centric relation concept

[impaction]

what is centric relation.
if the mouth is opened to its maximum limit, is then the relation of the condyles to the fossa known as centric relation.
plz help with the answer

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[Streetwolf]

Centric relation is ligament guided and is when the condyle is in the most superior and anterior position within the articular eminence. It is a reproducible position (the patient should be able to reproduce this exact position whenever necessary and there should be little to no change between any given attempt).

 

[impaction]

thanks for ur reply

so it is the position in which the jaws remain when there is no movement or function

and what does most easily reproducible mean
is centric relation different from rest position?
whats the difference?

 

[foreigndentist]

thanks for ur reply

so it is the position in which the jaws remain when there is no movement or function

and what does most easily reproducible mean
is centric relation different from rest position?
whats the difference?

Centric relation is totally different from rest position.

Hope you will understand this...
In simple terms it is the position we record when we make full dentures , remb. we tell the patient to wide open his mouth (when we register bite)& then try to close so that both the bites touch each other on all aspects.

 

[fefzie]

It is the most anterior superior position of the condyles inthe glenoid fossa when minimum or no number of teeth are in contact! and yes all above is true too by streetwolf.

 

[impaction]

then how is it differnet from rest postion?
what about the contacts of the maxillary and mandibular tooth.
are they in contact with each other in centric relation?

 

[Streetwolf]

Rest position is muscle guided. I suppose you can think about it as the point where you don't have to apply any force and your jaw will just sit in that position.

To move to centric relation you need to move your jaw from rest position. Like I said, it is ligament guided, so there comes a point where you can no longer move your mandible towards that position. Since the condyle goes to the most superior and anterior position of the articular eminence, it is easily reproducible. There's really only one spot it ends up in each and every time, so the relationship between mandible and maxilla will always be the same in this position.

 

[impaction]

thanks streetwolf
is there any diagrams that show both of these positions.
you have any referal

 

[Streetwolf]

Unfortunately without scanning my own notes this is the best I could find on the web:

Just to orient you, you are looking at the sagittal plane from the right side (so looking towards the left).

Centric relation is the left-most dot of the 3 bunched together on top. Maximum intercuspation is up and right. Protrusive is the one on the top right. Maximum opening is on the bottom.

Now connect the bottom dot (max opening) to the dot on the top (max intercuspation). Somewhere near the top of that line is rest position.

 

[simkarl]

Isn't the centric relation the relation of the mandible to the maxillae when the condyles are in their most posterosuperior. and you said
"It is the most anterior superior position of the condyles inthe glenoid fossa" ???

 

[impaction]

thanks street wolf

 

[Streetwolf]

Isn't the centric relation the relation of the mandible to the maxillae when the condyles are in their most posterosuperior. and you said
"It is the most anterior superior position of the condyles inthe glenoid fossa" ???

No, definitely anterosuperior.

 

[aphistis]

No, definitely anterosuperior.

+1.

 

[skabbaraju]

Isn't the centric relation the relation of the mandible to the maxillae when the condyles are in their most posterosuperior. and you said
"It is the most anterior superior position of the condyles inthe glenoid fossa" ???

I kind of agree with simkarl. I read these posts a day or two ago and it immediately caught my attention. CR should be the most postero-superior and not antero-superior. If the condyles are in the most antero-superior position, then the jaw would be open wide.

 

[impaction]

if you read the book its given , most posterio superior, but if you read wikipedia it is most anterio- superior

 

[Streetwolf]

I would not trust Wikipedia as a valid source. I could have sworn I saw anterosuperior in my occlusion notes but I will double check.

And the jaws wouldn't be wide open if the condyle is still within the articular eminence.

 

[Regmata]

Centric relation is the relationship of the mandible to the maxilla when the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anterior-superior position against the shapes of the articular eminences. The position is independent of tooth contact.

It can by hard to visualize, if you draw out the TMJ and the teeth, you may be better able to visualize the relationships.

 

[skabbaraju]

I would not trust Wikipedia as a valid source. I could have sworn I saw anterosuperior in my occlusion notes but I will double check.

And the jaws wouldn't be wide open if the condyle is still within the articular eminence.

Well, yeah, if the condyles are still within the articular eminence, thats correct.
So, I have referred a good text for Occlusion and found out that the definition for CR has changed in recent years. Previously, it was thought that the most retruded and superior most position of the condyles (superoposterior) was the most reproducible position but guess what this has been changed.
Streetwolf is correct, the muscle stable position is anterosuperior or superoanterior position. Thats news to me.

 

[impaction]

thats true , recently they have changed the definition, and the old edition books still has the old definition.
so better to get new book

 

[simkarl]

thanks all for clarify this point

 

[fefzie]

I know where u are coming from...that is the OLD concept! Now abandoned!! remember this!! its is the most Anterior superior position of condyle in glenoid fossa!..some old books say posterior which is now proved WRONG!.
good luck

Isn't the centric relation the relation of the mandible to the maxillae when the condyles are in their most posterosuperior. and you said
"It is the most anterior superior position of the condyles inthe glenoid fossa" ???

 

[simkarl]

I know where u are coming from...that is the OLD concept! Now abandoned!! remember this!! its is the most Anterior superior position of condyle in glenoid fossa!..some old books say posterior which is now proved WRONG!.
good luck

you are right,, and will not forget this point. but still a long way and more concepts are needed to be clear.
thanks and good luck to you tooooo.