When would you restore to Centric Relation?

[Oracle DMD]

So I've been learning about taking CR records and such, and I'm still confused when you would restore to CR. Here's my thoughts/questions about it so far.

-Unless you are doing a full mouth rehab, why would you restore to CR?
-Non-ideal occlusion schemes are often times very stable, when would you attempt to change with fixed prosth?
-If you WERE going to change a total occlusal scheme, why would you not do ortho instead of a ton of restorations?
-How often do you achieve CR with 1-3 crowns?
-With only a semi adjustable articulator, which does not replicate true mandibular movements, why mount a case at all?
-It seems that building to CO is as good as building to CR in at least 95% of patients, what gives???

Thanks for all the input in advance, I really would like a better understanding on the philosophy/ real life practice of restoring to CR.

---

Members don't see this ad.

 

[mike3kgt]

So I've been learning about taking CR records and such, and I'm still confused when you would restore to CR. Here's my thoughts/questions about it so far.

-Unless you are doing a full mouth rehab, why would you restore to CR?
-Non-ideal occlusion schemes are often times very stable, when would you attempt to change with fixed prosth?
-If you WERE going to change a total occlusal scheme, why would you not do ortho instead of a ton of restorations?
-How often do you achieve CR with 1-3 crowns?
-With only a semi adjustable articulator, which does not replicate true mandibular movements, why mount a case at all?
-It seems that building to CO is as good as building to CR in at least 95% of patients, what gives???

Thanks for all the input in advance, I really would like a better understanding on the philosophy/ real life practice of restoring to CR.

This concept takes several days to talk about and comprises probably 10 folders of literature review.

If you really want a good summary of the philosophies of when to work in CR vs. a habitual position and all the cases of when to work with articulators of various types and such take the basic Dawson course or at least go to the dental library to check out his book.

His course & book is some of the best $$ you can ever spend. 2.5 days of learning nothing but restorative dentistry, CR, OVD etc. He also wines and dines you and you have the opportunity to sit down and pick his brain.

This is not an advertisement, but just some of my experience.

Good luck!

 

[mike3kgt]

So I've been learning about taking CR records and such, and I'm still confused when you would restore to CR. Here's my thoughts/questions about it so far.

I, will, however, try to throw some ideas out there for the dental students out there.

-Unless you are doing a full mouth rehab, why would you restore to CR?

The time I would want to restore to CR is primarily two reasons:

1) re-organizing the occlusal scheme with restorative dentistry for esthetics or patient factors
2) clinical pathology with also a need for restorative dentistry

#1 more than #2. Research shows that putting a patient into CR solely to treat TMD or joint pathology is ineffective.

-Non-ideal occlusion schemes are often times very stable, when would you attempt to change with fixed prosth?

CR is:
- repeatable
- recordable
- physiologic

MICP is:
- repeatable (in non-diseased dentitions)
- difficult to record
- sometimes physiologic, sometimes non-physiologic

NM (neuromuscular position) is:
- difficult to repeat
- recordable
- not phsyiologic

-If you WERE going to change a total occlusal scheme, why would you not do ortho instead of a ton of restorations?

You can! However, many patients don't want to shell out 5k for treatment that lasts 1-2 years when they can put that $ into crowns and have it done much faster with crowns. Not all cases can be done this way, but many can.

-How often do you achieve CR with 1-3 crowns?

I hand articulate cases like this into the patient's habitual position. Research has proven that hand-articulation of casts is as accurate and often times more accurate than more laborious techniques.

-With only a semi adjustable articulator, which does not replicate true mandibular movements, why mount a case at all?

Because semi-adjustable articulators allow you to replicate border movements which one can measure with checkbites or mandibular motion studies (pantographs etc). If you want to have some fun, take a set of full arch impressions for a single unit crown and they will use a little plastic hinge throwaway articulator. Take a second set of the casts and mount on a semi-adjustable articulator. Move the crown around between casts and see the effects of canine guidance and eminence angle on the cusp height of the crown.

-It seems that building to CO is as good as building to CR in at least 95% of patients, what gives???

The term CO no longer exists. MICP is the correct term. Again, it works in the majority of single unit cases and relatively stable occlusions. When you have a non-stable occlusion, CR has been shown to be the preferred choice.

 

[Oracle DMD]

Thanks for the input Mike! In the cases that you have restored to CR, have you been able to move from MICP to CR in 1 or 2 restorations, or have the cases been more complex?

 

[Oracle DMD]

I'm glad to hear about the hand articulation vs fully mounted point. I really hate putting in all that extra lab time for marginal if any improvements!

 

[SeattleRDH]

What does MICP stand for? Why no more Centric Occlusion?

