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Home > Wellness > Health Library > Mouth Breathing and Malocclusion
A partially blocked airway is often the cause of mouth breathing,
usually due to allergies or enlarged adenoids or tonsils. A doctor should
evaluate any of these conditions. Frequent mouth breathing can cause dry, red,
swollen gums. This can be especially noticeable around erupting baby and
In children younger than 8, about half do some breathing through
their mouths, presumably not due to a medical problem. Most children outgrow
this habit by the age of 8.1
The relationship between ongoing (chronic) mouth breathing and
malocclusion ("poor bite") is unclear, although the
two are often seen together. The most common trait of people who chronically
breathe through their mouths is an elongated (longer) lower face and a narrowed
upper arch in the mouth (maxillary constriction). Cheek muscles pressing in on
the upper side teeth cause these traits. However, experts still question
whether mouth breathing is really responsible for these skeletal and dental
Christensen JR, et al. (2005). Oral habits. In JR
Pinkham et al., eds., Pediatric Dentistry: Infancy Through Adolescence, 4th ed., pp. 431–439. St. Louis: Elsevier
January 11, 2011
Kathleen Romito, MD - Family Medicine & William F. Hohlt, DDS - Orthodontics
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