Mouth breathing

Mouth breathing, medically known as chronic oral ventilation, is long-term breathing through the mouth. It often is caused by an obstruction to breathing through the nose, the innate breathing organ in the human body. However, by the early 20th century, the term "mouth-breather" had developed a pejorative slang meaning connoting a stupid person.

In the early 20th century, "mouth-breather" was a technical term used by doctors to describe children who were breathing through their mouths due to an underlying medical condition. English lexicographer Jonathon Green notes that by 1915, the phrase "mouth-breather" had developed a pejorative connotation within English slang, defined as a "stupid person". Currently, the Macmillan Dictionary defines the term "mouth breather" as a pejorative noun that is used to mean "a stupid person".

In about 85% of cases, it is an adaptation to nasal congestion, and frequently occurs during sleep. More specialized causes include: antrochoanal polyps; a short upper lip which prevents the lips from meeting at rest (lip incompetence); and pregnancy rhinitis, which tends to occur in the third trimester of pregnancy.

The impact of chronic mouth breathing on health is a research area within orthodontics (and the related field of myofunctional therapy) and anthropology. It is classified into three types: obstructive, habitual, and anatomic.

There is a noted order of cause and effect leading to airway dysfunction related to mouth breathing. This first starts with an inflammatory reaction then leading to tissue growth in the area which leads to airway obstruction and mouth breathing and then finally an altered face structure.

Nasal breathing produces nitric oxide within the body, while mouth breathing does not. In addition, the Boston Medical Center notes that the nose filters out particles that enter the body, humidifies the air we breathe and warms it to body temperature. 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.

Conditions associated with mouth breathing include cheilitis glandularis, Down syndrome, anterior open bite, tongue thrusting habit, cerebral palsy, ADHD, sleep apnea, and snoring. In addition, gingivitis, gingival enlargement, and increased levels of dental plaque 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.

Breathing through the mouth decreases saliva flow. Saliva has minerals to help neutralize bacteria, clean off the teeth, and rehydrate the tissues. Without it, the risk of gum disease and cavities increases.