Spring 2000 Presentation Summary:

Sleep medicine is the fastest growing subspecialty in medicine and dentists are often called upon to assist in managing problems of snoring and obstructive sleep apnea with oral appliances. While the most effective treatment is provided by positive-pressure breathing machines, they are not well tolerated by most patients, and oral appliances that enhance airway patency are often more effective with mild to moderate obstructive sleep apnea problems.

Apnea is defined as the cessation of breathing for ten seconds or longer. Snoring and apnea are related, but not the same entity. Mild snoring is controlled by not eating late and avoiding alcohol. Moderate snoring is correctable with a nudge and a roll over. Heavy snorers persist in any and every position. Not all individuals who snore suffer from apnea, but all apnea sufferers snore. Snoring is a nuisance, but apnea kills.

Defining Sleep Apnea

Dr. Lowe presented linear classification, or working definitions of snoring and sleep apnea. The apnea index refers to the average number of episodes per hour. With mild sleep apnea—the index is under 20—there is a 95% survival rate over a nine-year period. The index range for moderate apnea is 20 to 40, and an index over 40 is considered severe. When the apnea index exceeds 20, the nine-year survival rate decreases to 64%.

Apnea occurs in about 4% of the adult population. It is five to ten times more prevalent in males and incidence increases with age and weight. As the level of testosterone falls, the incidence of sleep apnea increases. It is not known whether this is a cause and effect relationship or two simultaneously occurring events, but in some respects, sleep apnea can be considered related to male menopause.

The correlation with weight is striking. A 10% loss of body weight will result in a 50% reduction of apnea symptoms.

Considering the striking effect of weight loss in reducing symptoms, it seems an effective means of controlling the problem. However, depression often accompanies sleep deprivation. Because it has proven difficult to motivate depressed individuals to shed pounds, the sleep disorder community has abandoned this mode of treatment. Alcohol consumption is also a major factor to consider in the evaluation and regulation of apnea. Alcohol and hypnotic or sedative medications are to be avoided in the hours before bed time.

Symptoms

The following statistics present another way of looking at the interplay between age, snoring and apnea. At age 50, five out of ten males snore and three in ten have sleep apnea. By age 60, eight out of ten males snore and half suffer sleep apnea.

Sleep apnea presents half a dozen signs and symptoms, morning headaches being a classic example. Daytime sleepiness is the most common symptom, and because traffic accidents are frequently linked to sleep deprivation, a growing number of states require physicians to report patients with high apnea indices for suspension of driving licenses until effective management can be demonstrated.

Apnea sufferers experience frequent awakenings while gasping or choking causing fragmented and non-refreshing sleep. They may log long hours of sleep, but most of it will be stage one or two, not the deeper stage three, four, five or REM sleep. Poor memory and clouded intellect are other consequences of sleep deprivation. Decreased sex drive and impotence also result.

The physiology of obstructive sleep apnea generates related anatomic alterations. Edematous enlargement of surrounding tissues further constricts the air passages. The volume of the uvula increases by 30% or 40% during snoring. Pressure from chest movement causes the base of the tongue to become enlarged. Difficulty in swallowing is experienced on wakening as a result of engorgement of the epiglottis, tongue and soft palate.

Types of Apnea

Two types of apnea are recognized in sleep medicine: obstructive and central. Physical obstruction prevents air intake, although strenuous breathing efforts persist. With central sleep apnea, air flow stops and there is no chest movement. Accurate diagnosis is critical as appliance management is obviously not indicated.

Therapeutic options include continuous positive airway pressure (nasal CPAP), oral appliances, medication and surgery. Nasal CPAP is by far the most effective, but compliance is very poor unless the patient’s condition is severe. Oral appliances will successfully reduce 80% of mild to moderate snoring and half of the sleep apnea with an index under 40. Pharmaceuticals are not very effective.

Doctors have employed a variety of surgical interventions with varying degrees of success. A tracheotomy is generally effective since it inserts proximal to the site of obstruction. Obliteration of the uvula and part of the soft palate can be effective with morbidity minimized by laser surgery. Mandibular and maxillary advancements to protract the tongue away from the posterior pharynx achieve only modest success.

Results of recent research indicate that oral appliances can achieve positive outcomes more predictably than anything except nasal CPAP, particularly in mild to moderate conditions where compliance is much better.

A large number of oral appliances have been employed in attempts to control obstructive sleep apnea. Dr. Glenn Clark at UCLA has achieved a degree of success with removable Herbst appliances. Mandibular repositioners can also be effective, but both of these appliances have drawbacks.

