I have technical questions for dentists

I have technical questions for dentists

I have technical questions for dentists. When an impression is taken and then the model is being made, how is the back side of the model cut? I mean how does a dentist decide at what plane (angles) to make that flat cut? Or is it done at random “direction” (this is a 3-dimensional system so it’s not one direction, of course)? From my experience, when a dentist is analyzing the models, he/she is nearly always judging by positioning the models on these planes which might have nothing to do with the plane of occlusion nor with the actual horizontal plane of the body (skull). Very often dentists would just position the upper and lower models together and decide what should be done to the occlusion.In my case, they never (!) positioned the models the way my jaws were in the mouth when my body was balanced and pain-free.Even in cases when the bow transfer was made, the way models appeared on the articulator was rarely reflecting precisely the actual 3-dim. position of the jaws. It is very easy to make an error in determining the horizontal plane, especially if a person is already compressed and skewed from muscle contractions. And again, from my experience (of 15 years and countless dentists), a dentist would never update the bow transfer. Then the back side of the model might indeed be as “accurate” as the bow articulator. I hope I explained the problem though it might have been much easier to show this on the models. What are your insights and comments on this? I’d really appreciate them!


Discussion


Thelma Louise Davis good post. I also wonder if the mounting of the impressions on articulators affects the plane, as I have had 2 dentists tell me that the initial models of my bite taken before my molars were equilibrated were “mounted wrong” and are therefore misleading.

Brian McDowell Tatiana, that is a great question! I mount based on the upper model. I use the Hamilcar notches and the incisal papilla as my 3 reference points. The Hamilcar notches are behind all of the teeth and bony growth and the papilla is located right behind the front teeth. This gives me a pretty accurate mount- usually is identical to the way the maxilla sits in your mouth. I do verify by taking a symmetry bite to double check. I have found this mounting to give me the closest representation. Hope that helps!

Bjørn Hogstad You need to mount the models in an instrument called an articulator With the upper models mounted with a facebow registration and the lower model with an occusal indeks that is made in centric relation. This mounting procedure ensure the models are mounted in articulator exactly the same 3 dimential position you dental arches are in the mouth in relationship to the jaw joint, The occlusal index in centric realtion ensure the the occlusal registration is made in a position where the condylar heads in the jaw joint is in the right position. This is the only way you can properly do a model analysis. Hand held models og wrongly mounted models will not do the job.

Tatiana Gelfand Thank you so much! That’s exactly what I was doing for aligning my jaw before the last dental disaster (though I didn’t know these terms). I’d position my thumbs against the H. notches and the tongue against the maxilla incisal papilla. It oriented the head and everything pretty well.
However, since the last dental disaster, 6 years ago, my last molars which are no longer both crowned mislead me, plus the cervical spine does not center from a sidebending with rotation “dislocation” no matter what I do

Tatiana Gelfand Bjorn Hogstad, do you push the jaw back to put it in the CR occlusal index? I can’t tell you how many times I was made disabled by this dental procedure. The consequences were ranging from “stars in the eyes” for a few hours, to two nights of sitting by the wall and holding ice on my TMJ’s or to 2-3 weeks of being gray-green color in my face and hardly being able to walk. Is this what is called the jaw joint right position?
In my post, I was pointing out not to the fact of ariculating the models (yes, this is the only way to make the teeth properly) but to how a dentist makes sure that the plane of occlusion and the horizontal plane are accurate on the articulator. For example, taking the bow transfer in the “turn towards me” position or simply on a patient in severe cervical-madibular spasms might not show anything precisely enough for any successful model mounting.

Brian McDowell Very true Tatiana! Haven’t mounted that way since starting the neuromuscular journey!

Tatiana Gelfand Brian McDowell, what would you do if a patient cannot tolerate TENSING?
I have this loop: without relaxed muscles and aligned cervical spine there is no way to align my jaws. But there is no way to relax the spine and muscles completely withouth having at least a semi-functional bite.

Brian McDowell I would get them hooked up on the K7 computer and do some stretching/relaxation exercises and then get as low EMG readings as I could to at least get a starting point to fabricate an orthotic.
I have found, if we can get started, most will tolerate TENS as they start feeling better, then we reline or remake the orthotic

Tatiana Gelfand The K7 which I had done showed that my jaw was “going in loops” and this was when I was still in a much better state than I am currently.

Brian McDowell Tatiana, not sure what that means? Sorry were you low EMG, then spike high and loop like that?

Tatiana Gelfand I don’t know exactly. That’s what the NM dentist told me while looking at the screen. I think it meant that my jaw was going left and right, and left and right in slow motion. And this was after TENSING me for about 1.5 hours.

Brian McDowell Were you opening and closing? Looping then? The muscle readings don’t show that, there are other scans that show that- jaw tracking a

Tatiana Gelfand i think you might be right that it was jaw tracking. I remember I had lots of wires hooked all over my head and jaw.
The main problem now is that if the cervical spine feels more aligned then I am feeling terrible. When I manage to feel better then the head is “hanging” on one side and the jaw is completely dislocated as well. The neck, jaw and the brain just don’t work together any more– 🙂.BTW, I wonder if there are other patients who experience a similar situation?

Brian McDowell Absolutely! You need to have your AA/ AO joints (upper neck/ cervical area) aligned, that should help to align the jaw with the rest of the body as long as your orthotic is working as it should! Tatiana, you are definitely not alone!

Bjørn Hogstad Tatiana . Thank you for your comment. Centric relation is not a position where the dentist push the jaw back in the joint. If the condyle is pushed back in the joint space it will impinge on the retro discal tissue which contains among other thing nerves and that could be painfullCentric relation is a position where you hinge the condyle up into the joint space so the condyle is position on as far up and foreward in the jointspace as it can go and at the same time the condyle should be placed on the disc . In this position you should be able to load the condyle without any pain or sensitivity .

Roy Hakala The way the models are cut has nothing to do with the way an appliance is made.

Add a Comment

Your email address will not be published. Required fields are marked *