Rethinking Equilibration

Greetings again! The following is the third in the series of articles on various aspects of dentistry derived from my years of experience in a TMD head, neck and facial pain practice.

Rethinking equilibration—before you grind on teeth to correct the bite, please consider this.

“What must be understood is that occlusal alterations that are not accurately performed, are incomplete, or are done on patients with active intracapsular TMDs (italics mine) can and often do result in more serious signs and symptoms.”
~ Peter E. Dawson, Functional Occlusion From TMJ to Smile Design.

It’s Sunday, October 2nd. It’s a nice sunny Southern California day, a day perfect for a barbecue, a trip to the beach, a ride in the country…or looking over material for another newsletter, or blog, or whatever this turns out to be. As I review my list of you—the readers—I’m concerned that I may be preaching to the choir. You personally may already know the following material very well. And yet, I see enough problems from bite adjustment, that this might just be useful. You wouldn’t touch a diamond spinning 400,000 rpm to the teeth if you think an articular disk might be out of place? You’re correct. Take the day off. You’re not sure? Read on.

Let me introduce Carol. She’s a fairly typical TMD patient. She’s 48 years old, suffers from jaw pain, headaches, and pain when chewing. But there is one twist. She says her dentist told her he could solve her pain problems with a proper bite adjustment. Even a quick, almost cursory look displays heavy diamond marks on several posterior teeth on the left side. And not just on inclines either. Whole cusp tips look like they’ve been wiped out with a coarse diamond. The result according to T-Scan is fairly well balanced occlusion right to left. Had to be the right thing to do, correct? But what if it wasn’t about the teeth? Hang in there. You’ll soon see what I mean.

Now I think we should consider what equilibration is. It’s a rather minor reshaping of inclines to eliminate interferences to lateral and protrusive function and to eliminate interferences to comfortable closure—I guess you could call that centric relation. It does not mean reducing the cusp tips (centric holding cusps, sometimes referred to stamp cusps) that maintain vertical dimension. But in Carol’s case, there had been wholesale reduction of lingual cusps of the upper posterior teeth and buccal cusps of lower molars aimed at correcting very high occlusion on several natural posterior teeth on one side.

“How did it work out for you?” I asked Carol.

“It didn’t, “Carol tells me. “I still have exactly the same pain.”

It occurs to me that among the lay public, and even among many physicians, and some dentists, there is a total conceptual disconnect between the joints and teeth. They can conceive of no possible connection between the teeth and joints. As if the joints are Connecticut and the teeth are Miami Beach. Yet, how can such a thing possibly be? The mandible is one bone. At the distal ends of the mandible are the two condyles. Think of each of them as the ball, in a ball and socket joint, although the TM joint is far from that simple. Now on top of each condyle sits an articular disc made of cartilage. This forms a condylar-disc assembly. The discs keep the condyles separate from the temporal bone, and provide lubrication and smooth movement. Think of the discs as shock absorbers.

In Carol’s case, joint images show the left condyle displaced so far up and back that the mandible and temporal bone appear to touch. And, what happened to the teeth? It’s vitally important that you visualize that the mandibular teeth also move up and back.

I show Carol her joint images. Right condyle well centered in the glenoid fossa with good disc spacing. Left condyle is apparently touching bone up and back in the glenoid fossa. Joint vibration analysis shows joint noises consistent with a piper Stage IV anterior disc displacement on the left side.

“Think of it this way,” I tell Carol. “The disc is a shock absorber. You lost the shock absorber on the left side. The whole lower jaw then moved up and back on the left. And of course the teeth went along for the ride. Result? You felt the left teeth hitting first and hitting hard every time you closed.” I lose a lot of patients and even a few dentists at this point. “How can the disc displacement affect the teeth? I don’t get it.” Okay, take some time to think about it. The joints and the teeth are part of the same bone. The bone went North on the left and so did the teeth.

But Carol gets it. “So that’s why, all of a sudden, I mean almost overnight, all my left back teeth were hitting hard!”

“Exactly. Now, I can get that shock absorber back in place. There’s an excellent chance that your pain will go away and the joint will stabilize. But now there’s another problem we’ll have to see about later.”

Carol ponders that one for a few seconds and then I can see the light of understanding in her eyes. “When we’re done, my back teeth won’t meet on that side. He took too much away.” Carol is smarter than most. The majority of patients don’t see it, at least not right away.

“That’s right. Actually, taking any tooth structure away was too much in your case. There never was a problem with the teeth or the bite as far as I can tell. It was a displaced disc. When the joint is corrected and the pain goes away, I’ll have to see how much tooth structure needs to be added. I think it could mean a couple of crowns and composite bonding.”

“You know,” Carol says, “I didn’t think it was right at the time. Darn.”

Darn, indeed. This is a scenario that’s repeated in my office at least a couple of times a month. I know we were all taught in school that if there’s a high spot, grind it down. If there’s an interference to normal closure, get rid of it. If there’s pain, it’s probably an occlusal problem. Put a diamond in your handpiece and fix it.

But as Mark Piper teaches in his Joint Centered Dentistry courses, it’s possible that our thinking in dentistry has been backwards. What if it was not the malocclusion that caused the pain, but the painful joint problem that caused the malocclusion? And which is most common? I don’t know the answer to that last question. But, I can tell you that it’s routine in my practice to see an anterior displaced disc on one side and the posterior teeth hitting first and hardest on that side.

And unfortunately, it’s also common to I see diamond tracks on the occlusal surfaces of the teeth on that side, including the upper lingual cusps and lower buccal cusp tips. To paraphrase Pete Dawson, if there’s an internal derangement of the joint, leave the darned teeth alone! Don’t grind on them!

Does that mean that bite adjustment is always wrong? Of course not. But, how do you know it’s the correct action? When a patient comes to my office, I do a physical exam of the head and neck—including joint loading—I get joint images and I check the occlusion with T-Scan. There are times when the joint images display a perfectly normal architecture and there is no joint pain on palpation and no pain on joint loading. Now I look to the occlusion. If there are prematurities or occlusal interferences, I send a print-out of the T-scan results to the referring dentist to guide bite adjustments.

Sometimes, there’s a joint problem and an occlusal problem. If there is joint pathology, I want to correct that first, then evaluate. Most of my patients require no correction of the occlusion after appliance therapy. Some require equilibration. Some require restorative dentistry, even full mouth reconstruction or orthodontics. But those patients are in the minority.

For your patients who have muscle and/or joint pain and obvious occlusions problems, I strongly suggest you evaluate the joints. If there is someone in your area who can do a thorough evaluation of the joint, including joint images, send your patient there first. Or take some classes and learn how to interpret joint images and evaluate the patient yourself. I see too many patients who require whole quadrants of dentistry to undo the damage done by unnecessary—and inappropriate “equilibration”. Equilibration is in quotes because it’s not really equilibration by anybody’s definition.

Please feel free to call or email us with your comments about this article as well as suggestions for future articles.

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