Recapturing the dislocated disk

SUMMARY

In early stages of forward disk dislocation, orthopedic treatment may be able to restore normal disk position in a process known as disk recapturing.  The process involves permanently resetting your lower jawbone forward just far enough to prevent your disk from dislocating.  In the first phase of treatment, a sophisticated telescopic night appliance and a tight fitting thin inconspicuous day appliance are used to reset the lower jawbone forward. After the disk has been held in place for long enough to stabilize and a 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 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, and the symptoms will likely recur.  

Disk recapturing creates rapid relief, because it immediately and permanently stops the repetitive dislocation that is ultimately responsible for the symptoms.  However, the finishing phase of the disk recapturing process requires permanently changing the bite, which can involve significant dental work.  If the dental work was not also needed for other reasons anyway, such as replacing old fillings or missing teeth, this dental work can be a significant otherwise unnecessary expense.  Thus, if you are considering disk recapturing, the severity of the symptoms and the ability to relieve them with simple treatments (such as wearing a stabilization appliance during sleep) need to be weighed against the time and expense ultimately required for dental work to change the bite. Because of these considerations, before you undertake disk recapturing, you need to understand the protocol you will need to follow and the way that completing the process will affect your teeth.

 YOUR DISLOCATED DISK

When your mouth is closed, your disk is dislocated. It goes back 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 is dislocated.  Below is an illustration of the sequence of disk dislocation and relocation during opening and closing.

                                                     MOUTH FULLY CLOSED 

                                                        MOUTH FULLY OPEN

NATURAL PROGRESSION OF THE DISK DISLOCATION 

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

In most early stages of disk dislocation, the clicking or popping sounds are clear, and they can be completely eliminated by holding your lower jawbone slightly forward while opening and closing.  The opening click or pop puts the disk back into place, and it stays in place as long as you can keep your lower jawbone forward, because your condyles have not gone back far enough to dislocate the disk again. Subsequently, each time you open, there is no click or pop made by the disk going back into place, because it is already in place.  Then, as soon as you bite back into your regular bite with your back teeth touching, the disk will go back out again, and the next opening will be accompanied by the clicking or popping sound made by the disk going back into place.

Over time, disk recapture becomes progressively more difficult and then impossible.  As the ligaments attached to the dislocated disk get stretched out, 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 impractical.  Also, disks that are dislocated sideways or misshapen are more difficult to recapture.

IMAGING 

The only reliable way to determine the shape, condition, and location of the dislocated disk is with MRI. X-rays show bone shapes clearly, but changes in bone shape are not well correlated with symptoms.  In addition, many arthritic changes seen on X-ray occurred long ago and no longer have any relevance to the clinical condition or its treatment.  The disk is made of fibrous conective tissue, so it can't be seen with X-rays unless dye is injected above and below the disk, and the presence of a disk can be inferred from the space where no dye goes. However, this arthrography procedure 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 arthrography is outdated. MRI is preferred because it is safe, painless, and more clinically useful. 

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 before the correction is undertaken. The lower jawbone is supported in the new proposed therapeutic position by a mold of bite putty which Dr. Summer will make for you in the office and which you’ll bring to the MRI.  If the MRI confirms the disk recapture, we can 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.

We like using MRI to confirm both the disk displacement in the old bite and its recapture in the new bite using MRI, but the MRI costs more than the first phase of treatment. Therefore, when the diagnosis can me made with good confidence on the basis of clinical signs and history, 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.

PHASE ONE TREATMENT

The goals of phase one treatment are to hold your disk in its proper place while it stabilizes there and to develop an ideal new therapeutic bite which can be later used for finishing.  During this initial phase of treatment, the disk is held in place by a combination of day and night appliances.  The daytime appliance usually consists of two separate tightly fitting right and left side pieces with no midline plastic to impede normal speech.  Within a day, then nobody will know there is anything in your mouth.  The night appliance is sophisticated and foolproof, because it must provide absolute protection for the TMJs during nocturnal clenching and grinding when the jaw undergoes great pressure.  Together 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.

As soon as you begin wearing the appliances, you should be able to open your mouth full wide anytime day or night without hearing the click or pop that 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 previous clicking or popping noises or if you don’t feel dramatic relief within a week, you should call the office right away, because the disk recapturing treatment is probably not working and should be changed immediately to "off the disk" treatment.

As the disk is held continuously in place, it progressively stabilizes. When you first begin the disk recapturing process, your disk will tend to dislocate again relatively easily if the appliances are not worn faithfully.  After your disk has been in place for weeks continuously, the anatomy of the TMJ changes 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, it becomes 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 that once kept it in place.

Assuming your initial few weeks of disk recapturing has been successful and your TMJ has begun to stabilize, your day appliance won’t need all its steep inclines, and they can be reduced. Shallowing the inclines makes chewing easier, but it must be done gradually.  It usually takes a couple of appointments spread out over the course of a couple of months.

