Improving the Occlusion of your Scans
Quadrant dentistry is fairly predictable. You take a quadrant scan, take a buccal bite, design your crown, adjust your occlusion on the CEREC software, deliver your restoration and boom, everything is good.
Where we start to doubt this process is for larger scans. Full arch scans that everyone has taken result in inconsistent occlusion. You take the buccal bite on the right side, the occlusion is heavy on the right side and the left side is wide open. Conversely, you take the bite on the left side and the right side is wide open.
So you take a larger buccal bite and hope that corrects the problem. Well, not really as you can see from the screen shot below:
So how do we improve on this? Is it where you take the buccal bite? Or is it something else? We decided to do some investigation and see if there were steps we could take to get the occlusion and the models- as accurate as possible. I would love to hear your comments and feedback on the situation.
I did a webinar on that subject, of course asking Bobby Chagger for that and it is true. I have not done study on current software but probably will. Gregory
Very cool study and interesting. There are two other methods of scanning the buccal bite I wonder how they compare. The first being to take a "tall" buccal bite, drag that to both opposing arch catalogs, cutting out the opposite and imaging from there. Second being scan one arch, drag that to buccal bite catalog, pick up scanning and scan opposing arch.
Love it Sam....
I had done a little buccal bite project awhile back to compare Chairside vs ortho and trying to see if a segmented buccal bite in CS made a difference ( a pseudo double buccal bite if you will) like:
wasn't well controlled and was just playing around.... but realized that the way I had scanned the models was also different, if unintentionally--- so REALLY like what you are showing here....
Mark
Thank you Sam, Mark, and whoever else participated in this clinical trial. I am anxious to try it out.
Thanks to all for getting this out there. I have been playing with this since returning from IDS, but I was not following the exact workflow from ortho. I still see some variation in bite on occasion when doing quadrants. I am wondering how much effect cutting a preop scan has on the integrity on the model as well as possible effect from extra imaging to fill in blank areas and excesive roll shots to capture adjacent contacts or areas below high water margind. I will be delivering a couple appliances over the next couple weeks that I fabricated from full arch impressions in the chairside software, so we will see how that goes. I delivered one NG last week scanned with this method, actually a slight variation of the linear scan, but essentialy the same. It fit well, but the occlusion was a bit off. The problem may have been how i positioned the patient. More to follow
Hats off to the Scottsdale team for the research ! This was a very interesting read. As Mark Thomas had mentioned, I wonder what the effect is if I'm doing a quadrant biocopy ("functional beauty") that I cut out.
Many THANKS for this !
Winnie
Mark-
We will test that with the new software. Initially my thought is that the cut tool is not a great method. However, the new software likely will have a solution for that.
The way you take the buccal bite doesn't matter much if the models are constructed correctly.
So do you suggest scanning in chairside exactly like in the ortho software?
- lingual of right side
- occlusal of right side
- buccal of right side
- transverse scan near canine
- repeat on left side
Because figure 8 in the article made it seem more like:
- scan buccal of right and left
- scan lingual of right and left
- scan occlusal of right and left
- transverse scans to tie it all together.
Very interesting study. I want to make sure I'm scanning how you guys were scanning!
Nathan-
the order of the scan is irrelevant. Just follow a linear pattern and let us know how it goes with your next case.
Can't wait to try it. My first patient tomorrow is now going to get a full arch scan no matter what procedure I'm doing. Occlusal composite? "I'm gonna need to scan your upper and lower teeth before we start"
Thanks everyone for your hard work on this project.
Let us know how it goes. Right now it's a theory- hopefully with the help of the community, we can validate this.
Intraoral scans:
Here is arbitrary scanning with the buccal bite on the right side. Occlusion is isolated on the right side:
Here is the same case with the buccal bite on the left side. Arbitrary scanning again:
My theory is that if a linear scanning technique was employed- the occlusion would be much more accurate. This patient is coming back in a few weeks- Ill update the file.
Sam and whomever participated in this: What are you doing for common data to tie the scans together? Are you starting on the occlusal of the second molar as in ortho?
Did you look at a linear, but continuous mode ie : start lingual of second molar, proceed anteriorly, roll onto occlusal and proceed back to the second molar, roll onto buccal and proceed forward again. Stop, go back and add in the transverse roll across the canine? This is basicly what I have been doing following Moritz's diagram he showed in Zurich
It's funny. I've had this paper done for 4 months. When Moritz presented his stuff my jaw dropped. Same concept halfway around the world.
Here is my webinar in Russian on occlusion checking Bluecam and Omnicam. You can watch the video, it is self explanatory. Gregory
What does the occlusion look like if you do a linear scan preop, cut out the teeth that are prepped, and image post prep? I'm about to start a case with multiple crowns, will see how it works!
Ever since taking the ortho course I have been scanning that way just out of habit. I wonder why this is more accurate?
John
Great read and totally makes sense!!
I have been applying a slightly modified version of the ortho technique for months and have been getting great results.
I always start on the occlusal surface of the most distal molar and scan past the centrals. Once on the centrals area, the camera has already seen enough lingual data, therefore, I transition to the lingual surface and scan towards most distal molar making it for very little disconnect and very clean scan. Then I transition from lingual all the way to buccal, and since the camera already captured the occlusal surface I get virtually no disconnect. Once on the buccal surface of most distal molar I continue to scan past centrals and slightly rotate camera back to incisal edges towards occlusal of canine/premolar (which is very close to a full transversal scan).
I then stop scanning, cut any 'noise' and only fill in missing/cut data as we would in ortho.
By following this pattern, I get clear, consistent, and relatively small (data quantity wise) scans.
I usually say that good data + good data = bad data, therefore, I avoid overwriting good data as much as I possibly can. Similar principle applies when cutting, except that my goal is to cut as little of good data as I can so filling in is quick and easy.
I hope this makes sense.
Dr. Dennis Fasbinder is conducting a clinical study to check out the accuracy of the claims in the paper that the linear scanning technique is more accurate than arbitrary scanning.
If you would like to learn more about the study and participate- please visit:
https://www.cerecdoctors.com/discussion-boards/view/id/58015
