Intraoral scanner crown margins

[HawkeyeDDS]

I am a dentist and we have been using the 3shape Trios for about 3 mo. now. I have been using the same little C & B lab for ~10 years. They are excellent. With PVS, the margins of our crowns were fantastic. I am always able to send a PVS impression capturing at least 0.5mm below the margin, usually 1.0mm. I would have to say that after a few months of scanning, I think the margins are just acceptable, not excellent. Is this a problem with my lab or is scanning really not as good as advertised? Thanks you all for your help in advance.

 

[TheLabGuy]

I am a dentist and we have been using the 3shape Trios for about 3 mo. now. I have been using the same little C & B lab for ~10 years. They are excellent. With PVS, the margins of our crowns were fantastic. I am always able to send a PVS impression capturing at least 0.5mm below the margin, usually 1.0mm. I would have to say that after a few months of scanning, I think the margins are just acceptable, not excellent. Is this a problem with my lab or is scanning really not as good as advertised? Thanks you all for your help in advance.

Do you mark your own margins?

 

[Markyboy]

The short answer.
Scanning really not as good as advertised. TRUE
PVS margins are cheaper and more accurate TRUE

 

[TheLabGuy]

The short answer.
Scanning really not as good as advertised. TRUE
PVS margins are cheaper and more accurate TRUE

I don't agree

 

[Markyboy]

I don't agree

Np I just want to give the man an honest opinion. Seems like he is coming to that conclusion on his own.
I just feel bad that he is questioning his lab after 10 years of doing good work. Scanning technology works
best on a stone model at the moment. Too many variables in the mouth.
Again just my opinion.

 

[Affinity]

Does it work and is it excellent are two different things..

Look at a stone die from PVS and a printed model of the same case, its not hard to tell which is more defined.

Take a look at a 3d mesh from a scanned case and compare to the same mesh from a lab-scanned stone die. Its not even close.
Easier or more accurate, pick one.

 

[mmbh]

I agree with labguy. We have had a great experience with scans vs impressions. Our Digital case margins are spot on. There are variables with scanning itself. If the time is taken for a clean prep area and good scan, its great. We have some trios accounts that are careful when they scan and prep nice clear margins, they don't mark their margins but they are nice and clear. Some of our other trios accounts are not careful when they scan buy they mark their own margins. We haven't had problems with margins either way. I will say this, the omnicam scans we get seem better than the trios scans we get. Not sure if its better data or just how the software cleans it up.

 

[mmbh]

To be honest, we don't touch the margins out of the mill except for maybe thinning down a bit. We pretty much leave them as is and just use printed models for occlusion and contacts. Same when we mill wax for emax.

 

[npdynamite]

There could be multiple factors here. I personally don't believe either is necessarily "better" I think they both can have their places that they excel and if someone wants to use one or the other exclusively they probably can at this point.

That said, I find that how intra oral scanners are sold and advertised as the biggest problem. If you can't take a good PVS impression you probably can't take a good intra oral impression. If you are having great results from PVS but not from intra oral, there is probably some learning to be done on the intra oral scanning side.

I have seen doctors who take great impressions get told by sales reps that they no longer need to pack chord with a 3d scanner and next thing I know all of their impressions have tissue covering margins when they used to have great physical impressions.

I also have seen labs that receive digital scans choose to print the model, scan the model and work from that. The reason they would do this is to ensure that the crown and the die had perfect margins to each other, though it could result in a lower degree of accuracy in the mouth.

 

[TheLabGuy]

Np I just want to give the man an honest opinion. Seems like he is coming to that conclusion on his own.
I just feel bad that he is questioning his lab after 10 years of doing good work. Scanning technology works
best on a stone model at the moment. Too many variables in the mouth.
Again just my opinion.

That's fair, and to be honest I wasn't trying to get into a analog vs. digital plssing match, hence why I left it at I disagree. However, from my standpoint, most of what I do is digital and thank goodness. I remember spending days trying to get implant abutments parallel, now it's one click. All the hours of sitting there hand waxing, done in mere minutes now. Is it cheaper, not at first...those machines will put your dlck in the dirt but they pay for themselves pretty quickly and then you're seeing a profit margin worth a damn. But hey, I have smarter friends than me agree with me and just as smart friends that don't...so I can see both sides and drink a cold one with ya at the end of the day.

 

[HawkeyeDDS]

I am not marking the margins. I never have with PVS.

I use a soft tissue laser and/or a two cord technique. Preps are always bone dry. I can clearly see the margin 360 without question and I know it would be a slam dunk with PVS.

I will check to see if my lab is scanning the printed models. If so, that would be a problem.

 

[mmbh]

I am not marking the margins. I never have with PVS.

I use a soft tissue laser and/or a two cord technique. Preps are always bone dry. I can clearly see the margin 360 without question and I know it would be a slam dunk with PVS.

I will check to see if my lab is scanning the printed models. If so, that would be a problem.

