In contrast, however, mouth breathing "pulls all pollution and germs directly into the lungs; dry cold air in the lungs makes the secretions thick, slows the cleaning cilia, and slows down the passage of oxygen into the bloodstream." As a result, chronic mouth breathing may lead to illness. In about 85% of cases, it is an adaptation to nasal congestion,: 281  and frequently occurs during sleep. More specialized causes include: antrochoanal polyps;: 350  a short upper lip which prevents the lips from meeting at rest (lip incompetence);: 281  and pregnancy rhinitis which tends to occur in the third trimester of pregnancy. : 435

Potential effects
Conditions associated with mouth breathing include cheilitis glandularis,: 490  Down syndrome,: 365  anterior open bite,: 225  tongue thrusting habit,: 225  cerebral palsy,: 422  ADHD, sleep apnea, and snoring. In addition, gingivitis,: 85  gingival enlargement,: 85  and increased levels of dental plaque: 108  are common in persons who chronically breathe through their mouths. The usual effect on the gums is sharply confined to the anterior maxillary region, especially the incisors (the upper teeth at the front). The appearance is erythematous (red), edematous (swollen) and shiny. This region receives the greatest exposure to airflow during mouth breathing, and it is thought that the inflammation and irritation is related to surface dehydration, but in animal experimentation, repeated air drying of the gums did not create such an appearance. : 85 Breathing through your mouth decreases saliva flow. Saliva has minerals to help neutralize bacteria, clean off the teeth, and rehydrate the tissues.
Its presentation on radiography is a radiolucent cleft often called a vacuum phenomenon, or vacuum sign. Pneumarthrosis is associated with osteoarthritis and spondylosis.Pneumarthrosis is a common normal finding in shoulders as well as in sternoclavicular joints. It is believed to be a cause of the sounds of joint cracking. It is also a common normal post-operative finding at least after spinal surgery. Pneumarthrosis is extremely rare in conjunction with fluid or pus in a joint, and its presence can therefore practically exclude infection. Other
Subcutaneous emphysema is found in the deepest layer of the skin. Emphysematous cystitis is a condition of gas in the bladder wall. On occasion this may give rise to secondary subcutaneous emphysema which has a poor prognosis.Pneumoparotitis is the presence of air in the parotid gland caused by raised air pressure in the mouth often as a result of playing wind instruments. In rare cases air may escape from the gland and give rise to subcutaneous emphysema in the face, neck, or mediastinum. Terminology
The term pneumatosis has word roots of pneumat- + -osis, meaning "air problem/injury". References


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