Orofacial Myofunctional Disorder

The normal way to breathe is through your nose. As we grow and develop, certain things such as pollen, cow milk, and other variables can cause an allergic reaction, causing the lymphoid tissues known as tonsils and adenoids to become swollen. As the tonsils and adenoids become swollen, they develop into an obstruction for nasal breathing and slowly, mouth breathing begins to be the primary intake of air into the body. In order to breathe through the mouth, the lower jaw comes down, the tongue comes off the palate and settles on the lower teeth. Nasal breathing is the correct way for air to enter the body, and during nasal breathing, the tongue rests at the palate and the pressure of the cheeks is balanced by the tongue.

During mouth breathing, the pressure from the cheeks is unopposed by the tongue. The oral system becomes unbalanced and results in the deformation of the upper jaw, creating a v-shaped arch as opposed to a correct u-shaped arch. This also produces an incorrect swallowing function. Upon swallowing, the tongue rests on the lateral teeth, hindering normal tooth eruption, causing a lateral tongue thrust. A constantly open mouth causes the incisors to over-erupt. The result is the deformation of the lower arch known as the bicuspid drop-off. The result of this deformation of the upper and lower arches is the presence of premature contact upon closing which shifts the lower jaw distally off of the physiologic trajectory. The narrowing of the upper arch pushes the lower jaw back - this forces the TMJ condyle to shift distally while the TMJ disc shifts forward. Upon opening, the disc can shift onto the condyle to restore the TMJ's correct position and then shift back to an incorrect forward position upon closing. This is what causes a reciprocal click. In addition, the muscles could be in a state of hypertonus or spasm which can result in tension headaches. An incorrect position of the lower jaw can result in pair functional activity of the muscles, such as clenching and grinding. Over time, grinding can result in severely worn down teeth. As a result, the teeth become even shorter, the lower jaw shifts distally even further and the vertical of the bite decreases. In time, joint degeneration occurs. The joint becomes deformed, and the ligaments of the joint become damaged. As a result, the TMJ disc can get trapped in front of the condyle. While the click may go away, limited mouth opening will occur. A distally shifted jaw and tongue position results in even further restrictions of the airway. In order to open up the airway, the neck moves forward and the head tilts backward. This stresses the spine and fatigues the neck muscles which results in neck, back, and shoulder pain.