CENTER FOR FACIAL PAIN             MEMBER ONLY SITE                         INJURY AND TM DISORDERS

    Temporomandibular Disorders, like other musculoskeletal disorders, can be caused by, or initiated by injury.  These disorders may be acute, as the direct cause of the trauma, or they may be chronic. When chronic, the injury may be the "initiating" factor, and other factors my perpetuate the condition.

    Acute injury to the TM joint usually comes from a direct blow to the mandible. Even a minor blow to the center, or either side of the chin can drive the condyle back against the posterior wall of the socket, especially if the teeth are not occluding during the blow. This backward pressure of the condyle can crush and injure to some extent the posterior attachment of the disc, as well as the joint synovial tissue of the joint. Depending on the force of the blow, the extent of the injury can produce anything from a mild inflammation of the posterior disc attachment, to swelling of the tissue in the posterior compartment, to bleeding into the tissues (hemarthroma), to fracture of the neck of the condyle, to fracture of the wall of the mid cranial fossa and impalement of the condyle into the brain cavity.

 A blow to the side of the chin can also drive the condyle sideways and potentially cause a stretching or tearing of the lateral ligament which normally holds the disc tightly in place on the head of the condyle. This is believed to be the first step in eventual displacement of the disc.
 

    The same type of injuries can be initiated or exacerbated by minor injuries over an extended period of time (microtraumas). These include parafunctions such as fingernail biting, excessive gum chewing, excessive nocturnal clenching or bruxing, etc.

    This type of injury may not be apparent at first, because the condyle and disc can still function normally even though the ligament holding the disc has been stretched.  It is only when the muscles around the joint are "tight" that that tightness, placing more pressure on the disc, causes the disc to catch and bunch-op in-front of the condyle and cause a click in the jaw joint as the condyle passes over the posterior portion of the disc.

    This sudden muscle tightness can come from various sources including a whiplash injury to the neck. The reason for this is called "centeral convergence." In this case the muscles of mastication "perceive" that the injury is to the jaw joint and the response is for the periarticular muscles around the jaw joint to "tighten-up" or splint around the joint.  This can have an effect on the jaw muscles, as well as the jaw joint, especially in the presence of a "loose disc."