Children may experience chronic blockage of the nose for a variety of reasons, including allergic rhinitis, nonallergic rhinitis, or enlargement of the adenoid gland. When the child lies down to sleep, the blockage often becomes worse because of increased blood flow through the nasal mucosal tissue due to gravity, which causes the membranes to swell. In addition, the blockage may worsen because of positional factors that cause the adenoid gland to encroach upon the upper airway. When nasal obstruction becomes severe, either during the night or day, the breathing pattern shifts from breathing through the nose to breathing primarily through the mouth, which may result in snoring, dryness of the mouth, and sore throat.
In addition, mouth breathing places the oral cavity under significant stress and eventually causes the palate of the mouth to become narrow and higharched and the lower jaw to move backward toward the neck. These anatomic changes ultimately cause the teeth to become crowded and may lead to the development of an overbite. Oral problems like this are often noticed around age 4 or 5 years; once established, they may require a palatal expander and other orthodontic appliances to enlarge the palate and straighten the teeth. These orofacial problems highlight the importance of diagnosing and treating nasal blockage in young children.