Other Causes

Enlarged Tonsils and Adenoids

  • When the tonsils and adenoids are enlarged, the airway can be significantly compromised which can make it difficult to breath through the nose and create the need to breathe through the mouth.
  • Mouth breathing prevents the tongue from resting in the palate with the consequence of compromised facial growth. The face will grow more vertically and narrower when there is chronic mouth breathing (ref).
  • The constriction of the airway resulting from enlarged tonsils and adenoids can also contribute to sleep disordered breathing in children (ref).
  • The removal of enlarged tonsils and adenoids has been shown to improve sleep disordered breathing in children in the short term (ref). If the myofunctional disorder and the mouth breathing are not corrected, the sleep disordered breathing in most cases will return a few years later (ref).
  • Sometimes enlarged tonsils and adenoids are the cause of mouth breathing and sometimes mouth breathing is the cause of enlarged tonsils and adenoids.
  • Human physiology is based on breathing through the nose except in peak physical exertion.
  • When breathing through the nose, the air is warmed, filtered, humidified, and partially disinfected by nitric oxide before it passes the adenoids, the tonsils, through the throat and into lungs.
  • This well conditioned air in the lungs is ideal for the exchange of oxygen from the lungs to the blood.
  • When mouth breathing, the cold, contaminated, and dry air flows directly over the tonsils, through the throat and into the lungs.
  • This is hard on the sensitive tissues in the throat and lungs, compromises the effectiveness of oxygen exchange, and increases the risks of respiratory infections.
  • The tonsils are part of the lymphatic system that is responsible for removing contaminants from the body but it can be overwhelmed by mouth breathing.
  • In some cases, simply by changing breathing from mouth breathing to nasal breathing, enlarged tonsils and adenoids heal and shrink.
  • In cases where the tonsils and adenoids remain enlarged even though nasal breathing has been established or in cases where nasal breathing cannot be established, the removal of the tonsils and adenoids should be considered.
  • Referral to an Otolaryngologist (ENT) can take up to a year and often there will be guidelines in place whereby the removal of tonsils and adenoids will not be considered unless the child has had acute tonsillitis or strep throat multiple times (sometimes as many as seven times).
  • Some ENTs are more open to considering the removal of tonsils and adenoids in light of the effects on sleep disorders and poor facial growth.

Other Airway Related Factors

  • Any factor that compromises nasal breathing and results in mouth breathing will have a detrimental effect on the development of the jaws and teeth.
  • Other impediments to nasal breathing such as enlarged turbinates, polyps, or deviated septum can lead to mouth breathing with associated detrimental effects on the development of the jaws and teeth.
  • ENT specialists are often hesitant to perform surgery for these problems until growth is complete.
  • Small nostrils can also present an impediment to nasal breathing . This can sometimes be alleviated with “Breathe Right” strips or similar device to enlarge the nostrils. This can sometimes provide enough improvement through the night to decrease sleep disordered breathing symptoms.
  • Allergies can cause enough inflammation in the nasal passages to restrict nasal breathing to the point that mouth breathing is used with the associated detrimental effects on development of the jaws and teeth.
  • A corticosteroid spray such as Nasonex can sometimes provide relief from allergies sufficiently to allow nasal breathing to continue.

Abnormal Swallow

Normal Swallow

  • The normal swallow, once an infant has transitioned to solid foods, is with the tongue completely in the roof of the mouth (palate).
  • Some of the chewing muscles are active during swallowing but none of the muscles of facial expression are activated during the correct swallow.
  • The teeth contact together during a normal swallow.

