In Neuromuscular dentistry, we consider and correct the relation of the mandible (lower jaw) to maxilla (upper jaw) which is part of the cranium. One of these six dimensions is “roll”. The others are vertical, anterior/posterior, lateral, pitch and yaw. Roll is the position of the mandible as seen from the front, where the right side of the mandible is higher or lower than the left side.
When the bite is rolled (higher on one side for example) the shoulder will be lower on the opposite side to the roll. This is due to the fact that the ‘rolled’ high bite results in compensatory shoulder tilt from feedback to the balance organ – the semicircular canals and utricle and saccule otoliths in the inner ear.
A simpler way to understand it is as follows:
Imagine the child’s stacking blocks. When one block is off center, the next one has to be off set to keep from falling off. Our body posture has to work in a similar manner to keep the balance.
Brachial plexus of nerves exit at C4, 5, 6 levels, travel between anterior and middle Scalene muscles. They later travel between the clavicle and first rib and down the arm.
This shoulder compensation for a tilted bite etc. causes spasm of the scalene muscles and compression of the brachial plexus and vessels while emerging from between the scalene muscles. Pinching this nerve causes paresthesia of the dorsum of the hand. Palpate radial pulse and note that on raising the arm the pulse diminishes and explains paresthesia.
It may also occur on the opposite side due to stretching of the scalene muscles through which the brachial structures pass.
This compensation of posture does not stop at this level. A pelvic tilt could cause symptoms in the hip or knees. So symptoms may be perceived far removed from the mandible. Far-fetched as it may seem, a poor bite has far reaching impact on the body’s posture.