MULTILEVEL ORAL APPLIANCE TREATMENT
SUMMARY
Obstructive sleep apnea (OSA) is caused by choking on the tongue base and soft palate during sleep. The following paper describes treatment of this condition for people with a normal set of healthy teeth. Many dentists now treat OSA in these people with mandibular advancement appliances, and the appliances are well tolerated; but they are only effective in 50% of patients, because the mandible is only loosely attached to the tongue and not at all attached to the soft palate. Therefore, Dr. Summer has devised mechanisms that can be added to ineffective mandibular advancement appliances in order to also control the positions of the tongue and soft palate. For people without teeth (denture wearers), the treatments are described under the file TREATMENT FOR DENTURE PATIENTS. For people who want a detailed description of the new mechanisms and a protocal for comprehensive oral appliance treatment of OSA, the protocol and rationale can be found in the file entitled, MULTILEVEL ORAL APPLIANCE TREATMENT under the FOR DOCTORS tab.
BACKGROUND
OSA affects millions of people, but current treatment for it is problematic. Minor surgeries can be helpful but rarely curative. CPAP is usually effective if the pressure is high enough, but compliance is poor, because many people find it difficult to tolerate. Oral appliances currently used to treat the problem work by advancing the mandible, which increases the space available in front of the tongue; but it cannot draw the tongue forward into that space, because the mandible is only attached to the tongue by muscles, which naturally lose their tonus during sleep. As a result, even extreme mandibular advancement cannot prevent the tongue from falling back into the throat to block the airway, it just has further to fall, and mandibular advancement only cures about half of the people treated, as seen consistently in hundreds of studies.
New mechanical devices can now be added to ineffective mandibular advancement appliances to make them more effective by also holding the tongue to prevent it from dropping back into the throat, elevating the middle of the soft palate to draw its back end away from the obstruction, and prying the tongue base off the pharyngeal wall. To prevent unnecessary treatment, these modalities can be added one at a time until the problem is solved, as described below:
STAGE ONE
MANDIBULAR ADVANCEMENT - The first stage of multilevel oral appliance treatment for patients with natural teeth involves using an adjustable mandibular advancement appliance to gradually move your mandible further forward until you find the most advanced position that you can comfortably tolerate. A variety of oral appliances are currently available from many dentists for this "titration" process. The appliances cause bite changes, which should be treated by bite adjustment, usually by the dentist who made your oral appliance, as explained further at the end of the file entitled MULTI-LEVEL ORAL APPLIANCE TREATMENT OF SLEEP APNEA under the FOR DOCTORS tab.
Telescopic (Herbst) appliances have the longest history of success in treatment for sleep apnea and the best control over mandibular position, but the hardware they employ was designed more than a century ago for bite jumping in children, and it is unnecessarily bulky and restrictive when used in adults, leading to discomfort and breakage. To solve these problems, Dr. Summer's high push Herbst appliance has a lower profile for comfort, free lateral movement to prevent binding and breakage, an upward vector of force on the mandible to prevent mouth breathing, and unlimited adjustability without tools by just rotating the tubing assembly on the threaded connector, as shown below.
A SOFT PALATE ELEVATOR - is often added to the mandibular advancement appliance in stage one in order to open the nasopharyngeal airway by pulling the distal end of the soft palate out of the narrow gap between the tongue base and the pharyngeal wall, because the two treatments work together better than either one alone. Drawing the distal end of the soft palate away from the obstruction works like removing a gasket from a seal. It can immediately open the airway, but it cannot prevent formation of a new gasket without changing the functional environment that formed the gasket. Mandibular advancement changes the functional environment, but it may not change it enough to restore airway flow without also removing the gasket.
The soft palate elevator employs a silicone rubber bulb on the end of a thin flexible arm to “tent” the middle of the soft palate, where there are few gag reflexes, in order to draw its distal end, which is full of gag reflexes, upward and forward away from the obstruction, as shown above. The soft palate is a thin flap of tissue that has almost no tonus during sleep, and a light force is able to keep it elevated about 1/4” all night without causing any discomfort.
At the end of stage one treatment, some type of follow-up sleep testing is necessary to find out how well the treatment is working. If it's only partly effective, you'll feel better; but you'll likely relapse over time, as the remaining incidents continue stretching out the soft tissues of the pharynx.