Methods of Treatment

Dr. Lowe employs three devices in his practice. A tongue-retaining device in which the patient bites on a rubber bulb to protract the tongue via a vacuum is useful for individuals whose dentition is inadequate for retention of a conventional appliance. "Snore Guard," marketed by a dentist in Albuquerque, is primarily a boil-and-bite appliance, useful in emergencies or as an interim measure while a more effective device is being fabricated or repaired. The flagship appliance in Dr. Lowe’s armamentarium is the "Klearway," which shows considerable promise in ongoing studies. Like the other devices, it is designed to protract the mandible and particularly the tongue away from the posterior pharyngeal wall so the airway can not be occluded. It consists of maxillary and mandibular occlusal cover acrylic members connected by a Hyrax screw rotated 90 degrees so that opening the screw will position the mandible forward. This arrangement also permits side to side mandibular movement. This is important as there is a high incidence of bruxism in apnea patients.

The protocol for oral appliance management of obstructive sleep apnea is to obtain a medical work up. Under no circumstances should a dentist deliver an oral appliance without an attending physician’s diagnosis and written request to do so. Ideally, the medical work up will include a copy of the sleep study along with the written request for appliance therapy. To ignore this protocol is to engage in the illegal practice of medicine. Furthermore, it is foolhardy for a dentist to be treating a medical condition with a 36% mortality rate over a nine-year time span.

Dr. Lowe’s standard procedure is to do a comprehensive evaluation of oral and dental health, in addition to his standard orthodontic work up for these patients. This makes good sense when one considers that alteration of mandibular position is the objective of treatment and that occlusal changes may be one of the appliance’s side effects.

A trial procedure with an inexpensive, uncomplicated appliance will aid in the selection and design of the permanent appliance, although this becomes less crucial as experience and confidence are acquired.

Side effects, fortunately, are few and generally minimal, and initial discomfort usually dissipates in three to four months. Over the four years of an ongoing study funded by the Canadian government, temporomandibular dysfunction has generally proven to be transitory. Intracapsular edema will occasionally result in a bilateral posterior open bite. Other occlusal changes are essentially limited to proclination of lower incisors and retroclination of upper incisors with incidence in the 10% to 15% range. Salivation, soft tissue irritation and sore teeth are occasionally mentioned. Some patients, unused to mouth breathing, may complain of dryness.

Design elements of the Klearway appliance, which Dr. Lowe feels contributes to its success, include retention, variable range of adjustment and material flexibility. Of these, retention is of utmost importance, especially when enhanced by accurate impressions and the thermo-sensitive material from which the appliance is constructed. The appliance is so retentive that it must be heated for insertion and removal. Vulnerable restorative dentistry should be protected or replaced. Lateral mandibular movements are possible for the 48% of sleep apnea patients who brux.

The unique feature of the Klearway appliance is its ability to permit a range of adjustments for precise mandibular repositioning. This adjustment requires a certain amount of effort. Locating the point of mandibular positioning that opens the airway is an interesting proposition. It is referred to as titration. Unlike the nasal CPAP device, which is titrated overnight in the sleep lab and merely involves increasing the pressure to a point where the obstruction is overcome, the Klearway must be adjusted gradually over a prolonged period of time. This may take as long as six months, at which point the patient should be referred back to the attending physician for revaluation.

In some respects, the location of the adjustment (at which the airway is opened) is a matter of subjective interpretation of symptoms. There is "a point at which a small change in mandibular advancement dramatically increases the airway."

Care must also be taken to limit mandibular position changes to the horizontal since vertical opening can worsen obstruction. The Hyrax screw should be positioned to avoid depressing the tongue, and the attachment wires need to be positioned as far apart as possible for the same reason.

Conclusions

Dr. Lowe reemphasized the importance of not becoming involved with snoring and sleep apnea patients unless a written request for treatment, accompanied by the appropriate diagnosis, has been submitted in writing by the referring physician. Even at this point, one must be cognizant of indications and contra-indications. Oral appliances are likely to work for primary snoring. For selected obstructive sleep apnea patients, the probability of success is good, primarily for those where the condition is mild or (to a lesser degree) moderate.

The use of oral appliances may be indicated if all else fails, for example, when treating CPAP-intolerant patients or those individuals who present surgical contraindications. In such cases, they will work only occasionally and the probability of success is low. However, oral appliances should never be considered a first-line treatment for patients with severe obstructive sleep apnea or for persons afflicted with central sleep apnea.

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