Those words describe this new method of creating a centric-relation bite record
By Jerry Simon, DDS
In dentistry, there are some fundamentals that need to be executed consistently and flawlessly in order to produce excellent treatment results. One of them is certainly the ability to perform an accurate assessment of the patient's current condition. That includes the periodontal, biomechanical, and cosmetic conditions in the patient's mouth compared to the situation desired by the patient and dictated by good dental health. Some patients are essentially in good health, have an acceptable appearance, no significant biomechanical breakdown, and have no history of head, neck, and facial pain. These patients can get by with a standard oral exam and evaluation. However, many patients are not so fortunate and require more extensive dental care. A more in-depth evaluation is essential to properly determine how to treat the patient so as to provide for long-term comfort, health, function and esthetics.
Excess biomechanical force is second only to bacterial plaque in causing dental disease. Patients with more extensive dental requirements need to have their bite evaluated to create an ideal treatment plan. Establishing a centered jaw relationship in the mouth is a very important step, then you must successfully transfer that relationship to an articulator to first diagnose the occlusal condition before determining the appropriate treatment. You can evaluate how the teeth come together and how they fit against each other, free from the distraction of the tongue, lips, and cheeks. You can look from any angle and direction you desire, and you can make changes by adding wax or grinding down the cusps to see what effect that would have before you make irreversible changes in the mouth. However, it is vital to realize that dental articulators share one key quality with computers — while they are both wonderful instruments that can provide the operator with important information, if they are not programmed correctly, they are not only unhelpful, but have the potential to provide misinformation.
Much of the debate in the dental field about occlusal relationships is not really about the significance of occlusal relationships. It is about the ability to first define those relationships, then accurately capture them and transfer them to an instrument that allows proper analysis. Therefore, this article has three purposes:
- To define what a centered jaw relationship is and how to achieve it
- How to capture that relationship accurately, quickly, and consistently
- How to easily transfer that relationship to an articulator
A centered jaw relationship, defined by Dawson in Evaluation, Diagnosis and Treatment of Occlusal Problems as "centric relation," is when the condyles are centered in the jaw socket with the disc interposed such that the support for the condyles is primarily through the disc to the bone and there is minimal muscle tension. This can be verified by being pain-free under loading pressure and being consistently reproducible.
The controversy about this centered jaw position really centers more on the difficulty of consistently achieving it than if it is, in fact, the best position to have the condyles in when the teeth are together. In order to enable the swallowing reflex and to bite completely through food, the inclined planes of the tooth cusps literally force themselves to slide together so that there are a maximum number of teeth contacting and the upper and lower teeth are relatively stable.
The problem is that if, in order for the teeth to fit together, the jaw must shift out of the centered condylar position, and the condyle is no longer in a stable braced position. In any mechanical system, if the fulcrum is not stable, the system cannot function. To compensate for this lack of a stable position, the muscles of the jaw, head, neck, and often the shoulders become active to support the condyle on the inclined slope of the emenentia. Long-term continuous stability of any joint system should be based on the bones and ligaments (which do not fatigue). When the support and stabilization is shifted to the muscles, there is a very unfavorable situation. The muscles are not designed for long-term continuous activity so they will become fatigued, strained, and often cramped, and sometimes clinically painful.
When the dentist attempts to assist the jaw joints into a centered joint position, they run directly into the cramped fatigued muscles trying to brace the jaw joints so that they can function in the off-centered position they have been forced into by the teeth. As a result, the dentist, despite his or her best efforts, often fails to capture that centered jaw joint position. The solution is to eliminate the posterior interferences, release the muscles and thereby allow the jaw joints to center. It is like the classic "chicken and the egg" problem — if you cannot center the jaw joints, the muscles will not release, but if the muscles will not release, you cannot center the jaw joints.
The requirements of an ideal system to center the jaw joints is that it is:
- fast and simple to use;
- permissive in that it allows the posterior teeth to be disengaged and lets the condyles center from side to side and mildly directive to encourage the incisors to track up and back so as to allow the condyles to center up at the apex of the socket, free of the necessity for muscle support;
- stable in the mouth and the dental laboratory;
- immediately reproducible — the dentist should be able to place it in and out of the mouth in the exact same position each time, giving the dentist and the patient the ability to pre-experience how it will feel with a centered jaw relationship; and
- useable by the patient and dentist short-term to recreate the centered jaw position on demand, both at home and in the dental office, both to facilitate treatment and for short-term pain relief as necessary.
