Introduction: One-step apexification using mineral trioxide aggregate (MTA) has been reported as an alternative treatment modality with more benefits than the use of long-term calcium hydroxide (CaOH) for teeth with an open apex. However, the orthograde placement of MTA is a challenging procedure in terms of length control, especially in teeth with a wide-open apex. Therefore, we took advantage of the desirable properties of Ca(OH)2 in the formation of apical barriers in order to control the length of MTA during placement. Case Presentation: We would like to report the successful treatment of tooth 8 (in a 10-year-old girl) with an open apex and periapical lesions. In this case, we first used calcium hydroxide to form the primary apical barrier for six months and then we placed an MTA plug. Conclusions: Based on evidence, both MTA and Ca(OH)2 can be used for the endodontic treatment of non-vital immature teeth. In this case, we took advantage of special properties of MTA and Ca(OH)2 in apexification.