A few recaptured disks stabilize slowly and could become dislocated again from a single mistake like falling asleep with the day appliance or receiving a minor blow to the jaw.  It is difficult to identify in advance which people will have slowly stabilizing disks.  If you notice an occasional click or any other indications that you are not stabilizing as quickly as normal, finishing may be delayed.

Even if the recapture fails, the symptom relief often lasts. 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 about half of these patients experienced a return of symptoms. As a result, there are still dentists who advocate “weaning off” the appliances after phase one even though the disk will eventually redislocate. 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.

PHASE TWO (FINISHING)

Once your jaw feels stable and comfortable in its new position, the second phase of treatment frees you from dependence on a daytime appliance.  This finishing step is necessary, because the disk acts like a shim under a table leg. Initially, the dislocation of the disk removed the shim and thereby slightly changed the angle of the lower jawbone so the teeth no longer fit together exactly the same way. Subsequently, the teeth shifted in order to recreate a stable bite with the disk dislocated.  When recapture puts the disk back between the bones, the addition of the shim creates a small gap between the back teeth. The daytime appliance keeps the disk in place by temporarily filling that gap. Later the gap will need to be filled on a more permanent basis, or the daytime appliance will wear out and the lower jawbone will be gradually forced back into its old position until the disk gets dislocated again. 

The choice of what type of finishing is best for you depends largely on your dental condition. The cheapest option is a cast metal overpartial - a permanent metal version of the removeable daytime appliance. The best option for people with multiple large fillings is crowns or onlays made to support the new bite.  Options for many people who have healthy teeth include composite resin build-ups and functional orthodontics.

THE CAST METAL OVERLAY PARTIAL

The removeable metal bite restoring appliance known as an overlay partial denture looks like a car bumper and will last forever.  It's advantages are that it rips and tears food effectively, and it is relatively inexpensive ($1900).  Usually if fits on the lower teeth where it doesn't show much.  However, your bite will still be dependent on a removeable device.  If you lose it, you will have no bite and eventually your disk will become dislocated again.

The cast metal overlay partial can be gradually replaced by building up the teeth as described below.  One portion of the bite surface can be cut off and replaced by building the underlying teeth to the correct height, and then other portions of the bite surface are cut off and replaced one or two at a time until the cast metal overlay partial is no longer needed.

BUILDING UP TEETH

When all the natural teeth are present, transferring the new therapeutic bite onto them often 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.  Although it would often be ideal to build up both upper and lower teeth, it is rarely necessary. 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, because it will chip or wear down over time, and will need to be maintained by your general dentist.  Chips or even repairing a cavity beneath a composite build-up does not require replacing the whole build-up, because the material bonds to itself and to tooth structure, but eventually these teeth will still need crowns or onlays to bind them together as a structural unit that cannot fracture.  

The best way to rebuild a bite is with crowns and onlays made of porcelain or gold.  Porcelain has excellent esthetics, but the lab process required makes it difficult to create an accurate bite surface, 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.   For a combination of esthetics, function, and economy; gold onlays on the molars are frequently combined with composite resin onlays on the premolars which are smaller teeth and are exposed to smaller biting forces than molars.

Ideally your general dentist should make your crown or onlays, because he or she knows your teeth and will later need to maintain them.  However dentists are trained to precisely duplicate bites, not to change them.  To make their job easy and predictable, we usually do the finishing on a provisional basis with composite resin.  Later your dentist can replace the resin a couple of teeth at a time with permanent crowns or onlays.  Replacing even a couple of resin build-ups with crowns or onlays greatly reduces wear of the composite on the rest of the teeth.  

ORTHODONTICS

In people who do not have fillings, finishing may be accomplished at least partly by functional orthodontics which uses removeable appliances rather than braces.  The removeable orthodontic appliances can contain orthopedic portions which can maintain proper lower jawbone and disk position while moving teeth with springs and wires so they can ultimately support the lower jawbone in the same position. In some cases, front teeth which are in the way of the new therapeutic jaw position are tipped out of the way with finger 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 (passive eruption) or by attaching little buttons to the teeth and then using rubber bands to pull the erupting teeth toward each other (active eruption).  

The main 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, eliminating some of their height, and allowing relapse of the pathologic lower jawbone position and redislocation of the disk. Therefore, after the orthodontics is complete,  stabilizing the bite and using a retainer every night are important for maintaining the disk recapture.

FOLLOW-UP CARE

It's recommended that you continue to wear the night appliance on a long term basis to protect the teeth and the TMJs from the effects of nocturnal grinding and clenching, as well as to maintain the fit of the night appliance.  Maintaining the fit of the appliance ensures that it stays available to you as a tool and you can use it right away if you ever need it because of TMJ trauma or a period of excessive central nervous system stress producing excessive tightening of your jaw muscles.

COSTS

Normally a telescopic appliance costs $1300, and a set of daytime bite restoring appliances costs $1100, but for disk recapturing, the initial cost of fabricating the appliances is reduced to $1900.  The costs for finishing vary from several hundred to several thousand dollars.  These finishing costs are usually covered under the dental portion of your health plan, especially if the teeth already have old fillings.