This article is not about the “how” of airway orthodontics. It’s about the “why”. But it does suggest that a regard for the rationale of airway orthodontics will spur a change in the way we do things in orthodontics altogether.
For years, the orthodontic profession has polarized around many issues: genetic vs environmental etiology of malocclusion, extraction vs non-extraction, straightwire vs conventional vs self-ligating bracket, and early vs one-phase treatment. With the increasing awareness of the ravages of obstructive sleep apnea (OSA) as a breathing disorder and the realization that orthodontics has the capability of offering medically indicated solutions in this area, it is time to reexamine the last of these conundrums: the early orthodontic treatment concept.
The early orthodontic treatment concept came about from the long-discussed idea that malocclusion originated earlier than “braces age” of 12-14 years. Proponents (Angle, Rogers, Tweed, Graber, Woodside, Ricketts, Farrell, Ramirez, and may Europeans over the years) have argued that by starting treatment earlier, say, after seven years of age, it would be possible to mitigate the causes of malocclusion and help teeth erupt in a better formation from the start, even if braces would be needed to neaten things up afterward. Detractors, bolstered by high level research comparing two models of early treatment against the traditional model of waiting for full eruption (Tulloch), argue that the arrangement of the teeth (based on Angle Classification) was similar enough in all cases that going to the extra effort and expense (for both patient and practitioner) of early treatment was unnecessary.
What we have come to realize, now that we know about the risk factors leading up to obstructive sleep apnea, is that the real rationale for early treatment goes far beyond the teeth, rendering the arrangement of the teeth less important than the ability to breathe well at night and swinging the pendulum back toward the early treatment side. In this article, I will connect the dots backward from OSA to provide an updated rationale for early orthodontic treatment and to paint a picture for a new and vital role for orthodontics as a medical service in the 21st century.
The Gold Standard
Obstructive sleep apnea occurs when the oropharyngeal airway closes off sufficiently during sleep that breathing ceases, at least until the brain, sensing a drop in blood oxygen, activates the sympathetic nervous system and the hypothalamic-pituitary axis to scare the body into lighter levels of sleep or even arousal so that breathing can begin again. These mini-suffocations can occur all night long, fragmenting sleep and eliminating the restorative benefits of sleep, putting strain on the heart and other systems, and setting up the sufferer for daylong fatigue and sleepiness.
The social ramifications of people who fall asleep at work are well recognized, especially when that person is driving a train, bus, plane or boat. Plus the comorbidities of hampered breathing and oxygenation are filling up our hospitals with chronic diseases whose connection to poor breathing is going largely unrecognized (DaSilva). We recently lost a US Supreme Court Justice to “death by natural causes” that was later connected to poorly treated OSA.
The current “gold standard”, if gold is the appropriate color, of medical treatment is to pry the airway open with a stream of compressed air to prevent the throat from collapsing (CPAP), or alternatively, to position the mandible forward enough to pull the tongue out of the back of the throat using a tooth-borne appliance (MADs). Both of these treatments are merely symptomatic crutches to help a person get through the night. To qualify for insurance coverage for these treatments a person has to go through these choking episodes at least 10-15 times every hour. So far, this is the best modern medicine has to offer. If this is where treatment of this insidious disease begins, it is certainly not where the disease begins.
Long before the airway collapses and airflow stops entirely, there is a long lead up where the body works hard to keep oxygen levels stable throughout the night. The airway may be narrow or congested or inflamed and it may become difficult to breathe but the air passage remains open. If oxygen levels begin to drop, the body will find ways to compensate to get oxygen supply going again. Cortisol is secreted. The heart beats faster to get the blood flowing. The mouth may open, the head tilt back, or the body roll over in an effort to keep the airway open. Within seconds, the drop in oxygen is halted and levels begin to rise again. This rise and fall in O2 levels may actually be subtle enough that it wouldn’t be noted as a desaturation in a sleep study. But the brain knows it. This cycling of O2 levels during the night is a form of intermittent hypoxia that is thought by some to be even more damaging to specific brain loci than all out desaturations (Harper, Gozal). The phenomenon of Inspiratory Flow Limitation has been credited with being behind a whole host of daytime symptoms that include not only fatigue, but fibromyalgia, mood disorders, TMD, and more, and is now being called Central Sensitization Syndrome (Gold).
So why are we having so much trouble breathing at night? Why is this problem so prevalent?
There are three factors that lead to flow limitation in the upper airway: 1) The size and shape of the airway, 2) The condition of the structures within and surrounding the airway, and 3) The manner in which air is moved through the airway. Each of these factors have origins that begin early in life, and each of these factors can be mitigated in an orthodontic practice (along with some interdisciplinary help).
