Over the past few years, Dr. Williams has taken over 200 hours of continuing education in the realm of occlusal science. Occlusal science is the study of understanding how the masticatory system (or bite system) works. The anatomical components of the masticatory system are the TMJs (temporo-mandibular joints), the muscles of the jaw, the neurological system which controls the muscles, the teeth and the bones in which they are anchored. It is a complex system which in some ways will never be fully understood, but in others can be broken down into fundamental components which can be treated in simple ways. One of those treatment modalities is occlusal splint therapy, which involves the use of plastic appliances which fit onto the teeth, temporarily and reversibly affecting how the bite fits together when the jaw joints are in varying positions.
What are the goals of occlusal splint therapy?
There can be three goals with the use of an occlusal splint:
Palliative: When the aim of the splint therapy is to relieve pain or improve a debilitating condition.
Diagnostic: When splint therapy is used to reveal symptoms which can lead to a diagnosis of a condition.
Protective: Because the splint separates the teeth, they are unable to touch and thus unable to wear against each other. When used for protection, they are commonly referred to as occlusal guards.
What kind of occlusal splint therapy appliances do we use in our practice?
There are myriad types of splints that we have knowledge of and expertise using. The type of splint employed depends on the goal of the splint therapy. Palliative and diagnostic goals can involve numerous different designs depending on the nature of the pain or condition which the patient is suffering.
Protective goals, however, can usually be achieved with the use of our most commonly used appliance: The Dual Arch Anterior Scribe Appliance (or DAASA).
How does the DAASA work?
As the name implies, the DAASA involves 2 components which fit onto the teeth of each arch. Normally, each component will cover the front 8-10 teeth on its arch. The lower component has a nub or button right at the edge of the front central teeth and the upper component has a flat plane right behind the front teeth. The nub will hit on the flat plane when the patient bites down and it will glide smoothly when the jaw is moved around.
Because the nub is the only point of contact, the masticatory system stops trying to fit the teeth together and instead the TMJs are free to seat fully when the jaw muscles relax. The jaw muscles are able to relax for several reasons. First, because the nub glides smoothly on the plane, there is no resistance for the muscles to fight when it moves. Naturally, when the muscles are not struggling to create movement, the movements they do will be smooth and the tension will be less. Second, research has shown that when the lower front central teeth are the only ones which are compressed when biting, there is an inhibitory neural pathway which is activated which shuts down 70% of jaw muscle intensity. This reflex is known as nociceptive trigeminal inhibition. Google this term and you will learn all about NTI splints which the DAASA was created to improve upon.
As you can imagine, when jaw muscle intensity is decreased by 70%, patients often find that there is a marked decrease in facial tension. Patients also often find there to be a decrease in frequency and intensity of headaches that they had never realized were related to the muscles that control their jaws.
Another advantage of the DAASA compared to other occlusal guards is that because there are upper and lower components, when the patient bites down, occlusal contact will be acrylic against acrylic instead of acrylic against tooth as is the case with single component appliances. This results in less wear of the acrylic. The acrylic will still wear down over time, but this process will be slower than most conventional occlusal guards.
It is important to understand that no occlusal guard or occlusal scheme will decrease the tendency to grind and clench if it is present. However, a DAASA or NTI appliance will decrease the intensity of the grinding and clenching and thus limit the damage it can do.
Overall, the DAASA has been a certifiable success in our practice. Patients have found relief from TMJ pain, headaches, muscle tension and grinding/clenching habits. There will be some asymptomatic (pain-free) patients seeking relief from a grinding/clenching habit who may not notice a difference in how they feel (i.e. no change in muscle tension), but these patients can still rest assured that when they wear the appliance, they are protecting their teeth from the destructive jaw movements which were wearing their teeth down before.
A Note About Tooth Wear:
Often when examining a patient, I see wear on teeth. Patients often ask, “isn’t there some amount of normal wear?” This is a tricky question, because while it is true that the vast majority of the population have wear on their teeth, thus making it a “normal” condition, it is still caused by a pathological process, has negative consequences and can be fixed and/or prevented.
Enamel is the hardest substance in the human body and unless your diet consists of a regular helping of rocks, the foods we eat are not hard enough to cause attrition (wearing of the teeth). Attrition occurs when the teeth grind against each other. When teeth grind against each other, the teeth receive sheering horizontal forces. Enamel, porcelain and composite resin are very strong in compression. This means they can take a very large amount of vertical force. However, they are about 5 times weaker in resistance to tensile forces which is what horizontal force is. This is why teeth break down when the teeth are ground against each other, but do not when the teeth are closed against each other vertically. In a proper occlusal scheme, only the canines and central incisors are positioned to receive any horizontal forces at all. When the jaw shifts, all the other teeth immediately separate. The only way for the other teeth to touch is when the jaw is closed vertically.
Furthermore, due to the reflexes which govern the muscles of the jaw, when all of the teeth hit evenly with canine guidance when the jaw is moved to the side and central incisor guidance when the jaw is moved forward, the intensity of the clenching or grinding is minimized. This results in a situation where the central incisors and canines wear very slowly.
I am tardy in expressing my thanks for your solving my “jaw clicking” problem. About two years ago I was plagued with my jaw clicking every time I chewed something. It did not hurt but was bothersome and I had the feeling that it would work into something uncomfortable or painful. You suggested a mouthguard which I wore 24 hours a day for the first two weeks and I now wear it only at night. Your diagnosis was a jaw misalignment and you must be right because I no longer have the clicking sound. I appreciate your concern, diagnosis, and problem-solving. It is a relief to no longer be bothered by the worry that something was going wrong with my jaw.