It seems that;
- an almost complete change in diet has hugely reduced the work that our chewing muscles are required to do.
- epidemic levels of allergies are leading to frequent blocked noses. If you cannot breathe through your nose you have to open your mouth and lower the tongue which is supporting the top jaw. This impacts on facial growth.
- Children are not breastfeeding for nearly as long, which interferes with the normal function of the tongue and lips.
- Children are being weaned onto soft food instead of foods that require them to chew, which is disrupting a move from an infantile suckle to an adult swallow.
1 and 2 are the most important for the shape of the face, while 2 and 3 are the most important for the position of the teeth.
If you have weak muscles and you hang your mouth open, then the face drops down. See anyone who has a stroke, although this only affects one side of the face. The changes can be seen clearly in school children.
In those who mouth-breathe, the face lengthens (or downswings), the cross-sectional area reduces, leaving insufficient room for the larger adult teeth. The leads to crowded, crooked teeth and affecting the airway.
Good medicine is about identifying the causes of the problem and preventing them, not merely alleviating the symptoms and possibly worsening the underlying problem in doing so. We would like to see a move to an evidence-based approach to the treatment of crooked teeth that is focused on prevention and on understanding the implications for the whole face and respiratory system.