Figure 1-5:  The patient is able to extend the tongue well, but has a higher palate, crowded dentition and open bite due to a tongue thrust.  Under the tongue reveals a substantial tongue restriction.

Growth and Development Impact

Articles related to the impact of mouth breathing on facial growth

These articles can be downloaded and will explain in more detail how mouth breathing can impact and change growth.  The will help explain this impact at a deeper level. 

Nasal Breathing is Extremely Important for Various Reasons

As humans we were designed to breathe through our nostrils and allow the nose to perform various functions.  The turbinates in the nose help slow the air flow down so that it can be humidified (add moisture), clean debris and allergens from the air and add nitric oxide to the air.  The addition of nitric oxide by nasal breathing allows this air to be transported to the lungs and taken up by the blood stream.  Nitric oxide is produced by the paranasal sinuses that connect into the nasal airway and passages.  Nitric oxide helps lower the blood pressure and act as a bronchodilator and allow for easier overall breathing and homeostatis of the body.  When you breathe through your mouth, you do not allow for humidified air, cleaner air or nitric oxide infused air to reach the body or the lungs.  Individuals with OSA (obstructive sleep apnea) typically have higher blood pressure and may be partially as a result of poor nitric oxide inhalation.

The act of nasal breathing also helps keep the lower jaw (mandible) positioned forward and keeps the tongue out of the airway. The tongue is fixed to the roof of the mouth and essential held up and out of the airway, to allow for an open nasal passage for breathing.  The horizontal growth of the face, as depicted in "A" below, shows how a jaw is properly positioned and the facial profile is more ideal.   

The next face ("B") shows what can occur in a patient who will mouth breathe and lead to a more vertical growth of the skull.  Notice the TMJ (tempro-mandibular joint) is displaced from it's ideal resting place in the skull.  This malpositioned jaw will put stress on the TMJ and can change the shape of the upper and lower jaws.  With mouth breathing the tongue must rest lower in the mouth and does not rest or push upwards onto the maxilla like it is designed to do.  Notice the profile of the patient has changed and the face is longer and the chin and neck and poorly defined.  This picture does not depict the changes that can also occur to the bridge of the nose.  Without the vertical force from the tongue the midface portion will remain setback and can lead to the nasal bone creating a large bump as the rest of the nose is pulled down. 

The last face ("C") shows a complete shift of the head ad neck forward to allow for the airway to stay patent so air can pass either from the mouth or the nose t the lungs.  The will obviously change the facial profile to a less ideal appearance, but puts an extreme amount of stress on the neck and the neck and shoulder musculature.  The spine is suppose to serve as a supporting column for your head.  As the head moves forward to compensate for breathing obstruction or difficulties, an additional 10 pounds of stress and weight is added to the neck and shoulder muscles to support for each inch forward the heads is positioned.  With only a few inches of forward head posture the amount of stress on the neck and shoulder muscles can be excessive and over a longer period of time lead to chronic pain and discomfort for the patient. 

It is not just about nursing and breastfeeding​

One of the most important aspects of understanding comprimised tongue positioning and function or the negative impact of excessive bottle or pacifer use is to understand how it may impact long-term growth and development.  An infants skull is made up of many bones that are not fused together and this is so the head can grow.  Once the infant is free from the restricted womb, the bones and sutures within the head are very easily influenced by muscular stimulation and forces.  If the tongue is allowed to function properly  and other muscle groups are in a balance with the forces of the tongue, growth and development should progress uneventfully.  When forces are not balanced or excessive forces are exerted on the facial and cranial bones, a change can happen in growth of the head and jaw.  A great example of how external forces can impact the face and it's structural appearance is found in pre-mature infants. These pre-mature babies who spend the first months of their life in the NICU until they are ready to go home.  As the infant lies on one side of the face or the other, with minimal breastfeeding, the facial structure can rapidly become very long as the weight of the head and gravity push on the head and minimal tongue forces are applied to the head to counterbalance.  

Airway Development

The lower jaw or mandible is typically slightly recessed or set back in an infant.  This occurs because the infants chin is positioned closely to the chest in the already confined uterus.  Once the child enters the world, the chin will slowly start to grow in a downward and forward direction with proper guidance from the tongue.  The main growth center for the mandible is located at the Temporal Mandibular Joint or the TMJ.  The facial muscles and tongue will exert a force that act on the maxilla and mandible.  When these forces are in balance, growth and development will proceed normally and in balance.  When facial muscle exert a force that is not balanced by the tongue it may restrict the growth of the jaw.  When the jaw growth is restricted the tongue is displaced to the posterior portion or back of the oral cavity and can impinge the airway.  As air passes through the nose, back to the nasopharynx and into the oropharynx the tongue may obstruct this path.  If this is the case, the body will either switch to mouth breathing which will allow the tongue to then be positioned forward and down and out of the airway.  This mode of mouth breathing can lead to irritated tonsils, a dry mouth and in turn a lower pH of the mouth and higher incident of caries. 

