I get some of my best ideas much as Wordsworth did: while walking. Okay, maybe some not so good ideas as well, I admit. This morning, while walking on the bluffs of Torrey Pines, California, this idea popped into my head.
“Andrea, I know the title of my next article.”
“Oh? And what’s that?”
“Equilibration without a clue.”
“Well, that might p*** some dentists off.”
“So be it.”
I know that generalizations are generally unfair, you know, as a general rule, but over the past year or two I have seen more and more dentists attempting bite adjustment (equilibration) and ending up with questionable, poor, or down-right disastrous results. In short, many dentists don’t have a clue how to do equilibration, nor do they know what to do when the process lands them in trouble. Many don’t know when equilibration is appropriate vs. when they had better not touch the bite at all.
Your Patient’s bite is very important. Don’t take it away from her! ~ Dr. Clayton Chan
Print that statement out and paste a few copies up in your operatories and on your bathroom mirror. Seriously.
And of course there is 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.
Equilibration has fallen out of fashion among many in dentistry over the last two decades, and that is not necessarily a good thing either. As a blurb from the Dawson Academy states:
“Dentists who have developed proficiency in equilibration universally agree it is one of the most practical skills they use routinely . . . ” http://thedawsonacademy.com.
I personally attended several courses at what is now called the Dawson Academy in the 1980s (I know, ancient history to you young guys, right?) And the indications and exact sequence of adjustments as taught by Dr. Dawson were extremely valuable.
Assuming the concepts taught at the Dawson Academy have remained pretty much the same over the years, you can be sure that what is taught there is miles ahead of whatever you learned in dental school.
Another excellent teacher in dentistry today is Dr. John Kois. His Course II deals with equilibration and certainly his teaching far outshines anything you might have learned in school.
If you want to use 21st century technology for your occlusal analysis, I’d recommend a course in occlusal analysis and correction with Dr. Robert Kerstein, utilizing the Tekscan system. I use T-scan every day in my practice and truly think that computerized occlusal analysis will become standard of care one day.
I have several patients in my practice presently who illustrate my point about disasters in bite adjustment. One young lady came to my office as a new patient only yesterday. She had many of the symptoms of TMD including masseter muscle pain and limited opening. Her dentist had told her that she needed her bite adjusted and proceeded to do a few visits of equilibration. After each session she told him that her bite felt worse, not better.
He told her it was all in her head, and that her bite was perfect.
When she came to me she said that she only felt her right side teeth touching when she closed and that she couldn’t make her teeth touch on the left side (click on graphic to see larger image).
As you can see, her perception was pretty close to reality. Eighty percent of her occlusal force is on the right side back teeth. Her left side teeth meet with only 20% of total force. It is true that the teeth on the left side do touch, but with so little force, that to her it feels as if they don’t touch at all.
When I looked at her occlusion the old fashioned way, with articulation paper, I could not see any marks on the left side. Why her dentist thought he had done equilibration, i.e. equalizing occlusal force left to right, I have no idea. Is this a disastrous result or am I overstating things? Well, thanks to her dentist’s “equilibration” this young lady is facing extensive restorative dentistry and/or orthodontics.
Another recent patient, again someone who came in because of TMD symptoms, told me she had no problems until her dentist adjusted her bite.
“I just had this little filling on the upper right, and when the dentist was done with the filling he said, ‘Oh, I’m also going to even out your bite.’
“I told him my bite was fine and please don’t do anything. But he said, ‘Oh you’ll love it. It will feel a lot better.’ So he went ahead and ground on a bunch of my back teeth. When he was done, it felt awful.” (click on graphic to see larger image)
It felt awful because it was.
Are these rare and isolated cases? While I hope that is the case, I can tell you that in my practice I hear stories like these and see results like these almost daily.
Am I going to teach you how to do equilibration in these pages? No. But I can offer a few guidelines.
First and foremost I’d be very cautious about altering occlusions at all. Is it necessary at times? Yes. But be slow to reach for your diamonds and your handpiece.
