Improved oral appliance treatment for sleep apnea
Obstructive sleep apnea (OSA) occurs when people choke on their tongues during sleep. In millions of people, these airway blockages occur frequently enough and for long enough to become a serious health problem, but treatment for it is problemmatic. The standard medical treatment, CPAP, is usually effective, because it balloons out the whole pharynx and thereby makes it too large for the tongue to plug it. However most people hate CPAP. Dentists make a variety of oral appliances to treat sleep apnea by protruding the lower jawbone (advancing the mandible), and patients find them much more tolerable than CPAP; but numerous studies show that their success rates never exceed about 50%, because the lower jawbone is only loosely attached to the tongue and therefore has limited ability to keep it from dropping back into the throat. To make oral appliances effective in these cases, we have developed a new tongue holding device that can be added to a jaw protrusion appliance to hold the tongue forward together with the lower jawbone. If needed, it can also include a tongue rear depressor and a soft palate elevator. By protecting airway passage through the whole pharynx, such a multi-level oral appliance approach is likely to become a first line treatment for sleep apnea.
PATHOPHYSIOLOGY OF SLEEP APNEA
Obstructive Sleep Apnea (OSA) occurs during sleep when the tongue gets sucked back into the throat and creates a plug that prevents all breathing until the resultant decrease of oxygen levels and increase of carbon dioxide levels trigger an adrenalin release which causes a gasp that temporarily restores the airway. In millions of older people, these recurrent intermittent airway obstructions last long enough and occur frequently enough to pose a serious health problem. Almost half of those over the age of 60 suffer from OSA. In some people the blockage involves just the base of the tongue filling the pharynx. In other people the blockage may also include some loose tissues from the soft palate or lateral tonsillar walls that fill in around the base of the tongue to help complete an airtight plug.
CURRENT MEDICAL TREATMENT
Studies using imaging to try and locate the pharyngeal airway obstruction in OSA have found that it is too variable to provide a basis for targeting one area for treatment. As a result, surgery is only predictably effective if it occurs at all levels of the pharynx (multi-level surgery). CPAP (continuous positive airway pressure) employs an air compressor to balloon out all levels of the pharynx, and it is predictably effective if the pressure is high enough. However, most people hate it. Nearly half of those who have been given a CPAP machine do not use it on a regular basis. An additional problem is that the nightly ballooning of the pharyngeal soft tissues stretches them out much the same way that aging does and thereby makes them more easily sucked into the airway, creating CPAP dependency. A large number of simple treatments (nasal strips, a nasal valve called provent, chin straps, and various over the counter mouth appliances) are aggressively marketed but only occasionally effective.
CURRENT DENTAL TREATMENT
Dentists make a variety of oral appliances to treat sleep apnea by protruding (moving forward) the lower jawbone and thereby making a space into which the tongue can protrude to allow airway passage behind it. However, in the hundreds of studies that have been performed over the last two decades, jaw protrusion is never more than about 50% effective, because creating a space in front of the tongue cannot move the tongue forward into that space. The lower jawbone and the tongue are only attached by muscles, which lose tonus during sleep. Consequently even extreme jaw protrusion can’t always prevent the tongue from falling back and obstructing the pharynx - it just has a little further to fall.
There are a few other types of oral appliances that are occasionally used for treating OSA, but they also have limited success. The tongue retaining device (TRD) uses a rubber suction bulb to grasp the tongue and hold it out between the lips, but the extremely protrusive tongue position it requires is difficult to tolerate. Tongue rear depressors and soft palate elevators have shown some success, but they are rarely effective when used alone.
NEW MULTI-LEVEL DENTAL TREATMENT
Combining all of these treatment modalities into one oral appliance offers obvious advantages in both effectiveness and comfort, because their actions are highly synergistic. The lower jawbone provides the base of operation for the tongue (which has no bone of its own), so protruding the lower jawbone helps protrude the tongue. Protruding the tongue makes its rear portion more accessible for mechanics that push it down and away from the soft palate, which works better when combined with a soft palate elevator pushing the end of the soft palate upward and away from the tongue rear. Pushing the rear portion of the tongue down and forward helps keep the body of the tongue forward by denying it a space into which it can retrude.
However combining all of these treatment modalities has not been possible previously, because the mechanical components needed for each modality have not been compatible. For example, the silicone rubber of the TRD cannot be easily attached to dental acrylic.
We have developed a new tongue holding device (THD) that is entirely made of dental acrylic so it can be added to almost any jaw protrusion appliance in order to hold the tongue forward together with the lower jawbone for people in whom a jaw protrusion appliance was tolerable but unsuccessful. The THD has been shown in a preliminary study to be well tolerated, especially when used together with jaw protrusion.
Our clinical protocol is designed to integrate these oral appliance modalities in a manner that provides minimal necessary treatment. We begin with a jaw protrusion appliance, and we only add the THD if follow-up testing shows that jaw protrusion is unsuccessful. If that combination of two modalities is still ineffective, we add first a tongue rear depressor and then a soft palate elevator. Following this protocol, your oral appliance will contain only the modalities you need to solve your problem.