The Size of the Airway
The size and shape of the upper airway is determined by the growth and development of not only the nasal and pharyngeal structures, but also, the maxilla and mandible. The maxilla (with the soft palate hanging off the back of it) and the mandible (with the tongue attached to it) form the anterior wall of the oropharynx. As both jaws grow in size in a trajectory that moves forward in the face, the airway increases in size (Enlow). The width of the maxilla determines not only the width of the dental arch but also the width of the bony nasal cavity. A wide maxilla provides ample room for the tongue to sit up on the palate and away from the back of the throat. A more forward position of the mandible carries the back of the tongue forward away from the throat and helps keep the hyoid with its attendant musculature positioned upward and forward as well.
On the other hand, if there is a limitation in the forward growth of either or both jaws, then the airway fails to open up as fully. A smaller airway is more likely to be affected by the other factors of flow limitation (condition and airflow) and puts the patient at risk. The depth of the face has been implicated as a major risk factor for sleep disordered breathing in adults (Dempsey) and in children (Ikavalko). This risk is totally independent of obesity (which is usually blamed for OSA).
The anthropologists tell us that the size of the airway, the maxillo-mandibular “snout” and the size of the jaw bones has indeed been getting smaller, especially in the post-industrial modern era. These facial changes not only track with the incidence of malocclusion but with the incidence of sleep apnea as well (Lieberman, Corruccinni, Boyd).
Although there are arguments within the orthodontic literature as to whether one can make the airway smaller using certain retractive orthodontic procedures (yet another issue to polarize around), there is evidence that helping the jaws to grow forward can certainly help the airway open up (Singh and Hang). Giving support for forward movement of the jaws in the growing face would seem to be an important factor in protecting a person from flow limitation. Since facial growth is at its greatest acceleration within the first four years of life and since 80-90 percent of the growth of the facial skeleton is completed before the age for “one-phase” orthodontics, such support must start well before straightening the teeth would even be considered. In fact, if one is to consider the size of the airway as a critical factor in future airway health, then it is almost indefensible to allow the airway to grow hampered in size simply because it makes more sense for straightening the teeth.
The Condition of the Airway
Anything that causes a constriction in the flow of air (or fluid, for that matter) within a tube creates turbulence of the flow. The turbulence makes flow more difficult and in fact may create negative pressure that can worsen the constriction by pulling the sides of the tube inward. (Snoring is the flapping of tissue due to negative pressure). This phenomenon is made all the more critical since a one unit constriction of the tube can create a sixteen-fold change in flow resistance. Therefore, anything that juts into the airway, blocks the airway, or makes the sides of the airway more swollen or more flabby, can exacerbate turbulence and make breathing more difficult.
A list of conditions that can impinge upon the airway include: swelling from allergies, constriction from asthma, swollen turbinates, collapsed or deviated nasal cartilages, swollen lymph tissue, irritation from acid reflux, fat deposits, and poorly toned musculature. Swollen tonsils and adenoids are especially common in children. While sleeping, especially in a supine position, the relaxation of muscles (constrictor muscles and tongue) allows for even more closure. The binding of muscle function by tight or restricted fascia (ie. tongue tie) can also change muscle positioning in the airway.
Each of these issues should be addressed at whatever age they are found to be relevant, even in infancy. While clearing the nasal airway and the pharyngeal airway is mostly outside the purview of dentistry, there are many ways we can help, including with the assessment and referral to appropriate sick care and well care providers, and with educating our patients about the importance of good breathing and sleep. Again, the medical necessity of proper ventilation trumps any notion of tooth alignment.
The Manner of Airflow
Breathing involves three stages of respiration: External respiration is the way we move air in and out of our body. Internal respiration is how the body exchanges and distributes the gasses in the lungs and capillaries. Cellular respiration is how the endproducts (oxygen and carbon dioxide) are used and produced by metabolism (Litchfield). Each stage affects the efficacy and efficiency of the others.
Efficient external breathing should be done through the nose, powered by the diaphragm, at just the right rate and volume to allow maximal gas exchange at the alveoli of the lungs. The nose conditions the air for proper uptake in the lungs by filtering, moistening, warming, and sterilizing the air with nitric oxide produced in the sinuses. The contraction of the diaphragm acts as a bellows to pull air down into the lungs. There should be just enough air going in to be processed properly and then shunted out again.
Carbon dioxide in not just a waste gas to be expelled. It has important biochemical functions at both the lung interface and at the tissue interface when oxygen is released from hemoglobin. It is stored in the blood and in the lungs. However, breathing through the mouth or breathing at too high a rate can chronically lower CO2 stores and hamper the way we process oxygen.
