What is CENTRIC RELATION?

Temporomandibular Disorders and Occlusion” and he compares two different definitions or approaches

What is CENTRIC RELATION?
I am reading this book by Okeson “Management of Temporomandibular Disorders and Occlusion” and he compares two different definitions or approaches:


1) Okeson (I dont know if it is his own theory or if he took it from some other author) states that CENTRIC RELATION is the most SUPERIOR and ANTERIOR position of the condyle in the fossa touching the POSTERIOR WALL of the ARTICULAR EMINENCE (with the disc in between)

2) He compares this to GELBs concept of occlusion and CENTRIC RELATION that states that condyles are in the optimal position when they are HALF WAY their movement BELOW the ARTICULAR EMINENCE, so more DOWN and FORWARD


Okeson strates that to put the condyles in Gelbs position the inferior external pterygoids have to be contracted, however the force of the elevating muscles is going upwards and somewhat anterior , so to keep this condylar position the strentgh of the pterygoids would have to overcome the strengh of the elevating muscles and this could lead to muscle fatigue, as it is two uncompatible forces working in an antagonistic way. I would like to hear opinions about this, what is the most accepted model of occlusion today? Are there other definitions of centric relation besides these two? what are the dentists in this group using as a model of occlusion and centric relation when building their patients splints?


(sorry if my translation is not accurate I attach the original text I am reading in spanish)


Discussion


Jeffrey Brown
Yes, Rodney Baier – this is a big part of my TMD practice- I now have an osteopath here twice a month (wish he could be here every day) who works on the whole body and I teach many of my patients about posture and airway- it helps a lot

Mazza L. Marcello
Good question Clayton Chan. Which is related to another one:
Is CR a stable skeletal relation or can it be changed?
Most ignorant dentist advocate that they work in CR beacuse it is a stable and unchangeable skeletal relation-position, with the condyles pressing against bone.
Any of us who have dystonia and posrural collapse have experienced a CR that is not stable. Moroever, we use dental splints and ALF to prpduce orthopedic forces that change even massively the position of CR.
Moreover, when the disk is tipped medially and moving, CR can change massively.

Rodney Baier
Seems like lots of current research about the effects of breathing(issues) and how they might be influencing posture, head position, jaw growth and development…….

Jeffrey Brown
Stephanie Hylton- much agreed on Zoe Fry’s comments- postural structure is critical to the whole body- if you do not work on that too, nothing will work long term. The problem is these days that we hunch over computers, ipads, phones, etc and it makes our posture worse- we should probably get rid of all those things!

Thelma Louise Davis
there’s such a thing as too much space between teeth as well – you can’t just make a statement like that – that teeth never touch – and expect others will understand that there are physiological constraints to it – that is why every dentist I went to wanted to file down my teeth – removed all the lingual contacts, shortened my molars and bingo, no cervical stability and suddenly I can not swallow properly or even stand upright. stop making people having bites based on one acceptable standard. if you ever moved a heavy object or lifted weights you know your teeth need to make contact in order for the neck to bear the load.

Dagmara Dagmara
Ooh that’s not good. But that’s the problem with these explanations… There is so much that can be added…. A whole documentary series on the discovery channel

Guilad Weil
Teeth should only touch when you swallow saliva, food, or when you chew food, so they are in contact for a very small amount of time during a day.
When your mouth is closed , your teeth should not touch… doesn’t matter in what position

Dagmara Dagmara
Agree

Rodney Baier
If only that always happened we would see far less issues. Parafunction is a large component of problems

Paula Circa
Really? in a normal occlusion, normal person, no parafunction , etc (none of us of course lol) teeth dont touch in resting position?

Denise Wells-Johnson
My major malfunction!

Thelma Louise Davis
Paula Circa – my teeth used to lightly rest on each other, maybe more so than some as I had ortho and the molar bands were used to close the bite.

Guilad Weil
Paul Circa…exactly…when your mouth is closed and Masseter and Temporal muscles.are relaxed teeth do NOT touch

Dagmara Dagmara
Teeth can touch but very lightly. Essentially the muscles should not be firing at rest. If there is too much or interfering contact, muscle EMG s will be high.

Thelma Louise Davis
maybe your teeth don’t touch and those of some others but not everyone has the same bite or anatomy – have you checked millions of people to make this claim, Guilad Weil?

Dagmara Dagmara
Well exactly. That’s are various variations of normal or healthy…. Various range of adaptability. We are taking here about what to do for someone with symptoms hopefully… No need to perfect an already working and healthy system. Perfection is the enemy of good.