Second, in general (I know, generalizations again) you can trust your patient’s proprioception. If your patient states she’s hitting hard on one side, she probably is. Yes, there are those people whose perception does not match reality, but they are few.
Next, have a few tools beyond the basics in your toolbox. I typically use blue articulation paper when marking centric occlusion and a fine red (such as Accufilm® by Parkell) marking paper for excursive movements. The contrast of red vs. blue is quite distinct and usually easy to differentiate.
I also use shim stock on a daily basis. Is the tooth in occlusion or not? Does that new crown contact when the patient goes into excursive movements? Your patient tells you that her last two molars on one side don’t seem to touch when she closes. Is she correct? Place a piece of 8 mm wide shim stock over the occlusal surfaces and ask her to firmly close. Can you easily pull the shim stock through? If so, then your patient is correct, even if your articulation paper shows a mark you can be sure that there is no actual contact.
There are quite a few excellent articles in the dental literature on the use of shim stock. I’d recommend a Google search on the subject then read up.
Checking and adjusting occlusion should be done with the patient sitting upright whenever possible—you’ll find that the occlusion when your patient is upright is quite different from the occlusion when she is reclined. You adjusted with your patient lying back? Fine. Now check it when she’s upright and re-adjust for comfort.
Generally, when doing bite adjustment, you would be wise not to reduce the functional cusps, i.e. buccal cusps of the lowers and lingual cusps of the uppers. One of my current patients had all functional cusps of the posterior teeth reduced in an effort to reduce TMD symptoms. This resulted in a decrease in vertical dimension and posterior displacement of both mandibular condyles and a tremendous worsening of TMD. An MRI post bite adjustment shows complete anterior displacement of both articular discs. Did she have disc displacement before “equilibration?” That’s hard to say. But whatever her situation was before bite adjustment, it was certainly worse after.
In short, I don’t think you can correct a disc displacement with your donut diamond, but you sure could create one.
The take home lesson here is that bite adjustments have to be done with lots of finesse. It’s an art and science. There are some obvious indications, most commonly those gross working and balancing side interferences upon lateral excursive movement. You do need to decide though whether it’s best to adjust the interference or add to the cuspids—it’s often best to look carefully at the canines. Are they badly worn? Then bond composite to the lingual of the maxillary canines and avoid grinding away on the inclines of the posterior teeth. Will it require only minor adjustment on a couple of back teeth to relieve the interference? If so, by all means adjust.
Do you believe the person needs extensive bite adjustment? I recommend you do a careful facebow mounting of study models and do your equilibration on those models. True, the articulator does not duplicate the motion of the patient’s mandible, but you will have a good idea how the bite adjustment will go. Doing this exercise has sometimes led me to the conclusion that equilibration would not solve the obvious bite problems; instead, orthodontics would offer a better treatment choice.
That, ladies and gentlemen, means it may be best to keep your handpiece in its holder. An orthodontic consult would make more sense in situations like that; or perhaps addition (bonded composite or crowns) instead of subtraction. Best not to be stuck grinding tooth after tooth when you thought you were just going to reduce an incline on one tooth.
And of course be aware that you may be dealing with a true TMJ problem with anterior disc displacement. In those cases, I would not recommend occlusal adjustment at all (See “Rethinking Equilibration”).
Have you been to the Dawson Academy or Kois? It would be worth looking into programs such as those before trying to balance out an occlusion. I know that God creates a few million perfect bites every day, but for us mere humans, it’s just not easy. Some advanced C.E. is always a good idea.
In short, the process of getting the bite just right is harder than it looks. And as Pete Dawson famously stated, equilibration incompletely or inaccurately done can result in serious signs and symptoms—that is you might just make your patient worse. Unfortunately, I see that result almost daily. Want to do some bite adjustment? Be cautious. And if in doubt, don’t be shy about referral to a good prosthodontist or orthodontist.
