The periodontal ligament is a unique specialised connective tissue between the cementum covering the tooth root and the alveolar bone. It is believed that periodontal ligament cells are responsible for not only osteogenesis and osteoclasia of the alveolar bone but also for fibrogenesis and fibroplasia of the ligament itself, as well as cementogenesis and the presence of cementoblasts on the root surface. Injury to the periodontal ligament (PDL) and its compromised healing (external inflammatory resorption and replacement resorption) has been cited as one of the major reasons for the failure of transplantation and replantation procedures. The necessity of having a healthy PDL so that the tooth can re-attach and be retained in the socket determines the prognosis of replanted teeth. Thus, the importance of maintaining the periodontal viability has led to an increased interest in the development of platelet concentrates, which have been considered as autologous biomaterials having the ability to potentiate healing, repair, and regenerate. PRF (platelet rich fibrin) is a living biomaterial derived from human blood containing fibrin, platelets, growth factors, leukocytes and stem cells entrapped in a fibrin-based scaffold / matrix, which has been documented to promote bone and soft tissue healing and regeneration. PRF technology has grabbed the attention of clinicians because it is readily available, is easy to prepare, can be produced immediately at the chairside, is easy to use, and widely applicable in dentistry, while being financially realistic for the patient and the clinician. Thus, the purpose of this review is to enumerate the biologic, chemical and physical properties of PRF and highlight the essential role it plays in periodontal regeneration and repair, which can be highly beneficial in improving the treatment success rate of transplantation and replantation procedures. KEY WORDS Platelet Rich Fibrin, Replantation, Transplantation, Periodontal Ligament, Periodontal Regeneration

Biocompatibility of dental materials has always been a highly scrutinized theoretical domain that is often not given due attention in the clinical practice. Often, the lack of awareness on the part of the orthodontist of biocompatible material substitutes leads to a lack of treatment in this small but significant subset of the patient population that encounters such mishappenings. This review aimed to provide contemporary orthodontist with methods and substitutes that can be implemented in the clinical scenario and improve the biocompatibility quotient as well as the treatment outcomes. These methods will lead the way to better patient compliance in case of hypersensitivity-prone cases and a more customized approach to attain the end treatment goal while maintaining the biological integrity of the patient.