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A Note From Dr. Leland
I wrote this paper to explain my views on why taking an airway-focused approach to orthodontic treatment is important. As I mentioned, the evaluation and treatment of a patient’s airway requires the expertise of practitioners in a variety of fields. Along these lines, another aim of my paper is to provide a comprehensive explanation of the overall airway “situation,” including the characteristics of an ideal airway, characteristics of a compromised airway, as well as how orthodontic treatment can help.
The most important detail to gain from this paper is the importance of treatment timing, in its success. During the Golden Period (my own terminology) of orthodontics, the possibilities for correction of skeletal jaw issues are at a maximum. After this period, however, the window of opportunity has largely closed, and options for correction without surgery are significantly more limited. This is not a surgically-focused paper, but rather an explanation of how to take advantage of minimally-invasive but maximally-effective treatment to care for a patient’s airway.
The intended uses for this paper are the following: provide a resource for my orthodontic team to further understand my thoughts and approach to airway-conscious orthodontic treatment as this has become an important aspect of our orthodontic practice, provide information for referring doctors and their teams to understand my approach to airway-conscious orthodontic treatment and as a resource for interested patients as well. As you can see, the audience for this paper is wide. Please excuse the language used if it is overly simplistic, or overly complex, as it is a challenging task to write one version for such a vast audience.
A Shift in the Way Medicine & Dentistry Are Practiced
There is a recent movement in the fields of medicine and dentistry where practitioners in a variety of specialties are placing an increased emphasis on the patient’s airway when diagnosing and planning their treatment. There is nothing more central to healthy human life than the act of breathing, yet there are few specialists focused specifically on this aspect of health. Breathing involves nearly all of the body’s systems, which makes it very difficult for one individual to handle on their own. For this reason, I believe that the airway has traditionally not been a central focus for many practitioners, each thinking that someone else would be the main driver of this important care.
With the evolution of knowledge and collaboration, however, the airway is becoming more commonly accepted as everyone’s responsibility; a truly interdisciplinary endeavor. Professionals involved with treating airway include, but are not limited to: general practice physicians, pediatricians, ear nose and throat physicians (ENT), sleep physicians, dentists, pediatric dentists, dental hygienists, orthodontists, oral and maxillofacial surgeons, myofunctional therapists, speech therapists, among others.
What Makes Up an Airway?
There are two main parts to a person’s airway: the nasal airway and the pharyngeal airway. The nasal airway is the air passageway through the nose. The pharyngeal airway is the air passageway down the throat, into the lungs. These two connect with each other. If a person cannot breathe through their nasal airway, this can be bypassed by breathing through the mouth, directly into the pharyngeal airway.
The nasal airway is outlined by hard tissues, including nasal cartilage, nasal bones, and the floor of the nose (which is bone). The pharyngeal airway is lined by soft tissues, including the back surface of the tongue and the back of the throat. A key feature of how the nasal airway is affected by orthodontic treatment is this: the roof of the mouth is the same structure as the floor of the nose. To understand, consider this analogy: think of a two-story house. In the house, the ceiling of the 1st story is the same structure as the floor of the 2nd story. This example is analogous to the roof of the mouth being the same structure as the floor of the nose. More on why this concept is important later.
An important note is that the nasal airway is lined by rigid, hard tissues, which never move or collapse. The pharyngeal airway, on the other hand, is lined by soft tissues like the back of the tongue and the throat, which frequently move and change shape during a person’s breathing cycle, or when they’re asleep.
What Happens During Sleep, and How Is Sleep so Closely Tied to Breathing?
Clearly, we breathe when we sleep, but we also breathe when we’re awake. That being said, when doctors are assessing breathing, they often assess a patient’s quality of sleep…why? The simplest answer to this question is that when we’re sleeping, our airways are in their most vulnerable position. When a person falls asleep, they lose muscle tone throughout their body. Also, they’re horizontal, so their airway is more likely to close due to the effect of gravity. Within the pharyngeal airway, tongue and throat muscles lose tone and fall inward, making the airway smaller.
Sleep is the time for our body to recharge, which can only be done if we’re breathing well while sleeping. Also, since our breathing muscles are “at their worst” when we’re sleeping if we can breathe well while sleeping, then we can almost certainly breathe well while awake. For these reasons, it’s common for sleep quality to be taken into serious consideration when a person’s airway is being assessed.
Snoring is not normal for anyone and indicates a compromised airway. The sounds made during snoring are created when an airway collapses during sleep (as described above). Air is trying to make its way down the airway to the lungs, and the soft tissue structures of the airway are vibrating back and forth against each other, as the air forces its way through. Snoring indicates that the brain is not getting the oxygen it needs to operate properly and become fully rested. In this way, improper breathing is a serious health condition that requires treatment.
