Upper Airways and Obstructive Sleep Apnea: What Should Dentists Do for Their Patients?

Knowing this, screening patients for signs and symptoms of OSA should be part of a dentist's routine when checking a patient's medical history. This can be done by incorporating questions regarding commonly associated symptoms, which in adults include snoring, witnessed gasping during sleep, and daytime sleepiness; in children with OSA, typical indications are snoring, restless sleep, and behavioral issues like hyperactivity, inattention, and crankiness. Follow-up and referral to a physician should be made if review of the patient history is suspicious of OSA.

Screening for OSA, however, generally should not rely appreciably on investigation of deficient dentofacial or airway anatomy, including CBCT data. A static CBCT image of the upper airway in a patient who is upright and awake typically will provide scant useful information on how the airway actually functions during sleep. Indeed, research has shown that healthy patients who happen to have a narrow airway can overcome this limitation through a greater amount of active dilation during respiration.¹Recent research has revealed different phenotypic traits for OSA patients and that most of these patients have one or more non-anatomical pathophysiologic traits, such as an abnormally low arousal threshold, or an incompetent neuromuscular activation response to negative pharyngeal pressures.² This complexity is reflected in the fact that only approximately half of adult patients treated with a mandibular advancement oral appliance will be effectively treated.³ In other words, despite undergoing a substantial anatomical change in airway size and mandibular position while wearing the mandibular advancement oral appliance, patients still experience airway obstruction and arousal from sleep.

Because of the complex pathophysiology of OSA, it is unreasonable to expect that enlarging the airway modestly by maxillary expansion will consistently improve airway function in all or even most patients. While it may help in any given situation, improvement does not always occur; therefore, maxillary expansion for the purposes of OSA management should be performed in conjunction with monitoring from a physician and also possibly objective sleep testing. Future research will focus on improved phenotyping of OSA and identification of patients in whom deficient anatomy contributes most significantly to the disease. This will enable effective, efficient treatment to be targeted to particular patients instead of a misguided one size-fits-all approach.

As healthcare providers, dentists should care about not just teeth, but everything around the teeth and its effect on a patient's general health. According to the American Dental Association policy statement adopted in 2017, dentists are encouraged to evaluate the patient's airway and screen for potential sleep disturbances.

It has long been known that nasal obstruction, due to such possible factors as a deviated septum or enlarged tonsils and/or adenoids, can interfere with normal craniofacial growth, and malocclusion may develop during an individual's growth phases. Adults forced to become mouth breathers due to nasal obstruction may experience detrimental effects both dentally and periodontally. Obstructions or airway anatomy may also contribute to sleep disorders. Dentists should assess the etiology and not just treat the symptoms.

Despite increased awareness of obstructive sleep apnea (OSA), about 75% of individuals that have this condition remain undiagnosed.⁴ This is a large number of people, considering that one in five Americans have at least five sleep apnea events per hour,⁵ during which the individual stops breathing for at least 10 seconds and shows a decrease in blood oxygenation, causing him or her to wake up gasping for air. Interrupted sleep prevents an individual from reaching deep sleep stages where the body restores, releases hormones, mobilizes its defenses against illnesses, and removes neurotoxic waste products that accumulate in the awake central nervous system.

Current policy dictates that only a physician can diagnose a patient with OSA or any other sleep disturbance; however, dentists can greatly help their patient population by performing routine risk assessments. Implementing a validated risk assessment mechanism in a dental office is easy to do. Commonly used and accepted tools are the pediatric sleep questionnaire (PSQ) for patients under 18 years of age, the STOP-Bang questionnaire for adults, and the NOSE questionnaire, which evaluates for nasal obstruction.^6-8These surveys can be completed and assessed in a few minutes and provide an objective result, letting the dentist know if a referral to a sleep physician is recommended. Clinical and radiographic examinations should also be performed in which the tonsils and adenoids are evaluated, and even a simple Mallampati analysis can be done.⁹

Dentists' most common contribution regarding treatment or management of OSA is through the use of either maxillary expansion to potentially help with nasal breathing or oral appliances to manage sleep apnea when the constriction is pharyngeal. Maxillary expansion has been an effective treatment for OSA but should be used only when it is anatomically indicated (maxillary constriction), and the prophylactic approach should not be used to prevent sleep apnea.