Sounds good to me.

 

[TheLabGuy]

I am not marking the margins. I never have with PVS.

I use a soft tissue laser and/or a two cord technique. Preps are always bone dry. I can clearly see the margin 360 without question and I know it would be a slam dunk with PVS.

I will check to see if my lab is scanning the printed models. If so, that would be a problem.

Scanning is all about isolation and retraction. If you can see the margin and the margin is the issue here, take two seconds and mark it. Makes no sense to me why Docs don't, you literally just prepped it. However, if they are printing and making a restoration from that printed die/model, that's a big no-no. Always make your restorations from the scan data.

 

[doug]

Yoour lab shouldn't need to scan the printed models The Workflow is you scan, they import scan into their software. Design crown and produce. Print model to tweek contacts and occlusion, if needed.

 

[Pronto]

If your margins are so visible then it should be easy for you to mark them. Do that and then compare the results.

When I have a stone die that I can't ditch, I send them back to the Dr to ditch so they can see how bad they missed the impression. 90% of them come back ditched wrong. I finish the crown to their "margins" and send it. If it doesn't go then the remake is on them. They ditched it not us. If it fits that margin we did our job.
We don't get many scans but the ones we do suck. The margins are too deep and very hard to read. Even if they were stone, it would be a challenge. Dr. error not the scanner's fault. Like others said, if you can't make a good prep and take a good regular impression, then a digital impression will just as useless.

 

[sirmorty]

Calibration of your scanner would be a good place to start.

 

[sirmorty]

I love digital and the workflow but I really question how accurate the 3d printed models are.

Doesn't matter if it's a Carbon Printer or an Asiga or Sprint Ray or some low budget Dental Printer .

I mean if they claim it's so accurate and you can't scan the 3d printed model and design a crown and have it fit. How exactly is it accurate representation of the mouth.

I know you can have the same with stone models. The 2nd pour won't be the same as the first.

I have learned to trust the scans and keep my mill and scanner calibrated.
Still have issues from time to time but I'm doing my best to make sure it's not because of something I should have been doing.

I just listened to a webinar about 3d Printing models and how with each stage from scanning to milling and Printing about how many microns you can be off and it had my head spinning.

 

[FASTFNGR]

I am a dentist and we have been using the 3shape Trios for about 3 mo. now. I have been using the same little C & B lab for ~10 years. They are excellent. With PVS, the margins of our crowns were fantastic. I am always able to send a PVS impression capturing at least 0.5mm below the margin, usually 1.0mm. I would have to say that after a few months of scanning, I think the margins are just acceptable, not excellent. Is this a problem with my lab or is scanning really not as good as advertised? Thanks you all for your help in advance.

Scanner are only good for above gum line margins. According to statistics most crowns preps need packing cords and sometimes double cords. They are not the miracle that the big tech companies pushing them to be. PVS is still the better and cheaper way to capture margins in my opinion. The only question is: do you mark your margins? If you do then the problem is on your side. If your lab does then the question is:
is he getting a good scan from you?

 

[rkm rdt]

I am a dentist and we have been using the 3shape Trios for about 3 mo. now. I have been using the same little C & B lab for ~10 years. They are excellent. With PVS, the margins of our crowns were fantastic. I am always able to send a PVS impression capturing at least 0.5mm below the margin, usually 1.0mm. I would have to say that after a few months of scanning, I think the margins are just acceptable, not excellent. Is this a problem with my lab or is scanning really not as good as advertised? Thanks you all for your help in advance.

Hey Hawkeye, come join the Trios Study Club on Facebook. We’re there to solve your problems and renew your relationship with your lab.

 

[JohnWilson]

People that say digital is not comparable to analog are stating this out ignorance or cursory knowledge. Yes this is my opinion....

While we still are using gypsum in my lab we are getting closer to being gypsum free. We are 80% digital today, and with not just simple single unit restorations but full arch comprehensive treatment with some of the finest clicitians on the planet.

If the OP is really asking for real world expectations and is not trolling I will answer you. Every single restoration is able to be manufactured with digital technology with not just "acceptable" results but what I consider "exceptional" results. The most important part is we ELIMINATE about 10 variables over analog paths on even the most simple restorations.

Did this happen overnight? Of course not. Did I acquire the knowledge on how to exploit technology AKA gain wisdom? Hell yeah I did, and with that my lab, my clients and our patients have benefited.

If you really want to have exceptional clinical results you really have to understand machining and match you canvas to the machine you intend to use. Anything less you are going to have mixed results at best and you will then look to point blame RATHER than gain the wisdom you need to improve.

If you want to learn more ask the tough questions, be willing to self reflect on your OWN ability. Do not ask the broad brush reactive questions that every single person can answer with OPINION rather than facts. Evaluate every case, draw conclusions on similarities and be willing to see the differences without blaming the tool.

As cheesy as this line is KNOWLEDGE IS POWER.