 

[Oracle DMD]

What does MICP stand for? Why no more Centric Occlusion?

I'm assuming it's Maximum Intercuspation Position or something along those lines.

 

[The Hammer]

Hey Big J. CR is not the mystery that everyone seems to want to make it out to be. Here are a couple of things to know about CR

The difference between CR and MI is that CR puts the head of the condyles into a position in the glenoid fossa that allow physiological rest of the muscles of mastication. MI usually doesn't do that because having all of the teeth occlude trips the proprioceptive fibers around the teeth causing the muscles to fire

This is why in a full mouth rehab you restore to CR. Its repeatable but also it keeps your restorations from being destroyed by the patients occlusal forces.

When do you restore to CR? For me its whenever I have a non-desirable occlusal scheme that is causing the patient (or my restorations) damage. But if their occlusal scheme is working for them I leave it alone. Don't fix what isn't broken

 

[The Hammer]

I, will, however, try to throw some ideas out there for the dental students out there.



The time I would want to restore to CR is primarily two reasons:

1) re-organizing the occlusal scheme with restorative dentistry for esthetics or patient factors
2) clinical pathology with also a need for restorative dentistry

#1 more than #2. Research shows that putting a patient into CR solely to treat TMD or joint pathology is ineffective.



CR is:
- repeatable
- recordable
- physiologic

MICP is:
- repeatable (in non-diseased dentitions)
- difficult to record
- sometimes physiologic, sometimes non-physiologic

NM (neuromuscular position) is:
- difficult to repeat
- recordable
- not phsyiologic



You can! However, many patients don't want to shell out 5k for treatment that lasts 1-2 years when they can put that $ into crowns and have it done much faster with crowns. Not all cases can be done this way, but many can.



I hand articulate cases like this into the patient's habitual position. Research has proven that hand-articulation of casts is as accurate and often times more accurate than more laborious techniques.



Because semi-adjustable articulators allow you to replicate border movements which one can measure with checkbites or mandibular motion studies (pantographs etc). If you want to have some fun, take a set of full arch impressions for a single unit crown and they will use a little plastic hinge throwaway articulator. Take a second set of the casts and mount on a semi-adjustable articulator. Move the crown around between casts and see the effects of canine guidance and eminence angle on the cusp height of the crown.




The term CO no longer exists. MICP is the correct term. Again, it works in the majority of single unit cases and relatively stable occlusions. When you have a non-stable occlusion, CR has been shown to be the preferred choice.

what he said

 

[Doc Smile]

What does MICP stand for? Why no more Centric Occlusion?

I beleive because Centric Occlusion is very ambigious and is sometimes used to define a pt's normal occlusal relationship while other time to define the pt's ideal occlusal relationship...

We took a class on occlusion our D1 first semester which was way over all of our heads and all the upperclassman tell us it will make sense after D2,3, and 4. So, what I am trying to say is, I don't really know what I am talking about. but that is my understanding.

 

[mike3kgt]

This is why in a full mouth rehab you restore to CR. Its repeatable but also it keeps your restorations from being destroyed by the patients occlusal forces.

Hammer,

Unfortunately, restoring to the CR position will not prevent a patient from bruxing. Parafunction is multifactorial and depending on which article/expert you subscribe to, is difficult to control. What we do know is that it is not going away anytime soon!

I have seen patients who had CR/MI slides have full mouth rehabs restored into CR with no slide developing a slide one year later. Good clinicians restoring the case. Just happens that the mouth is very dynamic.

The only way you can protect your restorations is to fabricate an occlusal device so the patient can brux against acrylic resin. Then again, there is no guarantee that the patient will actually wear the device

 

[jay47]

I still have the same original question about CR vs MI as Oracle; I understand every single thing you guys have listed above, but I don't understand when doing 1-2 restorations/crowns how that changes things. For example:

Let's say I am doing 2 crowns on someone- do I restore in MI or CR?

If I restore in CR, and MI does not equal CR for the rest of the dentition, then the crowns built in CR will be at odds with the rest of the teeth during functional movements. It's not like we have changed how the rest of the teeth will fit together by placing 1-2 crowns. I know that when doing full mouth cases, it would be ideal to have all restorations placed in CR, this makes sense to me, but for a crown or two, it actually seems counterproductive to mount in CR as you will probably end up grinding away half of the crown's occlusion to get them into a comfortable position.

Of course the ideal situation would be to have CR=MI, but that is not often the case.

