The Role of The Bite in TMJ Disorders
Page 4 of 6BITE STRAIN
Even if your bite is stable, it may still be strained. In other words, even if your bite forms a stable platform on which all of your back teeth hit at the same time, that platform may still be located in a lower jawbone position that is too far back or off to one side and is not easily accommodated by your muscles or TMJs.
The jaw muscles are arranged in bilaterally symmetrical slings that converge down onto the lower jawbone at various angles from their widespread attachments on the skull. When the lower jawbone is at rest, it should hang from these slings in a central position. Then, when the jaw muscles contract evenly, they should close the lower jawbone along a trajectory that is also determined by the anatomy of the slings. At the top of that trajectory should be a stable platform formed by the simultaneous fitting together of most or all the back teeth, the central bracing or intercuspal position of the lower jawbone.
In many TMJ disorder patients, the central bracing position of the lower jawbone is not located at the top of an unstrained lower jawbone closing trajectory. Instead, for the lower jawbone to access its central bracing position, it must shift away from its preferred natural closing trajectory and torque or twist into a different location. That process can displace the condyles within the sockets of the TMJs and force the jaw muscles to do all of their exercise in a strained position - like riding a bicycle with the seat too low or lifting weights with your feet planted slightly off to the side. As a result, those jaw muscles may spend hours every day clenching or grinding and still never become strong and healthy like muscles in other parts of the body that are exercised for hours every day.
Even if your bite forces your lower jawbone into an extremely strained position each time your mouth is fully closed, you are unlikely to become aware of the strain, because the teeth are protected by neuromuscular reflexes that continuously program the jaw muscles to only close the jawbone wherever the teeth fit together. During evolution, the jaw muscles were strong, and the teeth were delicate. Neuromuscular reflexes protected them so well that even a very strained bite can feel perfectly natural.