Abstract: Objective: To assess skeletal and dental changes immediately after rapid maxillary expansion (RME) in Class II Division 1 malocclusion adolescent. Methods: Sixteen subjects with Class II Division 1 malocclusion and maxillary transverse deficiency underwent RME. CBCT images were collected pre-RME (T1) and post-RME (T2). Measurements were taken with Dolphin Imaging Software^® 11.8. Paried t test and One-Way ANOVA (P＜0.05) was used to compare differences between T1 and T2. Results: The midpalatal suture was opened successfully in all patients with a greater magnitude anteriorly in contrast to posteriorly. Significant transverse increase were identified in maxillary with a gradual increase from teeth to nasal base after RME. The maxilla moved forward and the mandible moved backwards, but there was no difference in vertical dimension. The width and angulation of upper and lower posterior teeth increased except for lower first premolar. Conclusion: The mid-palatal suture could be opened successfully with a greater magnitude anteriorly. There was transverse and anteroposterior changes in maxilla and mandible after RME.

Key words: Rapid maxillary expansion, Maxilla, Mandible, Teeth