Sleep-Disordered Breathing

A New and Evolving Role for the Dentist

Everyone sleeps, and no one thinks much about sleep until something goes wrong. When sleep does go wrong—and it can, in many ways—the effects can be more than just feeling a little tired in the morning. This chapter explores the exciting and evolving role of the dentist with an interest in sleep-disordered breathing (SDB): helping patients to breathe, sleep, and ultimately function better each day.

Snoring and sleep apnea (apnea means cessation of breathing) are points along a spectrum that extends from benign or simple snoring with no sleep disturbance to obstructive sleep apnea (OSA) with excessive daytime sleepiness and the physiologic consequences of recurrent asphyxia.²¹ Over the years, there have been many dubious claims made regarding snoring cures. However, our knowledge has now greatly improved,¹³ and much can be done to manage OSA and its associated consequences. It is in the provision of oral devices for OSA that a key role for suitably trained dentists is developing.

Sleep apnea can be caused by a lack of central drive to breathe. Later in this chapter is an overview of the less common types of apnea: central, mixed, and complex.

Professor Colin Sullivan was the inventor of the mainstay therapy for sleep apnea: positive airway pressure (PAP) therapy. He was also an internationally renowned key opinion leader, and he advocated ⁵ for dentists, as part of a multidisciplinary team, to play a critical role in four areas:

1. Treating adults with oral devices for snoring and mild to moderate OSA to slow the progression of the disease

2. Identifying patients at risk (both children and adults) by looking at their upper airways on a regular basis

3. Treating children with rapid maxillary expansion and avoiding deleterious orthodontic treatments

4. Recognizing the need for bimaxillary osteotomy among young adults with a need for maxillofacial correction

Sleep-Related Breathing Disorders and the Periodontium

The prevalence of impaired breathing in patients who are also susceptible to periodontal disease and whose periodontitis experience may be affected by a sleep-related breathing disorder is sufficient to compel dentists and their teams to develop recognition strategies.

Whereas diagnosing OSA is the responsibility of a qualified physician, the dentist is capable of identifying and differentiating clinical signs of possible airway issues, often before the patient becomes suspicious of a potential health risk. Information shared by the patient regarding his or her overall health status should be reviewed and correlated with clinical observations of oral indicators of attempted compensation by the patient for any significant degree of airway obstruction or resistance.

The value of early recognition and intervention cannot be overstated. The growing understanding of the deleterious effects of sleep-related breathing disorders and resultant periods of asphyxia on cardiovascular health, endocrine function, neurologic function, and masticatory system integrity adds to the urgency of dentists including recognition protocols during their initial and recurring evaluations of their patients.

It is important to state that a multidisciplinary team approach ²⁵ that incorporates respect for each team member’s professional role is essential for accurate diagnosis and to facilitate the provision of the most appropriate treatment.

The following sections discuss sleep, apnea, and the dentist’s role in the provision of oral devices, which is one of the increasingly favored OSA treatment options.

Dental Identification of Signs and Symptoms

Sleep, Breathing, and Apnea

A basic understanding of sleep physiology, normal sleep cycles, and the variety of sleep disorders will provide the dentist with the means for effective communication with patients and patients’ physicians.

Sleep is classically defined as a cyclic, temporary, and physiologic loss of consciousness that is readily, promptly, and completely reversed with appropriate stimuli. Not being able to breathe would seem to qualify as an appropriate stimulus; however, affected individuals are rarely aware of any difficulty.

Normal sleep progresses through different stages that are typically depicted on a hypnogram (Figure 28-1).

Figure 28-1 Simplified hypnogram of a normal adult’s sleep. (Courtesy Adrian Zacher, 2013, Snorer.com.)

Snoring is a vibratory noise that is generated by the back of the relaxed tongue, pharynx, and soft palate. Further loss of tone or narrowing produces not only louder snoring but also labored inspiration. Still further narrowing may cause complete collapse of the airway. This obstruction is known as an apneic episode.

