What Happened to Our Airways? A Brief History Lesson…
Around 12,000 years ago, before the development of agriculture, humans’ skulls and faces were much more ape-like, with wide jaws and rounded facial structures. This allowed for large nasal openings through the sinuses, plenty of room for the tongue, and a lower jaw that could comfortably rest in a forward position, which created open airways in the throat. The staples of a hunter-gatherer lifestyle up until that point included meat, fruit, nuts, wild grains, and vegetables, most of which were uncooked and difficult to chew. The introduction of agriculture changed the human diet to a diet of soft foods such as cooked beans and grains that didn’t require the same level of chewing strength. Over time, the shape of our faces began to change. The jaws narrowed, and airways were more restricted.
Fast forward to the Industrial Revolution, and one can see other factors contributing to the narrowing of our airways. Take breastfeeding, which plays a crucial role in normal facial development. The sucking and swallowing action creates the musculature and bone formation that are needed for proper airway development. Yet as women left home to work, nursing began to fall out of favor. In addition to this, our soft and nutrient-deficient Western diet contributed to malocclusion (problems with how the upper and lower jaws fit together, the “bite”), which was observed to be virtually nonexistent in non-industrialized cultures. These new problems, underdeveloped jaws and narrow airways, were not the result of a genetic change but rather the epigenetic effect (changes in gene expression) that had occurred.
Here’s the bottom line: Smaller jaws leave less room for teeth, causing crowding. There is also less room for the tongue, forcing it to move backwards into the throat. During sleep, the tongue tends to fall back even more, where it tends to block the airway. Blockages of the nasal passages and/or throat can affect breathing 24 hours a day. There is extensive documentation of the myriad negative effects of breathing difficulties during sleep, collectively known as sleep-disordered breathing. Disrupted or fragmented sleep has profoundly disturbing effects on the brain, causes systemic inflammation, oxidative stress, and a host of severe health problems. Deep, restorative sleep is critical to our ability to thrive. Indeed, it is critical to our survival.
Due to all this research, in October 2017, the American Dental Association (ADA) released a policy statement addressing dentistry’s role in sleep-related breathing disorders. The policy encourages dental professionals to screen their patients for Obstructive Sleep Apnea (OSA), Upper Airway Resistance Syndrome (UARS), and other breathing disorders. The ADA advocates working in collaboration with other trained medical colleagues and emphasizes the effectiveness of intra-oral appliance therapy for treating patients with mild to moderate OSA and CPAP-intolerant patients with severe OSA. With the endorsement of the ADA, screening and treating sleep-related breathing disorders has become the newest focus of integrative dental medicine.
History (signs & symptoms)
Are you aware of being a mouth breather? Mouth breathing is considered dysfunctional breathing, because it bypasses the critical physiologic benefits of nasal breathing. Through the nose, air is humidified, warmed, sterilized/anti-microbial effect of nitric oxide produced in the para-nasal sinuses, and the breathing rate is controlled to help maintain an optimum carbon dioxide-oxygen ratio in the bloodstream (Bohr Effect). If breathing through the nose does not happen, nitric oxide is not released. Therefore, mouth breathing eliminates the possibility of ideal physiologic breathing, allowing “dirty air” containing microbes, pollutants, pesticides, smog, allergens, pollen, and spores, to name a few, to pass through the mouth straight to the lymphoid tissues of the adenoids and tonsils. This can result in both inflammation and infection in the posterior throat. Even if tonsils and/or adenoids are removed to help breathe through the nose, 90% of the cases rebound within a year unless your child is shown how to nose breath. This means the tonsils and adenoids actually grow back!
Are you aware of snoring in your sleep? Snoring is a sign of airway blockage as the tissues of the soft palate vibrate against the posterior wall of the pharynx. This can be accompanied by the tongue dropping back as well. Approximately one in three snorers also suffers from obstructive sleep apnea.
