PROGRESSION

When your mouth is closed, your disk is dislocated. It goes into place for a second when you open wide enough to click, shift, or pop; and then it goes back out again as soon as you close.  Thus, the vast majority of the time, your disk stays dislocated.  It only goes into place for a second when you open wide enough to click, and then it goes back out again as soon as you close,

The anatomical changes which normally result from disk dislocation make recapture progressively more difficult and eventually impossible over time. The transition from a dislocated disk which is easily recaptured to a dislocated disk which can no longer be recaptured usually takes a few years, but the rate of progression varies a great deal. Some disks which have only been dislocated for a week can no longer be recaptured, and some disks which have been dislocated for a decade can still be easily recaptured.  

 

In most early stages of disk dislocation, the clicking or popping sounds which accompany disk dislocation and relocation when you open and close your mouth are clear, and these sounds can be completely eliminated by holding your lower jawbone slightly forward while opening and closing. You can easily demonstrate this yourself in front of a mirror. When your mouth is closed, your disk is dislocated.  When you open widely enough to click or pop, your disk goes back into place. Then, if you close with your lower jawbone forward so only your front teeth touch (as if you were trying to bite your fingernails), your condyles have not gone back far enough to dislocate the disk again. Thus, the next time you open, there is no click, clunk, or pop made by the disk going back into place, because it is already in place. As long as you can keep your lower jawbone forward, you can open and close repeatedly without hearing any clicks or pops, because the disk stays in place.  Then as soon as you bite back into your regular bite (with your back teeth touching) the disk will go out and the next opening will be accompanied by the clicking or popping sound made by the disk going back into place.

 

In later stages of disk dislocation, disk recapture becomes more difficult. Over time, the ligaments attached to the displaced disk get stretched out, so your lower jawbone can open farther before it has to jump over the back end of the disk, and therefore your lower jawbone must be held farther forward to eliminate the clicking or popping sounds. Eventually your lower jawbone will need to be held so far forward that disk recapturing becomes impossible or at least impractical. At the same time, the displaced disk often becomes misshapen and therefore more difficult to stabilize over time while held in place by oral orthopedic appliances.

 

The only reliable way to determine the shape, condition, and location of the displaced disk is with MRI. X-rays show bones very clearly, and they can detect even small arthritic changes. However the disk is made of fibrous conective tissue rather than bone, so normal X-rays can’t produce any image of the disk. In a special X-ray procedure called arthrography, dye is injected above and below the disk so the presence of a disk can be inferred from the space where no dye goes. However, arthrography can be very painful, because it requires injecting fluid into a joint capsule that is usually already swollen by inflammation, and it uses a lot of ionizing radiation. Therefore most TMJ disorder specialists consider arthrography outdated. MRI is preferred because it does not expose you to any ionizing radiation, it is completely painless, and it gives more clinically useful information – especially regarding disk position and shape. When MRI is used to assess the prognosis for disk recapturing, the images are taken with the lower jawbone in its old natural bite (should show the disk dislocated) and then again with the lower jawbone in the new proposed therapeutic position (should show the disk recaptured). Thus both the pathology and the anatomical correction can be verified. The lower jawbone is supported in the new proposed therapeutic position by a mold of bite putty which I’ll make for you in the office and which you’ll bring to the MRI.  You’ll then save that bite putty because, if the MRI confirms the disk recapture, we can later use that bite putty during the fabrication of the disk recapturing appliances to assure that they hold your lower jawbone in the same position which produced recapture on the MRI.

 

I like to see MRI before undertaking disk recapture, but it costs more than the first phase of treatment. Therefore, in cases where I feel very confident of the diagnosis, you may choose to go ahead with the initial phase of disk recapturing treatment and simply wait a week to be sure that symptom relief is dramatic enough to confirm the diagnosis. At that time, if there is any doubt about the success of the treatment, imaging will be necessary

 

Recapturing a dislocated disk is accomplished by permanently resetting your lower jawbone forward just far enough to prevent your disk from dislocating. In the first phase of treatment, removeable day and night appliances reset the lower jawbone forward. These appliances act like a cast on a dislocated knee or ankle, so one appliance or the other must be worn at all times. Taking the daytime appliance out to eat or sleeping without the night appliance would be like taking the cast off a dislocated knee to run around the block.  After the disk has been in place for long enough to stabilize and an ideal new therapeutic bite has been developed on the plastic bite surface of the daytime appliance, a second phase of treatment is necessary to transfer that ideal new bite from the daytime appliance to the natural teeth so you’ll no longer need a daytime appliance. If this second phase of treatment is not completed, the disk dislocation will almost certainly recur. Since successful disk recapturing involves a commitment to complete both phases of the treatment process, it is important for you to understand all that is involved in both phases of treatment.

 

The goals of phase one treatment are to hold your disk in its proper place, to allow the disk to stabilize in place, and to develop an ideal new therapeutic bite which will keep the disk in place for the rest of your life. In phase one, the disk is held in place by plastic appliances that snap over your back teeth and prevent your lower jawbone from access to a position which will force the disk to dislocate. The night appliance is designed to be foolproof, and the day appliance is designed for comfort.

