Need Help 3D Model Print Gold Crown

[DentalFix1234]

Hi, we have been having issues with 3D models and removable die. Hoping that someone out there has experience with the following...

One of our dentists uses an intra-oral scanner. We design the model and outsource for printing. Once the model and removable die return, we wax and cast for a gold restoration (40%). When the dentist tries to seat the crown, it does not seat all the way down, yet it is perfectly seated on the printed model? Has anyone had this experience here? We are thinking that the issue is not using a die spacer. As I understand, when a restoration is milled, (zir, gold etc....) I was informed that a digital die spacer is used, (milling out the inside of the restoration a bit) and my thought is to use a die spacer on the printed die to compensate.

If you have any experience with this scenario, I'd appreciate your input.

Thanks Kindly

 

[CoolHandLuke]

everything needs die spacer

you only need Drill Compensation when Milling, otherwise you can print objects fine without it

but you still need die spacer

 

[ztech]

This has nothing to do with die spacer. If your casting fits the model and not the mouth, then your model is incorrect. You need to either get with them to correct the problem or find another model supplier.
Die spacer compensates for the film thickness of the cement. Most cements need a minimum of 20um of spacer so you should use die spacer when waxing but that isn't causing the crown not to fit the mouth.

 

[DentalFix1234]

everything needs die spacer

you only need Drill Compensation when Milling, otherwise you can print objects fine without it

but you still need die spacer

Thanks CoolHandLuke for your input. Much appreciated and will try using die spacer this time.

 

[DentalFix1234]

This has nothing to do with die spacer. If your casting fits the model and not the mouth, then your model is incorrect. You need to either get with them to correct the problem or find another model supplier.
Die spacer compensates for the film thickness of the cement. Most cements need a minimum of 20um of spacer so you should use die spacer when waxing but that isn't causing the crown not to fit the mouth.

Thanks for your reply ztech! We are using Argen for our printed models, (Carbon). We're trying another provider and waiting for the models to arrive... should be tomorrow. This new provider uses Asiga 3D Printers. It will be interesting to see if there is any difference between the two providers. Thanks again for your help!!

 

[ztech]

Thanks for your reply ztech! We are using Argen for our printed models, (Carbon). We're trying another provider and waiting for the models to arrive... should be tomorrow. This new provider uses Asiga 3D Printers. It will be interesting to see if there is any difference between the two providers. Thanks again for your help!!

That's why I now have my own printers. Argen is wildly variable in quality and precision and I don't tolerate that well.

 

[Tayebdental]

I think it has to do with the printed model, are you able to design the crown on IOS stl scan file from the dentist without model? If so mill or print the wax crown, cast the crown and finish on the printed model coming from milling center to find out the fit on the die

 

[RileyS]

I’ll say it. 3d printing sucks! I have an Asiga, rapidshape from Straumann and Formlabs. I’ve used several outsourcing centers. I’ll take a physical impression and stone model over printing any day all day! (Except for printing Diagnostic waxup designs. Love that)

 

[Toothman19]

I’ll say it. 3d printing sucks! I have an Asiga, rapidshape from Straumann and Formlabs. I’ve used several outsourcing centers. I’ll take a physical impression and stone model over printing any day all day! (Except for printing Diagnostic waxup designs. Love that)

Sorry you are having so many issues with your printing. What have those companies told you the problem was? I can try and help if you like

 

[RileyS]

My issue is the same issue I have with all dental marketing and sales reps. Their products are so effing freaking amazing and life simplifying that you'll have nothing but sunshine days for the rest of your life. That's problem number 1.
The other problem is that doctors believe the reps and still think that we techs are pure magicians that can see things that aren't there. Some times the cases take waaaayyyyy longer to design than they should because margins are invisible or there are so many things to virtually trim off and holes to patch and then the software sometimes says there's something wrong that needs to fixed and gives you tips on which settings to change and those settings are nowhere to be found within the software or the internet! So you spend 20 minutes making little tweaks until you luckily make the right change and the software advances to the next or final step.
My favorite quote from a doctor was made after I requested he mark the margins and he said "I don't know how you can always find the margins cause I'm not exactly sure what to mark."
Then, I have to trust the printer is accurately printing. the formlabs was an absolute failure that I spent months talking with formlabs trying to fix. Never once had a good fit to anything. The asiga and rapid shape are way better but every now and then the milled crowns don't fit to to the model. So do I make the crown fit the model? I make a a few tweaks to the crown sometimes but after close to 20,000 milled crowns of various materials I 100% trust the mills output over the prints.
I really just like to tell the doctor that we made a crown that perfectly fits all aspects of the stone model that had margins trimmed and verified in the impression with microscope rather than say, "Well, gee Wally, I suppose the digital impression could have been off or maybe my printers aren't outputing a good product. And since I know your scanning wand is the most amazing thing ever to have been created it has to be my equipment."