Thelma Louise Davis
how does a dr determine more space is needed between teeth vs less space? how does a dr know if the symptoms started bc previous fillings or crowns etc were left too low – or would they just presume everything around those is interference and file them down to match – leaving the patient with shorter teeth all around which simply does not work with their anatomy.

Dagmara Dagmara
Never never assume and grind down. Ever. I can’t even imagine.

Dagmara Dagmara
Thelma Louise Davis there are so many different patterns I look for in addition to very detailed chronological medical and dental history.

Guilad Weil
To make this claim I study the papers published by professors Frank lobbezoo, Gilles Lavigne, winocour ,Dra ambra micheloti, Sandro palla, Danielle Manfredini , and other top reaserchers, who work maybe not with Millions but thousands , plus my own experience in day and night time Bruxism practice

Dagmara Dagmara
Thelma Louise Davis then we can measure muscle activity in various jaw positions, relaxed, lightly touching, full bite, and we can also now** check with a device called tek scan to see which teeth actually touch first and with what relative load.

Thelma Louise Davis
its probably the reason the nm dentist couldnt get my muscles to relax even after an hour of tensing – my teeth werent making contact. so in essence he was just over working muscles which were being forced to function beyond their adaptive range.

Dagmara Dagmara
Thelma Louise Davis sometimes there will be one or two interferences before the complete intercuspation (full bite). Some people will wear those down themselves. Other people’s brains will direct the jaw to work around these interferences and that will cause a problematic trajectory of the jaw, sore muscles, slipping disc, etc…. In that case if the jaw joint is Not affected yet and can take the load / disc in right place, I mount the models and see where that spot is (after some other things I measure). If I have an educated guess that the bite is really close except for a spot or two, I grind the model and check and see what contacts next : is everything is now even then I feel comfortable doing this equilibration in the mouth. But if I see that I would need to adjust too much, or too many teeth, my strategy will be different. Maybe I need to instead fill in the missing contacts. Not necessarily open the bite much but fill in the voids if that makes sense.

Dagmara Dagmara
Thelma Louise Davis what year what this done on you?

Dagmara Dagmara
Oh wow sooo long ago. Knowledge and technology has advanced so much since then. I promise you.

Paula Circa
yes I remember reading john mew saying teeth should lightly touch, besides I think if we let them fall too much apart that could cause joint problems, there should be some healthy pressure keeping disc/condyle in place, otherwise maybe we risk getting an open mouth posture, which I dont believe is good

Dagmara Dagmara
Well it depends what is your starting position. If the disk is displaced and space diminished you need to decompress the joint space. Pressure / compression will lead to further deterioration of the situation

Paula Circa
Dagmara Ventresca Leandro Nehuén Ormachea answered this better than me, apart from that needed pressure (of course if the joint is deranged no pressure is good) but still some contact is needed, which is different than parafunctional habtis like bruxism, teeth support the skull, and this can only be noticed by people like us that have a sinking skull to one side, “normal people” dont even notice that their teeth are supporting their skulls, but that does not mean it is not happening, try removing a good amount of molar height and then tell me what happens!

Dagmara Dagmara
Of course. But we never leave the joint unsupported. If the joint needs to be decompressed, we add a supportive element to the bite to support that position so there is always contact in the desired situations / lisitions. Once the joint is rehabilitated depending on the entire situation, we either place onlays, crowns or move teeth orthodontically to maintain this support. Paula Circa

Paula Circa
yes I know that, but this all started as a discussion on whether teeth should be in touch or not, and I think they should

Dagmara Dagmara
I have an issue with the word “should”. ” Should ” implies THE correct way, as in there is no ambiguity, no other option even remotely comes close. And i don’t agree with that. So I would say touching teeth is one correct way, if they are lightly touching and if there are no symptoms… But we of course are going to assume for the sake of keeping all controls equal, that muscles are not firing at rest, the individual is not clenching, and there are no symptoms. I have seen and experienced several of the variations, ie up to 2 mm space at rest, that are asymptomatic and therefore I do not uphold the idea that one way is the absolute only way. I realize Mew teaches that teeth touching is the most correct way. Tongue position on roof of the mouth helps with support too. Thank you for the discussion 😁

Dagmara Dagmara
Paula Circa above

Paula Circa
of course , should probably is not the correct way to express , you are right about that! and I do believe in open minded thinking, and maybe things not working equally for everyone, so maybe for some not touching teeth for a while could help! in the end with a proper bite teeth benefit from touching at times! and yes tongue supports the skull as well, I do believe that!

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