What is neuromuscular dentistry?

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 largely
determined 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!

The importance of a correct bite

As you have now learned, neuromuscular dentists evaluate the muscles and joints in addition to the teeth to establish a neuromuscular occlusion that they believe is crucial to achieving optimal results in virtually every type of major dental procedure and in treating many types of pain and dysfunction. No matter what type of treatment you are considering, it is important that you understand the significance of getting your bite right.

How do we get the bite right?

Now that you know how important your occlusion is, let's discuss how the neuromuscular dentist evaluates your bite and establishes your neuromuscular occlusion.

Muscle relaxation

Earlier we discussed the important role that muscles play in your bite and temporomandibular joint health. We learned that muscles will accommodate to overcome an otherwise bad bite and to allow the teeth to come close to occlusion. And, that as a result, the muscles are sometimes subconsciously held in abnormal continual contraction through the process of proprioception. So, if this is done subconsciously, how do we get those muscles to relax?

It is extremely difficult, if not impossible, to achieve true muscle relaxation by just asking someone to relax those muscles. Proprioception may be overcome through a process called biofeedback training, but that generally takes a long time and is not practical for clinical use during dental appointments. Further, the muscles will again assume their tense state as soon as the biofeedback session ends or you start biting.

The way that the neuromuscular dentist achieves relaxed muscles is through the use of electrical muscle stimulation, sometimes referred to and TENS (Transcutaneous Electrical Neural Stimulation). A device called the Myomonitor is used to deliver gentle electrical stimulation to your muscles to help them get to that relaxed state. The Myomonitor is a battery operated electrical muscle stimulator. Mild electrical stimulation is delivered through adhesive electrodes attached to the skin over muscle sites and nerves that control specific muscle groups. The stimulus delivered by the Myomonitor will cause your facial and jaw muscles to twitch or “pulse” once every one and one half seconds (40 times per minute).

Tense muscles suffer from restricted blood flow. As the muscles are “exercised” with the electrical stimulation and the muscles being to relax, blood flow in the muscles increases. This not only brings more oxygen and nutrients to the muscles, but flushes away accumulated waste products of metabolism. Usually after 30-60 minutes, this electrically induced “exercise” will allow your muscles to overcome their programming and go to a state of physiologic rest.

We learned that tense muscles in the neck or upper back (cervical muscles) can affect head posture and therefore have an affect on occlusion. If the dentist determines that to be the case, they may also want to use electrical stimulation to help relax those muscles.

Muscle relaxation can also be an effective means of pain relief. If pain (such as the temporal headaches referred to earlier) is originating from muscle tension, relaxation of the muscle with electrical stimulation may result in pain relief as the muscle is restored to a more normal physiology. This can be an effective means of drug-free pain relief for some patients. However, this pain relief is temporary. It does not get at the underlying cause of the pain so it more than likely will return unless the underlying problem is treated.

Once your muscles are relaxed, the neuromuscular dentist will confirm and record the position of your jaw through a process called bite registration.