Exocad crown occlusal problems with intra oral scans (Will mail top shelf Scotch if you can help me)

Sda36

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you'll want to use Correct antagonist and create overclosing in a uniform way, along the wear facets that exist, and then let the Articulator open those intrusions. if they are uniform, the act of opening should bring the scans to the correct bite. if the intrusions are not uniform, the bite will appear very open.

exocad's approach to this is either to give you a truly vertical opening by shifting everything along the Z or by using the theoretical patient approximation of the articulator hinge to open the jaws, which is why i suggested this to begin with.

however what you can then do is save the new relationship by exporting the scene as one stl or object file before proceeding with any design; once done, you can use this as the bite scan instead, and when aligned with the bite scan, it doesnt matter what the articulator does, they will spring back to the same spot everytime.

you can also use 3rd party software like blender, meshmixer, meshlab, etc, to re-orient and realign data. that lab's skill with mesh work probably stems from some years of familiarity with the digital space so i'm not sure what tools they'd use because everyone's bag of tricks varies; i've given you what i'd do in exocad. this is usually good enough to create jaw relationships with better centric relation and when push comes to shove there's always your software support who should be experienced enough to help you no matter what the problem is. over the years the go-to-answer for any product question of "what do i buy" has always culminated in "the product with the best support" usually for exactly these reasons.
Honestly Matt, you are far more accomplished and knowledgeable than I read in your 1st post. Have really enjoyed all of the responses so far and helpful insights. It just seems sometimes that no matter how much care and attention you put into your work with virtual articulator, surprises happen, just sucks sometimes. So many variables involved, quality of scan which may Look OK?????, import and manipulation. We had a case today for a bite splint, not ios and Man you couldn't find a true centric at all by hand. Dr. Took an open bite record without an anterior stop of any fashion, how is that remotely possible. Squirt in a bunch of pvs and close, but not close, anywhere -impossible! Was wider open in the molar region ×3 compared to the anteriors.
Been at this a while, trust in the Lucia Jig method, 3 bite records in which 2 of 3 must agree. This digital path is so far away from that approach its not even comparable. I do believe however that some excellent tools in digital may be nearer than farther away. That's my hope.

As far as correcting bite and distance from antagonist, its mainly a reflection from feedback from clients. Some need more, some less. Also as ps2thtec said there's no periodontal ligaments in any of our models, quality of provisionals is another concern. I always check my proximal contacts with shimstock, adjust until it pulls through without tearing. Had a new client experiencing proximal contact problems and I suggested they use this standard with the shimstock and bingo we're now having excellent results.
Lots to learn and experiment with, great topic Matt, hope it keeps on going 🙂
 
ps2thtec

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Honestly Matt, you are far more accomplished and knowledgeable than I read in your 1st post. Have really enjoyed all of the responses so far and helpful insights. It just seems sometimes that no matter how much care and attention you put into your work with virtual articulator, surprises happen, just sucks sometimes. So many variables involved, quality of scan which may Look OK?????, import and manipulation. We had a case today for a bite splint, not ios and Man you couldn't find a true centric at all by hand. Dr. Took an open bite record without an anterior stop of any fashion, how is that remotely possible. Squirt in a bunch of pvs and close, but not close, anywhere -impossible! Was wider open in the molar region ×3 compared to the anteriors.
Been at this a while, trust in the Lucia Jig method, 3 bite records in which 2 of 3 must agree. This digital path is so far away from that approach its not even comparable. I do believe however that some excellent tools in digital may be nearer than farther away. That's my hope.

As far as correcting bite and distance from antagonist, its mainly a reflection from feedback from clients. Some need more, some less. Also as ps2thtec said there's no periodontal ligaments in any of

Not trying to finally derail this thread but for as much as I like impressions and stone models, this case came in for pvc bridge. Sent back to get a bite. Patient bit in protrussive and you can’t remount with just anterior teeth. Banghead
7EDF6D77-DF00-4AB0-B2AC-D4948A7446D7.jpeg
 
CoolHandLuke

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i don't need to tell you, we've all seen similarly bad and far worse, here on this very site in the Facepalm thread.

 
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i don't need to tell you, we've all seen similarly bad and far worse, here on this very site in the Facepalm thread.

Man, every single one of these posts...yes I totally relate to all these challenges. Building a large posterior bridge with no posterior stop...these dentists really don't understand what we do and expect miracles from us. Well I really appreciate all of you guys helping me out, I will for sure share my experiences with you regarding the occlusal outcomes.

Gru: Thanks for the kind response, and thanks to you guys for troubleshooting with me!

SDA36: I hear you brother, what can you do when you get bad impression information? I went to school for Computer Science, and on the very first day, the professors stressed a motto, "Garbage In, Garbage Out". That's basically what a poor impression and sometimes poor bite will accomplish. Can't remember if it was Mclaren or Spear but I thought one of them said, " you can get away with a bad prep, but you can't get away with a bad impression." What blows my mind is that these young new dentists I have conversations with are surprised at how critically important the impression is in the overall restoration. One of them said they didn't realize it was so important and that their schooling didn't cover it much. It seems like many of these dental schools have serious flaws in their teaching philosophy to overlook something so critical. Like ps2thtec said, we can only do so much with the information we are given. In regards to your proximal contact protocol with shim stock and pulling it through, I do the exact same thing, and it is very reliable! Glad we got proximal contacts down!

