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793: The Biggest Misconceptions About Centric Relation Every Dentist Needs to Know – Dr. Jim McKee

If you're intimidated by centric relation, this is the episode for you! To increase your understanding and appreciation of CR, Kirk Behrendt brings back Dr. Jim McKee, founder of Chicago Study Club, to explain what it means, why it’s misunderstood, and how learning more about it will improve your practice. To hear the myths and misconceptions debunked by one of the masters of occlusion, listen to Episode 793 of The Best Practices Show!

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Main Takeaways:

  • Centric relation is simple. It’s normal joints in normal joint sockets.
  • Know the difference between fully seated condylar position and CR.
  • CR is not for everyone. For some patients, it is not possible to achieve.
  • Understand the advantages and disadvantages of being or not being in CR.
  • By understanding CR, your confidence level in treatment planning will increase.

Quotes:

“What is centric relation? Centric relation is no more, no less, the normal joints fitting in normal joint sockets. That's all it is. It's nothing mystical. It's not a crazy concept. It's an anatomic position is what it is. Now, you'll note I said normal joints fitting in normal joint sockets. That means a normal disc is on top of a normal bone fitting into a normal joint socket. Now, that sounds pretty logical. But part of the problem is, a lot of times, we're dealing with patients who may not have normal joint anatomy, and therefore the system may not work the way it's supposed to.” (3:21—4:12) -Dr. McKee

“Typically, when we talk about centric relation, what we do is we talk about if we were able to get the condyle fully seated in the joint socket because we always think about it as a positional discussion. Did I achieve a fully seated condylar position? If you did, you were a good dentist. If you didn't, you were a bad dentist. You had to have the scarlet CR on your chest because you couldn't get it. The problem is, the reality is most of those cases that you couldn't get, it probably wasn't possible to achieve because we didn't have normal joints fitting in normal joint sockets. If that's the case, it's not that you're a bad dentist. It's not that centric relation is even the right position to be thinking about. It simply tells us there are anatomic changes in the joint, and as a restorative dentist I want to understand that from a treatment planning perspective because it's going to change the way I frame the patient's expectations. That's really, I think, the easiest way to start the conversation.” (4:13—5:23) -Dr. McKee

“When I got out of dental school, most of the prosthodontists around me and most of the really good restorative dentists around me used centric relation, and I had no understanding why. I never used it in dental school. I understood what it was to pass the test. But once I got out, the first two, three, four years, I never even thought about it. In fact, I thought it really doesn't make sense because if you check the bite in centric relation, what happens is most of the time the back teeth touch and the front teeth don't. Pete Dawson talked about that for years. So, then you're like, ‘Okay, what do I do now? Now, I've got a bite that doesn't fit. I'm not going to pay any attention to that stuff. I'm just going to build a bite where the teeth fit together, and I want to call it a day.’ And fortunately, for a lot of patients, maybe most of the patients, that works — most of the patients, not all of them. For a lot of them, it works. So, I understand why most dentists really don't have an interest in this and don't think it's a really important topic.” (5:41—6:50) -Dr. McKee

“If you think about why the good restorative dentists and the prosthodontists and a lot of the giants in dentistry that have come down over the years who have been some of our best educators have advocated using centric relation, it’s because it does have advantages. The primary advantage of centric relation is twofold. Number one, if the disc is on top of the condyle and it's attached at the medial and lateral pole like a bucket handle, that gives us a soft tissue cushion between the condyle and the joint socket. Ultimately, one of the functions of the joint, let's put it that way, is to help dissipate the load that's generated when we bite down. Now, here's when I started to realize that maybe I should start to take a look at centric relation a little bit more carefully. Do you know what it was? When the restorations I put in on the back teeth started to break. Really, what I was doing is I was building into a potentially unstable environment, but I had no idea about that. And I have to credit Pete Dawson on this because Pete is really the one that opened my eyes to this many years ago. If we can look at the joint as a force distribution unit and we can look at the teeth as another force distribution unit, now we can split the force between the front and the back end of the system, and maybe all the porcelain that I just put in isn't going to break now. So, for me, it became a point of dissipating the load that the patient was generating. That's really what it came down to.” (6:56—8:47) -Dr. McKee

