Temporomandibular Joint Disorder - what is it?
TMJ stands for Temporomandibular Joint and TMD stands for Temporomandibular Disorder of the jaw joint. There are two Temporomandibular Joints (TMJs), one in front of each ear, connecting the lower jaw-bone (the mandible) to the skull. The joints allow the jaw to move up and down, side-to-side, and forward and back - allowing for all the mobility necessary for biting, chewing and swallowing food, speaking, and making facial expressions. It is by far the most complex and over-worked joint in the human body.
Over 10 million people in the USA suffer from TMJ dysfunction, a condition in which the Temporomandibular Joint does not function correctly and as a result usually generates varying degrees of pain.
The TMJ connects the temporal bone, which is the bone that forms the sides of the skull, to the jawbone. These TMJs when improperly aligned with the muscles of the head, neck, and face combined with poor dental occlusion (the way the teeth fit together) can result in TM Disorders. This condition often produces pain in the muscles and joints of the jaw that frequently radiates to the ears, face, head, neck, and shoulders.
There may also be difficulty opening the mouth all the way, with clicking, grinding, and popping noises sometimes occurring during chewing and movement of the joint. Headaches, dizziness, and/or ringing in the ears, together with difficulty opening and closing the mouth normally can occur as well.
Signs and Symptoms
Signs and symptoms of TMJ Disorders may include one or a combination of the following:
- Aching/stabbing pain in and around the ear
- Aching/stabbing pain in front of the ear - TM Joint
- Recurrent headaches
- Facial pain
- Jaw tenderness
- A clicking sound or grating sensation with opening the mouth or chewing
- Locking of the joint, making it difficult to open or close the mouth
- Inability to chew certain foods, or eating only a soft diet due to pain
- An uneven bite or an uncomfortable bite
- Generalized neck ache or stiffness that may radiate to the shoulders
- Ear congestion or stuffiness in the ear
- Ringing in one or both ears
Varying degrees of pain and tenderness may be experienced, even when there is no movement of the jaw. Chronic tension and anxiety may cause the increased tone of jaw muscles, together with grinding of the teeth (bruxism) at night, can escalate the pain. A dull discomfort in the jaws and muscles upon awakening in the morning or an ache that progressively worsens throughout the day may be the result of this unconscious activity during sleep.
Understandably, this overuse of the TMJ and its supporting muscles may cause pain by means of constant joint compression. This is often accompanied by chronic jaw-joint muscle fatigue and spasm. Inflammation within the TM Joint can result in increased pain and a shift in the dental bite. Frequently the pain or tenderness worsens when the jaw is in motion or upon chewing as the joints and muscles are called upon to function. Jaw joint sounds are common in the form of popping, clicking, or a grinding sound but often reduce when the jaw begins to lock. When the inability to open widely increases, the dysfunction often progresses and can lead to arthritis in the TM Joints
Normally, the TMJ allows the jaw to open and close smoothly. The lower jaw has rounded ends (condyles) that fit into a concave indentation (fossa) located in the bottom of the skull. They glide in and out of the joint socket (glenoid fossae) when you talk, chew or yawn. There is also a disk made of cartilage between each condyle and the inner surface of the glenoid fossae to protect, and absorb shock, keeping the movement smooth and frictionless.
If movements of your left and right TMJs aren't synchronized, abnormal stresses are generated eventually resulting in varying degrees of pain and and other symptoms that can affect not only the jaw, but also the head, face, neck and shoulders together with the ability to swallow properly. Furthermore, the combination of symptoms over a prolonged period of time leads to varying degrees of depression and sleep disorders - perpetuating a vicious cycle.
An improperly aligned bite can contribute to dislocation of the small movable (floating) disc located on top of the condyle, between the jaw and the skull. Pain in the TMJ can also result from degeneration of, or trauma to, the joint proper, such as by a blow to your jaw resulting in injury to muscles/ligaments and disks, generating a reactive inflammation with muscle splinting. Chronic tension and anxiety may cause the grinding of teeth (bruxism), often at night, or the maintaining of clenched jaws. This overuse of the TMJ and supporting muscles may result in varying degrees of pain and/or discomfort, and dysfunction of the jaw and supporting structures.
The TMJs are embedded in an intricate web of pain-sensitive nerves and delicate muscles. The disk that separates the lower jaw from the skull can slip out of position or a condyle, upon which it is positioned, can become dislocated. Either occurrence can result in severe pain and/or the inability to open the mouth or jaw fully. The force of normal chewing and of clenching or gritting the teeth creates great tension and pressure in that area of the face.
The cartilaginous disc that cushions the joint may become displaced or even wear out, causing bone-on-bone contact within the TMJ, rather than smooth frictionless gliding. In some instances, a misalignment of the jaw and teeth prevents synchronous, coordinated operation of the joints.
The most common underlying causes of TMJ Disorders are anatomic-structural abnormalities. The structure of the cranium and/or the mandible can be abnormal resulting in a TMJ disorder. The structural imbalance created is similar to anatomic situations involving other parts of the body; for example, a short leg eventually creating hip and back pain and disorders. A poor bite, missing posterior teeth, an old and worn denture, direct injury to the face and jaw (such as blunt force trauma or whiplash) can also cause a TM Disorder. Certain systemic diseases including fibromyalgia, rheumatoid arthritis, and other connective tissue disorders may lead to a TM Disorder. Aggravating factors can include emotional stress that can cause clenching or grinding the teeth (bruxism). Habits, such as one-sided gum or food chewing or thumb sucking, can aggravate the problem.