Purpose The aim of this study was to evaluate the clinical outcome of autotransplantation of a mature third molar to a fresh molar extraction socket using three-dimensional (3D) replicas and a preoperative simulation, which includeduse of preoperative cone-beam computed tomographicy(CBCT) planning and 3D replicas of donor teeth to prepare the artificial tooth sockets. Methods Three patients underwent autotransplantation using 3D replicas and preoperative simulation. Before the procedure, the direction and depth of the donor tooth were confirmed with a computer using replica data, then a simulation was performed using the replica and the research model as pseudo-autotransplantation surgery. The replica was manufactured using a 3D printing technique. The surgical procedure was based on guided autotransplantation surgery methods associated with Andreasen’s technique. Results Based on Chamberlin's criteria for successful transplantation, all three patients had good results. The average extraoral time of the donor tooth was shortened to an average 3.33 minutes when using a 3D replica. Additionally, we previously presented a report of a case without 3D replica autotransplantation with a time of 16 minutes. Conclusions The present approach enables planning and production of a 3D printed surgical template with use of the latest diagnostic methods and guided autotransplantation surgery techniques. Autotransplantation using a 3D replicas with preoperative simulation is an effective method that can reduce extraoral time as well as periodontal ligament damage to the donor tooth, and can reduce the rate of failure.

Auto transplantation is a fast and economical option when a suitable donor tooth is available for replacement of a tooth considered impossible to treat. The purpose of this case report is to describe methods used for autotransplantation and its advantages for cases with a missing bilateral mandibular firstmolar, as compared with a dental implant, removable partial denture, and other methods of prosthesis. In the present patient who underwent auto transplantation, clinical and radiographic outcomes were considered satisfactory at one and two years postoperatively. Bone healing was observed around the roots of transplanted teeth, which showed good function. In autotransplantation cases, even when the donor tooth has complete root formation, a high success rate can be achieved when the patient is properly selected and treated. Although the chance of root resorption remains because of necrotic pulp and periodontal irritation during manipulation, auto transplantation should be considered as a good treatment modality in feasible cases. Based on the present findings, even though autotransplantation is not common in general dental practice, we consider that it offers a clinically and economically viable alternative as compared to other more complicated prosthetic and dental implant treatments. The purpose of this report is to show that auto transplantation is a superior treatment method for single molar defects as compared to other prosthetic methods, as the periodontal ligament of the patient can be used and cutting adjacent teeth is avoided. In addition, it is a treatment method that can effectively utilize a wisdom tooth.