is a term that describes a broad continuum of breathing abnormalities that occur during sleep. On one end of the spectrum, mild narrowing and/or laxity of the airway tissues may first present as snoring. This is sometimes termed “benign snoring” because it does not cause sleep disturbances. However, snoring alone may increase a patient’s risk for stroke, so it is difficult to know for certain if any amount of snoring is “benign.” Next on the continuum is upper airway resistance syndrome (UARS). This occurs when the narrowing of the airway causes increased effort to breathe. This phenomenon can cause poor sleep quality, morning headaches, insomnia, and mood disturbances, among other problems. It is important to note that not all patients with UARS snore and not all patients even realize they sleep poorly. It is possible to be asleep the whole night, but not get into deeper, more restorative sleep because the body is fighting to keep the airway open. When the airway narrows to a point that oxygen saturation in the body is significantly affected, the patient has obstructive sleep apnea-hypopnea syndrome (OSAHS). A hypopnea is a partial narrowing of the airway for a minimum time associated with a certain oxygen saturation drop. An apnea is a complete or almost complete blockage of the airway for a certain time.
The term “obstructive sleep apnea” is a hot topic in dentistry right now, but all sleep-related breathing disorders may be problematic. Snoring and UARS, for example, may progress to OSAHS with changes in age, weight, hormonal status, and other factors. With snoring and UARS, the body responds to negative pressure changes in the airway and mild oxygen desaturations by taking the necessary steps to open the airway. It is possible that after repeated exposure to these negative pressure drops, the reflexes the body employs to maintain an open airway can become blunted, resulting in frank obstructive sleep apnea.
With this background information in mind, dentists have a unique opportunity to screen for at-risk patients. Our dental and health history intake forms have many questions that are red flags for a sleep-related breathing disorder. If some of these questions are not on your health history form, consider the benefit of adding them.
Let’s start with the patient demographics:
– Our first risk factor is revealed on only the third question of my patient intake form! Males are more likely to have obstructive sleep apnea-hypopnea syndrome than females. There are a number of reasons for this, but males tend to store more fat in the neck than females, males have further laryngeal dissent than females (a mechanical risk factor), and females have some hormonal protection against OSAHS. These hormonal differences may be one reason females present with different symptoms than men. Men tend to present with more obvious OSAHS symptoms (snoring, tiredness, and witnessed apneas), whereas females may present with more UARS symptoms (fatigue, insomnia, mood disorders, or TMD). UARS is a little harder to detect, but can be equally impactful in terms of quality of life. Of course, both sexes can present with any of these symptoms, so be careful not to be biased based on gender alone. Also, do not assume every patient with a mood disorder or insomnia has a sleep-related breathing disorder.
– Age plays a big role in the presentation of sleep-related breathing disorders. Children with sleep-related breathing problems will often present with adenotonsillar hypertrophy, mouth breathing, bedtime problems, bed-wetting, or hyperactivity/difficulty concentrating during the day. Older adults will more likely present with tiredness, anatomical risk factors (i.e., narrow palate), or snoring. It is important to know the signs and symptoms that predominate with each age group.
Medical health history
The association between high blood pressure and sleep apnea has been extensively validated in the literature. The metric with the highest association appears to be intermittent hypoxia, which is detectable with a variety of monitors. OSAHS is a condition that induces inflammatory markers (for example, C-reactive protein and tumor necrosis factor-α) responsible for hypertension. The good news is, continuous positive airway pressure has been shown to reduce these inflammatory markers quickly. Personally, I have seen patients lower their blood pressure or reduce their blood pressure medications when their OSAHS is controlled through an oral appliance.
