Rapid maxillary expansion on oral breathing children: effects on tongue location, hyoid position and breathing. A pilot study.

Background Oral breathing and downward tongue position are generally associated with transverse hypo-development of the upper maxilla. Rapid maxillary expansion aims to expand the upper maxilla transversely. This pilot retrospective clinical study evaluates the effects of rapid maxillary expansion therapy on the resting position of the tongue, on the position of the hyoid bone and on clinical respiratory pattern in a group of mouth breathing patients with mono- or bilateral cross-bites due to transversal deficits of the maxilla. Methods A total of 39 prepubertal oral breathing subjects with posterior cross-bite (mean age 8.5 year) have been studied. Before (T0) and after treatment (T1), changes in the position of the hyoid bone and tongue were evaluated by comparing latero-lateral radiographs (TLL), while the modification of respiratory patterns by a clinical and anamnestic assessment. Results After the treatment, the dorsum of tongue moved closer to the palatine vault, the position of the hyoid bone did not undergo significant variations and the respiratory pattern clinically improved in 64% of subjects. Conclusions In patients in early stages of oral respiratory development, rapid maxillary expansion promoted correct tongue position but did not produce significant changes in the position of the hyoid bone. It has been observed a general improvement of the breathing pattern.