3. Sleep Apnea
Have you been diagnosed with sleep apnea or been observed to stop breathing in your sleep? Obstructive sleep apnea is a very serious breathing disorder that has significant systemic effects due to mechanical collapse of the posterior throat airway. An apneic event occurs when breathing ceases for 10 seconds or longer accompanied by drops in oxygen saturation in the bloodstream. During sleep, multiple events in intervals of several minutes or longer can mimic the experience of choking and stimulate activation of the sympathetic nervous system, the “fight or flight” response. Stress hormones, including cortisol, are released into the bloodstream, producing an acute excitation of the heart rate. The increase in blood flow is an attempt to deliver needed oxygen throughout the body. Chronic elevated cortisol levels in the blood can produce several deleterious effects including increased blood pressure, cardiac arrhythmia, insulin resistance, and leptin/ghrelin imbalance. An increased hunger drive can be stimulated by imbalances between leptin and ghrelin leading to obesity because your body thinks its needs to store the fat since it thinks you will need it since your sleep cycle is off.
4. Poor Sleep Quality
Do you sleep poorly or wake up during the night? Breathing disorders during sleep disrupt the normal sleep pattern. Stimulation of the sympathetic “fight or flight” response to decreased oxygen levels, the release of steroid hormone cortisol from the adrenal glands, and increases in heart rate are all involved in producing arousals from deeper to lighter sleep levels or even waking up. Frequent urination at night is a common side effect that actually most often has nothing to do with the need to urinate but more to do with the fact that you woke up from the flight or fight response due to your pulse increasing from your mouth open.
5. Daytime Sleepiness
Do you feel tired and sleepy during the day? Failure to spend adequate time in deeper sleep stages produces nonrestorative sleep and its consequences: daytime fatigue and sleepiness. Also, failure to progress through all stages of sleep will leave you with very little focus during the day and make your day mentally challenging.
6. Nasal Congestion
Do you experience frequent nasal congestion or difficulty breathing through your nose? Nasal congestion due to allergies from food or environment, nasal stenosis, deviated septum, nasal polyps, turbinate enlargement, and/or acute and chronic sinusitis will affect breathing and often cause a conversion to dysfunctional mouth breathing. Eustachian tube blockage can produce a fullness feeling in the ears.
7. Forward Head Posture
Does your neck bother you and do you find yourself in a forward head posture? “Mouth-breathing syndrome” is characterized by significant nasal obstruction, whereby an effort to overcome this resistance increases the work of accessory muscles of inspiration. Furthermore, forward head posture, common among mouth breathers, facilitates the air to enter the mouth, which can lead to a deterioration of the pulmonary function. Often neck and shoulder tension is the result of a tongue-tie.
Do you have a tongue-tie or any tongue restrictions affecting sucking, swallowing, or speech? A short lingual frenulum has been associated with difficulties in sucking, swallowing, and speech or a posterior tongue that is hidden leads to oral-facial dysmorphosis, decreasing the size of upper airway support. Progressive change increases the risk of upper airway collapsibility during sleep. Tongue-tie also causes a tension in the fascia system throughout the body. Many feel much looser from their heads to their toes after a tongue-tie release.
9. Chronic Cough
Do you have a chronic cough, sore throat, or difficulty swallowing? Chronic cough and similar throat issues are highly correlated with sleep apnea and gastroesophageal reflux disease (GERD), which often occur together. It’s reported that 80% of the 60 million Americans who’ve been diagnosed with GERD report worse symptoms at night, and 3 in 4 wake up routinely from sleep. Often by breathing in the cold, non-filtered air, a cough continues to be aggravated and lingers.
10. Deviated Septum
Are you aware of having a deviated septum or nasal deformity or damage? A deviated septum can be present from birth, be the result of poor maxillary development, or can occur after injury. It can contribute to difficulty breathing through the nose, nasal congestion, recurrent sinus infections, nosebleeds, difficulty sleeping, snoring, sleep apnea, headaches, and post-nasal drip.
1. Neck Circumference > 16 in. women, > 17 in. men
It has been demonstrated, through several studies, that enlarged necks are associated with increased soft tissue volume in the throat area. Neck size can be associated with being overweight, same as waist size.
2. Mallampati > 2
The Mallampati Score  comprises a visual assessment of the distance from the tongue base to the roof of the mouth, and therefore the amount of space for an adequate airway. The score is assessed by asking the patient, in a sitting posture, to open the mouth and protrude the tongue as much as possible, rating in 4 classes:
- Class 1: Soft palate, uvula, fauces, pillars visible
- Class 2: Soft palate, uvula, fauces visible
- Class 3: Soft palate, base of uvula visible
- Class 4: Only hard palate visible
A higher Mallampati score is a predictor for risk of OSA and can be a helpful screening tool during the clinical examination. However, its role in predicting severity of OSA remains doubtful and needs further study. It should be noted that some individuals with a Mallampati 1 or 2 may have serious airway compromise.
