Modified Hyrax expander for the correction of upper midline deviation: a case report

This article describes a case report of a patient treated by the modified version of the Hyrax rapid palatal expander described by Farronato et al. in 2009. This device can be utilized for the treatment of patients in mixed dentition who, due to the maxillary hypoplasia and to the premature exfoliation of some deciduous teeth, manifest a migration of the permanent incisors with a reduction or closure of the space for the permanent teeth substituting those previously exfoliated. This expander presents a vestibular arm for correcting maxillary asymmetric transverse discrepancies. The activation method, the therapeutic benefits as well as the clinical advantages are described. The use of this appliance allows to restore the correct transverse maxillary diameters, to regain space and at the same time to restore the symmetry of the midlines up to 5-6 mm. Moreover, a recovery of the arch length can be obtained, as demonstrated by the case report presented. The expander with vestibular arm represents an interceptive treatment which can reduce the duration of the orthodontic therapy with fixed appliances.