There comes a point at which the increased inspiratory effort or the oxygen desaturation that may accompany the apneic episode is sensed by the sleeping brain, and a transient arousal will be provoked. This is a brief awakening to breathe before the individual returns to sleep. These arousals can be seen in Figure 28-2 as decreased-duration periods and increasingly frequent interruptions in the descent into deeper more refreshing sleep. Disregarding complaints about the snoring noise, these repetitive arousals occur for the most part without the individual being aware, sometimes several hundred times a night.

Figure 28-2 Simplified hypnogram of an adult’s fragmented sleep. (Courtesy Adrian Zacher, 2013, Snorer.com.)

Each apneic episode may last from a few seconds to approximately 2 minutes. The individual’s descent into the deeper and more restorative slow-wave stages of sleep is interrupted, because he or she has partially awakened to restore the airway. Sleep becomes highly fragmented, and the consequent daytime sleepiness known as hypersomnolence increases the individual’s risk of accidents at home, at work, and on the road.⁵⁰

OSA has a significant impact on an individual’s quality of life.¹⁰ If left untreated, it has neurologic and physiologic consequences,³⁷ including increased morbidity and mortality³⁵ and, particularly for men, impaired cardiovascular⁵¹ and metabolic¹⁸ function.

Prevalence of Obstructive Sleep Apnea

Sleep apnea affects a large number of people, but it continues to be largely unrecognized. Estimates suggest that 24% of men and 9% of women who are 30 to 60 years old with an average body mass index of 25 kg/m² to 28 kg/m² are affected.⁴⁹ When considered within the context of the concurrent metabolic dysfunction epidemic (which is manifest in obesity, cardiovascular disease,^31,26 and type 2 diabetes in men^12,40,39), the prevalence of sleep apnea becomes alarming. Indeed, the International Diabetes Federation urges health care professionals to ensure that a person diagnosed with OSA is considered for the presence of type 2 diabetes and vice versa.⁴¹

Central, Mixed, and Complex Apnea

In contrast with OSA, central sleep apnea (CSA) occurs without a physical obstruction of the airway. CSA is caused by a group of disorders that are characterized by the intermittent loss of the respiratory drive (in Figure 28-3, note the lack of chest wall movement in the patient with CSA). Cheyne-Stokes respirations as a form of CSA are most often seen in patients with heart failure. Mixed apnea is, as expected, a combination of OSA and CSA. Complex apnea occurs when CSA events emerge in response to PAP therapy for OSA.¹⁷

Figure 28-3 Obstructive versus central apnea. (Courtesy Learning Center, ResMed.)

This chapter is confined to OSA because it is by far the most common form of apnea, and it is in the provision of oral devices (also known as mandibular repositioning devices [MRDs]) for OSA that the suitably trained dentist may play a role.²²

Chronic Disease

The maintenance of a separate “silo” approach and viewing one aspect of an individual’s symptomatology in isolation could be argued to be flawed thinking. OSA in isolation and as a potential component of metabolic syndrome (i.e., syndrome Z ⁴⁷) requires a multidisciplinary chronic disease management approach. The World Health Organization⁴⁸ states that chronic diseases are projected to be the leading cause of disability; if they are not successfully prevented and managed by 2020, they will become the most expensive problems for health care systems.

Diagnosis of Obstructive Sleep Apnea

Snoring is a symptom of a partially impeded airway, the walls of which are vibrating as the air passes. Simplistically, how frequently the walls of the airway vibrate (i.e., snoring noise) or collapse (i.e., apnea events of varying duration) indicates the severity of the OSA.

As mentioned at the beginning of this chapter, a multidisciplinary team approach for the diagnosis and treatment of OSA is necessary. Dentists are experts when it comes to mouths and should be recognized as such. For OSA treatment, dentists need to build relationships with physicians so that they may, when appropriate, provide a dental solution to a medical condition; however, it is important to recognize that the diagnosis of OSA is not within the purview of dentistry.⁷

The closest thing to internationally accepted practice parameters, which are those issued by the American Academy of Sleep Medicine,¹⁴ state that the “presence or absence and severity of OSA must be determined before initiating treatment.” In practice, this means that a dentist must not initiate treatment with an oral device unless the patient has been assessed, medically diagnosed, and then referred to the dentist (Figure 28-4).