Proper Breathing
We can breathe through our noses and mouths, but both are not created equally. If we breathe the healthy way, the vast majority of our breathing occurs through our nose, not our mouth. Of course, breathing through our mouth is fine for short periods, while talking, if our nose is stuffed up, or during strenuous exercise. In general, however, breathing should be done through the nose.
Nasal breathing offers numerous health benefits. First off, when a person is breathing through their nose, it allows them to have their mouth closed. While their mouth is closed, proper resting posture includes having their tongue braced in the roof of their mouth, against their palate. During palatal development in children, it is this forward and lateral pressure from the tongue that drives the growth of the upper jaw bone (the maxilla). Following from the key concept we learned before: the roof of the mouth (the palate of the maxilla) is the same structure as the floor of the nose, if the upper jaw bone is narrow, the nasal airway is narrow too! Clearly, if the nasal airway is narrow, it increases the likelihood that they will have more difficulty breathing through their nose.
Another benefit of nasal breathing is that the air being breathed in is filtered. This is what the nose hairs do! Air breathed through the mouth does not undergo filtration, so any pollution and contaminants flow directly into the person’s lungs. In addition, there is more resistance to airflow through the nose than through the mouth. Although this may not sound like a benefit of nasal breathing, the increased resistance causes the main breathing muscle (called the “diaphragm”) to work harder, which promotes deep breathing.
Deep breathing increases the amount of oxygen intake into the lungs, ultimately allowing more oxygen to be distributed throughout a person’s body. In addition, nitric oxide gets added to air as it passes through the nasal cavity, which does not get added to air that flows directly through the mouth. Nitric oxide improves the lungs’ ability to absorb oxygen, which is another mechanism that allows more oxygen to be distributed throughout the body, leading to greater health.
What Are the Effects of Chronic Mouth Breathing?
We learned about the health benefits of nasal breathing in the last section, which a person obviously misses out on when their mouth breathes. I’ll list these again, briefly: mouth breathers often have underdeveloped upper jaw bones, and shallow breathing which decreases the amount of oxygen transferred into the body, nitric oxide is not added to inspired air which decreases the lungs’ ability to absorb oxygen, and the air being breathed through the mouth is unfiltered.
The aforementioned are the most direct negative effects of mouth breathing. Unfortunately, there are also indirect negative effects of chronic mouth breathing (meaning for a person who mouth breathes habitually, for instance whenever they’re sleeping) which stem from getting inadequate oxygen to the brain.
These negative effects include non-restful sleep, a constant lethargic feeling, irritability, difficulty focusing on tasks, poor performance at school/work, ADD/ADHD, getting labeled as a “problem child,” bedwetting, as well as more dentally-focused issues including significantly increased risk for getting cavities and periodontal disease. It is uncommon for a single patient to experience all of these symptoms, but any combination of them will commonly be present in a patient who breathes chronically through their mouth.
Timing of Jaw Growth & Orthodontic Treatment
An orthodontist’s training extends far beyond simply aligning the teeth. In truth, this is the easiest part of what we do. A significant amount of our training is focused on learning and understanding the growth of the jaws and, in the event that the growth of one or both is improper, how to make modifications to allow the patient to end up with symmetrical, matched-up jaws.
TIMING IS EVERYTHING when it comes to orthodontic treatment to change the relationship of jaw bones. If you take away one key point from this paper, this is it: 7-9 years old is the Golden Period in every child’s orthodontic development. During this period, jaws can be modified any way that is needed and space can easily be created for erupting teeth. If this window is missed, however, it is gone forever. The Golden Period is when major changes that will benefit the patient for life can be made relatively simply, without highly-invasive treatment like surgery.
Phase 1
Phase 1 occurs when the patient is 7-9 years old. This is the GOLDEN PERIOD in every child’s orthodontic development. This is when a child’s jaw growth can be modified in any dimension that needs adjustment. In this phase, the primary objectives are as follows: align the jaws properly so when growth is finished, the jaws are in proper size and shape and are matched up well with each other.
By aligning the jaws properly, we’re putting the airway in the best possible position, as well. An important note about this time period is that the patient is in mixed dentition, which means that roughly half of the teeth in their mouth are still primary (baby) teeth. The fact that the jaws are at their most adaptable point when there are still lots of permanent teeth that are yet to erupt, presents a frequent challenge for orthodontists.