The jaw protrusion appliance we use to initiate treatment is a patient adjustable telescopic appliance. Telescopic appliances have a long history of proven effectiveness in treatment for OSA. However the commonly used Herbst and SUAD telescopic components were designed more than half a century ago for orthodontic bite jumping in children. When used in adults, they are unnecessarily bulky and restrictive. We have redesigned them for use in adults by flattening the telescopic components to better fit the buccal vestibule (the space between the teeth and the cheeks) for comfort, allowing a free range of motion laterally for TMJ health, and making them micro-adjustable by the patient over a range of ½” without special tools for the titration process, explained below.
Jaw protrusion appliances that can also be used as the base appliance for multi-level treatment include the Somnomed, EMA, and Herbst appliances. Patients who have used one of these jaw protrusion appliances and found it tolerable but unsuccessful in relieving their apnea can have the multilevel modalities added to their old appliance in order to make it effective. A few dentists make monobloc appliances to reduce their costs. Monobloc appliances cannot be used as a base appliance.
TITRATING your jaw protrusion appliance means gradually adjusting it further forward until you get it as far forward as you can tolerate without discomfort. Titration of jaw protrusion appliances has been shown in multiple studies to increase their effectiveness. Monobloc appliances cannot be titrated.
After you have titrated your appliance, it needs to be tested to determine if it is effective. We use a home sleep test that records data over multiple nights, because it takes a few nights to sleep normally while wearing any new device and because there is a 15% variability in recordings from different nights. If the appliance is to provide a long term solution, it must not just reduce but substantially eliminate your sleep apnea. If you simply have fewer apnea events, each event continues to stretch the pharyngeal tissues, and after a few years you will likely end up with the same degree of apnea you had before using the appliance, even with the appliance in place.
If testing shows that you still have OSA despite jaw protrusion, stage two treatment begins with adding a tongue holding device (THD) that grasps the tongue between upper and lower tongue gripping surfaces, each containing thousands of miniature forward-slanted bristles which act like directional velcro. The bristles on the upper tongue gripping surface fit between each of the little papillae on the top of the tongue. The bristles on the lower tongue gripping surface, which engage the more sensitive mucous membrane on the underside of the tongue, are much smaller and feel like a cat's tongue. Because of the 45 degree angle of all the upper and lower bristles, your tongue can easily slide forward into the space between the tongue gripping surfaces, but it cannot slide backward out of that space (shown below right) without opening widely enough to release the tongue.
As shown below, wide opening releases the tongue, because the force that grips the tongue is provided by a trans-palatal orthodontic elastic (dashed lines) which pushes the upper tongue gripping surface down into the top surface of the tongue only until the middle of the elastic reaches the same plane as the ends of the elastic. Any further mouth opening (bottom figure) separates the tongue from the tongue gripping surfaces and thereby releases the tongue.
|RESILIENT SUSPENSION OF TONGUE GRIPPING SURFACES|
If another multi-night home monitoring study shows that you still have OSA in spite of tongue and lower jawbone protrusion to clear the lower pharynx, your airway is blocked in the upper pharynx where the soft palate gets sucked into the space between the tongue rear and the back wall of the pharynx, as shown below.
To restore airway passage in the upper pharynx, we add two more modalities, as shown below. The first is a relatively strong and flexible arm that pushes the back of the tongue downward and forward away from the back wall of the pharynx but also allows the movement of the tissues in swallowing. The length and angle of the arm can be adjusted as necessary to avoid gagging or discomfort. The second is a lightweight arm that extends upward and backward from the back of the appliance to elevate the middle of the soft palate and thereby "tent" that very flexible structure in order to pull its back end upward and forward away from the area of obstruction.
The result of combining all these treatment modalities operating at different levels of the pharynx is a true multi-level treatment oral appliance that contains only the modalities needed to solve your problem. Such a multi-level approach is likely to become the key to predictable success with oral appliance treatment of OSA, just as a multi-level approach has proven necessary for predictable success with surgical treatment of OSA.
Many people are occasional mouthbreathers when nasal inflammation due to cold or allergies prevents adequate airway passage. The multi-level oral appliance permits mouthbreathing, because the upper tongue gripping surface of the THD descends with the lower jawbone when the mouth is part way open and thereby creates an oral airway passage just under the hard palate. In addition, the multilevel oral appliance can include interarch elastics that prevent the lower jawbone from dropping open during sleep. The elastics are attached to little metal buttons on both upper and lower segments, and they are available in a wide variety of sizes and strengths. If this additional effect is desired, both upper and lower portions of the appliance must be specially made to fit the teeth tightly enough to resist being pulled off by the weight of the lower jawbone.
COST OF TREATMENT
The cost of the entire treatment protocol is normally $3800. That includes $1900 for the phase 1 (jaw protrusion) treatment (which is also provided by other dentists) and $1900 for the second phase (the additional modalities including tongue holding, tongue rear depression and soft palate elevation), which is only needed if jaw protrusion is ineffective. However, during 2017, we are collecting data for a study of the phase 2 modalities. Therefore, if you are willing to follow the above described treatment protocol carefully, the second phase may be free.