Regarding oral appliances, a patient may opt to use one instead of a continuous positive airway pressure (CPAP) machine. Typically, after referral to a sleep physician, if appropriate the dentist would then receive the patient back with a proper diagnosis and work together with the sleep physician. The literature shows that a custom-made mandibular advancement appliance is superior to a prefabricated tongue stabilizing appliance.³ Treatment can then be taken to the next level with proper titration using objective methods such as oximeters or portable monitors, and follow-up visits may be implemented to reduce the chances of dental changes occurring.

Nasal obstructions, airway problems, and sleep disturbances are areas in which dentists can contribute significantly. By regularly performing sleep and nasal obstruction risk assessments on their patients, dentists can increase the awareness and recognition of OSA and position themselves as major players in this arena.

Many clinicians ask whether pediatric orthodontic interventions may be used to prevent adult onset sleep-disordered breathing. Presently, it appears that not much can be done to stave off the possibility of futuresleep breathing challenges. The evidence of this is hidden in human dynamic respiratory physiology, including changing neuromuscular tone, situational respiratory instability, and ongoing regressive anatomical adjustments that all humans experience. To wit, how many "one and done" cases find their way to the plastic surgeon, never to return? Not many, and although one can hope that pediatric intervention may bring about a more static change with long-term respiratory benefits, the evidence to date is lacking.

With regard to the natural, progressive course of pediatric sleep-disordered breathing, the literature reveals that in anywhere from 60% to 90% of cases in children, this condition is remitted by late adolescence.¹⁰ Recidivism within sleep-disordered breathing is strongly correlated to both male gender and obesity. Central obesity and increase in tongue volume adiposity appear to be strong predictors of future disease. There does not seem to be an association between snoring and future disease manifestation. Females tend to exhibit even higher cure rates due to the protective nature of hormones, particularly estrogen and progesterone. Also, during puberty both sexes experience lymph tissue volume reduction in the nasopharynx and oropharynx, as the anatomical volume of the pharyngeal airway is increasing.

In adults, the use of mandibular advancement devices (MADs) frequently results in increased airway dimensions; however, true normalization of respiratory parameters with these devices occurs in only 52% of patients.¹¹ Certainly, ample literature suggests that in both adults and children the minimal cross-sectional area and the overall volume of the pharyngeal airway may respond favorably to MAD or palatal expansion. Yet, there is a body of literature confirming a lack of correlation between increasing airway size and reduction of respiratory events. Also, those who experience the largest absolute increases in pharyngeal airway post-orthodontic therapy do not necessarily experience the greatest reduction of respiratory variable. Additionally, while meta-analysis clearly demonstrates that most patients who undergo maxilla-mandibular advancement experience respiratory event reduction, many do not.

One adult study published in 2016 shockingly quantified just how dynamic the human airway is in the face of increasing age.¹²  A moderate obstructive sleep apnea (OSA) adult cohort had been successfully treated with MAD to near normalized levels. Fifteen years later (unchanged body mass index and device compliant) the cohort experienced further regression to severeOSA levels as compared to the initial baseline, and when the cohort was retested with the MAD the apnea levels were worse as compared to the new baseline.

Orthodontics may have a role in the acute management of pediatric OSA. Still, it is increasingly evident that sleep-disordered breathing is hardly just an anatomical disease that can be ameliorated by changing anatomical structure alone.

Benjamin Pliska, DDS, MS
Associate Professor, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada; Fellow, The Royal College of Dentists of Canada

Juan Martin Palomo, DDS, MSD
Professor and Director of Orthodontic Residency, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio; Diplomate, American Board of Orthodontics

Mitchell R. Levine, DMD
Associate Professor and Director of Dental Sleep Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee; Diplomate, American Board of Dental Sleep Medicine; Diplomate, American Board of Orthodontics