The structures that make it possible to open and close your mouth include the jawbones, jaw joints, and chewing muscles. These are very specialized and must work together whenever you chew, speak, or swallow. Your teeth are also inserted in your jaw bone. At the other end of your jaw bone are the temporomandibular joints. These joints attach your jaw to your skull. Muscles attach both the bones and joints and allow them to move. Any problem which prevents the complex system of teeth, muscles, bones, and joints from working together in harmony may result in TMD.
A “Bad Bite”
There are various ways this system can be disrupted, such as accidents involving a blow to the face or a whiplash. Yet the most common cause of TMD relates to your teeth and your bite. If your bite isn’t right, it can affect both the muscles and the joints. What do we mean by a “bad bite”? We mean that your upper and lower teeth do not come together in a way that provides the proper bracing support for your jaw against your skull. This might result from a missing tooth, misaligned teeth, or bite that has drifted due to tooth wear or teeth grinding.
Your upper and lower teeth must come together firmly each time you swallow. This happens over 1000 times each day and night! When your bite is unstable your muscles must work extra hard. This extra work makes them shortened and stiff. Eventually this strain makes them feel painful. A vicious cycle begins of increased tissue damage, muscle tenderness, and pain. The pain makes you feel tense and uptight. This worsens the muscle spasm, which in turn increases the pain.
The position of your teeth can also affect the position of your jaw joints. Each jaw joint is a ball and socket joint. When functioning properly, the ball and socket do not actually touch because a thin disc of cartilage rides between them. The disc acts as a cushion and allows the joint to move smoothly. Each disc is held in place and guided by muscle. If your bite is not right, the disc is pulled forward by hyperactivity of the muscle. Since the disc no longer serves as a cushion, the joint itself now rubs against the boney socket and presses on pain fibers. Mild displacements cause a clicking or popping sound in the jaw joint; more severe displacements can be very painful and eventually can cause permanent damage to the joint. An unstable bite can cause both jaw joint displacement and muscle strain and pain. When this condition is prolonged, the body begins to compensate and adapt by involving muscles in the neck, back, and shoulders.