SUMMARY
Introduction: Mouth breathing is a pathological respiratory disorder affecting many oral, dental and craniofacial structures.GOAL: Evaluate the clinical manifestations of mouth breathing and explore the mechanisms causing oral breathing, craniofacial, oral and dental alterations in children.METHODS: Using the key words: mouth breathing, frequency; mouth breathing, etiology; mouth breathing, signs and symptoms; mouth breathing, pathophysiology, mouth breathing, diagnosis and mouth breathing, treatment, we entered such terms in www.google.com. RESULTS: We retrieved 25 papers written in english in the period 2000-2016 and four papers published in the period 1981-1997. All these papers had sufficient oral breathing associated content in order to prepare the current study.CONCLUSIONS: Clinical manifestations of oral breathing in children and adolescents include dental changes, craniofacial alterations, postural abnormalities, musculoskeletal disorders, anatomic alterations, occlusal, oral and neuromuscular disorders. Mechanisms of mouth breathing causing pathologicl disorders include obstructive, postural, reduction of vertical effect on the muscles, anterior tongue thrusting, anatomical, disruption of muscle forces exerted by the tongue, increased expenditure of energy during sleep, smaller oral cavity, retruded maxila and mandible and increased nasal airway resistance.