rehab cases, but was careful to
qualify his statement/opinion that he also segments his full arch cases into multiple
fixed units and not a single full arch prosthesis.
Hope that helps.
LCM