This challenge comes in the form of educating patients and parents about the extreme importance of Phase 1 treatment for certain children who need jaw modification, even though it means they’ll need an additional phase of orthodontic treatment 3-4 years later (Phase 2, please see below). Although we’re always interested in achieving an esthetic outcome, the primary goal of Phase 1 is NOT esthetics. In Phase 1, appliances like expanders and facemasks are frequently used.
Phase 2
Phase 2 can occur as early as 10 years old, and includes all patients older than this. Phase 2 refers to what most people think of when they think of orthodontic treatment. The goals of Phase 2 are: to create an amazingly esthetic smile, completely align teeth, and align the bite for long-term dental health. By the end of Phase 2, all permanent teeth have erupted into the mouth and have been aligned. In essence, the goal of Phase 2 is to end treatment with as close to ideal results as possible in every regard to the patient’s smile esthetics, tooth alignment, bite, and airway.
Early Orthodontic Treatments That Enhance Airway
In addition to an esthetic profile, jaws that are appropriately matched are critical to allow a patient to breathe properly as well as for proper support of the teeth. As the focus of this paper is on airway and breathing, we’ll continue to focus on that topic. A short explanation of how properly aligned jaws influence the long-term health and stability of teeth will be included in the Appendix.
Let’s explore several common treatments orthodontists perform to correct an improper jaw-bone relationship.
Situation #1: Maxilla (Upper Jaw Bone) Is Too Narrow
Solution: Rapid Palatal Expander (RPE)
Explanation: The maxilla is part of the skull. It includes the roof of the mouth (the palate), which is made of two bones that come together and meet in the middle. The point where these bones come together is called a “suture.” This specific name for the suture separating the right and left palatal bones is called the “mid-palatal suture.” Sutures are the outer edges of bones, which are the primary locations where growth occurs. To expand a palate, we attach an expander (an RPE) to both of the patient’s upper first molars (2 total, one on the right and one on the left).
To activate the expander, a screw joint is turned and the expander gets wider. We expand at a rate of .2 mm/day (one activation of the expander screw). So, every time you activate the screw, the upper jaw gets a tiny bit wider. The point at which it’s expanding is the suture. As the suture gets wider, new bone fills in. After the final turn of the expander screw, this appliance must be left in a patient’s mouth for 4-6 months, to make sure the bone has fully backfilled in the space created. If the expander was removed immediately after the expansion was complete, the suture would not be filled in with new bone and the jaw would recoil back toward its original position.
Timing for maxillary expansion: On average, I feel comfortable expanding a patient’s maxilla any time before they turn 12. At 12 years old, the mid-palatal suture “fuses,” which means that the gap turns into solid bone. After this age, expansion doesn’t work because there is no “weak point” in the maxilla.
The previous explanation was made extremely simple, to serve as a baseline. Of course, as with anything in life, nothing is that simple. There are variables, and each patient is unique. For example, jaw growth in females generally finishes earlier than in males. So, you can often “get away with” a little bit later expansion in males than in females (For example: It’s more likely with males you could expand at 12, or possibly even 13, and be okay. With females on the other hand, expansion more commonly needs to be complete by the time they turn 12).
Situation #2: Both Upper & Lower Jaws Are Too Narrow
Solution: Rapid Palatal Expander (RPE) in the upper jaw and Slimline expander in the lower jaw
Explanation: To make things easy, we’ll refer to both upper and lower appliances simply as “expanders.” The upper expander serves the same purpose as described previously. The lower expander has a different design than the upper expander because there is a tongue there. There is no suture in the lower jaw like there is in the upper jaw. So the method of expansion is different as well.
Lower jaws expand by moving the teeth outward, as well as stimulating the bone immediately surrounding the teeth to grow outward. Lower expansion is much less “clear cut” than upper expansion and therefore is used much less frequently by orthodontists across the world. Although the mechanism is different, lower expansion does work well and offers numerous medical and dental benefits to the patients who receive it. I believe lower expansion is one of orthodontics’ best-kept secrets.
Timing: The mid-palatal suture fuses around age 12, as previously mentioned. There is no suture in the lower jaw. My opinion is that expansion done early (by “early,” I mean 7-8 yrs. old) is more beneficial than expansion done closer to 12 years old, because the younger patients’ bone is more “malleable,” and adapts more favorably to the expansion forces being placed on it. In addition, if a patient has a constricted airway, I believe it is extremely important to correct this issue as early as possible, so the child does not spend unnecessary time receiving inadequate oxygen during these critical developmental years. It is very common in our practice to treat 7-8-year-olds with upper and lower expanders.