Perhaps I'm in agreement with the LVI philosophy on the subject more so, not that I think Dawson is an idiot- he is a leader in the topic. I definitely agree that placing someone in CR to alleviate TMJ problems is not always effective as well.

http://www.leadingdentist.com/articles/cr_repeatable.html

 

[The Hammer]

Hammer,

Unfortunately, restoring to the CR position will not prevent a patient from bruxing. Parafunction is multifactorial and depending on which article/expert you subscribe to, is difficult to control. What we do know is that it is not going away anytime soon!

I have seen patients who had CR/MI slides have full mouth rehabs restored into CR with no slide developing a slide one year later. Good clinicians restoring the case. Just happens that the mouth is very dynamic.

The only way you can protect your restorations is to fabricate an occlusal device so the patient can brux against acrylic resin. Then again, there is no guarantee that the patient will actually wear the device

I agree. I've found that when I restore to CR with a cuspid disclusion you greatly reduce the harm that a patient can do to their teeth when they brux. The goal is not to "cure" the patient of bruxing (which you are correct, it can't be done just by restoring to CR) the goal is to manage the occlusal forces when they brux. You are also correct that fabricating an occlusal orthotic is absolutely necessary if you want to protect the nice porcelain that you have just placed in their mouths. I usually make one before any work is done to start "normalizing" the muscles. I put the patient in long term temps to work out the occlusal scheme and I make another one once the restorations are seated. And even after going to all that trouble I still have the occasional heavy bruxer bring in some fractured porcelain after about 6 months. And of course when you question them the fracture usually coincides with, you guessed it, their discontinuation of wearing their splint

What are you gonna do? Well other than make sure you charge a lot for your rehabs

 

[Dr. Dai Phan]

So I've been learning about taking CR records and such, and I'm still confused when you would restore to CR. Here's my thoughts/questions about it so far.

-Unless you are doing a full mouth rehab, why would you restore to CR?
-Non-ideal occlusion schemes are often times very stable, when would you attempt to change with fixed prosth?
-If you WERE going to change a total occlusal scheme, why would you not do ortho instead of a ton of restorations?
-How often do you achieve CR with 1-3 crowns?
-With only a semi adjustable articulator, which does not replicate true mandibular movements, why mount a case at all?
-It seems that building to CO is as good as building to CR in at least 95% of patients, what gives???

Thanks for all the input in advance, I really would like a better understanding on the philosophy/ real life practice of restoring to CR.

Hello,

Q1 -Unless you are doing a full mouth rehab, why would you restore to CR?

Unless you plan to completely restore patient's dentition with previously unstable habitual position (MICP), then CR is the place to go. That is because that position is the position that we can duplicate repeatedly. However, if the patient has a repeatable habitual position that they function at, then you restore at that position. Remember, CR is a forced or operator induced position, it is not the position where the jaws find its "comfort zone". If you restore a single crown, you restore at MICP but make sure that you do not have premature contacts/interferences in CR because the mandible at times can go into CR during function. You do not want non-working contacts in lateral and protrusive movements.

Q2-Non-ideal occlusion schemes are often times very stable, when would you attempt to change with fixed prosth?

You do not attempt to change anything that is stable even if it is not "ideal" on paper unless you plan to give a patient full mouth construction. Just because I have a non-working contact on #19 for so many years and I have no problem, it makes no sense for me to have it adjusted to make it into an "ideal" tooth. If it ain't broke, then don't touch it. However, if you plan to do full mouth reconstruction, then you aim for anterior guidance or group function because on paper, it makes sense from engineering point of view.

Q3 -If you WERE going to change a total occlusal scheme, why would you not do ortho instead of a ton of restorations?

Full coverage will give you better occlusal contacts than orthodontics because we have better control of the occlusal scheme during wax up. Orthodontics just moves the teeth and it is impossible to have proper occlusal contacts unless you change the anatomy of the occlusal surface that can be only done through full coverage.

Q4 -How often do you achieve CR with 1-3 crowns?

If you place 1-3 crowns and now patient occludes in CR instead of MICP, then your occlusion is off.

Q5 -With only a semi adjustable articulator, which does not replicate true mandibular movements, why mount a case at all?

That is because it brings you closer to the proper arc of closure. With closer duplication of the patient's true arc of closure, you will have less premature contacts as the teeth come together. That means less hyper-occlusion and adjustments during delivery. Now, if you mount a case on a semi-adjustable articulator WITHOUT taking a face bow, then you are wasting your time because your arc of closure is now arbitrary. In that case, just use the simple hinge articulator and that will do you the same.

Q6 -It seems that building to CO is as good as building to CR in at least 95% of patients, what gives???

Because 95% of us or more function at MCIP rather than CR. Remember CR is an induced position rather than where the jaws find their comfort zone. DP

 

[Dr. Dai Phan]

I still have the same original question about CR vs MI as Oracle; I understand every single thing you guys have listed above, but I don't understand when doing 1-2 restorations/crowns how that changes things. For example:

Let's say I am doing 2 crowns on someone- do I restore in MI or CR?