Abnormal Swallow

  • An abnormal swallow is sometimes also known as a tongue thrust swallow, a reverse swallow, deviant swallow, or atypical swallow.
  • Different disciplines and groups have assigned different names to a swallow that is not normal.
  • An abnormal swallow can affect the development of the jaws and teeth significantly.
  • With an abnormal swallow, various muscles of facial expression are used (reference) and since a person typically swallows between one and two thousand times a day (reference) these muscles become hypertrophied (overly toned).
  • These overly toned muscles in the chin, lips, and cheeks appear to create an abnormal force on the jaws and teeth that influence the growth and development of the jaws and teeth.
  • This imbalance of muscle forces appears to be part of the environmental influences that are causing orthodontic problems.
  • There are many variations in which muscles are overly toned and various resultant effects on the teeth and jaws.

Abnormal Tongue Rest Posture

Proper Tongue Rest Position

  • The proper rest position of the tongue is in the roof of the mouth (palate). It should be in this rest position at all times except when talking or eating.
  • When the tongue is resting in the palate it resists the light inward and downward force from the cheeks and lips with the result that the upper jaw grows larger, more forward, wider and higher.
  • If the tongue is not resting in the palate the upper jaw grows smaller, further back, narrower, and lower.
  • A variety of orthodontic problems can result from an improper tongue rest position.
  • It is imperative to have proper rest position of the tongue in the palate with the blade of the tongue contacting the entire hard palate, the tip of the tongue just behind the upper front teeth and the sides of the tongue touching the palate but not the teeth, for proper growth of the jaws.
  • Any other tongue rest position than this is an orofacial myofunctional disorder.

Forward Tongue Rest Position

  • When the tongue rests in a forward position against the front teeth the light continuous force of the tongue pushes these teeth forward resulting in spaces between the teeth and a gap between the upper and lower teeth.


Low Tongue Rest Position

  • When the tongue rests in a low position in the lower jaw and does not touch the upper front teeth but touches the lower side teeth, the lower jaw grows more forward and wider while the upper jaw grows further back and narrower.


Low and Back Tongue Rest Position

  • When the tongue rests in a low and back position and does not really touch the jaws or teeth at all, both upper and lower jaws grow further back, narrower and lower. This is a very common dysfunctional tongue rest position.


Back and Lateral Tongue Rest Position

  • When the tongue rests between the upper and lower teeth along the sides the result is that the side teeth do not touch together which is called a posterior open bite.
  • All of the biting and chewing function occurs on the front teeth which results in premature wear to the front teeth and a compromised chewing function.

Other Tongue Rest Positions

There are many more variations of tongue rest positions and accompanying orthodontic problems.

Abnormal Chewing

  • Normal chewing requires the use of the muscles of mastication (masseters, temporalis, and pterygoids). The muscles of facial expression are not required.
  • Abnormal chewing includes the use of some of the muscles of facial expression, usually the mentalis (chin), orbicularis oris (lips), and the buccinators (cheeks).
  • This excess use of some of the muscles of facial expression result in these muscles being overly toned and there are resultant detrimental forces on the jaws and teeth.
  • Open mouth chewing is abnormal chewing. It is generally considered to be impolite to chew with an open mouth.
  • Air is incorporated in food that is chewed with open mouth chewing and when this air is swallowed along with the food it can cause digestive problems such as bloating, gas, and discomfort. The digestive process in the gastrointestinal tract is not designed to deal with air.

Poor Posture

  • The airway is held mostly open and is therefore more efficient with good posture.
  • The head should be positioned directly in line with the spine and the shoulders should be slightly back and down.
  • When sitting, the shoulders and head should be directly in line with the sit bones.
  • Unfortunately, good posture like this is very rare.
  • One of the most common negative effects on posture is the use of electronic devices.
  • When using a device the head usually drops forward and downward and the shoulders roll forward. The body usually assumes a slouch instead of an upright position.
  • This slouch and forward head and shoulder position compromises the airway so the airflow is somewhat compromised.
  • This can trigger mouth breathing which in turn has a definite negative impact on facial growth and development. The face grows more vertical and narrower with mouth breathing (ref).
  • If the airway is compromised due to poor facial growth or enlarged tonsils or adenoids, the body often automatically responds by posturing the head forward with an upward tilt as this opens the airway to some degree.
  • This can become a chronic poor posture habit that appears to contribute to jaw joint, neck and upper back problems.

