# Influencing Factors in Autotransplantation of Teeth with Open Apex: A Review of the Literature
## 4 Review
Altogether, it is essential that the periodontal ligament covering the tooth is not damaged to avoid ankylosis and root resorption, and induce the formation of bone for the healing of the area [36], as well as the Hertwig sheath, in order to continue the development of the root of the transplanted tooth [36]. The factors that need to be considered in order to categorize the receptor alveolus as optimal are the following:* **Location:** Regarding the maxillary or mandibular location of the receptor alveolus, better results are described in the maxilla [28], although little significant differences are mentioned [25]. Nevertheless, authors describe how autotransplants in the anterior maxilla require greater aesthetic results [28]. * **Volume of alveolar bone and quality:** It is stated that if the bone is deficient both in quantity or quality, it has a negative influence on the success of the transplant, since the surgery is hindered and the aesthetic result may be compromised. For this reason, an adequate thickness of the buccal and lingual cortical bone of the area where the tooth will be transplanted is required [17]. In fact, [PERSON] et al. [35] reported that one of the primary factors for the transplant's success is that the walls of the recipient socket must have acceptable dimensions to guarantee the stability of the donor tooth. Additionally, if the extracted tooth presents ankylosis or infection in the recipient socket, it could influence the new tooth's adaptation to the socket. [17]. Early tooth loss during the patient's growth period and the absence of replacement by dental autotransplantation has a negative influence on the quality of the residual bone, which will be needed for the placement of an implant after the growth period has ended [17]. This results in the need for previous bone graft procedures [17; 26]. * **Tissue damage during the procedure:** Some authors stated that the affected tooth must be extracted carefully, trying to contact the ligament as little as possible to avoid ankylosis and other complications [5; 27; 35]. [PERSON] et al. [27] also highlighted the importance of minimizing the iatrogenic damage caused by the excessive attempts to fit the replica in the alveolus. The following factors influence the technique:
* **Use of a 3D replica [30]:** that has been manufactured from a previous CBCT [27] and that facilitates the dental autotransplantation process [16; 27; 28; 37; 38], reducing the manipulation and extra-alveolar time of the transplanted tooth [26; 39]. By using the replica of the donor's tooth, the extra-alveolar time is minimized to less than 1 minute [27], even seconds [40]. At the same time, as an alternative to this individualized replica of the patient's tooth, a pre-designed surgical template or guide of the type of donor tooth in question could be used, which can be sterilized and reused, but this entails a size discrepancy between the template and the donor tooth [27; 38]. [PERSON] et al. [30] made use of this surgical guide to favor the position of the donor tooth and confirmed that as a result of the use of the replica, the time of the surgery itself was reduced, going from 40 to 90 min in surgeries without replication and up to 30 to 45 min in surgeries where this replica was used. Furthermore, [PERSON] pointed out that everything manipulated using this replica is not performed on the donor's tooth, so it helps to keep its periodontal ligament intact, avoiding future root resorption, pulp necrosis or other possible complications [30]. * **Stabilization of the donor tooth and its duration [17]:** It is important to stabilize the donor tooth to prevent mobility, since a lack of retention increases trauma and instability while healing occurs [41]. There is controversy about the material to be used and the time to splint the donor tooth. Sutures cause less risk of ankylosis compared with wire, while the probability of failure will be higher [27; 29]. [PERSON] et al., [PERSON] et al. and [PERSON] et al.