TRAUMA AND TEMPOROMANDIBULAR (TMJ) INJURY
This article will assist the legal professional in the determination of temporomandibular (TMJ) injury and whether or not it is related to trauma. The TMJ or jaw joint is the joint immediately in front of the ears. Although this joint is frequently injured these TMJ injuries are often misdiagnosed and have only recently received widespread attention. The temporomandibular joint is unique in that this joint dislocates itself within its ball and socket arrangement so the jaw can fully open. This intricate arrangement lends the TMJ susceptible to injury during traumatic episodes such as rear-end collisions involving cervical whiplash and other blows to the face. Pain disorders often head and neck in general and TMJ dysfunctions in particular are complex disorders and are difficult to diagnose precisely and treat effectively. These disorders are progressive and, if left untreated, can increase the range of functional implications which can be devastating to the patient. Few medical and dental practitioners have the specialized training and experience in such disorders.
How Does the TMJ Injury Occur?
In read-end collisions there is a cause and effect relationship during whiplash injuries that can cause damage to the temporomandibular joints. There is a sudden impact in which the head can snap in multi-directional planes. This happens so quickly that the neck muscles never have a chance to relax; thus they anchor and hold the jaw still. As the head is forced backwards by the impact, the mouth will excessively open and hyper extend. This leads to tearing of the muscles and supporting ligaments within the temporomandibular joints, resulting in scar formation, neurogenic and muscular pain and edema. This can also occur from other sources of trauma. As an example a blow to the jaw from a fight can push the jaw back, tearing the restraining ligaments, as can a fall, contact sprorts (football, hockey) especially which a chin strap is utilized.
Aside from direct TMJ problems and internal derangements within the joint there is a high incidence of injury to the other supporting structures of the jaw, most notably the stylomandibular ligament. This ligament originates just behind the ear and then attaches to the back side of the jaw bone at t he level of the ear lobe. Its function is to limit jaw motion. During a traumatic injury, such as a blow to the head, a fall or in a whiplast-type injury this ligament can be stretched beyond its physiological adaptive point. Often impact and traumatic injuries can cause internal derangements of the temporomandibular joints and pain syndromes in associated structures.
How is TMJ Diagnosed and Documented?
Diagnosis can be made after a through clinical and physical examination including radiographic surveys. There may exist the need for diagnostic anesthetic blockage and trigger pint injections to quickly isolate the problematic areas. Documentation can be made with CT scans, dynamic MRI, Doppler studies, range of motion studies, thermography and arthography. Dynamic MRI documentation has proved to be an effective tool in visualization of the disc and its displacements along with concurrent bony changes. It has the ability to get a superior image of the temporomandibular joint including the disc and other soft tissue.
How is the Temporomandibular Joint Treated?
Treatment should not be delayed once there has been a diagnosis of temporomandibular joint injury. The treatment plan may include construction of an orthopaedic repositioning appliance (bite splint), moist heat therapy, trigger point injections, nutritional counseling, myofunctional therapy, occlusal equilibration and other physiotherapeutic and pharmacological modalities. The treatment is directed towards orthopaedic realignment of the mandible to the skull, stabilization of the right and left temporomandibular joints and restoring them to their normal physiological function.
Treatment of injuries in the conservative phase takes between four to nine months. If conservative treatment is not successful surgical intervention would be initiated. This could include new arthroscopic evaluation and treatment, traditional open surgery or radiofrequency thermoneurolysis. Once the patient is pain-free and functioning normally, restorative phase of treatement would begin. This allows the patient to cease wearing the orthopaedic repositioning appliance by replacing the space which the appliance occupies with either crown and bridge restorations to build up the heights of the teeth or orthodontic rehabilitation to raise the heights of the teeth. Occlusal equilibration may also be necessary. This phase of treatment varies from months to years.
Potential Long-term Implications:
Even with the best diagnostic techniques and treatment many patients will have a residual disability due to the very nature of this type of injury. The temporomandibular joint is a highly innervated sensitive joint which has very complicated movements within it leading itself to susceptibility for injury. When these problems exist for an extended period of time acute pain can turn into chronic pain with significant behavioral changes occurring leading to the need for invervention for health care providers outside the area of dentistry.