Tongue Tie

  • A tongue tie is where the tongue is tethered tighter than normal to the floor of the mouth somewhere along the underside of the tongue.
  • An anterior tongue tie is one in which the tip of the tongue cannot protrude very far out of the mouth or lift very high into the palate. The tissue at the centre of the tip of the tongue pulls back when protruding or lifting the tongue.
  • A posterior tongue tie is one in which the back part of the tongue cannot lift very high into the palate. The centre of the back part of the tongue “dishes” when trying to lift the tongue to the palate.
  • A tongue tie restricts the range of motion of the tongue which in turn can prevent the correct rest posture of the tongue and a correct swallow.
  • In newborns, a tongue tie can prevent proper breast feeding and is recognized in many delivery rooms as something to be checked and corrected immediately upon birth.
  • This does not occur universally and there is a patchwork system with Alberta Health Services on how to deal with tongue tie.
  • The cost of tongue tie release surgery (also known as lingual frenectomy) is covered by Alberta Health Services with certain practitioners.
  • Tongue tie release procedures are done mostly by some pediatric dentists, oral surgeons, and general dentists.
  • Correction of a tongue tie involves a relatively minor surgery along with some exercises to assist in healing with an increased range of motion.
  • In infants, the simple action of breast feeding following the surgery is mostly sufficient to achieve improved range of motion as the surgical site heals. Some very simple exercises and massage by a caregiver are sometimes prescribed.
  • In children and adults a more rigorous post surgery protocol is required to ensure proper healing with the desired increase in range of motion of the tongue.
  • A tongue tie presents a distinct orofacial myofunctional deficit and can be the primary cause of an orofacial myofunctional disorder.
  • A tongue tie can be related to jaw joint discomfort and facial pain.
  • An orofacial myofunctional disorder can rarely be corrected when a tongue tie is present. The exception is when the tongue tie is very mild and the range of motion of the tongue has not been severely compromised.


  • Diets in the developed world are extensively processed and much softer than diets in the developing world where traditional foods are still the norm.
  • It is considered by many that this softer diet has contributed to the generally smaller jaws found in developed countries.
  • The theory is that bone responds to forces and with the greater biting forces required for a coarser and tougher diet, the jaws respond by growing larger and more capable of handling the greater forces.
  • When skulls from a few hundred years ago in Europe were analyzed it was found that very few people at that time had orthodontic problems (ref). The jaws were larger and wider with sufficient space for all the teeth, including wisdom teeth.
  • Most people in the developed world now have smaller jaws and crowding of the teeth. It is considered by many that the increased processing of food and the general softening of the diet has contributed significantly to this.
  • Dr. Westin Price travelled extensively around the world in the 1930’s to record the development of jaws and teeth in societies recently exposed to a western diet (ref).
  • The first generation following the exposure to a western diet experienced pronounced deficits in the growth of the jaws and teeth.
  • Another aspect of diet in the developed world that appears to have a negative impact on facial growth is the use of bottle feeding in infants and the use of soft blended foods in the transition from breast feeding to solid foods (ref).
  • Both of these dietary choices appear to contribute to the development of an abnormal swallow which is an orofacial myofunctional disorder that can adversely affect the growth and development of the jaws and teeth.
  • For an informative discussion on weaning for infants, please check out the book “Baby Led Weaning” by authors Gill Rapley and Tracey Murkett.

Lip or Tongue Piercings

  • Lip piercings can prevent a normal lip seal which can contribute to an orofacial myofunctional disorder with subsequent detrimental effects on the development of the jaws and teeth.
  • Tongue piercings will prevent normal tongue rest posture in the palate and will prevent a normal swallow. Both of these issues will adversely affect the development of the jaws and teeth.