3 shape issues with occlusion

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Crown maker Carol

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When scanning for the bite, it appears to be accurate. When designing and articulating occlusion with the software, articulator is used, adjustments are made as needed. It shows to be accurate and within normal limits on my end as the lab tech. When delivering the crown, occlusion is completely off, needing big adjustments. This concerns me as it compromises the strength of the crown. I have called support for help but coming up empty. I noticed in another thread the response was to use the optimize button in the articulator mode. Should this be done with every case? Any suggestions would be welcome! Thanks!
 
CoolHandLuke

CoolHandLuke

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In my experience this is a threefold problem.

1. It is common for triple tray impressions to distort during pour. More common than you'd think. Reconsider your pour method. Pour diestone on both sides instead of cheaper blue or plaster opposing. Pour opposing first.

2. Scanning with elastics. Its a common problem that elastics don't close the bite properly. I suggest you to soften the plstic triple tray hinge with a flame, hold it in place while the plastic sets. This is a fix for patients who don't bite properly too. Improper bites are quite common in triple trays.

3. User error. With 3shape its easy to understand how to go from start to finish so a lot of labs hire 'kids' or family who are 'good with computers' to do this work, and may not be aware of the adjustments necessary for proper bite, excursions. It is also hit and miss with dentists who love crowns that have no occlusion and are simply 'there' instead of functional. This is especially true in north america where patients tend to sue for malpractice over the slightest inconvenience.

But to answer your question directly, yes my recommendation is to use the Optimize function to help close the distance gap so that distance measurements can be done accurately. If the optimize function moves the jaws out of correct alignment though, simply cancel and move them by hand.
 
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Crown maker Carol

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I should have explained, we scan in the mouth for all patients.
 
CoolHandLuke

CoolHandLuke

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Does the lab trim the digital scan correctly so that no artifacts remain to impede or restrict the movement of the jaw in the articulator? Artifacts such as these May pose a difficulty when trying to move excursively and impede the jaws from optimizing centric occlusion.
 
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Crown maker Carol

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It does appear to be trimmed clean. I used the E4D system for years with no issues at all. This has continually occurred on this software.
 
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Crown maker Carol

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I often wonder if it is a scanning issue and not a issue with design software.
 
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AVAN

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We have had recent issues with our cases coming out too high all of the sudden..... we had to change our settings/parameters for occlusion to fix the problem...but we have no idea what has changed. might be a software thing because this is def. not the first time I have heard this especially when we were just figuring this out. Just started happening around 2 or 3 months ago but this summer they were all designed fine?
 
CoolHandLuke

CoolHandLuke

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If it is happening out of the blue, scan the crowns and compare with your design. High occlusion would be the result of miscalibrated z axis.
 
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Crown maker Carol

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We have had recent issues with our cases coming out too high all of the sudden..... we had to change our settings/parameters for occlusion to fix the problem...but we have no idea what has changed. might be a software thing because this is def. not the first time I have heard this especially when we were just figuring this out. Just started happening around 2 or 3 months ago but this summer they were all designed fine?
Interesting. Same here. Started happening the last few months! We also calibrate every single morning.
 
SJ

SJ

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"my recommendation is to use the Optimize function to help close the distance gap so that distance measurements can be done accurately. If the optimize function moves the jaws out of correct alignment though, simply cancel and move them by hand."

Couldn't have said it any better. You have to keep in mind that these scanners give you a very light occlusal contact. If you don't adjust the bite through the design software to close the gap, the crowns will always be heavy in occlusal contact.
 
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Crown maker Carol

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scanners shouldn't be calibrated every single day... once a week should be more than enough to run accurate scans.
It is interesting. We have been given a different answer on how often to calibrate everytime we have called them. So now I am really confused.
 
Affinity

Affinity

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Carol you will find that most people on the other end of the phone dont have a friggin clue. Theyre reading from a script and Im willing to bet most tech support havent even used the equipment theyre 'helping' you with. 99% will not even bother to call you back! Its very discouraging.
 
SJ

SJ

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Always ask for a head technician that works at the company, tech support are like salesmen that have no clue what they're selling.
 
Affinity

Affinity

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When you know more than the person youre on the phone with, you know youre in trouble.. Having to explain things to a child is frustrating.
 
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