Situation #3: Maxilla is too short (Upper Jaw Too Far Back)
Solution: Facemask
Explanation: When a patient has an underbite, it’s often because their maxilla is too short, so their upper teeth are farther back than they should be, which creates the underbite relationship.
The concept of the mid-palatal suture was explained in the last situation. The mid-palatal suture is only one of many sutures in the skull. In fact, the skull is made up of 22 individual bones which are all joined together by sutures! Following this, various jaw movements can be achieved by expanding a suture in a growing patient, and subsequently holding this position so that bone fills into the void.
A facemask is an appliance that is worn outside a patient’s mouth, on their face (called an “extra-oral appliance”). It attaches to a metal orthodontic appliance that is fixed inside a patient’s mouth to one molar on each side of the upper jaw (This is very similar to an expander. In fact, if the patient needs modification in both the transverse AND antero-posterior dimensions (meaning that the maxilla is too narrow and too short), a facemask can be combined with an expander and both are used at the same time! This is very common.
The way the extra-oral appliance attaches to the intra-oral appliance is by hooking up a rubber band to both appliances and linking them together. The specific rubber bands needed are supplied by the orthodontist, and the patient is responsible for hooking them up every time they put their facemask on. Facemasks are to be worn 12 hrs./day for maximum effectiveness.
Ideally, a patient will place their facemask 2 hrs. before they go to bed, wear it all night (assuming 8 hrs. of sleep), and continue to wear it 2 hrs. after they wake up, for a total of 12 hrs. A strict rule we have in our practice is that patients NEVER wear the facemask outside their house. We know that kids can be unkind, and wearing a facemask in public could have the potential to increase name-calling, bullying, and other unwanted occurrences. We take steps to get the maximum benefit out of treatment without being exposed to the negative social consequences of an extra-oral appliance.
Timing: Timing is everything, especially with facemasks! The maxilla finishes growing forward at approximately 8 yrs. of age. If a maxilla is too far back toward the back of the skull, it is extremely important that the patient be seen by an orthodontist around the age of 7, so proper treatment can be done before jaw growth finishes.
Situation #4: Lower Jaw (Mandible) Is Too Short
Solution: MARA Appliance
Explanation: The MARA appliance is an intra-oral appliance that has two pieces: one that attaches to the upper jaw and one that attaches to the lower jaw. When the patient bites down, the MARA appliance causes the mandible to be positioned forward of where it naturally wants to sit. By slowly advancing the mandible forward into the ideal position, and holding it there for 6-9 months, the mandible will grow to be larger (and more forward) than it was before. After the MARA is removed, the patient’s jaw stays in the correct position.
Timing: The forward growth of the mandible is the last dimension of jaw growth to finish. The most effective time to use a MARA is at the beginning of Phase 2, approximately 11½ years old. This is a key difference between a MARA appliance and the other appliances that have been mentioned: MARAs are utilized later in treatment. They are far more effective when used closer to the pubertal growth spurt (age 11-12) than during Phase 1 (age 7-8). MARAs are almost always used in tandem with braces or clear aligners.
Other Important Notes
Expansion Makes Space For Permanent Teeth
We’ve learned about how proper jaw position is necessary to allow both the nasal and pharyngeal (the throat) airways to be large enough to allow for normal breathing. Airway is the main focus of this paper. Another significant benefit of orthodontic expansion is that it makes space for all of the teeth to fit in the mouth! Teeth are held in place because they sit in a socket of bone. These sockets are essentially cutouts in your upper and lower jaw bones.
If a person’s upper and lower jaw bones match up in width (known as “transverse”) and length (known as anteroposterior) dimensions, they effectively allow the upper and lower teeth to mesh together properly when a patient bites down. In addition, allowing space for all teeth to fit prevents the need for extractions. Extractions are occasionally appropriate in orthodontic treatment, but I like to avoid them whenever possible.
First of all, patients generally do not like the thought of having teeth extracted. Secondly, after teeth are extracted the spaces must be closed orthodontically by pulling the remaining teeth together. In some cases, I believe this leaves less room for the tongue, forcing the tongue backward, which could potentially further compromise a patient’s airway.
The Relationship Between Orthodontic Expansion & Surgery To Remove Tonsils/Adenoids
Tonsils and adenoids are structures in a patient’s throat that can become large and obstruct the airway. Having them removed can often be an effective way to enhance a patient’s airway. In this case, we’re taking material that is making the airway smaller, and taking the material out, which makes the airway larger.
