Proper Coping Design

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patmo141

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Hi guys. I'm dabbling around with a coping module for my Blender project and I was wondering if someone could point me to a resource for the fundamentals of coping design. I know there are many different types (depending on margin design etc) but lets say for a PFM or PFZ coping, where can I find out about proper design? My google searches are proving to not be very fruitful.


Here is an example of what currently gets made automatically with the script I have written. Thickness and angle of cervical convergence are both adjustable. It's also fairly simple to add in interproximal support. I have a way of keeping some basic anatomy with the final restoration in mind but for now, I'm trying to understand the fundamentals.

adl.dropbox.com_u_2586482_SreenShots_coping_design.png

adl.dropbox.com_u_2586482_SreenShots_coping_design_2.png
adl.dropbox.com_u_2586482_SreenShots_coping_design.png adl.dropbox.com_u_2586482_SreenShots_coping_design_2.png
 
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e...w...h

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Proper design will fully depend on the prep, occlusion, excursion, etc...

But, I'm sure you are in the right place to find the answers. You might just need to be more specific in your questions.
 
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patmo141

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Right, I totally understand that. I was more looking for resources. Eg, I know there are preparation guides (for example at Glidewell.com) but I haven't stumbled across any "coping guides." Admittedly I haven't spent a ton of time looking but I was just trying to find any quick links or old pdfs from school people might know of.
 
TheLabGuy

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Ivoclar has a metal framework design pamphlet/book. It's free and probably exactly what you're looking for. PDF file is here.
 
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patmo141

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That looks perfect! It appears ivoclar's website is down for the moment though. Google's cached version gives me the gist but there are no figures or images so I will just have to wait for them to come back online. Thanks so much.

-Patrick

edit: website is back and the pdf is downloaded and exactly what I was after.
 
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DMC

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landmarks to use for single tooth should be neighbor tooth's marginal ridges.

We need to be "x" distance from the margiNAL ridges of adjacent tooth/teeth in both the x/y and then dropped on the z another measurement.

That's how I'd do a single substructure

If you can have auto recognition of marginal ridges, then proper substructures should be so easy without having to make a full anatomy first, then dialing back.
 
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charles007

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Designing coping 101 course :
Fundamentally its very simple, and most techs learn this with enough experience and after seeing thousands of broken crowns/bridges on the models we're working with..
Porcelain breakage/ shearing off, is mostly on marginal ridges then lingual cusps on posteriors. On anteriors, porcelain breaks mostly on incisal edges. All this breakage is caused from lack of support and thick porcelain. Now the questions is, how do you design to have the least failures. Its not in books, like what you maybe looking for, its knowing what the crown will look like in full contour and using a minimum of porcelain with substructure support with no sharp edges on frameworks. Bottom line, you want a miniature coping of the finished crown.
Using zirconia, I would fill in the interproximal as much as possible so that you have very little thickness of porcelain on the marginal ridges with support below the height of the marginal ridge. You want see pictures of this design that I know of, but this will prevent breakage. I call these wings in hand waxing my pfms. If I were to use my scanner, I would design a wall in the interproximal areas for zirconia posterior coping.... This would prevent breakage and create very little shrinkage to save on grinding in proximal contacts.
Ideally, you need to use full contour with cutback for layering of porcelain then add more support in proximals areas for the most ideal framework.
I know this info will not help you since your looking to design quickly, but this is what you must strive to do when designing coping ..........
Now we need software designing to full contour with a cutback in seconds rather than minutes, to make ideal coping for layering to have the highest success rate.
Sorry I couldn't give you a simple design.....
 
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patmo141

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Charles this is exactly the kind of info I'm looking for. I was looking for concepts and ideals to strive for not cookie cutter shapes. The ivoclar document above and your description there will at least give me something to tool around with. Thanks so much guys. I hope to post some show and tell in a few days.

-Patrick
 
k2 Ceramic Studio

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exocad.com - Dental CAD software

(look at the reduced waxup pic)

Have a look at this, have been told that you can set the % cut back to what you want.
would be great if a patient went from a denture to an implant bridge but wanted to keep the origional shape/style of what they had.
 
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patmo141

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Anatomical Coping with Support

Started with a simple "uniform thickness" coping then "waxed in" the interproximal support by hand.

I'm thinking I can get 50% there automatically, then have the user touch up the rest with virtual waxing.

see thumbnail.
supported_coping.jpg
 
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patmo141

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This is the result I can get automatically. This is totally based on the fully anatomical crown with no regard for the minimum thickness bubble or even the prep surface for that matter. I can't really come up with a good way to blend cutback from crown with step away form prep. It's one or the other right now and then the user will have to make other adjustments manually. The region of the coping which provides support can be easily modified as well (eg, making a buccal feather and a lingual band). That's all for today!

Any suggestions?
Anatomic_Supported_Automatic.jpg
 
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