STAGE TWO – The next stage of multi-level oral appliance treatment is to hold the tongue against the advanced mandible between specialized upper and lower tongue gripping surfaces that each contain thousands of forward slanted bristles, (AKA tongue velcro), to prevent it from dropping back into the pharynx. Their grip is so effective that a single orthodontic elastic or a lightweight spring connecting them provides enough compressive force to hold the tongue without discomfort all night in the space shown below.
A lower tongue gripping surface is shown below left and an upper tongue gripping surface is shown below right.
To prevent accidental release of the tongue during sleep, at least one of the upper tongue gripping surfaces (the upper for patients with teeth and the lower for denture patients) is mounted in a continual biasing mechanism that creates a cushioned grip which persists throughout the submaximal mandible and tongue movements that occur during normal sleep. The cushioned grip continues until the mouth is opened wide enough to release the tongue. In most people, the target position for the tongue is just far enough forward for its tip to maintain light contact with the lips closed around it, as shown below. Patients go to sleep with the tongue in this target position, and they awake with the tongue in the same target position, because the tongue cannot escape during sleep.
STAGE 3 - If follow-up sleep testing shows that the apnea persists, the remaining airway blockage probably occurs down lower in the hypopharynx, where the tongue base directly contacts the pharyngeal wall. To treat the hypopharyngeal obstruction, the tongue base is gradually pried off the pharyngeal wall by incremental adjustment mechanisms called tongue base titraters that are mounted on the back of the upper tongue gripping surface to shift its tail segments, in progressive weekly increments, further down and back as the patient gets accustomed to them.
The three rows of apertures in the tongue base titraters enable the direction of depression to be varied by 25 degrees, as shown below.
UNADJUSTED DOWN AND BACK DOWN AND FORWARD
FACTORS COMPLICATING TREATMENT
MOUTH BREATHERS - Mouth breathing is devastating to health, because the air that hits the back of the throat has not been warmed, filtered, and moistened by the nose; which leads to more frequent upper respiratory infections. Some people are obligate mouth breathers, because their nasal cavity is too narrow to allow adequate airway flow. Other people have a nasal cavity that is just wide enough to allow normal nasal airway flow, and thehy become obligate mouth breathers whenever allergies or rhinitis causes swelling of the nasal mucous membranes. Obligate mouth breathers can be converted to nose breathers after palatal expansion to widen the nasal airway. However, palate expansion rarely eliminates apnea, because the area that is widened is located far from the back of the throat where the obstruction occurs. Habitual mouth breathers use an oral airway despite having an adequate nasal airway passage, and their mouth breathing habit can usually be eliminated by almost any mechanism that can hold the mouth closed; including chin straps, lip taping, thick foam cervical collars, or interarch orthodontic elastics on an oral appliance that fits on the teeth tightly enough to resist being pulled off them by the weight of the lower jawbone.
TMJ DISORDERS - can make it difficult to advance the mandible rapidly or extensively, but they usually resolve by middle age when OSA begins, so they rarely prevent gradual mandibular advancement, and they do not even interefere with soft palate elevation or tongue holding.
BITE CHANGES - are frequent consequences of mandibular advancement due to a combination of tooth movement and jawbone growth. Patients usually find that their back teeth no longer fit well together in the morning and then throughout the day, because the upper front teeth have shifted backward, the lower front teeth have shifted forward, and the mandible has elongated. The resulting "posterior openbite" can make chewing less effective, but chewing capacity can be easily restored by having your dentist adjust your bite forward. Dentists are trained to adjust bites backward rather than forward, so it is often difficult for them to understand why they need to do it and how, but adjusting the bite forward in treatment of sleep apnea can provide important benefits. The resting posture of the mandible is controlled by its central bite position. Advancing the central bite position thus advances the resting posture of the mandible and tongue, which facilitates daytime airway flow and reduces dependence on the mandibular advancement appliance, because the mandible that gets used to being in a forward position can stay there for short periods of time, like when taking a nap.
COSTS - Many different types of mandibular advancement appliances are available from many dentists. We employ a fully adjustable (titratable) high push Herbst appliance. The fee for that appliance for stage one treatment is $2600. Stages two and three costs depend on circumstances, and they can be waived if you are participating in one of the two ongoing clinical studies to evaluate the effectiveness of the treatment using after before and after home sleep testing.