This problem was recognized long ago and there have been many solutions proposed, such as the leaf gauge developed by Dr. Long, the gothic arch tracings, and other variations ranging from the medical doctors tongue blade to the ubiquitous cotton roll and newer Best-Bite™ Discluder. They all have the same aim, that is to disengage the posterior interferences that trigger the muscle activation that ultimately prevents the jaw joints from centering. Each of these methods can assist the dentist in centering the jaw joints, but they also fail to achieve all of the ideal requirements. For example, the leaf gauge and tongue blade are very effective at discluding the posterior teeth, but they require someone to hold it and cannot easily be replaced at exactly the same angle or used by the patient at home. The cotton roll is very inexpensive and available, but it is not entirely passive in that the teeth indent into it, it gets wet and messy, it cannot be replaced in exactly the same position, and it cannot be accurately transferred to the dental laboratory. The Best-Bite™ Discluder is a new device that meets all of the requirements and can be used quickly and easily as described below.
Custom-fitting the Discluder in seconds
1) Place the custom liner material in the bite former so that the bite former is evenly filled, and place the Best-Bite™ Discluder on the upper central incisors so that the top teeth bite into the custom liner material. The bite former should sit squarely on the teeth so that the flat surface on the bottom is parallel to the incisal edges. The extension for the retention leash should be centered (see figure 1).
2) Immediately after seating the bite former on the top front teeth, the doctor should gently torque the jaw up and back by pushing down on the chin and up from under the angle of the mandible. Instruct the patient to aim to tap on their back teeth with a gentle force, so the lower jaw does not protrude, at a rate of 10-12 taps per minute. Do not attempt to force the jaw in any way as that will increase the muscle activity prohibiting the centering of the jaw joints (see figure 2).
3) Continue tapping gently until the custom liner material sets to a hard rubber consistency (approximately 90 seconds). At this point, the patient will be in a centered jaw relationship.
The next step in the process is to take a facebow recording and capture the tooth-to-tooth relationship when the jaw joints are centered, and transfer that relationship to a suitable articulating instrument for further study. However, in that position, often only one pair of teeth will touch, and the contact position will usually be on an incline. This is a very unstable position and requires the assistance of some type of bite-registration methodology. For this case, the Waterpik Technologies Denar Combi articulator and Slidematic facebow were used.
The ideal qualities of a bite-registration material would be fast and easy to use, be stable over time and temperature, be durable and nondistorting in the mouth and during the laboratory procedures, require minimal armamentarium, and be verifiable and testable. Remember, it must be taken in and out of the mouth multiple times to test the reproducibility of the relationship, as well as confirm the muscle-pain-free position. For this case, the Best-Bite Custom Liner Material was used.
Traditional materials that have been used such as plaster, waxes, acrylics, and even polyvinylsiloxane bite materials all lack at least one or more of the requirements in that they are difficult to work with in the mouth or laboratory, or not verifiable. As a result, the following methodology that allows the dentist to get a patient both free of occlusal muscle pain and create verifiable CR jaw records in the lab in less than five minutes is recommended.
1) After verifying with Best-Bite Discluder that you have a comfortable and repeatable jaw relationship by taking it in and out of the mouth several times, return it to the mouth one final time.
2) Paint a small line of adhesive and a bead of Custom Liner Material on the incisal table of the Discluder where the lower incisors will hit (see figure 3, above) and guide the patient to several taps and then remain closed in the previously verified centered jaw position (see figure 4, right).
3) While the custom liner material is setting in the incisor area, inject a larger bolus of custom liner material between the premolars and molars on both sides to capture the entire occlusal tables (see figure 5, left).
4) After 90 seconds, remove the stable and accurate bite record that will be used to properly mount the casts for the articulator (see figure 6).
The red circles surrounding the marking ribbons in the illustrations indicate that the relationship has been successfully transferred from the mouth to the articulator (see figures 7 and 8, below).
For patients with more complex dental problems and requirements, accurate occlusal analysis is an important component of a complete dental examination. The use of the discluding device makes bite records fast and accurate. This allows the dentist to take advantage of the analytical and treatment benefit of dental articulating systems.
Dr. Jerry Simon has been an active dental practitioner in Stamford, Conn., for more than 30 years with a focus on bite dysfunctions. He is also the author of the book, "Stop Headaches Now: Take the Bite Out of Headaches" and inventor of the Best-Bite™ Discluder. He can be reached through www.Best-Bite.com or by calling (888) 865-7335.
