The appliance for treatment of unilateral cross bite contains a palatal wireframe or a clasp on which, from the side of the dentition's lateral section, which is not subject to change, support-retaining wireframes and a tooth plate with imprints of antagonist teeth are rigidly fixed, see, FIG2 Mailyan 10-2. On the other side of the palatal support the support-retaining wireframes mountable on lateral teeth segments of both jaws are fixed through orthodontic springs. Such a construction of the appliance allows to differentially expand and constrict the dentition on one of the sides of jaws. If sagittal-transversal movements of the maxillary incisors are required , the wireframe for upper incisors is fixed on the palatal support through springs, see (Fig2).