Changes in skeletal and dental relationship in Class II Division I malocclusion after rapid maxillary expansion: a prospective study

original article Changes in skeletal and dental relationship in Class II Division I malocclusion after rapid maxillary expansion: a prospective study Carolina Baratieri1, Matheus Alves Jr2, Ana Maria Bolognese3, Matilde C. G. Nojima4, Lincoln I. Nojima4 DOI: http://dx.doi.org/10.1590/2176-9451.19.3.075-081.oar Objective: To assess skeletal and dental changes immediately after rapid maxillary expansion (RME) in Class II Division 1 malocclusion patients and after a retention period, using cone beam computed tomography (CBCT) imaging. Methods: Seventeen children with Class II, Division 1 malocclusion and maxillary skeletal transverse deficiency underwent RME following the Haas protocol. CBCT were taken before treatment (T1), at the end of the active expansion phase (T2) and after a retention period of 6 months (T3). The scanned images were measured anteroposteriorly (SNA, SNB, ANB, overjet and MR) and vertically (N-ANS, ANS-Me, N-Me and overbite). Results: Significant differences were identified immediately after RME as the maxilla moved forward, the mandible moved downward, overjet increased and overbite decreased. During the retention period, the maxilla relapsed backwards and the mandible was displaced forward, leaving patients with an overall increase in anterior facial height. Conclusion: RME treatment allowed more anterior than inferior positioning of the mandible during the retention period, thus significantly improving Class II dental relationship in 75% of the patients evaluated. Keywords: Palatal expansion technique. Angle Class II malocclusion. Clinical trial. Orthodontics. Objetivo: avaliar, por meio de imagens de tomografia computadorizada de feixe cônico (TCFC), as mudanças esqueléticas e dentárias, imediatas e após 6 meses de contenção, causadas pela expansão rápida da maxila (ERM) em pacientes com má oclusão de Classe II, divisão 1. Métodos: dezessete crianças com má oclusão de Classe II, divisão 1, e deficiência transversal da maxila, foram submetidas a ERM, de acordo com o protocolo proposto por Haas. TCFC foram realizadas antes da ERM (T1), imediatamente após a fase ativa (T2) e após 6 meses de contenção (T3). Alterações anteroposteriores (SNA, SNB, ANB, overjet e RM) e verticais (N-ANS, ANS-Me, N-Me e overbite) foram analisadas. Resultados: imediatamente após a ERM, enquanto a maxila se deslocou para frente, a mandíbula se movimentou para frente e para baixo, aumentando o overjet e diminuindo o overbite. Durante o período de contenção, a maxila retornou para posterior e a mandíbula deslocou em direção anterior, aumentando a altura facial anterior. Conclusão: a realização da ERM permitiu que a mandíbula se posicionasse mais anteriormente do que inferior durante o período de contenção, melhorando a relação molar de Classe II em 75% dos pacientes avaliados. Palavras-chave: Expansão palatal. Má oclusão Classe II de Angle. Estudo clínico. How to cite this article: Baratieri C, Alves Jr M, Bolognese AM, Nojima MCG, Nojima LI. Changes in skeletal and dental relationship in Class II Division I malocclusion after rapid maxillary expansion: a prospective study. Dental Press J Orthod. 2014 May-June;19(3):75-81. DOI: http://dx.doi.org/10.1590/21769451.19.3.075-081.oar » Patients displayed in this article previously approved the use of their facial and intraoral photographs. Professor, Department of Orthodontics, Federal University of de Santa Catarina, UFSC. 2 PhD resident inOrthodontics, Federal University of Rio de Janeiro. 3 Full professor, Department of Orthodontics, Federal University of Rio de Janeiro. 4 Professor, Department of Orthodontics, Federal University of Rio de Janeiro, UFRJ. 1 © 2014 Dental Press Journal of Orthodontics Submitted: January 29, 2013 - Revised and accepted: April 05, 2013 » The authors report no commercial, proprietary or financial interest in the products or companies described in this article. Contact address: Lincoln Issamu Nojima Avenida Professor Rodolpho Paulo Rocco, 325 – Ilha do Fundão Rio de Janeiro/RJ — Brazil — CEP: 21941-617 – E-mail: 75 Dental Press J Orthod. 2014 May-June;19(3):75-81 original article Changes in skeletal and dental relationship in Class II Division I malocclusion after rapid maxillary expansion: a prospective study of Rio de Janeiro with the approval of the Institute of Collective Health Studies Research Ethics Committee (ref.128/2009-0052.0.239.000-09) and with an informed consent form signed by patients and parents. Seventeen white Brazilian subjects (8 boys and 9 girls with mean age of 10.67 and 10.05 years old, respectively) presenting Class II Division 1 malocclusion and maxillary transverse skeletal deficiency were selected and diagnosed to receive RME therapy. In addition, patients were followed for the following six months. In selecting the sample, the following inclusion criteria were applied: Chronological age ranging from 7 to 12 years old; overjet greater than 3 mm; Class II molar (unilateral or bilateral) and skeletal (ANB ≥ 4o) relationship; maxillary skeletal transverse deficiency (distance from J point to facial frontal line > 12 mm);9 skeletal maturation CS1 through CS3 as evaluated by the Cervical Vertebral Maturation method. All patients were submitted to RME following the Haas protocol.4 The appliances were standardized with stainless steel wire, 0.047-in in diameter (Rocky Mountain Orthodontics) and expansion screw of 11 mm (Dentaurum, Magnum – 600.303.30). Upon insertion, the expansion screw was activated four turns (0.2 mm per turn) on the first day, and on the following days it was activated two turns per day, (0.4 mm daily). The active phase varied from 2 to 3 weeks, depending on the individual maxillary transverse deficiency originally diagnosed. Afterwards, the expander screw was stabilized with a 0.012-in double thread ligature and was passively kept in place for the following six months after which the appliance was removed. introduction Angle1 defined Class II malocclusion as the distal relationship of the lower first molar in relation to the upper first molar. Studies have recently shown that in addition to the anteroposterior and vertical problems related to Class II malocclusions, posterior transverse discrepancy is also frequently associated with it.2 Diagnosis of posterior transverse discrepancy often passes unnoticed at clinical examination as this problem is camouflaged by the Class II skeletal pattern. The characteristics of Class II malocclusion, in all three spatial planes, pre-exist in deciduous dentition and persist into mixed dentition without correction.3 As soon as transverse maxillary deficiency is diagnosed, rapid maxillary expansion (RME) should be implemented regardless of other skeletal alterations because transverse maxillary growth ends earlier than growth in other directions.4 The majority of studies assessing RME outcomes showed that the mandible rotated downward and backward,5 which is usually an unwanted effect in Class II patient (...truncated)