An orofacial variation that relates to the lips and teeth is an open mouth posture. This is usually seen in young children with nasal airway problems. Enlarged tonsils & adenoids, nasal allergies and rhinitis (inflammation of the mucous memebrane of the nose) are all conditions which may contribue to mouth breathing.
True Mouth Breathing occurs when the mouth is the primary mode of breathing and open during the resting posture.
Why should you be so concerned about mouth breathing?
Mouth breathing bypasses a very necessary filtering system. The nasal passages provide natural filtering of bacteria, polluted particles, and warms the air so the it can be easily accepted by the lungs. Mouth breathing habitually dries the tissues of the mouth which promotes gingivitis and can lead to periodontal disease if not corrected. The open mouth encourages a low, forward tongue resting posture which contribues to tongue thrusting and unwanted tooth movement.