If the disk recapture is successful initially, it gets progressively easier over time as the disk progressively stabilizes in its proper location. When you first begin the disk recapturing process, your disk will tend to dislocate again relatively easily if the appliances are not worn faithfully, because the anatomy fits together best when the disk is out of place. Before treatment, the disk only went into place for a second or two while your mouth opened wide, and the disk was already out again by the time your mouth closed. Thus, when the disk is first recaptured, it will relapse back out of place easily if given the chance. As your disk is kept in place continuously, the anatomy begins to change so that the disk will no longer dislocate again so easily.  In this manner, disk recapture is like pushing a ball over a hill.  If the disk recapture is successful, the changes which naturally occur in the TMJ anatomy make it more stable over time.  However if the disk continues to dislocate even once a day, it will never stabilize and will eventually dislocate more and more frequently - even with the same day appliance which once held it in place successfully.

The daytime appliance usually consists of two separate tightly fitting right and left halves so there is nothing to impede normal speech.  After one day, nobody will know there is anything in your mouth. However, learning to chew efficiently with the daytime appliance will take a full week, because it requires developing new muscle coordination - much like learning to do something with your left hand that you’ve always done with your right hand. 

 

The night appliance consists of two separate upper and lower segments which completely wrap around all the upper and lower teeth. The two segments are connected by two telescoping mechanisms, each of which is comprised of a tube attached to the upper piece and a rod connected to the lower piece. The rod slides in and out of the tube like a piston. When the rod bottoms out in the tube, the tube and rod assembly acts like a straight arm to prevent the lower jawbone from retruding any further on that side– even with your mouth open. Night appliances must be strong and foolproof, because people do extreme things with their jaws at night.  When the telescopic appliance is adjusted correctly, you cannot produce dislocation of your disk (and the sounds which previously accompanied it), even if you push your lower jawbone backward with your hands.

 

As soon as you begin wearing the appliances, the disk should stop dislocating immediately, and you should be able to open your mouth full wide anytime day or night without hearing the click or pop which was previously caused by the disk going back into place. At the same time, your TMJ disorder symptoms should diminish rapidly. If you still hear any of the clicking or popping noises which were caused by your disk dislocation or if you don’t feel dramatic relief within a week, you should call the office right away, because the treatment is probably not working correctly, and it should be changed immediately or you risk making your symptoms worse.

 

After your joint has stabilized, your day appliance won’t need all its steep inclines, and they can be reduced. Grinding down the steep inclines makes chewing easier, but it must be done gradually. The process usually takes a couple of appointments spread out over the course of a couple of months.

 

Although most recaptured disks are stable after a couple of months, a few stabilize more slowly. These slowly stabilizing TMJs could become dislocated again from a single mistake like falling asleep with the day appliance (instead of the night appliance) or receiving a minor blow to the jaw. If you notice an occasional click or any other indications that you are not stabilizing as quickly as normal, finishing may be delayed for 6 to 12 months.

 

Even if the recapture fails, there's probably about a 50% chance that the return of disk dislocation will bring about a return of symptoms. When disk recapturing first became popular and the finishing (phase two) process was poorly understood in the 1980’s, there were many patients who underwent a successful phase one but then started clicking again during or shortly after phase two. Only some of these patients experienced a return of symptoms. As a result, there are still dentists who advocate “weaning off” the appliances gradually after phase one rather than going through phase two. Although we do not recommend wean-off as a substitute for finishing, if your clicking returns without symptoms, you may want to consider the wean-off option.

 

Once your jaw feels stable and comfortable in its new position, the second phase of treatment frees you from dependence on a daytime appliance by transferring your new bite to your natural teeth.  This finishing step is necessary, because the disk acts like a shim under a table leg. Initially, the dislocation of the disk slightly changed the angle of the lower jawbone so the teeth no longer fit together exactly the same way. Subsequently, the teeth shift in order to recreate a stable bite with the lower jawbone at its new cant. After this shifting of teeth (which may be so slight that it may not be noticed) the teeth only fit together well when the disk is dislocated. When recapture puts the disk back between the bones, it creates a small gap between the back teeth. The appliances keep the disk in place partly by perfectly filling that gap. If the appliances are removed before the gap is filled on a permanent basis, the back teeth won’t touch until the lower jawbone is forced back to its old position and the disk will get dislocated again. Thus, to keep the disk in place permanently, the gap between the back teeth needs to be filled permanently.

 

The choice of what type of finishing is best for you depends largely on your dental condition. Teeth that have never had fillings may be moved with removeable functional orthodontic appliances (much like retainers) which can hold the lower jawbone in correct position while moving the teeth to support it there. Teeth that already have fillings are usually built up rather than moved, because they will need crowns or onlays someday anyway. Dentures or partial dentures can be modified or remade to the correct bite.

