PURPOSE: The aim of this study was to compare root development after transplantation of teeth into surgically created sockets or into fresh extraction sites. PATIENTS AND METHODS: The sample consisted of 62 patients with a total of 64 transplanted immature third molars. All transplants were at root development stages 3 to 4. In 22 cases, a new socket was created by means of burs. Forty-two teeth transplanted into a fresh extraction site served as controls. Postoperative root development was determined on intraoral radiographs taken immediately after transplantation and at the final follow-up. For all transplants, extraoral storage time and number of trials were recorded during transplantation. RESULTS: No significant intergroup differences were observed at root development stage 3. In contrast, at root development stage 4 transplantations to surgically created sockets showed a significantly lower final root length (P =.025) and root length increment (P =.038) than transplants in the control group. In addition, a significant correlation was determined in the prepared socket group at developmental stage 4 between root length increment and extraoral storage time (r = -0.910, r(2) = 0.828, P <.001) or number of trials in the recipient socket (r = -0.775, r(2) = 0.601, P <.001). CONCLUSIONS: Teeth at advanced developmental stages transplanted to surgically created sockets show an impaired postoperative root development. A possible explanation might be damage of Hertwig's epithelial root sheath during the transplantation procedure.