3. Scalloped Tongue
The presence of tongue scalloping has shown a high correlation for abnormal AHI and nocturnal desaturation. The presence and severity of tongue scalloping has shown a positive correlation with increasing Mallampati. In high-risk patients, tongue scalloping has been found to be predictive of sleep pathology. Tongue scalloping is a useful clinical indicator.
4. 40% Tongue Restriction (Tongue-tie)
There are a few classifications of tongue movement. One classification of normal range of free tongue movement is greater than 16 mm. According to Kotlow’s assessment as follows:
- Class I: Mild ankyloglossia: 12 to 16 mm
- Class II: Moderate ankyloglossia: 8 to 11 mm
- Class III: Severe ankyloglossia: 3 to 7 mm
- Class IV: Complete ankyloglossia: Less than 3 mm.
Class III and IV tongue-tie category should be given special consideration because they severely restrict the tongue’s movement. Restrictions include limitations of movement protrusively, laterally, and vertically.
This screening measurement is effective for speech, but if we want to get a complete history of the tongue restriction, we want to look at the Tongue Range of Motion Ratio (TRMR). One screening evaluation involves:
- Have the patient open their mouth as wide as possible. Normal maximum opening is 40-50 mm.
- While maximally open, raise the tip of the tongue, attempting to touch the incisive papilla behind the upper central incisors. Successful touching represents “normal” tongue mobility. Tongue restrictions can be visualized as a percentage of movement from rest to full extension towards the incisive papillae. 40% restriction or greater often has significant clinical implications. Many patients appear to have mobility but they are using the jaw and floor of the mouth muscles and compensating to aid in mobility. For example, they could be a grade 3 mobility compensating to a grade 2 mobility by using the floor of their mouth muscles.
5. Nasal Stenosis
A simple observation can be made by having the patient breathe in and out through the nose. Does the nostril on one or both sides collapse during nasal breathing? This provides a visible indicator of nasal airway collapse or obstruction. It would be common that these patients struggle with upper airway resistance and default to mouth breathing.
6. Skeletal Profile
Maxillary and/or mandibular skeletal underdevelopment can compromise airway volume. Arnett’s True Vertical is a useful assessment for mandibular retrusion, maxillary retrusion, and bimaxillary (maxillo-mandibular) retrusion, by observing the patient’s profile, facing to the right. A line dropped vertically down from the nose-lip intersection (SN) relates ideally to the fully developed lower face when:
- Upper Lip = 2-5 mm in front of the line
- Lower Lip = 0-3 mm in front of the line
- Chin Point = -4-0 mm behind the line
Measurements less than these ranges can implicate craniofacial, mid-face underdevelopment, with increased risk for airway compromise.
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In recent decades the medical and dental professions have become more aware of sleep-disordered breathing (SDB) acting as major contributors to a range of health problems. In addition to having a negative impact on mood, energy levels, ability to regulate stress, behavioral problems, and emotional well-being, severe sleep disorders, such as obstructive sleep apnea, have been associated with the causes of life shortening events such as heart disease or stroke.
SDB characteristically occurs when the flow of air through the nose or mouth is obstructed during sleep. While this airflow obstruction is typically caused by relaxation and poor muscle tone around the throat and jaws, there are many underlying causes of SDB. The most common of these are chronic mouth breathing, poor diet, obesity, and poor development of the jaws. Additionally, orthodontics with extractions can exacerbate breathing issues.
Traditionally, treatment for SDB, particularly obstructive sleep apnea, has involved the use of a Continuous Positive Air Pressure (CPAP) device. However, the inconvenience caused by the bulky CPAP machine and discomfort caused by the mask often discourages patients from using their machine. As a result, treatment with intra-oral appliances is now considered to be the most convenient way to alleviate SDB. However, much research is happening to prove great results from the use of widening the palate and moving the teeth forward, along with myofunctional therapy to strength the soft palate.