INCREASED OPENING

Effect of Increasing the Vertical Opening with the Mandible Advanced

When the mandible is advanced, the arch formed by the palatopharyngeus and palatoglossus muscles is splayed and tension is developed in the palatoglossus muscle. The tension in the palatoglossus muscle is transmitted into the arch of the soft palate and reduces vibration. This is analogous to tightening the string on a guitar.

However, only the component of the force vector that is parallel to the axis of the palatoglossus muscle produces tension in this muscle. As the diagram shows, for a given amount of mandibular advancement, you can increase the force vector along the palatoglossus muscle by increasing the vertical dimension. This explains why some patients who continue to snore with their mandible advanced by a Silencer (a dental appliance) will stop snoring when you increase the vertical dimension by putting in a longer pin.

But there is a trade - off. If you open the mouth too much, you will start to compress the tissues around the pharynx and promote collapse of the lateral walls. In some patients, you will also decrease the amount of contact between the back of the tongue and the palate and this will make it easier for the tongue to obstruct the airway. This is particularly likely to occur in a patient who has had a UPPP or a LAUP.