Case Report Complete Maxillary Crossbite Correction with a Rapid Palatal Expansion in Mixed Dentition Followed by a Corrective Orthodontic Treatment Orlando Motohiro Tanaka, 1,2 Isabelle Adad Fornazari, 3 Ariane Ximenes Graciano Parra, 4 Bruno Borges de Castilhos, 4 and Ademir Franco 5,6 1 Graduate Dentistry Program in Orthodontics, Pontif´ ıcia Universidade Cat´ olica do Paran´ a, Rua Imaculada Conceic ¸˜ ao 1155, 80215-901 Curitiba, PR, Brazil 2 Postdoctoral Fellowship at Te Center for Advanced Dental Education, Saint Louis University, St. Louis, MO, USA 3 Dentistry, Pontif´ ıcia Universidade Cat´ olica do Paran´ a, Curitiba, PR, Brazil 4 Orthodontics, Pontif´ ıcia Universidade Cat´ olica do Paran´ a, Curitiba, PR, Brazil 5 Department of Oral Health Sciences, Forensic Dentistry, KU Leuven and Dentistry, University Hospitals Leuven, Leuven, Belgium 6 Stomatology, Pontif´ ıcia Universidade Cat´ olica do Paran´ a, Curitiba, PR, Brazil Correspondence should be addressed to Orlando Motohiro Tanaka; tanakaom@gmail.com Received 6 February 2016; Revised 24 March 2016; Accepted 29 March 2016 Academic Editor: H¨ usamettin Oktay Copyright © 2016 Orlando Motohiro Tanaka et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tis case report presents the interceptive orthodontic treatment of a boy, aged 8 years 4 months with a Class I malocclusion with severe transverse maxillary defciency and complete maxillary crossbite and correction using Haas expansion and fxed appliance. Te treatment goals were to correct the posterior crossbite and anterior crossbite and restore the normality of the dentition and occlusion. In phase I, the patient was treated with a modifed Haas-type palatal expander, which provided a clinically signifcant palatal expansion and increased the maxillary arch perimeter with favorable conditions for orthodontic treatment with fxed appliances in phase II. Te optimization of E-space and the use of intermaxillary Class III elastics helped to maintain the mandibular incisors upright. A removable wraparound type appliance and a bonded lingual canine-to-canine retainer were used as retention. Although the literature has reported a high rate of relapse afer palatal expansion, afer 2 years 9 months of posttreatment follow-up, the occlusal result was stable and no skeletal reversals could be detected. 1. Introduction Te posterior crossbite is one of the most frequent malocclu- sions in orthodontics [1], and its possible etiologies include prolonged retention or loss at an early age of deciduous teeth, crowding, clef palate, genetic factors, tooth-size arch-length discrepancies, abnormalities in tooth morphology, eruption sequence, thumb sucking habits, and mouth breathing during critical growth periods [2]. Te rapid palatal expansion (RPE) is ofen used to expand the maxilla in patients with mixed dentition posi- tively impacting the treatment of related defciencies [3, 4]. Specifcally, this technique may be used to correct transverse and sagittal crossbite, generating space in the dental arch and, consequently, solving cases of borderline crowding [5]. Te RPE is extremely useful for the treatment of Class III patients and cases of real and relative maxillary defciencies [6]. Occlusal acrylic splints are considered the most efective devices for RPE in young patients because they produce therapeutic efects that are not only limited to the correction of crossbite or the increase in arch width [5, 7]. Posterior crossbite and anterior crossbite do not have a spontaneous correction and should be treated with maxillary expansion as early as possible, afer an accurate diagnosis with the patient in centric relation [8] and treatment planning Hindawi Publishing Corporation Case Reports in Dentistry Volume 2016, Article ID 8306397, 6 pages http://dx.doi.org/10.1155/2016/8306397