The Tongue: What Part does it Play?
It is hard to comprehend the full difference between the correct and incorrect action/posture of the tongue. The teeth are resistant to short-term force during biting or swallowing but they are very sensitive to light long-term force/posture, including the touch of the tongue. If you place a blob of resin on the lingual side of an unopposed molar it will move away from the light contact of the tongue because it is continuous while the strong push from the tongue during swallowing lasts barely a second and so has little influence.
The shape of the dental arch is determined primarily by the tongue but also by the cheeks and lips, all of which have far more influence than the genes. That is why the arch shape of all animals and our primitive ancestors reflects the shape of the tongue. That does not apply to people who have any malocclusion because all of them have displaced tongues. Usually children from industrialised countries rest their tongue to a greater or lesser extent between the teeth. In fact about 95% of civilised children do this, leaving the teeth and lips apart for varying periods which of course is why malocclusion is endemic.
William Profit’s research at South Carolina, showed very clearly that teeth erupt when out of contact and intrude when in contact (Proffit et al 1993). From this research it is obvious that teeth need to be in contact 4 to 8 hours a day for them all to meet evenly with the face the correct height. But if the tongue rests between the teeth this balance is distorted.
The problem has been that few clinicians who work in the mouth have realised how influential the tongue is for the growth and development of the jaws and face. This includes many Dentists, Ear Nose and Throat Specialists, Orthodontists, Speech Therapists, Orthognathic Surgeons, Oral Myologists and to some extent Beauty Specialists and Plastic Surgeons all of whom are involved in the shape and function of the facial skeleton. We could also include Anthropologists who study the historical shape of the face as well as the Cranial Osteopaths, and Chiropractors who treat internal deformation of the skull. Many of them visualise the tongue as a soft structure which adapts to the form of the tissues around it, rather than seeing it as the large powerful muscle it is.
Orthotropists believe that the natural growth and appearance of the face is largely guided by the position of the tongue, but no one has yet found an accurate way of measuring tongue posture and so this suggestion is as yet hypothetical. It is theorised that the forward growth of the maxilla (the mid face) depends to a large extent on support from the tongue but although there is incidental evidence to support this concept it is not widely accepted by orthodontists. Sadly because it can’t be measured, university researchers have shown little interest in tongue posture so we have little idea whether it is crucial or unimportant.
The illustration below shows the effect of enlarging the maxilla and taking it forward.