Do not ignore mouth breathing syndrome: respiratory functions are affected in early childhood.

Adenoid hypertrophy (AH-44.0%), allergic rhinitis (AR-11.3%) and AH co-existent with AR (34.6%) were the principal causes of MB. Entire airway resistance was higher, upper and lower airway reactance were lower in the MB group compared to the NB group. No difference was detected in terms of IOS parameters between the first and second visits of MB group. Upper and entire airway resistance parameters were higher in children with AH and AH co-existent with AR groups compared to the non-obstructive group. Entire airway resistance was higher, upper and lower airway reactance were lower, in children with adenoid size>50% compared to those with adenoid size mouth breathing, allergic rhinitis, adenoids, respiratory function test, pediatrics.