MANDIBULAR ADVANCEMENT

Mandibular Advancement in an Awake and Supine Individual

The above is an example of the airway dilation that can be achieved with mandibular advancement by a dental appliance in properly selected patients.

1. The base of the tongue is elevated off of the epiglottis.
2. The soft palate does not advance in this particular patient but the arch formed by the palatopharyngeus muscles is clearly stretched and placed under tension.
3. There is a dramatic increase in the width of the airway which results from putting the pharyngeal constrictors under tension, splaying the tonsillar arches, and taking the weight of the mandible and attached tissues off of the tissues surrounding the pharynx.

The tension that is developed in the pharyngeal constrictors and the tonsillar arches takes the place of muscle activity in these structures and the levator veli palatini muscles that is present during wakefulness but which diminishes during sleep. Suspending the mandible from the upper jaw takes the place of the muscle activity of the pyterygoid muscles which is also diminished during sleep. The dental appliance also prevents the mouth from falling open. This maintains contact between the tongue and the palate that prevents backward movement of the tongue.

These changes can also be demonstrated in an individual who has been paralyzed by a general anesthetic. Therefore, these changes are due to the anatomic relations and do not require muscle activity. However, they are reinforced by muscle activity. Placing the various muscles under tension can be considered a form of pre - loading that may enhance their response to changes in airway caliber caused by changes in airway pressure.