I just like not questioning my work. I still do the digital work but I don't like. Since Cerec I think the industry has just embraced mediocrity and it's not a good thing. I thin there is a lot of mediocrity in digital impressions with most doctors cause they think the technology cures their lack of effort.

 

[Dentalmike]

Hi, we have been having issues with 3D models and removable die. Hoping that someone out there has experience with the following...

One of our dentists uses an intra-oral scanner. We design the model and outsource for printing. Once the model and removable die return, we wax and cast for a gold restoration (40%). When the dentist tries to seat the crown, it does not seat all the way down, yet it is perfectly seated on the printed model? Has anyone had this experience here? We are thinking that the issue is not using a die spacer. As I understand, when a restoration is milled, (zir, gold etc....) I was informed that a digital die spacer is used, (milling out the inside of the restoration a bit) and my thought is to use a die spacer on the printed die to compensate.

If you have any experience with this scenario, I'd appreciate your input.

Thanks Kindly

Are you saying that your hand waxing to a printed model? Wouldn’t suggest that but yes to try spacer if so. If you’re sending to argen for models it may be more worth your time to also order a design in wax so that your able to make external corrections to your preference? And have digital spacer, proximal contacts, hopefully margins that you wouldn’t have to touch.

 

[DentalFix1234]

I think it has to do with the printed model, are you able to design the crown on IOS stl scan file from the dentist without model? If so mill or print the wax crown, cast the crown and finish on the printed model coming from milling center to find out the fit on the die

That's why I now have my own printers. Argen is wildly variable in quality and precision and I don't tolerate that well.

I’ll say it. 3d printing sucks! I have an Asiga, rapidshape from Straumann and Formlabs. I’ve used several outsourcing centers. I’ll take a physical impression and stone model over printing any day all day! (Except for printing Diagnostic waxup designs. Love that

I think it has to do with the printed model, are you able to design the crown on IOS stl scan file from the dentist without model? If so mill or print the wax crown, cast the crown and finish on the printed model coming from milling center to find out the fit on the die

We have an update to share. We received the printed models from our other supplier (Printed on ASIGA). The first supplier we used Argen, (Carbon). When we compared the two models, they were visibly different. The Gold crown that we waxed and cast on the Argen die did not fit the ASIGA die (The crown fit tightly, and the margin was open by 1mm, mostly on the buccal). The ASIGA under the microscope has a noticeably higher resolution (less "elevation-map" like steps) and had smoother margins (again less steps).

Moving forward, we have decided to use die-spacer on the ASIGA model, then wax and cast from here.

The doctor's main complaint was the crown wasn't seating and margins were open all the way around.

 

[DentalFix1234]

My issue is the same issue I have with all dental marketing and sales reps. Their products are so effing freaking amazing and life simplifying that you'll have nothing but sunshine days for the rest of your life. That's problem number 1.
The other problem is that doctors believe the reps and still think that we techs are pure magicians that can see things that aren't there. Some times the cases take waaaayyyyy longer to design than they should because margins are invisible or there are so many things to virtually trim off and holes to patch and then the software sometimes says there's something wrong that needs to fixed and gives you tips on which settings to change and those settings are nowhere to be found within the software or the internet! So you spend 20 minutes making little tweaks until you luckily make the right change and the software advances to the next or final step.
My favorite quote from a doctor was made after I requested he mark the margins and he said "I don't know how you can always find the margins cause I'm not exactly sure what to mark."
Then, I have to trust the printer is accurately printing. the formlabs was an absolute failure that I spent months talking with formlabs trying to fix. Never once had a good fit to anything. The asiga and rapid shape are way better but every now and then the milled crowns don't fit to to the model. So do I make the crown fit the model? I make a a few tweaks to the crown sometimes but after close to 20,000 milled crowns of various materials I 100% trust the mills output over the prints.
I really just like to tell the doctor that we made a crown that perfectly fits all aspects of the stone model that had margins trimmed and verified in the impression with microscope rather than say, "Well, gee Wally, I suppose the digital impression could have been off or maybe my printers aren't outputing a good product. And since I know your scanning wand is the most amazing thing ever to have been created it has to be my equipment."

