Managing the Arthritic TMJ

SUMMARY

Over time, a TMJ with a dislocated disk develops bone spurs, erosions, lipping, or flattening that make it fit the definition of an arthritic joint.  It may even have undergone extensive arthritic changes.  That label makes the condition sound serious, but the prognosis may still be excellent. These joints eventually heal by a natural adaptation process in which the chronically bruised retrodiskal (behind the disk) tissues transform into a pad of disk-like tissue which can look and function so much like a true disk that it is called a “pseudodisk”.  To enable pseudodisk formation and resolution of their symptoms, most patients just need a stable natural bite and the right type of joint protective oral appliance to wear during sleep.

NATURAL ADAPTATION
TMJ disorders are self-limiting because of natural adaptation. Studies of tens of thousands of patients have shown that the natural course of a TMJ disorder consists of gradual arthritic changes accompanied by symptoms that fluctuate for years and then eventually disappear with age.  
 
The symptoms disappear, because the TMJs adapt by fibrosis of the retrodiskal tissues.  In a normal TMJ, the retrodiskal tissues contain extensive blood and nerve supply. After the initial dislocation of the disk traps them between the lower jawbone ends (the condyles) and the skull, they develop all the characteristics of a chronic bruise - swelling, heat, pain, and blood leaking out of the vessels and into the tissues. However eventually the retrodiskal tissues adapt to repetitive bruising by transforming into a fibrous pad of scar tissue called a pseudodisk, as seen below. 
 
Pseudodisks look and function so much like normal disk tissue that, for many years, surgeons mistook them for normal disk tissue.  Surgeons removing problematic TMJ disks were routinely diagnosing them as elongated.  However, researchers pointed out that TMJ disks are made of collagen and cannot simply elongate.  Finally microscopic examination of these reportedly elongated disks showed that their rearmost portions contained remnants of blood vessels - proof that these areas were not originally disk tissue but were actually composed of retrodiskal tissues that had lost their blood supply and fibrosed.
  
ORTHOPEDIC TREATMENT
Protecting the retrodiskal tissues requires the use of oral appliances that control the position of the lower jawbone to prevent the condyles at its back ends from access to the retrodiskal areas, especially during the powerful clenching and grinding that occur as part of normal sleep.  TMJ protection during sleep can be provided by wearing a stabilization appliance or a telescopic appliance, both of which are described in separate papers on this website. 
 
Within the limits of movement needed to protect the inflamed TMJ tissues, joint protective oral appliances should allow a range of motion of the lower jawbone that is as wide as possible.  Joints depend on movement for their circulation.  To maximize TMJ circulation without sacrificing TMJ protection, the range of movement should be restricted only in the direction and to the degree necessary for healing.  
 
PIVOTING
When only one TMJ is inflamed, rapid short-term relief can be produced by adding a pivot to the rearmost section of the affected side of an oral appliance, a denture, or the natural teeth. The pivot is a high spot which hits slightly before the other teeth. Squeezing the jaw closed against a pivot produces a slight prying down of the back end of the lower jawbone (the condyle) in the TMJ on the side of the pivot. Such direct mechanical distraction relieves compressive forces and allows increased circulation into the injured TMJ. Pain relief should be almost immediate.
 
Pivoting is a temporary measure, because pivots eventually wear down or cause intrusion of the two teeth supporting the pivot. Thus pivoting must be considered a short term solution for an acute problem rather than a long term strategy.
 
BITE TREATMENT
To permanently resolve a TMJ disorder requires a stable natural bite.  All the body’s joints maintain a remarkable goodness of fit between the opposing bones, because functional forces trigger cellular activity which continuously remodels bone contours until pressure is perfectly distributed between them at rest and during function. For the lower jawbone, functional movements and even the resting position are controlled by the natural bite. Therefore, for the TMJs to acquire a perfect fit between the opposing bones, the natural bite must provide a consistent and centrally located bracing position for the lower jawbone as well as smooth consistent chewing pathways in and out of it. If the bite keeps shifting even slightly, the bony contours of the TMJs must constantly alter their shapes by remodeling to try and fit a moving target.
 
In many people with TMJ disorders, the bite has been destabilized by either the dislocation of the disk or ongoing TMJ degeneration that causes loss of height in one or both of the condyles.  The resulting change in the angle or cant of the lower jawbone can disrupt the fit of the teeth.
 
SUPPORTIVE TREATMENTS
After the vulnerable TMJ is protected from chronic bruising, supportive treatments such as exercises, stretches,  massage, jaw muscle retraining, drugs, psychological counseling, acupuncture, biofeedback, and various relaxation strategies can help eliminate any remaining symptoms.  
  
COSTS
Joint protective oral appliances cost from $1100 for a stabilization appliance to $1500 for an adjustable telescopic appliance. The cost of treating the bite depends on the time involved.  
 
CONCLUSION
Having a permanently dislocated disk does not condemn you to a lifetime of pain. There are millions of people who have asymptomatic dislocated disks. They bite, chew, open, and close without pain or limitation, because the damaged TMJ has undergone an adaptation which restores normal function. In the natural course of a TMJ disorder, that adaptation occurs eventually in everybody (except some surgical failures), but it might take years. Oral orthopedic treatment can greatly facilitate that adaptation process and thereby quickly relieve the symptoms.