“What I started to notice is patients would have different bites sometimes. Sometimes, they'd bite on this side, sometimes they'd bite on that side. If they had a disc — which, here's the way to think about a disc. This is the way I explain it to patients. Think about the disc as a gasket. That's a soft material between two harder surfaces. Basically, I say think of the plastic molding on the inside of your refrigerator door that keeps the cold air in in your refrigerator. That's a gasket, a soft material between two harder surfaces. That's basically what the disc is. It's a three-dimensional gasket that positions the condyle in space in a repeatable position. So, now I have a bite that can be repeatable, and I can give my technician enough information. Or if I'm digital, I can scan that in a condylar position now that allows me to build with the most effective load distribution position and a repeatable position. When you look at it that way, what that does, that takes most of the risk out of the treatment planning for restorative cases. Now, the only other thing I have to do besides that is to make sure that the front teeth aren't in the way of where the lower jaw is moving, which is anterior guidance, which is the second thing we talk about after we determine where we're going to build the case. So, really, centric relation is important in those types of cases because it allows a restorative dentist complete confidence. If I have a case where I know I have the disc where it's supposed to be, I'm 100% confident that I can get a result — let me rephrase that. I'm 99% confident that I can get a result that's going to be predictable, and it's going to be comfortable.” (8:50—10:50) -Dr. McKee

“I was called a CR zealot by a very prominent teaching instructor once. And it wasn't that I was a CR zealot, but I saw the advantages of centric relation. Now, does that mean you use it on everyone? No, because the reality is sometimes you can't use it on people because it's not possible to achieve. If I have a patient that has a clicking joint, I can't get centric relation. I don't have a normal joint. So, that takes the discussion right out of the system. Then, my discussion is, okay, where do I want the condyle to be when the teeth fit together? If you've got a disc at the top end of the system, that makes it easy. Then, you can have bracing at the top end on the right, bracing at the top end on the left, and all the teeth fitting together. It's like a three-legged stool. It's almost impossible to have a problem in that type of situation. If I don't have that, however, that's when I want to start thinking about talking to the patient differently. And ultimately, if I don't have that, I can't use CR in everyone.” (14:28—15:39) -Dr. McKee

“Part of the reason why centric relation got a bad name is because people thought they were treating the centric relation, and they were jamming the condyles up with no soft tissue protection. Patients didn't do well with that. It really wasn't centric relation. It was a superior condylar position, but it didn't have the soft tissue protection that's inherent in the definition of centric relation. So, centric relation took a lot of bad raps when, really, it wasn't true centric relation.” (15:40—16:14) -Dr. McKee

“We always jump to dessert before we eat the vegetables. We go to treatment before we go to diagnosis. If you notice, all we've done is talk about treatment. The diagnosis is what the first step of treatment planning is. We can't come up with a treatment plan until we know the back end of the system. I can't make a sleep appliance until I know the back end of the system. I can't do ortho until I know the back end of the system. I can't do restorative. I can, and I can guess, and I can hope I'm lucky. But I did that in the early years until I met fabulous teachers who steered me on another track. I saw my friends, who have practiced an entire career now, who never really were fortunate enough to have that guidance. They never enjoyed dentistry. They never felt confident doing the more complicated cases. It was an exercise in frustration for a lot of years. Really, the benefit of understanding these concepts that we're talking about, centric relation, fully seated condylar position, really comes down to predictability in restorative dentistry. And that is, on a day-to-day basis, what keeps dentists up at night, burning stomach lining.” (27:45—29:07) -Dr. McKee

“We send the patient to the orthodontist with a Class II occlusion, and what do we expect two years later? We expect a beautiful Class I occlusion to come back to our office. That's not the real world. We're hanging the orthodontists out to dry. We should never send a Class II patient to an orthodontist unless we've diagnosed it first. That way, we can be an advocate for the orthodontist, not someone who has unrealistic expectations for the orthodontist. The common question is, why doesn't the orthodontist image the Class II patient to see if they have true centric relation? It's our responsibility to manage the occlusion. It's the orthodontist’s responsibility to move the teeth. Now, someone has to do it. But honestly, it's going to put the orthodontist at a competitive disadvantage to the average orthodontists in their community, because now they're going to have to charge a fee for diagnostics, or they're going to not charge for it, which is going to cause a strain on their practice numbers. It makes more sense for us to do it. We're the ones who is going to see the patient long term.” (32:34—33:35) -Dr. McKee