Of all the factors involved in proper upper airway flow (size, condition and airflow), the mechanics of breathing is perhaps the most important and least appreciated. It is possible to breathe efficiently through a narrow airway if the air is pulling through gently. It is also possible to reduce inflammation and swelling in the airway by adjusting the breathing pattern. Several variables are at play here.
First of all, breathing through the mouth, while seemingly allowing for more airflow, paradoxically leads to more turbulence. The mouth allows unfiltered air to hit the mouth, throat and lungs, taxing the tonsils with the job filtering the air that the nose should be doing and instigating inflammation of the lymph tissues. Lack of stimulation of the nasal tissues by normal airflow leads to more congestion, setting up a vicious cycle that may begin with simple nasal congestion but worsens to a chronic state the more the mouth is used. The larger portal of the mouth allow for an excess of carbon dioxide to be released from the lung stores which leads to further congestion and constriction of the airway (Price, Litchfield, Kolb).
Second, the diaphragm can often be hampered by poor posture, fascial restriction, or reflex inhibition, causing a person to use auxiliary chest muscles and shoulder muscles to expand the rib cage. It requires a much more rapid cycle of breathing to keep air flowing using these inefficient muscles. Chest breathers may ventilate at 22-30 breaths per minute. Again, precious stores of carbon dioxide become chronically depleted with rapid breathing. Also, since the diaphragm is the pump for the lymph system of the upper part of the body, lymph drainage is hampered and can back up into tissues like the tonsils and adenoids above.
It’s been said that the perfect man breathes as if he is not breathing at all (Lao Tzu, ancient proverb). Overbreathing is, in essence, just as dangerous as overeating: it is not optimal for health. Restoring breathing patterns to optimal may take training (Price, Litchfield), but it is the only way to help the airway work most efficiently.
Let’s review: Before the time the airway collapses in apnea, there is a long lead up of inspiratory flow limitation. Inspiratory flow limitation is caused by a: 1) narrow airway that is in, 2) poor condition, 3) poor breathing mechanics. Poor forward growth of the face sets up the narrow airway. So the question is: where does poor growth of the face come from?
Most schools teach that the etiology of malocclusion is “multifactorial” but in practice it is treated as a “genetic” problem. That is to say, malocclusion is treated as a static condition that was unavoidable, and so is considered “The Problem” to be solved. What is not widely recognized in practice is that many of these “multi-factors” are well known and controllable if one takes the time to understand them and make the effort to correct them. Collectively, they are known as Soft-Tissue Dysfunctions, and with some notable exceptions, they are mostly related directly or indirectly to the factors that cause air flow limitation.
Since taking the next breath is probably the most important thing the body has to do at each moment to maintain oxygen to the brain, there are any numbers of compensations that can be made when things aren’t going optimally.
For instance, if a child’s nasal passage is small (size of airway) and becomes blocked by mucous (condition of the airway), they will compensate with oral breathing (manner of breathing) even if temporarily. However, if that compensation becomes chronic, it sets up a cascade of events that will eventually affect the way face grows. We’ve known for over a hundred years that mouth breathing changes the shape of the face (Caitlin, Angle, Graber, Harvold, Moss, Mew).
While the mode of breathing is critical for health, it’s not just the breathing that is relevant.The posture of the tongue is the key element in maxillary bone growth as the tongue is the scaffold over which the palate forms. Just as the functional matrix that surrounds them influences the other bones of our skull, the maxilla is particularly sensitive to the microenvironment in which it grows. Stimulation from the tongues resting posture, action during nursing, chewing and swallowing, and the balance of action that all other facial muscles have at both rest and function are at play. Since genetic control of the bones (and also the erupting teeth) is not precise, bone development requires additional guidance from the functional matrix (called the Tropic Premise by John Mew). When posture and function are compensating for the inability to breathe properly, growth changes for the worse.
This aberrant change in facial features is being called Craniofacial Dystrophy (M. Mew) and is described by orthodontists and anthropologists alike. Common signs are: 1) a collapse of the maxilla in all three planes of space (narrow, more vertical, and set back in the face, 2) retrusion of the mandible to either a similar degree (Class I) or a more compromised degree (Class II), 3) Flattening of the midface with a reduced development of the upper part of the maxilla which includes the nasal capsule, the maxillary sinuses and the infraorbital rim, and 4) collapse of the nasal cartilage downward to become a droop of the nose (and an apparent “bump” on the nose). Of course, this skeletal configuration reduces the chance of having the teeth erupt correctly and it is probably responsible for the vast majority of malocclusions.
The most important concept to understand is that these changes begin during the first years of life. Anything that creates a breathing compensation early in life will affect the trajectory of facial growth from that point on.
It’s the Airway, Stupid!
