Chronic mouth breathing may trigger a localized
immune response in the upper airway. The nasal passage regulates airflow, temperature, humidity, and microbial filtration. Mouth breathing increases direct exposure of the nasopharyngeal mucosa to irritants and
pathogens. This results in additional mechanical and immunological stress on the tissue. The increased stress may promote
Inflammation and hypertrophy of adenoid tissue, secondary lymphoid organs central to mucosal immunity, which are rich in
T cells and
IgA - producing
B cells. Repeated stimulation from unconditioned airflow can sustain adenoid activation and enlargement, potentially creating a cycle of immune-driven chronic mouthbreathing. 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. As a result, chronic mouth breathing may lead to illness. Conditions associated with mouth breathing include
cheilitis glandularis, anterior
open bite,
ADHD,
sleep apnea, In addition,
gingivitis, 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. Chronic mouth breathing in children may affect dental and facial growth. Conversely, it has been suggested that a long thin face type, with corresponding thin nasopharyngeal airway, predisposes to nasal obstruction and mouth breathing. ==Additional approaches to mouth breathing==