Your bite (or occlusion) is simply the position of your jaw when your teeth are together. This seems like a fairly basic idea, but your occlusion is very important and can affect your health in many ways.Until recently, most dentistry has been based on the assumption that wherever your bite was naturally (habitual or centric occlusion) was the correct position. Today, most dental treatments are still planned from the patient's existing occlusion. Because the habitual jaw position may be a reasonably good position and because our body system is often adaptable to less than ideal circumstances, maybe of these procedures have acceptable results. However, these are also many times that treatment procedures carried out with “textbook” accuracy do not produce the result that is fully functional and comfortable.
The growing field of neuromuscular dentistry goes beyond using your habitual bite as the basis for planning treatment. Neuromuscular dentistry considers the entire system that controls the positioning and function of your jaw: teeth, muscles and joints. The neuromuscular dentist seeks to establish a harmonious relationship among these three main factors, resulting in a jaw position that is called neuromuscular occlusion.
The role of the muscles
Different muscles come into play for posturing the jaw, opening and closing the jaw (biting or chewing) and swallowing. The muscles that open your jaw are in your neck.The 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 areaeven around behind the ear to some extent. The power muscles for chewing are in the cheek area. Swallowing muscles (like all muscles) must have something firm to brace against to function. Because the body is efficient, the posturing muscles generally hold the jaw at a position where the teeth are close to occlusiona millimeter or two apart. This is an efficient location since we must bring our teeth together to swallow hundreds of times a day. Control of all of this is done subconsciously without having to think about ityour brain is “programmed” to do this through a process that doctors call proprioception. If everything is just right and the jaw is not moving, most of these muscles are said to be at rest, or barely working to maintain posturing. If your natural teeth don't fit together properly, your muscles may accommodate, forcing the jaw to close on a path that stresses and fatigues muscles over time. This puts the jaw in a position where the teeth are close to occlusion, but at the same time prevents the muscles from being relaxed when they should be.
The role of the joints
The jaw is able to move since it operated on a joint called the temporomandibular joint, its name the basis for the often heard term “TMJ.” For descriptive purposes, you can think of a joint being something like a ball and socket, the jawbone portion (ball) of the joint functions within a depression in the skull (socket). There is also a soft pad called a disc that lies between these two structures.
The position of the jaw end of the joint (the condyle) within the corresponding depression in the skull (the fossa) is largelydetermined by where the muscles are holding the jawa position in turn affected by the bite (occlusion). If the system is in balance, the condyles will essentially be centered in the fossa and the disk moves freely with the joint. If the muscles of the mastication are accommodating as described earlier, the may be holding the jaw joint in an abnormal position, negatively affecting its function. Frequently this results in the disc being “pinched,” causing is 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 if often obvious to you and is a sign of abnormal joint function that may in turn be related to your bite.
The role of posture
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 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 if is you have a filling placed when you are in a prone positions 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!
We'll discuss the importance of the correct bite and how the "trained" dentists get that bite in our PART TWO of Neumuscular Dentistry.
- Cloverdale Dentist
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