Ditched Models in Exocad

[losmerengues]

Hello everyone, new technician here.
I want to create a trimmed model in exocad. My client demands models that allows him to examine marginal edge fit for all works. I normally work just monolitc and only create models for the cementation of the tibases. I never did this kind of model.
So i did some research and find that i can use the ditch tab to create this type of model. But only if we make a detachable die, we can make a ditch. How can I do this without detachable dies?
Thanks in advance.

 

[ztech]

In the modelbuilder program, select Formlabs 3B Plateless Model, then in dropdown that is on the next line select Solid Model with Extra Dies. This gives you a solid model for contacts and a die to perfect margins.

 

[erzdaemon]

If i understand correctly, you can make this "ditch" with the following option in Model Builder ( don't english translation sorry, also works with plateless model and extra dies ) : see attached image it's under plateless model > settings

This function in model builder to exposes the margin while keeping the die attached to the model.

3Shape has a way better function for this atm by cutting the gingiva up to a specific height ( saving the aprox-contacts) including substraction of your Crown Design on the gingiva/model.

I'll also make a seperate thread on a similar problem ( substracting the Crown-Design on the Model/Gingiva in Exocad )

 

[losmerengues]

In the modelbuilder program, select Formlabs 3B Plateless Model, then in dropdown that is on the next line select Solid Model with Extra Dies. This gives you a solid model for contacts and a die to perfect margins.

If i understand correctly, you can make this "ditch" with the following option in Model Builder ( don't english translation sorry, also works with plateless model and extra dies ) : see attached image it's under plateless model > settings

This function in model builder to exposes the margin while keeping the die attached to the model.

3Shape has a way better function for this atm by cutting the gingiva up to a specific height ( saving the aprox-contacts) including substraction of your Crown Design on the gingiva/model.

I'll also make a seperate thread on a similar problem ( substracting the Crown-Design on the Model/Gingiva in Exocad )

Thanks a lot. I found it and work it.
I'm worried about one thing: we perform a segmentation phase where we select the margins, and then we do the ditch. Does this margin we draw change the margins we create at the crown bottoms?
Honestly, I don't fully understand what the segmentation phase does.

 

[McTechnician]

Thanks a lot. I found it and work it.
I'm worried about one thing: we perform a segmentation phase where we select the margins, and then we do the ditch. Does this margin we draw change the margins we create at the crown bottoms?
Honestly, I don't fully understand what the segmentation phase does.

Drawing the margins dictates where the ditch begins as well as protects the tooth from any free form changes. Anything inside the margin is untouchable going forward in model creator.

 

[losmerengues]

Drawing the margins dictates where the ditch begins as well as protects the tooth from any free form changes. Anything inside the margin is untouchable going forward in model creator.

For example, if I exceed the crown borders inwards while performing segmentation (i.e. if I determine a margin inside the step of the veneer I prepared), will the ditch operation be performed in my veneer finish lines as well?

 

[McTechnician]

So actually this sounds like a niche issue with specifics in Exocad. In theory it would ditch from the drawn margin out to the distance dictated by the ditch settings. But I will say, and this is probably the heart of your specific problem, if you mark the tooth as a veneer when setting up the case in Exocad, you will not be able to preform the ditch function on the veneer prepped teeth. It just does not let you. In situations where we would like a ditch around a veneer prep we will have to mark them as crowns in set up, and then draw the margin around the base of the tooth rather than the actual veneer margin. This involves a little more work around in the design phase but produces the model we need.

 

[losmerengues]

So actually this sounds like a niche issue with specifics in Exocad. In theory it would ditch from the drawn margin out to the distance dictated by the ditch settings. But I will say, and this is probably the heart of your specific problem, if you mark the tooth as a veneer when setting up the case in Exocad, you will not be able to preform the ditch function on the veneer prepped teeth. It just does not let you. In situations where we would like a ditch around a veneer prep we will have to mark them as crowns in set up, and then draw the margin around the base of the tooth rather than the actual veneer margin. This involves a little more work around in the design phase but produces the model we need.

I think I understand. However, there's a problem: in many cases, the margin line isn't clear or the preparation is made feather edge. In such cases, selecting a second margin won't match the margins with the we determined first.

 

[losmerengues]

It's actually a simple process. Once the margins are determined, the crown bottom mesh is created. Isn't there a way to perform free form scan data while preserving this crown bottom mesh?

 

[McTechnician]

I'm having trouble visualizing the question so forgive me if this isn't what you are asking. But once the margin has been marked it should protect anything within that margin from free-form changes. You might need to use free-form model instead of free form scan data though at that point, They are functionally the same but once you make the model one affects the scan and one affects the model, but scan changes won't take unless you rebuild the model.

 

[losmerengues]

I don't think this is what I was talking about. But I learned that Exocad doesn't do ditch work when it comes to veneers. I did it by re-opening the case as an anatomic crown or transferring the margins.

 

[erzdaemon]

Another overly complicated but correct way to take it could be similar to what i did with the provisional dies here:

E

Post in thread 'Exocad eggshell provisionals and model design'

Dec 5, 2023

If you got any Problems with the instructions > Provisional Crown Dies feel free to ask, it took me some time to understand that load.

I finally nailed it

As sayd before, if you wanna go model with cutout dies you should be fine already, but if we want a model including that provisional die and 1x provisional die extra i went as follows:

When done with the tooth extraction in expert mode, go back to wizard and click on the tooth until light Blue ( option C step 8 ).
Then you can check "dies" and "settings" tabs. We don't want hollow model or undercuts for the die. Basically...

• erzdaemon

• 

You can save the dies in the correct relation to scene, then reload them as attachment and freeform the Model around the margin area, after that attach the dies to the model again ( delete tooth on model before that ).