TMJ
The temporomandibular joint, or "TMJ", is the hinge joint which allows your mouth to open and close. It is the joint between the Temporal Bone and the Mandible. The Temporal bones enclose the inner ears and form part of the skull. The Mandible is the lower jaw bone itself. The TMJ is located on each side of the face, just under the ear canals. If you place your finger just inside the ear canal, you can feel movement when the jaw moves. It is a highly complex joint, unlike any other in the body. The TMJ is a combination of a "ball and socket" type joint, and a "sliding" joint. The "ball and socket" are formed by the rounded heads of the mandible, called the condyles, which fit into an indentation under a small cartilaginous structure referred to as the disc. (The disc is sandwiched between the condyle head of the mandible and the temporal bone.) The top of the disc is more flat, which lies against the bottom portion of the temporal bone. This forms the "sliding" portion of the joint. When you open your mouth with your jaw in its most retruded position, the opening is very limited and acts strictly like a hinge because only the "ball and socket" portions of the joint are being used. Upon further opening, however, the mandibular condyles along with the disc slide forward along the flat incline of the temporal bone. This "sliding" (called translation) can also be accomplished without opening the mouth wide, by protruding the jaw. When moving the jaw side to side, one side will act as a fulcrum, while the other one slides.

The interesting thing about the TMJ and its associated musculature, is the intimate relationship that is formed with the teeth. More specifically, the way in which the teeth mesh together when biting or chewing, called occlusion, has a direct effect upon the joints and muscles used for chewing, and vice versa. In normal situations, the teeth, the joints, and the muscles of mastication work in harmony. However, due to a variety of reasons, if they are not functioning hormoniously, this leads to noises and/or pain eminating from these structures. This condition is known by the broad term "Temporomandibular Dysfunction Syndrome" (called TMD), or sometimes, simply TMJ.

TMD is usually associated with pain in the joint itself, and also tenderness of the muscles surrounding the joint. Additionally, noises are often heard upon opening and closing of the jaw. These noises are often "clicks" which occur when opening wide, and when closing. These clicks are usually caused by a temporary dislocation of the disc from the head of the condyle upon translation, and subsequent relocation. Often this is completely painless, and spontaneously disappears over time. When pain develops, this is an indication that an inflammatory process is present, which if not addresssed, can lead to further problems. A vicious cycle then develops where pain in the joint causes muscle spasms, which leads to grinding of the teeth, which alters the bite, and causes further irritation of the joint. In severe cases, the disc becomes chronically dislocated, and may result in severly restricted range of motion of the jaw. This usually occurs due to a combination of stretching of the ligaments which attach to the disc, and chronic muscle spasms.

Causes:
Emotional stress is probably the most common triggering factor in TMD, but usually some other predisposing condition is present, most notably, a discrepancy in occlusion (i.e. the bite.) Occasionally a discrepancy between where the teeth want to fit together and where the jaw joints want the teeth to fit together can itself cause TMD.

Treatment:
Before treatment can be rendered, a careful assessment of the nature of the problem must be made. Determinations must be made as to whether one or both joints are involved, the degree to which the muscles of mastication are involved, and the interrelationship with occlusion. At times, only an antiinflammatory drug will be prescribed to address joint inflammation, and/or muscle relaxants to minimize spasms. The most common initial treatment, however, is the fabrication of an acrylic "splint". This is often the most conservative treatment approach, as the splint simply snaps onto the upper teeth and can be easily removed at any time. These are often erroneously called "nightguards" because they are often worn at night, and prevent a patient from grinding his or her teeth. In contrast to a traditional nightguard, however, each splint is made for a specific purpose to address specific a problem, and different types of splints can be used depending upon the treatment indicated. A TMD splint is properly considered an orthopedic appliance, as one type of splint may be indicated to treat chronic muscle spasms, while a different type may be indicated to "recapture" a dislocated disc.

If the symptoms appear to be exclusively muscular in nature, often manifesting as headaches (see below), a muscle relaxant and specific jaw exercises may be prescribed.

Additionally, if an occlusal discrepancy is the likely cause of the problems, this can be permanently corrected by placing crowns on the teeth, which will have the effect of realigning the bite to correct the discrepancy.

Occasionally, if the symptoms become severe, and all less invasive options have been exhausted, surgery can be performed on the joint(s).

HEADACHES
TMD-related muscular spasms of the head and face are one of the most common causes of headaches. In a recent multi-institutional study, 60% of diagnosed migraines turned out to be muscle-tension headaches. These headaches, even though they emanate from pain in the muscles outside of the skull, may feel as though they arise from within the eyes or inside the head, imitating migraine pain. For this reason, a doctor may make a diagnosis of migraine by default, because no objective or quantifiable criteria are available for evaluation.

A great many of these muscle-tension headaches originate from clenching of the teeth. It is easy to see why stress is considered the most common triggering factor of this condition. Spasms in the jaw muscles can spread to the scalp and neck musculature, and may even cause soreness of the upper back teeth, which can feel like sinus pain.

We often see patients for evaluation after having been examined by different physicians, most often neurologists, ENT’s, and pain specialists. Many of these patients have presented with previous diagnoses of sinus infection, migraine, or even toothache. Surprisingly, the symptoms often disappear completely coinciding with bite-splint therapy, jaw stretching exercises, and/or muscle relaxants. These results strongly suggest that many headaches are misdiagnosed and therefore not treated appropriately. The problem is that in many cases there is just no way to know for sure, and obviously it is important to rule out the more serious causes of headache such as meningitis. However, the possibility of muscle-tension headaches should not be overlooked in any patient complaining of constant headaches.

Treatment:
Muscle-tension headaches are often treated similar to other TMD related problems. Depending on the nature of the problem and the judgment of the Dentist, different types of bite splints may be fabricated. A type that has recently garnered much attention is the NTI splint. The NTI is an acrylic appliance worn on the upper front teeth that makes it uncomfortable to close the teeth together. By being unable to clench, the cycle of muscle spasms is often broken. Additionally, head, neck, and facial massage may prove beneficial, plus jaw stretching exercises (holding the mouth open as wide as possible for 20 second intervals, ten or more times a day). Also, medications which tend to relax the muscles may be helpful such as Valium or Flexeril.