ABSTRACT
Rapid maxillary expansion is often considered the treatment of choice for the correction of maxillary constriction. Several studies highlight the effect of rapid maxillary expansion in increasing nasal length and volume. The aim of this study is quantifying the volumetric changes of the upper airway, the maximum restricted area of the upper airway and the nostrils area, after the intervention of a rapid maxillary expansion using bimaxillary CBCT. A retrospective study was carried out, in which 14 patients of 12 year old with a diagnosis of unilateral or bilateral crossbite and skeletal maxillary constriction were selected. The treatment was carried out with a Mcnamara-type rapid expansion device and 8 mm of disjunction was planned. An initial bimaxillary CBCT was requested and another 15 days after treatment. Measurements were made at the maxillary level, upper airway and the maximum restricted area and the cross section of the nostril area, using 3D measuring softwares. It was obtained that, for every 1 mm of planned disjunction, 0.65 mm of maxillary disjunction is achieved, an upper airway gain of 0.7 cm3, the maximum restricted area gain of the upper airway of 9 mm2 and a gain in the nostrils area of 7.4 mm2 on average. In conclusion rapid maxillary expansion generates a significant increase in the volume of the upper airway and its narrower area.