Regarding this whole IOS bite fiasco, technically I understand what the problem is and why it's happening, the challenge is getting the software to better accurately overlay the jaw scan data to the bite scan. With my desktop scanner, when I scan the bite relationship, and then the jaw models, I can trim the scans if I need to in order to help the software more accurately align them to the bite. Sometimes I will have to edit the scans significantly by selectively trimming in order to help the software find more matching reference points to be able to find common alignment points, and this editing will usually get a perfect alignment. But with the IOS scanners, this human finesse is taken out of the equation, and the bite alignment algorithms from the IOS scanner, or like Exocad's bite scan alignment function struggle to find a perfect match to the bite scan. When it attempts to match, often you will see the scan not quite overly perfectly, and this is a clear red flag that the jaws are off. In crown and bridge, a slightly misaligned bite is a mile off. Like CoolHandLuke was saying, I think these specialized digital dental labs are using separate software like Blender/Meshlab or who knows what else, and have found out how to reliably realign the jaw scans. In my particular situation, the IOS digital bite is the one main variable that is largely out of my control, and consequentially the cause of all my occlusion inaccuracy. That being said, I think ps2thtec's thoughts on bites usually being off vertically and not laterally is good food for thought. When trying to correct the antagonist in Exocad, I will try to do most of my adjustments through rotation of the bite to achieve uniform intensity across the arch. Sometimes I might find uniform intensity that matched wear facets but I moved the jaw too much to do that from the initial current scan, I think a centered buccal/lingual rotational approach might be a better way to start off trying to fix the bite uniformity, and not mess with any mesial/distal rotation. Then use CoolHandLukes approach to loading the new uniform bite into the articulator and opening the pin. This is what I will try while still seeing if I can search for a better bite alignment matching software approach through Blender or Meshlab.

I'll keep you posted with the results, Happy Sunday to y'all!

-Matt
 
Toothman19

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Man, every single one of these posts...yes I totally relate to all these challenges. Building a large posterior bridge with no posterior stop...these dentists really don't understand what we do and expect miracles from us. Well I really appreciate all of you guys helping me out, I will for sure share my experiences with you regarding the occlusal outcomes.

Gru: Thanks for the kind response, and thanks to you guys for troubleshooting with me!

SDA36: I hear you brother, what can you do when you get bad impression information? I went to school for Computer Science, and on the very first day, the professors stressed a motto, "Garbage In, Garbage Out". That's basically what a poor impression and sometimes poor bite will accomplish. Can't remember if it was Mclaren or Spear but I thought one of them said, " you can get away with a bad prep, but you can't get away with a bad impression." What blows my mind is that these young new dentists I have conversations with are surprised at how critically important the impression is in the overall restoration. One of them said they didn't realize it was so important and that their schooling didn't cover it much. It seems like many of these dental schools have serious flaws in their teaching philosophy to overlook something so critical. Like ps2thtec said, we can only do so much with the information we are given. In regards to your proximal contact protocol with shim stock and pulling it through, I do the exact same thing, and it is very reliable! Glad we got proximal contacts down!

Regarding this whole IOS bite fiasco, technically I understand what the problem is and why it's happening, the challenge is getting the software to better accurately overlay the jaw scan data to the bite scan. With my desktop scanner, when I scan the bite relationship, and then the jaw models, I can trim the scans if I need to in order to help the software more accurately align them to the bite. Sometimes I will have to edit the scans significantly by selectively trimming in order to help the software find more matching reference points to be able to find common alignment points, and this editing will usually get a perfect alignment. But with the IOS scanners, this human finesse is taken out of the equation, and the bite alignment algorithms from the IOS scanner, or like Exocad's bite scan alignment function struggle to find a perfect match to the bite scan. When it attempts to match, often you will see the scan not quite overly perfectly, and this is a clear red flag that the jaws are off. In crown and bridge, a slightly misaligned bite is a mile off. Like CoolHandLuke was saying, I think these specialized digital dental labs are using separate software like Blender/Meshlab or who knows what else, and have found out how to reliably realign the jaw scans. In my particular situation, the IOS digital bite is the one main variable that is largely out of my control, and consequentially the cause of all my occlusion inaccuracy. That being said, I think ps2thtec's thoughts on bites usually being off vertically and not laterally is good food for thought. When trying to correct the antagonist in Exocad, I will try to do most of my adjustments through rotation of the bite to achieve uniform intensity across the arch. Sometimes I might find uniform intensity that matched wear facets but I moved the jaw too much to do that from the initial current scan, I think a centered buccal/lingual rotational approach might be a better way to start off trying to fix the bite uniformity, and not mess with any mesial/distal rotation. Then use CoolHandLukes approach to loading the new uniform bite into the articulator and opening the pin. This is what I will try while still seeing if I can search for a better bite alignment matching software approach through Blender or Meshlab.

I'll keep you posted with the results, Happy Sunday to y'all!

-Matt
Can you share the files for the case? You mentioned it was a trudef case, can you share the .exo file and the .stl files. I'd like to take a look
 

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