There is a high association between acid reflux and OSAHS. This may be due to the many shared risk factors between the two conditions, but there may also be a more synergistic relationship. Exposure to the acid of reflux may have an inflammatory effect on the airway. The inflammation from these events could lead to a smaller diameter in the airway, which would be another risk factor for sleep apnea. In addition, sleep apnea generates strong negative pressures in the airway and may act like a vacuum to suck gastric contents up into the airway and surrounding structures. Regardless of the reason, it is important to know that these two conditions often coexist.
is a higher percentage of sleep apnea in patients with untreated hypothyroidism. Stress has also been implicated in some thyroid diseases. Patients with sleep-related breathing disorders are exposed to chronic stress nightly and may not even know it. When the airway starts to collapse or does collapse, the body needs to activate the sympathetic nervous system (the fight or flight system) to recruit the right muscles to open the airway, often resulting in an arousal from sleep that may or may not cause the person to wake up. This nightly chronic stress may be one reason for thyroid dysfunction. This is an observational and theoretical link that has not been scientifically proven to my knowledge, but clinically, I see a number of UARS and OSAHS patients with thyroid abnormalities.
Dental health history
Grinding may be a reaction to any number of things, but one of the most studied are sleep-related breathing arousals. I pay special attention to anterior bruxers, who may use this maneuver to push the jaw forward and open the airway. The good news is that studies have shown CPAP treatment or a mandibular advancement appliance may be an effective way of stopping or reducing bruxism in patients with OSAHS.
Studies have demonstrated that a high percentage of patients who present with TMD symptoms also have a sleep-related breathing disorder. For one, inadequate sleep has been shown to increase pain levels. Additionally, there are a number of other shared risk factors that would put patients at anatomic risk for both TMD and sleep-related breathing disorders.
There are multiple proposed mechanisms that result in headaches. First, as mentioned above, poor sleep increases pain. Second, low oxygen saturations can result in headaches. Finally, the physiologic connection between morning headache and sleep apnea may not be completely explained, but we know patients with sleep apnea often wake up with a headache, so it is an important symptom to pay attention to.
Open-mouth posture is one of the big developmental contributors to sleep apnea. To facilitate ideal lateral and protrusive growth during development, the tongue sits on the roof of the mouth. When a child mouth-breathes, the tongue has to either sit on the floor of the mouth or between the occlusal surfaces of the teeth. The first scenario may result in a Class I or II malocclusion and the second a Class III malocclusion. Even if the child does not have sleep apnea during development, he or she will be at greater risk as an adult because the maxilla, and sometimes the mandible, has not expanded enough to house the tongue once the mouth is closed.
Many of my adult patients will present with a scalloped tongue, meaning the lateral aspect of the tongue is indented from pushing against the teeth. This occurs through an increase in the mass of the tongue or an open-mouth posture that results in arches that are too small for the tongue. After treatment with a mandibular advancement device, more than one patient has remarked, “My tongue finally fits in my mouth!”
It makes sense in my mind that if the tongue is scalloped, the reflexes in the body are still trying to get the tongue out of the airway when obstruction occurs. Therefore, I am a big fan of oral appliances that provide maximum tongue space. The Narval, by Resmed, the lingual-less SomnoDent, and the Micr02, by MicroDental, all have designs that provide room for the tongue. The Narval and lingual-less SomnoDent also have the advantage of vertical adjustment, which is handful in some patients.
Pretty self-explanatory, but a great question to ask.
Obviously, ask this question only if you offer a solution. If you do not, then rephrase the question to ask about the presence of snoring. Remember, it is difficult to know if “benign” snoring is actually benign without a proper medical workup by a qualified physician. When sending a referral to the sleep physician, or primary care physician if the patient desires, a letter explaining the medical and dental findings of the screening exam is helpful. I enjoy having a collaborative working relationship with my physicians in which both parties know what is expected in terms of patient care. Plus, you are more likely to get referrals coming back to you also.
Surprisingly, a number of patients with undiagnosed OSAHS have answered “yes” to this question. They may not report it to their physician because they have never been asked.
This question opens a completely new line of questioning. For example, if the patient is on CPAP, you can ask about dry mouth and maybe make suggestions if this is a problem.
If dentistry truly wants to embrace the medical-dental connection, we can really derive a great deal of value from a thorough and thoughtful health history. As a word of caution, some patients will not understand the reasoning behind some of these questions. I do, however, feel screening for these potential risk factors and referral when appropriate can improve the quality of life for our patients.
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