Figure 28-4 Obstructive sleep apnea diagnosis and treatment route. (Courtesy ResMed, San Diego, CA, 2011.)

If OSA is suspected, then a referral is made for a sleep study. This may involve spending a night in a sleep laboratory or at home with an electronic monitoring device to wear while sleeping. A sleep laboratory is essentially a bedroom with monitoring equipment.

In a sleep laboratory, the patient undergoes what is known as polysomnography (PSG), during which multiple parameters are monitored while the patient is asleep. These include (but are not limited to) sound, video, oxygen saturation, respiratory effort, electrocardiography, electroencephalography, and body position. Attended overnight PSG is an expensive assessment to perform, with varying levels of availability and access that are dependent on geography.

Several screening protocols have been proposed over the years.24,20 In January 2012, the California Dental Association⁸ determined that it is appropriate for dentists to screen patients for the signs and symptoms of SDB and to work with physicians to diagnose and treat SDB. The Association also stated that SDB is a medical condition, and its diagnosis is outside of the scope of the practice of dentistry.

Whether a PSG is essential to diagnose OSA is now being questioned.³⁶ Since 2009 in the United Kingdom, a general dental practitioner working as part of a multidisciplinary team (including a sleep medicine specialist) may in certain defined circumstances screen, recognize, and initiate treatment with an MRD without a prior medical diagnosis.⁴⁵ Currently in the United States, both PSG and home study monitor results need to be interpreted by a physician.

The role of home sleep testing and who should interpret the data that it produces are points of contention and perhaps fuel the debate surrounding PSG. This questioning of the need for mandatory PSG may be in response to the following:

• Increasingly valid and competitively priced home sleep testing equipment

• Increase in the number of patients requiring assessment

• Perception that PSG is the point of contention in the treatment process

• Realization that oral devices are appropriate for milder forms of OSA and that dentists are uniquely placed to provide them because they may see the patient more frequently than sleep medicine specialists will see the patient

• Realization that a trained dentist, as part of a multidisciplinary team, may filter referrals to the sleep medicine specialist

A sleep laboratory’s main function is to diagnose OSA and then to offer treatment to those who are likely to benefit from it. If the symptoms are fairly disabling and if the diagnosis is confirmed by a sleep study, then PAP therapy is routinely offered. Increasingly around the world, oral devices are becoming a first-line treatment for mild to moderate OSA when they can be prescribed and monitored by a multidisciplinary team.

Figure 28-5 provides definitions and diagnostic criteria for SDB.⁴⁴

Figure 28-5 Sleep-related disorders in adults: definitions and diagnostic criteria.

Treatment Options for Obstructive Sleep Apnea

Otolaryngology or Oromaxillofacial Surgery

Surgical options for snoring and OSA are largely outside of the scope of this text. However, it is important to note that, when physical obstructions to the airway are present (e.g., tonsils, deviated septum, nasal polyps) surgical correction may improve breathing. For example, if adenotonsillar hypertrophy exists, then childhood correction is considered advantageous.³⁰

Limited evidence for adult palatal surgery, which is known as uvulopalatopharyngoplasty, exists; this surgery should be considered only after PAP therapy has failed.⁶ Maxillary or bimaxillary orthognathic surgery is rarely considered, whereas tracheotomy is an effective option of last resort, because it completely bypasses the affected area.

Positive Airway Pressure

PAP (Figure 28-6) is considered the first-line treatment for OSA, and it is very effective in terms of helping the patient to overcome daytime sleepiness symptoms. Individuals with severe sleep apnea do well with this therapy, despite the forbidding appearance. Possibly considered an arduous therapy, it involves wearing a mask over the nose (and sometimes both the mouth and nose) at night while being connected to a quiet blower. It works by slightly pressurizing the upper airway, thereby pneumatically splinting it open and thus preventing it from collapsing. PAP is particularly useful when there is a need for the rapid control of OSA.