 The most frequent causes of mouth breathers are the adenotonsillar hypertrophy. Adenotonsillectomy is the main choice for the elimination of the obstruction. However, this surgical treatment does not have its effect well elucidated and apnea has been cited in the literature as a residual outcome. Other types of supporting treatment may also been involved such as the use of corticosteroids, physiotherapy and orthodontic-orthopedic treatment, among them rapid maxillary expansion RME. 