SUMMARY
Over time, a TMJ with a dislocated disk usually develops bone spurs, erosions, lipping, or flattening that make it fit the definition of an arthritic joint, which makes the condition sound serious, but the prognosis may still be excellent. In fact, there is little correlation between X-ray findings and symptoms, because even severely damaged TMJs 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 called a “pseudodisk”. To enable this process of pseudodisk formation and resolution of symptoms, most patients just need a stable healthy (unstrained) natural bite and the right type of oral orthopedic appliance to wear during sleep, especially during times of increased stress when nocturnal bruxism is most severe and the condyles at the back ends of the lower jawbone get worked up into the TMJs with strong forces.
TMJ ADAPTATION
The natural course of a TMJ disorder consists of initial pain and bite change followed by adaptive remodeling as part of a healing process that makes the damaged TMJ once again function like a normal TMJ and eliminates any symptoms that were due to the condition of the joint itself (not necessarily muscle symptoms). Successful adaptation may take hours or decades, but it almost always occurs by middle age. Subsequently, some jaw muscle symptoms may persist as a subset of postural muscle strain, because the mandible is part of the postural system; and some ear symptoms may persist long after the cause is gone, because the inner ear does not recover well from injury.
The adaptation is due to fibrosis of the retrodiskal tissues. These tissues, that once provided blood and nerve supply to the TMJ from the area just behind its disk (retrodiskal area), get pulled by the dislocation of the disk into the former disk space, where they respond to the pounding of the condyle during chewing by converting into a pad of tough scar tissue called a pseudodisk. That process constitutes a complete healing of the damaged TMJ. Pseudodisks look and function so much like normal disk tissue that, for many years, surgeons mistook them for normal disk tissue and routinely diagnosed the disks they removed as elongated; until a group of researchers pointed out that TMJ disks are made of collagen and cannot 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 fibrosed connective tissue. The conversion process is pictured below:
Oral orthopedic appliances worn during sleep, when the jaw system undergoes its nightly workout, can facilitate the conversion so that full adaptation occurs within days or weeks rather than years. The type of oral orthopedic appliance that you need depends on the condition of your TMJs, the state of your jaw and neck muscles, and your facial growth pattern.
JOINT PROTECTIVE ORAL APPLIANCES
If a TMJ is still inflamed, it first needs to be protected by preventing the mandibular condyles from accessing the bruised retrodiskal area during the powerful clenching and grinding that occur in everybody as part of normal sleep. A joint protective stabilization appliance is all that is needed to allow rapid healing of most inflamed TMJs. A joint protective telescopic (Herbst) appliance is used when the protection needs to be extended to include mandibular postures with the mouth partly open or when the condition is complicated by other problems such as locking during the night or obstructive sleep apnea.
PIVOTING
When a TMJ is very inflamed and painful, rapid short-term relief can be obtained by adding a pivot to the second molar area of the affected side of an oral appliance. The pivot is a high spot which hits slightly before the other teeth. Because it is located behind the center of the mass of the jaw closing muscles, biting on it distracts the back end of the lower jawbone (the condyle) away from the cranium, which relieves compressive forces and allows increased circulation in the injured TMJ. Pain relief should be almost immediate. However, pivots eventually wear down or shift the teeth supporting the pivot, therefore pivoting must be considered only a temporary short-term solution for an acute problem.
MUSCLE TREATMENT APPLIANCES
After the inflammation is fully resolved, the damaged TMJ will no longer need mechanical protection, and treatment can focus on the jaw and neck muscles, which work together in the head posture mechanism. If the jaw muscles were held tightly for a long time to protect an inflamed TMJ, they can undergo an anatomical tightening called contracture, which requires forceful stretching. If they avoided using chewing forces for a long time to protect an inflamed TMJ, they can undergo atrophy, which requires exercise.
FACIAL GROWTH APPLIANCES
Long-term treatment should optimize the slow continual jawbone growth of adulthood to prevent the symptoms from returning by nightly wear of an oral appliance that redirects the forces of nocturnal bruxism to gradually remove the restrictions to healthy facial growth, which are ultimately responsible for the strains that cause the tissue damage. The type of oral appliance you need depends on your bite, your musculo-skeletal build, and your facial growth pattern; but the vast majority of patients need treatment that advances the lower jawbone and expands the upper jawbone.
BITE TREATMENT
One thing that is needed for healthy facial growth is a stable natural bite. For the TMJs to acquire a good fit between the opposing bones, the natural bite must provide a consistent and centrally located bracing platform 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 keep 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, and it has not yet restabilized sufficiently for healthy TMJ function. Restabilizing a bite in these cases usually requires only grinding down a couple of high spots, which usually costs a few hundred dollars, or building up a couple of low spots, which usually costs hundreds but not thousands of dollars. In a few cases, restabilizing a bite can require significant dental work such as crowns or orthodontics. These options are explained further in THE ROLE OF THE BITE under the tab TMJ DISORDERS.
OPEN SURGERY of the TMJ is risky, because failures can be disasterous due to a build-up of scar tissue can prevent natural adaptation. Further surgeries are necessary to clean out the scar tissue, but the chance of eliminating the pain decreases with each successive surgery. For that reason, even the oral surgery journals warn that open TMJ surgery should be considered a last resort. Unfortunately, there are still oral surgeons who only provide a simple nightguard before concluding that conservative treatment is ineffective and therefore surgery is necessary.
CLOSED SURGERY of the TMJ is safer. Arthroscopy and arthrocentesis are simply surgeries in which tubes and inserted into the joint to flush out the inflammatory tissues and sometimes also to perform some manipulation of the joint tissues, but they cannot recapture a dislocated disk.
CONCLUSION
Having a permanently dislocated disk does not condemn you to a lifetime of pain. About 30% of the population have a dislocated disk in at least one TMJ, and the vast majority of them no longer have symptoms. They may have experienced pain or other symptoms for days or years, usually between the ages of 20 and 40, but their damaged TMJ has adapted and is no longer causing inflammation or triggering muscle guarding. Therefore, the prognosis is good over time with almost any kind of treatment. Orthopedic treatment can provide relief of the symptoms within days and influence facial growth to prevent them from ever returning.