We usually don’t think about moving our jaw or about how this is done — “we just do it”. ‘When we do think of our bite we think of our teeth, but not of muscles or joints. However, muscles and joints play a very important role in your dental health.

Different muscles come into play for posturing the jaw, open— ing the jaw, closing the jaw (biting or chewing) and swallowing. The muscles that open your jaw are in your neck. Muscles that “posture” your jaw, or keep it from falling open, are rather delicate muscles that extend from the jaw upward through the cheeks and into the forehead area — even around behind the ear to some extent. Power muscles For chewing are in the cheek area.

Swallowing muscles (like all muscles) must have something firm to brace against to function. The body being “lazy (efficient), the posturing muscles generally hold the jaw at a position where the teeth are close to occlusion — a millimeter or two apart. This is an efficient location since we must bring our teeth together to swallow hundreds of times a day. When we swallow, the teeth are already close to occlusion. Control of all of this is done subconsciously without having to think about it — your brain is ‘programmed’ to do this through a process that doctors call proprioception. Ileverything is just right, when the jaw is not moving most of these muscles are said to beat rest, or barely working to maintain posturing. Ifyour natural teeth don’t fit together properly, your muscles may accommodate, forcing the jaw to close on a path that stresses and fatigues the muscles over time. This puts the jaw in a position where the teeth are close to occlusion, but at the same time prevent the muscles from being relaxed when they should be.

The jaw is able to move since it operates on a joint called the temporomandibular joint, its name the basis for the often heard term “TMJ”. If you think of a joint being something like a ball and socket, the jawbone portion of the joint (ball) Functions within a depression in the skull (socket). It is really not a ball and socket joint, but close enough for our descriptive purposes here. There is a soft pad called a disc that lies between these two structures. The position of the jaw end of the joint (condyle) within the corresponding depression in the skull is largely determined by where the muscles are holding the jaw — a position in turn affected by the bite (occlusion). If the system is in balance, the condyles will be essentially centered in the joint space of the skull and the disc moves freely with the joint. If the muscles of mastication are accommodating as described above, they may be holding the jaw joint in an abnormal position, negatively affecting its function. Frequently this results in the disc being “pinched”, causing it to resist the movement of the joint until it finally releases. As the “pinched” disc releases, it results in the joint popping or clicking. This sound is often obvious to you and is a sign of abnormal joint function that may in turn he related to your bite.

Posture can also play a significant role in your occlusion. The jaw could be considered one end of your inter-related skeleton, with the feet being the other end. If any part of the skeletal system is affected, it may in turn affect other parts of the system. You can experience this by lightly touching your teeth together, taking care to note which teeth first touch. Then, tilt your head back as far as you comfortably can and repeat the process. Don’t be surprised if the teeth first touch in a different location now. You have altered the balance of the skeleton (and your bite) by simply changing your head posture.

Another example is if you have a filling placed when you are in a prone position in the dental chair. Under anesthesia, it feels as if the filling fits fine. Then, later when the anesthesia wears off and you are sitting or standing upright, you notice that the filling is uncomfortably too high. It is for this reason that the neuromuscular dentist establishes your occlusion when you are seated in the upright position — the position in which you normally use your jaw. If it is established when you are in a reclined position, the jaw may have moved back, resulting in a position different than that in which you normally function.

With head posture affecting occlusion, and because of the inter-relationship of the entire musculoskeletal system, the neuromuscular dentist will want to know if there is tension in the muscles of the neck and upper back. If there is, it may well affect the occlusion and therefore the outcome of the diagnosis or treatment.

Now we are beginning to see that the bite is Far more complicated than just the way the teeth fit together! The muscles and joints also play a key functional role in your occlusion.