“If you can learn to do this, the number of patients who need diagnosis will keep your assistants busy on a regular basis. Now, this is the patient's best opportunity to get, I think, an accurate prognosis discussion about their treatment. So, it is in the patient's best interest to do this procedure, and it's in our wheelhouse. This is our responsibility. Whether we choose to accept it or not, it's our responsibility. So, it's not as if we shouldn't be accepting this responsibility because it's already ours. We've already accepted it by the fact that we went to dental school. We're the ones in charge of the joint. We need to own it. No one talks about that point, but that is the reality. So that's, I think, the advantage because if you can do that, imagine how valuable you become to the orthodontists in your community.” (34:45—35:46) -Dr. McKee

“We're intimidated by centric relation. That means we don't want to talk anything about the joints. If we understand centric relation, we can understand when we don't have centric relation. And then, we can start to get a little better idea of what our options are. That's where the diagnosis comes. So, screening is really two things. Screening is history and screening is looking at the bite. Those are the two ways to screen for this. They'll tell you, ‘I've clicked and popped for ten years. I clicked and popped since I was twelve years old, and then I stopped when I was 22. I had ortho because I had an overbite. I had teeth pulled when I had my braces.’ That means they weren't growing. ‘I needed a palatal expander when I was ten.’ They're not growing. The likelihood is the disc was off since they were young. ‘I've been clicking as long as I can remember.’ That's a pretty common one. So, they'll tell you. The other thing is, look at the bite. Check their bite in a normal, regular bite and check their bite with the joints in the socket. You can use bimanual for that. You can use a leaf gauge. You can use an anterior deprogrammer that's taken down to the first point of contact. Any way you want to do it is fine.” (36:33—37:46) -Dr. McKee

“If you can't achieve CR, if they're pain free, I'm just going to treat them in a normal bite and we're going to do the best we can. So, if I can get an occlusion that works, it may not be perfect, but I'll tell them that I may have to use composite to pick up some contacts in a couple areas if things don't fit exactly. But if I can get a balanced occlusion and they seem to be comfortable and they seem to be working well, okay. The more the teeth are uncoupled, it usually means the greater the skeletal deficit. We make this about the teeth because we're dentists. The reality is, if the teeth don't fit, it's usually because the skeleton doesn't fit. That's the issue. The teeth are just the markers of the skeleton. They're just the ones delivering the bad news. It's the skeleton that doesn't fit. That's the issue. So, if that's the case, then we have to think about what we can do to try and get the skeleton to fit together, or we get the best fit we can with the teeth and take it as it is. That's why you see bite appliances, because what that does, that gives us a way to bridge the gap with some type of removable appliance to try and help protect the teeth when we can't get the skeletal bases to fit together the way we want them to.” (40:56—42:12) -Dr. McKee

“I'm hoping [centric relation is] not as misunderstood as it was when we started. Centric relation is normal joints in normal joint sockets. If you have it, you have advantages. If you don't have it, then you’ve got to see what the anatomy looks like so you can have a realistic idea of what to talk to the patient about. That's it. It's really about predictability. It gives you confidence when you're treatment planning. I think you talk to patients differently. Patients hear that. So, I think it's an invaluable tool to understand the concept. And I think that, yeah, there's maybe some misconceptions about it. But if you understand the topic, your confidence level on treatment planning is really going to increase, and you'll notice that in your case acceptance.” (48:49—49:38) -Dr. McKee

Snippets:

0:00 Introduction.

2:29 Why centric relation is an important topic.

6:51 Advantages of using centric relation.

10:51 Fully seated condylar position versus centric relation.

14:14 Do we need to use centric relation for everybody?

20:22 What to do if the disc isn't in the right position.

22:50 Disadvantages of not achieving centric relation.

29:08 There's only one true diagnosis.

31:22 Who should manage occlusion?

33:47 How to screen for injured joints.

38:55 The importance of imaging.

40:49 How to treat patients who you can't achieve centric relation for.

42:14 Other treatment options.

46:00 About Dr. McKee’s upcoming occlusion courses.

48:42 Final thoughts.

Dr. Jim McKee Bio:

Dr. Jim McKee is a member of the Spear Resident Faculty. He has maintained a private practice since 1984 in Downers Grove, Illinois, where he treats a wide variety of cases with a focus on predictable restorative dentistry. He is a member of the American Academy of Restorative Dentistry and former president of the American Equilibration Society. He has lectured both nationally and internationally for over 25 years and directs several study clubs. Dr. McKee graduated from the University of Notre Dame in 1980 and earned his dental degree from the University of Illinois College of Dentistry in 1984.
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