I just like not questioning my work. I still do the digital work but I don't like. Since Cerec I think the industry has just embraced mediocrity and it's not a good thing. I thin there is a lot of mediocrity in digital impressions with most doctors cause they think the technology cures their lack of effort.

Hi Riley, that's how we feel. Nothing is as accurate as a well taken impression with visibly clear margins. It's frustrating because I've never had any doctors returning cases where fit is the issue (unless the impression was distorted),until I started using the printed models.

It's a new dentist, that I suspect had issues with other labs as well. Their office contacted us over 4 months ago to see if we would make a gold crown and then they never sent us the file until a few weeks ago. I received two cases so far from him, one that didn't "fit" twice, and he ended up sending elsewhere. The second case also didn't fit, were remaking it now... on the ASIGA printed model. Fingers crossed...

 

[Car 54]

I’ll say it. 3d printing sucks! I have an Asiga, rapidshape from Straumann and Formlabs. I’ve used several outsourcing centers. I’ll take a physical impression and stone model over printing any day all day! (Except for printing Diagnostic waxup designs. Love that)

Agree. PVS and stone cast, especially on and for C&B bridges.

 

[Toothman19]

Sounds like I need to open a printing farm since the big companies can't get it done correctly

 

[bigj1972]

Look at the BS though. Manufactures push this crap to dentists as the future, oh so accurate.

Then they sell us the corresponding crap. And after all the checks clear, we're supposed to figure it out with mystery settings, while clients blame the lab for "not doing something right" and we gotta figure it out.

 

[CoolHandLuke]

Moving forward, we have decided to use die-spacer on the ASIGA model, then wax and cast from here.

stop.

just stop right there.

you are handwaxing on a piece of plastic. the minute your hot iron touches that plastic die - printed on asiga or carbon irrespective - you deform the die, and when you deform the die your final crown will still fit on the die but will NOT fit the patient and you are going to come back here in a week complaining of the same thing.

do NOT handwax on plastic models.

 

[ztech]

One thing I have learned with digital printing, trust your process that you know is correct and evaluate all of your processes constantly for accuracy. I check my mills calibration weekly and I check my printers calibration each day I use it. A well calibrated mill is a good check on your other processes also. If a milled crown doesn't fit, I reprint the models with a calibration block before I go any farther.

 

[Andrew Priddy]

stop.

just stop right there.

you are handwaxing on a piece of plastic. the minute your hot iron touches that plastic die - printed on asiga or carbon irrespective - you deform the die, and when you deform the die your final crown will still fit on the die but will NOT fit the patient and you are going to come back here in a week complaining of the same thing.

do NOT handwax on plastic models.

Not just distortion from waxing..
why would you take an accurate IO scan and adapt it to an inaccurate printed model? makes zero sense. i've seen this repeatedly,.. mill wax and then lute it to a 50um inaccuracy?

waxing anything on a printed model isn't gonna work. e.max as well. die spacer settings won't solve the problem.
mill/press/seat.
mill/cast/seat.
period.

 

[bigj1972]

50um is 0.05mm.

I think the real problem is printers can't print that good to start with. Anybody old enough to remember the old days of computers when they would sell a 100mb hard drive in big numbers, but the small print said using their proprietary Stacker compression software, it was really 50mb?
Or the 14.4k modems but only if it connected to another x2 modem so it was only a 7,200?

I don't think you could register 50um with an eye unless you were really trying. Not saying you can't reproduce a measurable artifact, but as many have said, including myself...... If your not printing your own, you don't REALLY know if your getting 50, 75, or 100+ um.