The other way to make an airway larger is orthodontic expansion. With expansion, we’re expanding the entire perimeter of the airway, making more space for the air to flow through. For a young patient with a compromised airway, it is a common approach to utilize both methods: expand orthodontically and have tonsils/adenoids removed.
The Effect Orthodontic Expansion Can Have On Large Tonsils & Adenoids
If you picture a small nasal airway that is being crowded by large tonsils and adenoids, the only apparent solution may be to remove the tonsils/adenoids to make the airway larger. No doubt, this is an excellent treatment for this issue and is often effective. There is another method to achieve a larger airway, however, which is to push the walls of the airway outward. This is what orthodontic expansion does. It makes the airway larger by pushing the walls of the airway apart. Oftentimes, these two treatments are utilized in concert to have the most significant effect.
An additional benefit of expansion is that it can cause tonsils/adenoids to shrink, even when they’re not removed. Tonsils and adenoids are glands, which are adaptive tissues. This means that they change size and shape based on their environment, just like a muscle gets larger when you exercise it. When an airway is narrow and/or when mouth breathing is present, adenoids/tonsils often swell up. This makes a bad situation worse because an airway that is already narrow gets narrower. Conversely, after expansion is completed, tonsils and adenoids often shrink because an airway is wider, often a patient has more ability to nose breathe, and the swelling goes down.
The Effect of Tongue Ties on The Airway
You know the skin between your tongue and the floor of your mouth that stretches out when you lift your tongue up? In some people, that attachment point is too close to the tip of their tongue, which limits their tongue mobility. Limited tongue mobility can impair a person’s speech and also make it difficult for the tongue to be held in the roof of the mouth. We’ve learned how important bracing the tongue in the roof of the mouth is to the proper development of the maxilla (upper jaw) and the nasal airway. The good news is, that the procedure to correct a tongue tie is relatively simple.
It requires a minimally invasive surgery, which is done in the dental or medical office under local anesthesia only (regular numbing used for dental procedures, no need to be put to sleep). After a couple of days of soft foods and healing at home, the patient is back to 100%. It is possible for a patient with a tongue tie that goes untreated to develop a narrow maxilla, and subsequently a narrow nasal airway. This happens because it is difficult for the patient to hold their tongue in the roof of their mouth, so the maxilla does not receive the outward pressure it needs to drive proper growth.
The tongue tie described above is called an “anterior” tongue tie. Anterior is the medical word that means “toward the front of the body.” There are also “posterior” (toward the back of the body) tongue ties, which are more difficult to detect. Posterior tongue ties can limit tongue mobility in other ways and have different negative effects.
Tongue tie screening is frequently done by a variety of healthcare professionals including (but not limited to): pediatrician, pediatric dentist, dentist, dental hygienist, orthodontist, myofunctional therapist, speech therapist. Ideally, a tongue tie would be corrected as early in life as possible, to allow for normal tongue mobility, normal jaw development, and normal speech.
The Importance of Myofunctional Therapy
You can think of a myofunctional therapist as a physical therapist for the oral (mouth) and facial muscles. An orthodontist is an expert at moving jaw bones and teeth into the correct positions to allow for proper function. A myofunctional therapist is an expert in teaching their patients to use the mouth and facial muscles optimally. This is important because if the patient receives treatments to align the oral and facial bones, teeth and muscles to be used properly (for example: orthodontic expansion and/or tongue tie release), but the patient does not know how to do this, they’re not getting the maximum benefits out of the treatment they received.
Just as physical therapy is often necessary for a person after knee surgery, myofunctional therapy is often necessary for a person who receives orthodontic treatment or a tongue tie release. The ideal sequencing of treatment is specific to the needs of each patient and will be coordinated by your orthodontist and myofunctional therapist.
The Value of 3D X-Rays
3D X-rays are becoming increasingly more common in dentistry and orthodontics, but there are still many practices that only use 2D. To assess an airway, having a 3D x-ray is essential. To better understand the difference, think of the analogy of the world. A 2D X-ray is like a map of the world, whereas a 3D X-ray is like a globe. Since the earth is actually a 3-dimensional structure, the globe is much more true-to-size than a map can ever be.
Ever notice how Greenland looks huge on a map, but much smaller on a globe? (hint: the actual size of Greenland is how it appears on the globe, not the map). The same thing happens with 2D X-rays. It is impossible to avoid distortion when you’re taking a 2D image of a 3D object. As we’ve learned, airways are generally fairly small spaces to begin with, so even a small distortion can change what’s actually a compromised airway to look “good.” Accuracy with X-ray imaging is extremely important to render the most comprehensive diagnosis to the patient.