If I restore in CR, and MI does not equal CR for the rest of the dentition, then the crowns built in CR will be at odds with the rest of the teeth during functional movements. It's not like we have changed how the rest of the teeth will fit together by placing 1-2 crowns. I know that when doing full mouth cases, it would be ideal to have all restorations placed in CR, this makes sense to me, but for a crown or two, it actually seems counterproductive to mount in CR as you will probably end up grinding away half of the crown's occlusion to get them into a comfortable position.

Of course the ideal situation would be to have CR=MI, but that is not often the case.

Perhaps I'm in agreement with the LVI philosophy on the subject more so, not that I think Dawson is an idiot- he is a leader in the topic. I definitely agree that placing someone in CR to alleviate TMJ problems is not always effective as well.

http://www.leadingdentist.com/articles/cr_repeatable.html

Hello all,

When you are faced with this question, then ask yourself this. Where does patient occlude at and where does patient function at? If you are only replacing 1-2 crowns, then restore at MICP because the position of the mandible is dictated by the 28 other teeth upon occluding. If you mount the casts in CR and restore the crown(s) to that position, then you will end up with a nasty anterior open occlusion to boot. Plus you will end up with all sort of non-working and protrusive contacts too. So in your case, patient occludes at MICP so you restore at MICP. Now, where does patient function at? The answer is both on MICP and CR as the madible at times will go into CR during function (remember the "shield" diagram taught in DS?). So you need to check in CR to make sure the restoration restored in MICP does not cause interferences in CR. This can be done by placing patient in CR and check the occlusal contacts. I can tell you that over 90%, the restoration will not be a problem in CR. I personally feel CR is overated because there are many factors that play a role on where the mandible is upon closing such as ligaments, age, habbits, teeth than just fossa and the condyle alone. DP

 

[HupHolland]

I still have the same original question about CR vs MI as Oracle; I understand every single thing you guys have listed above, but I don't understand when doing 1-2 restorations/crowns how that changes things. For example:

Let's say I am doing 2 crowns on someone- do I restore in MI or CR?

If I restore in CR, and MI does not equal CR for the rest of the dentition, then the crowns built in CR will be at odds with the rest of the teeth during functional movements. It's not like we have changed how the rest of the teeth will fit together by placing 1-2 crowns. I know that when doing full mouth cases, it would be ideal to have all restorations placed in CR, this makes sense to me, but for a crown or two, it actually seems counterproductive to mount in CR as you will probably end up grinding away half of the crown's occlusion to get them into a comfortable position.

Of course the ideal situation would be to have CR=MI, but that is not often the case.

Perhaps I'm in agreement with the LVI philosophy on the subject more so, not that I think Dawson is an idiot- he is a leader in the topic. I definitely agree that placing someone in CR to alleviate TMJ problems is not always effective as well.

http://www.leadingdentist.com/articles/cr_repeatable.html

Why are you in agreement with LVI? Explain....

As for restoring to CR...
Lets say you are doing crowns on #3 and #30.

You DON'T...
-Just prepare #3 and #30, impress, mount using CR record and fabricate crowns. If you did this, 75% of the population (the % of people where MI does not equal CR) would not be occluding evenly at all!

You DO...
-Verify CR using first point of contact- that is, verifying where the patient is hitting first clinically matches your articulator mounting.
-Fabricate a splint putting the patient in CR and observe changes in muscle tenderness, comfort and occlusal stability over a period of time. The splint will likely be adjusted several times at the articular disc will change over time as edema decreases.
-Some clinicians skip the previous step move on to selectively grinding and restoring the teeth to put patient into CR.. most times this can be done conservatively! (The grinding and restoring can be planned on the articulator)
-Now, the patient's MI = CR, so prepare the teeth for crowns, impress and hand articulate

Hup

PS- I'm NOT saying that every patient should be restored to CR. I'm just stating the clinical steps involved if one wanted to do it for a simple restorative case (1-2 crowns).

Personally, I would choose to restore someone to CR when they have clinical signs and symptoms of occlusal disharmony (attrition, tooth fracture, muscle of mastication tenderness) or when doing a full mouth case.

 

[jay47]

Why are you in agreement with LVI? Explain....

Perhaps I am not in agreement with the LVI, I just found that article online in the link that appeared to come from the LVI stating why restoring to CR is not always a good idea (check out the link- the source does look a little shadier than I originally thought).

I think that you and Dr. Phan clarified greatly my original questions regarding the subject- that you shouldn't always restore to CR, but it would be ideal if it was tolerable.