 

When all the natural teeth are present, the transfer of the new therapeutic bite to the natural teeth usually involves building up the bite surfaces of the individual back teeth to the same height and contour as the bite surface of the daytime appliance. In most cases, either upper or lower back teeth are involved. Rarely is it necessary to build up both uppers and lowers. After transferring the new therapeutic bite to the natural back teeth, each individual back tooth looks and acts like a normal tooth, except that its top is a carefully designed orthopedic bite surface which supports your lower jawbone in its ideal position.

 

The most inexpensive way to rebuild the bite is with a tooth-colored plastic filling material called composite resin. It bonds with tremendous strength to enamel, and it provides some structural reinforcement for teeth that have been weakened by fillings. No shots or drilling are needed.  However, composite resin cannot be considered a permanent filling material on molars in people with strong jaws, because it will chip or wear down over time. Eventually these teeth will still need crowns or onlays to bind them together as a structural unit that cannot fracture.  

 

Crowns and onlays can be made of porcelain which has excellent esthetics but also three important disadvantages. First, porcelain needs bulk for strength, so preparing a tooth for a porcelain crown or onlay requires significant tooth reduction which increases the chance of the tooth later dying and needing a root canal. Second, porcelain causes wear on whatever natural teeth it contacts. Third, it is very difficult to create an accurate bite surface with porcelain, because the porcelain must be initially made too high and then ground down until it is no longer too high, rather than being molded to fit correctly in the first place.

 

Gold is the ideal material for reconstructing bite surfaces, because it is extremely accurate, it is strong even when thin, and it has a hardness very similar to natural tooth structure – which minimizes wear. In addition, gold can be bonded to enamel with impressive strength. A tooth with a large filling can often be permanently restored with a gold onlay instead of a crown.

 

An onlay is somewhat less expensive than a crown, and the process is much less traumatic because the tooth does not need to be drilled down to a stump. Reduced drilling diminishes the chance that the tooth will eventually need a root canal. Thus gold onlays on the molars are frequently combined with composite resin onlays on the premolars.

 

Finishing can be performed at the TMJ Clinic or by your general dentist. Your dentist already knows your teeth and will maintain them long after disk recapture is completed, so it’s best for you to have your dentist involved if he or she is willing and able to take the extra time and care required to accurately create and maintain the new therapeutic bite.  We will be glad to provide all the support and information needed. However dentists are trained to precisely duplicate bites, not to change them, so some dentists will not be confident that they can change the bite correctly.  In these cases we often do the finishing on a provisional basis with composite resin or temporary crowns so you dentist can later replace them one or two at a time by duplicating the provisional therapeutic bite.

 

In young people who do not have more than a couple of fillings, finishing may be accomplished at least partly by orthodontics.  Braces make it difficult to wear a night appliance, because they are generally esthetic tools rather than functional tools, and they make it difficult to wear a removeable appliance at night, so most TMJ disorder specialists perform orthodontics using removeable appliances which can move the teeth while maintaining proper lower jawbone and disk position. In some cases, front teeth which are in the way of the new therapeutic jaw position are tipped out of the way with springs. In other cases, the back teeth are raised one or two at a time by using their natural tendency to erupt whenever they are no longer held down by the bite. This so-called “passive eruption” process is very inexpensive but also very slow. It can be hastened by attaching little buttons to the teeth and then using rubber bands to pull the erupting teeth toward each other (active eruption).  

 

The drawback of orthodontic finishing is that, after teeth have been moved, they are not stable for up to a year. If they are not adequately retained, nocturnal clenching or grinding may be able to re-intrude them, driving them back into the bones so they lose some of their height. This loss of height may allow relapse of the pathologic lower jawbone position and possibly redislocation of the disk. Therefore stabilizing the bite after orthodontics by shaving down high spots or adding small amounts of composite resin to low spots as well as using a retainer every night are important for maintaining the disk recapture.

 

Whatever the means used for finishing, it will still be necessary to keep wearing the night appliance for at least a year. After that time, you may experiment with wearing the appliance every other night to see if you notice some tension returning. If, after a couple of months, you notice no tension, you could reduce your wear to twice a week and again watch for tension.

 

Even if you feel like you may not need to wear the night appliance at all, using it one night a week is an easy way to be sure that the problem will not return. The one night a week of appliance wear breaks up the cycle of jaw muscle tightening – increased TMJ pressure – and more jaw muscle tightening. It is this cycle which probably caused the disk to get dislocated in the first place, and recurrence of the same cycle can cause a redislocation long after that disk has been recaptured. The periodic wearing of the night appliance also maintains the fit of the night appliance so you can count on being able to use it right away if you ever need it because of an injury to your jaw, a period of excessive central nervous system stress which causes excessive tightening of your jaw muscles along with the rest of your muscles, or the stress to the jaw muscles from a long dental appointment.

 

The initial cost of fabricating the normal day and night disk recapturing appliances is $1250. This cost includes one appointment for a follow-up evaluation which should be done within two weeks to be sure the treatment is working correctly.  This first phase of treatment is usually covered under the medical portion of your health plan. The costs for finishing vary from $800 for adjusting bites by selectively drilling down some teeth and building up others with composite resin to several thousands of dollars for crowns or onlays on 6 or 8 back teeth.