What is TMJ?

WHAT IS TMJ?

Temporomandibular Joint (TMJ) is a term often used to refer to the multi-faceted muscle disorders that can contribute to pain, jaw joint and occlusal problems. TMD refers to temporomandibular joint dysfunction.

According to the lay person the TMJ (Temporomandibular Joint) is a term that is often used to identify a multifaceted multi-etiologic group of problems that involve both medical as well as dental conditions involving the temporomandibular joint, muscles of mastication, the teeth/occlusion as well as the central nervous system (nerves). It is clear that TMD or TMJ problems consist of a complex set of problem that go beyond genetic and bio-psychosocially mediated causes. It is a combination disorder of the teeth, muscles, temporomandbular joints as well effecting the central nervous system in some that causes dysfunctions to the masticatory system as well as whole postural system of the body. It is not a single cause related just to a ‘bad bite’ or a ‘malocclusion’ but rather a problem that is multi-faceted in nature effecting all of the above.

“Experts estimate that 75 percent of all headaches are caused by muscle tension, which may be related to the bite.” AGD/Oral Health Resources, Temporomandibular Joint Disorder (TMD), March 30, 2007. Literature also reports that with a frequency of 92%, pain in the temporal muscle was the most common symptom, followed by pain during mouth opening (89%) in both genders. Bagis B, et.al.: Gender Difference in Prevalence of Signs and Symptoms of Temporomandibular Joint Disorders: A Retrospective Study on 243 Consecutive Patients. Int J Med Sci 2012; 9(7):539-544.

Cooper and Kleinberg (April 2008), Haskin (1995), Emshoff (2003), Tasaki (1996), Katzberg, et al (1996) also reported that TMD comprised of the following:

70-89% Prevalence of TM Degenerative disease.
71.8% had posterior mandibular displacements.
53.9% had lateral displacements.
82.1% had over-closures (excess vertical freeway space).
84.1% were not coincident with the myo-trajectory.

Note: A much smaller percentage of individuals that present with symptoms of temporomandibular joint dysfunction have also been diagnosed by their physicians and health care provides having biochemical imbalances related to nutritional/ vitamin deficiencies and hormonal issues leading to emotional and psychological anxieties and depressions. (Expert help in nutritional and psycho-social counseling may be of great importance to those with these particular needs). These factors should not be ignored!

TMJ is more appropriately called TMD (Temporomandibular Joint Disorder or Dysfunction).

Biophysiologic Neuro-muscular Approach: Scientific Evidence

A large percentage of these studies Scientific References have been published in support of a biophysiologic neuro-muscular approach rejecting old and biased theories promoting that genetics and biopsychosocially mediated symptoms (e.g. stress, tension, emotional upset) are the cause; that is, a belief that these symptoms leads to increased muscular activity, noctrunal bruxism, psychological unrest requiring stress related behavioral modification management, coping skills and pharmaceutical medication pain management to deal with the TMJ/TMD pain and dysfunctional problems.

Psycho-social Intervention for Chronic Orofacial Pain: Weak Supportive Evidence

The Temporomandibular Joint

The “TMJ” is a two joint system connected by the main body of the mandible and ramus on each side. The two condyles are the upper boney portion of the jaw bone (mandible) that is housed within the glenoid fossa within the boney skull just forward of the ear (auditory meatus). The condyles are able to swing and rotate within the fossa, but limited by the surround ligamentous attachments (temporomandibular ligaments) and surrounding muscles. The disc (articular disc) is a thin ligamentous tissue that acts like a cushion between the condylar head and upper glenoid fossa of the skull. Attached to the articular disc are fine muscles (lateral pterygoids) as well as surrounding ligaments that help in positioning the disc over the condyles as they move within the joint compartment during functioning and resting modes.

The temporomandibular joints are the only two joints that function together as a single unit unlike any other joint in the body in that they must coordinate with the coming together of the upper and lower teeth (accompanied by the surrounding periodontal ligamentous attachments, nerves and surrounding bones and gum tissue, during opening and closing cycles of chewing, swallowing, breathing, talking, wistling, kissing, sucking and resting modes.

WHAT ARE THE CAUSES OF TMJ?

Common problems that can occur with the temporomandibular joint are disc disorders or internal derangements of the disc, disc locations, tearing of the lateral and medial collateral ligaments due to traumatic injuries, inflammatory disorders as synovitis/capsulities, inflammatory arthritis, capsular fibrosis, ankyosis, subluxations, spontaneous dislocations, chronic (recurrent disclocations) contributing to clicks and audible popping sounds. Fractures and hemarthrosis within the TM Joint should also be considered. Masticatory disorders (muscle pain), chronic mandibular hypomobility, mandibular hypermobility, growth disorders of the jaw (i.e. coronoid hyperplasia), and functional abnormal jaw closure patterns due to mal-aligned jaws and bad occlusion (bites) also should be recognized. Common misdiagnosis’ are fibromyalgia, migraineous head pain, neuralgias of the masticatory system as well as cervical/neck/ shoulder and back pain.

Other terms the dental professional uses to describe this problem are the following:

Temporomandibular Disorders (TMD)
Myofascial Pain Dysfunction (MPD)
Orofacial Pain (OFP)
Craniofacial Pain (CFP)
Craniomandibular Dysfunction (CMD)
Cranio-mandibular Cervical Dysfunction
Musculoskeletal Dysfunction (MSD)

“TMJ” pain is not just related to the jaw joints, but also involves the surrounding masticatory muscles of the upper and lower jaws that also attach the cervical neck and head together to allow a postural relationship to occur between the upper and lower arches of teeth. (The act of the maxillary and mandibular teeth coming together is what has been defined as occlusion).

Philosophical Perspectives to Identify This Condition:

Many within the dental profession are often confused because this problem can present with an overlapping number of issues involving not only the head, neck, temporomandibular joints, teeth and muscles. Depending on which philosophical belief, school of thought and area of focus dental experts and clinicians believe that it relates to a lack of coordination between the muscles of mastication, the jaw joints, the teeth and the central nervous system. Academics may also call it Cranio-mandibular/ Neurovasomuscular/Cervical Dysfunction. Others focus diagnosis and treatment on the central nervous system (psychological as well as biochemical aspects) as it relates Orofacial or Craniofacial pain issues. Third party insurance groups may recognize it as, Musculoskeletal Dysfunction (MSD) of the head and neck resulting in Temporomandibular Joint Dysfunction.

Note: Disorders of the Temporomandibular Joint can mimic other dental and medical problems. A proper diagnosis regarding head and neck pain is very important because serious medical problems such as vascular disorders, neurological disorders, brain tumors, aneurisms, cervical disc disorders, throat and oral cancer, etc. can produce similar symptoms of TMJ disorders. It is important to inform your doctor of any change in your health history from that was previously provided.

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