According to Meredith, 60% of the growth of the face takes place during the first four years of life and 90% takes place by the age of 12. Development of the lower jaw continues until around age 18.8
Based on these observations, for correct craniofacial growth to take place, early intervention with nasal breathing and tongue posture is essential. In the words of Dr Carl Schreiner, The deleterious effects of nasal obstruction are virtually complete by puberty so the window of opportunity is relatively brief. Delay in intervention may result in unsuccessful orthodontic treatment which may require orhthagnathic surgery at an older age.9
All mouth-breathing children develop crooked teeth
The normal growth direction of the jaws is forward. This occurs as a result of the forces exerted by the lips and tongue. It works based on this same principal used by orthodontics: light forces move teeth.
The lips exert an estimated pressure against the teeth of between 100 gm and 300 gm.10 While swallowing, the pressure exerted against the anterior teeth by the tongue is estimated to be 500 gms,11 while the force required to move a tooth is as small as 1.7gm.5
We swallow an estimated 2,000 times per day, and each time we swallow, the tongue pushes upwards and flattens in the roof of the mouth, exerting a considerable force that shapes the jaws.5 The correct position of the tongue is resting in the roof of the mouth. As the child grows, the top jaw forms around the tongue. In other words, the shape of the top jaw is the shape of the tongue. As the tongue is U-shaped, it results in a broad facial structure with sufficient room to house all teeth. Nature dictates that the shape of the lower jaw will follow that of the top jaw.5
When the mouth is open, the tongue cannot rest in the roof of the mouth, resulting in a poorer developed, narrow, V-shaped top jaw. A smaller top jaw leads to a narrow facial structure and overcrowding of the teeth. “Low tongue posture seen with oral respiration (mouth breathing) impedes the lateral expansion and anterior development of the maxilla (top jaw).â€12
In the words of dentist Dr Raymond Silkman, The most important orthodontic appliance that you all have and carry with you twenty-four hours a day is your tongue. People who breathe through their nose normally have a tongue that postures up into the maxilla (the top jaw). When the tongue sits right up behind the front teeth, it is maintaining the shape of the maxilla (top jaw) every time you swallow. Every time the proper tongue swallow motion takes place, it spreads up against maxilla (top jaw), activating it and contributing to that little cranial motion. Individuals who breathe through their mouths have a lower tongue posture and the maxilla does not receive the stimulation from the tongue that it should.13
This is supported by Dr John Flutters statement: There is no doubt that the tongue has an enormous influence on dentition,â€14 and by Dr Mews statement: “Lack of tongue pressure hinders the growth of the maxilla (top jaw). Put conversely, the maxilla may not be able to achieve its inherited potential without assistance from tongue posture.â€1
In addition, “the main characteristics of the respiratory obstruction syndrome (blocked nose is addressed using the Buteyko method) are presence of hypertrophied tonsils or adenoids, mouth breathing, open bite, cross bite, excessive anterior face height, incompetent lip posture, excessive appearance of maxillary anterior teeth, narrow external nares, V-shaped maxillary arch (top jaw).15