The tongue will grow to fill in the mandible area when facial growth and development occurs properly.  The tongue exerts lateral, vertical and horizontal force within the oral cavity to help expand the entire mouth into an ideal "U" shape.  The widening of the jaw and maxilla allows for a wider arch that will better accommodate the developing dentition.  If the tongue does not exert the outward force to balance the facial muscles the dental arch can form a "V" shape.  Of course this can lead to an aesthetic issue and protruded teeth, but the airway and overall systemic effects are more impactful.

The prolonged use of a pacifier or thumb/finger habit and the intensity in which they are sucked can negatively impact the shape of the maxilla and mandible.  The palate will narrow and become higher and can cause the front portion of the maxilla to move forward and become more pronounced, increasing the likelihood for trauma because the lips can not protect the teeth. 

SIDS, of sudden infant death syndrome, in breastfed children is dramatically decreased as well.  The progesterone in breastmilk along with proper usage of the oral and facial structures will help develop and maintain a patent airway of the infant and improve the musculature tone and position of the tongue helps decrease the risk for SIDS.

Mouth Breathing

Mouth breathing, especially during the night, can have a negative impact on your teeth and oral cavity overall.  When we use the mouth to breath at night the oral cavity will dry out and the protective properties of saliva disappear. 

Saliva helps clear food from the mouth, remineralize the teeth to help strengthen them, provide enzymes to help the breakdown of food and buffer the oral cavity. 

The normal pH level in the mouth is 7.7, which is a balance between an acidic and basic environment.  Individuals with problems breathing through the nose when asleep can have a pH drop to a pH of 6.6 and even lower.  Once the pH reaches 5.5, the enamel will start to breakdown and cause demineralization within the tooth.  Prolonged exposure to an oral environment of this nature can lead to tooth decay.   

Choi, JE, Waddell, JN,, Intraoral pH and temperature during sleep with and without mouth breathing, Journal of Oral Rehabilitation Vol. 43, Issue 5, May 2016, Pages 356-63

Sleep Disordered Breathing (SDB) and Obstructive Sleep Apena (OSA):

Sleep disordered breathing (SDB) and obstructive sleep apnea (OSA) can occur at any age and have major short and long term impacts on school and work performance and overall health and well being.  Individuals who have been diagnosed or are symptomatic for these issues often have changes in not only behavior, but also physical appearance.  See article at bottom of this section to review.

These individuals may exhibit and open mouth posture, sclera or the white area showing under eye, a flat profile with no prominent cheek bones, slower body growth, crooked and crowded teeth that may stem from poor tongue positioning and posture.  As the individual sleeps, the lower set or poorly postured tongue will fall back into the airway and obstruct of block the flow of oxygen to the lung and in turn the rest of the brain and body.  This lack of oxygen is extremely tough on the brain and causes the brain to work overtime at night, when it should be resting.

The brain needs more oxygen at night to help the prefrontal cortex function and clear the brain of free radicals produced during the day.  Individuals with SDB or OSA will have a brain that remains awake and alert and not in a state of rest.  Poor breathing leads to poor oxygen uptake and delivery to the brain.  When the brain is alerted of lower oxygen level and higher levels of carbon dioxide, the brain will stimulate the body and force it to breathe.  The maintenance of oxygen levels will always supercede the brains resting state.   These children may fall asleep with little to no problem, but the depth and quality of sleep is compromised.

This lack of quality and sustained sleep can severely impact the performance these children have in school and adults at work or while driving.  Studies have shown that poorly performing and inattentive students at times are labelled as have ADD or ADHD because of their behaviors in school.  The major issue in many of these children was they were in fact not ADD or ADHD, but quality sleep deprived and were suffering from sleep disordered breathing at night and waking up and having to focus and function at school.     
Review the article here.
These patients with obstructed airways may have multiple environmental allergies, a higher arched palate, a deviated septum, enlarged turbinates in the nose, a lower set tongue with a resting position behind the lower teeth and lower muscle tone in the face. 

This is not an absolute either…..not all mouth breathers are ADD/ADHD and not all true ADD/ADHD are mouth breathers.  Kids still need a lot of sleep when they are young and still developing and must have the opportunity to have the recommended amount of sleep.  These children will display hyperactivity, impulsive behavior and poor focus.  These can then lead to anxiety and depression when untreated and not addressed.

In adults OSA leads to higher blood pressure, day-time sleepiness or sluggishness which is unhealthy for the individual, but may pose a risk for others if the individual is driving and poorly rested.  Weight management, redundant neck tissue and other medical conditions can predispose indivduals to OSA, but with proper tongue resting position, facial muscle tone and a healthy airway, the individual can rest better.  This theory is mimicked by the use of breathing machine at night forces the individual to breathe through the nose and if they try to mouth breath, the positive pressure air generated by the machine will forcefully stop air intake via the mouth.

Case Study:  Impact on dental arches with prolonged tongue tie.

The 4 year old pictured below is able to extend the tongue with no problem at all, but when examined under the tongue she has a tongue tie.  The dysfunctional swallow and limited range of elevation and lateral movement within the mouth has restricted the maxilla and mandibular growth.  The dental arches are narrow, the tongue thrusts forward when swallowing and has led to an open bite in the front teeth.  The tongue was unable to rest on the roof of the mouth and exert lateral forces to help widen the jaw.  She is now at an increased risk for crowding and future orthodontic concerns due to the narrow arch.