Orthodontic diagnosis must always ask these questions:
- Is there any limitation in the flow of air through the upper airway created by dystrophic growth of the maxilla or the positioning of the mandible? Is there anything else creating turbulence?
- If so, what are the compensations for breathing that the patient has had to resort to? Any postural, breathing or tongue functions that have become habitual as a result?
- Are there any consequences of these compensations that must be dealt with? Has the face changed shape? Are the jaws of improper size or position?
Airway Orthodontics answers these questions by addressing the compensations for a hampered airway. If a child cannot easily breathe through the nose both day and night, hold their lips together as a habit, rest the tongue on the palate when not talking or eating, or be able to swallow without the aid of facial muscles, then we know trouble will follow to some degree.
The sooner you can address the compensations, the more you can prevent the consequences (Craniofacial Dystrophy). If there have been changes to the face, then these have to be corrected using dentofacial orthopedic techniques, preferably before growth is complete. And finally, we make sure the proper habits for posture; breathing and tongue placement are in place for good health.
1. Nasal breathing using the diaphragm at the proper rate and flow
2. Lip seal without muscular strain
3. Tongue to palate resting posture
4. Swallowing with the tongue creating a seal on the palate
In addition, it is important to tackle whole-body issues by teaching:
5. Good sleep hygiene for both quantity and quality of sleep
6. How to keep the nose clean and clear
7. Good body posture for bones, muscle and fascia
8. Good nutrition that nourishes (and does not challenge) the body
If there are positive airway findings and all you do is straighten the teeth, then you have ignored the real problem. It’s like doing resuscitation on the canary in the coalmine. The teeth are not the problem. The teeth are a symptom and braces are as much of a symptomatic treatment for airway disorders as are CPAP and MADs.
A Look to the Future
The polarization around early treatment orthodontics is just distracting us from the important work that must be done to help our children grow up with the ability to sleep and breathe properly. As we connect the dots between airway and health, at least a certain portion of the orthodontic profession must begin to dedicate itself to helping children in this way. Though using orthodontics for the esthetics of a beautiful smile will always have a place in our society, there must be at least a certain regard for airway when straightening the teeth. Unfortunately, by the time a person is ready for esthetic orthodontics, the opportunity to positively affect the airway may have already passed.
Therefore, I propose two distinct subspecialties within our profession. Just as in building a house, where the people that lay the foundation and do the carpentry are never the same people that do the interior decorating, there must be a subspecialty that is devoted to laying the foundation for facial growth and airway development in the young child and then a separate subspecialty to arrange the teeth for decoration.
When a house is well designed, with proper room sizes and layout, placing the decor is simpler and the room spaces function well. If the house is built with odd-shaped rooms and narrow hallways, getting the furniture in place within the rooms becomes a problem. Helping the jaws to grow to their full genetic potential makes the arrangement of the teeth far easier, especially since much of the eruption can happen naturally.
The goal of the new early orthodontic treatment model has little to do with the teeth. It has everything to do with helping the jaws grow fully and allowing airway spaces open up to full size. The outcomes of early treatment are lessening the need for compensations and to see that the healthy habits needed for proper growth are established.
The early orthodontic treatment office will look different from most orthodontic offices of today. Although there will still be dental operatory space, areas devoted to education and training will be the main feature of the layout. The space will be fun and not as intimidating as a dental operatory. There will be computer screens and mirrors and health coaches to help train the children in the basic orthodontic competencies.
Space will also be provided for interdisciplinary work with myofunctional therapists, breathing physiologists, physical or osteopathic therapists and nutritionists. These professionals may be part of the practice or they may be independent contractors depending on local regulations, but they will allow for a more comprehensive treatment of the child.
As the medical profession begins to understand the possibilities that preventive airway development can have for children, physicians will create alliances with orthodontists to help their children get better. And finally, the day will come when third party players, inevitably overcome with their inability to handle all the comorbidities of airway dysfunction, will turn toward orthodontics to help this next generation grow healthier than did their parents.
Airway Orthodontics is not about the teeth. Early orthodontic treatment may have a beneficial effect on the teeth but that is not its main goal. Our goal is to establish the best possible airway at the earliest possible age. OH
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About the Author
Dr. Barry Raphael is a specialist in orthodontics and founder of the Raphael Center for Integrative Orthodontics in Clifton, New Jersey, USA. His focus is on dealing with the underlying environmental causes of malocclusion and using early treatment modalities to address both form and function. He teaches these principles at the Mount Sinai School of Medicine in New York City and at the Raphael Center for Integrative Education. He is currently the president of the New Jersey Association of Orthodontists, component of the AAO (no implication of endorsement assumed). He welcomes input and comments at email@example.com.