# Platelet-Rich Fibrin: A Viable Therapy for Endodontic-Periodantal Lesions? A Preliminary Assessment
## 4 Discussion  
Dental practitioners may face many challenges when it comes to the diagnosis of endodontic-periodontal lesions. On this account, taking a proper patient history, doing a thoroughly clinical examination, that includes inspection for cavities, palpation, percussion, the vitality test and the probing depth measurement and having a periapical radiography of the suspected tooth are of utmost importance in order to diagnose correctly the lesion [8]. Bacteria, dental trauma, teeth preparation under no irrigation, incorrect dental restorations, irritative materials, and malocclusion may lead to the inflammation of the pulp [31]. Untreated it can lead to pulp necrosis and to the inflammatory response of the periodontal ligament at the apical foramen or opening of accessory canals [1,31]. Through the apical foramen, dental tubules, lateral and accessory canals that communicate to the periodononium, inflammatory byproducts of pulpal origin may reach to the periodontal tissue and provoke an inflammatory response [1]. As for periodontal disease leading to the infection of the endodontic system, it occurs indirectly, when gingival recession is present [1]. If exposed cement does not protect the accessory canals, they become a way for pathogens from the oral cavity to penetrate the pulp, resulting in chronic pulpits and necrosis [1]. Usually, when pulp or periodontitis is affected and the second infection of the other one has just begun, the primary disease is the first to be treated [1,4,5]. In the case that the secondary infections is established and chronic, both endodontic and periodontal treatment is mandatory [7]. Routinely, the root canal treatment is performed first, then the periodontal therapy. [5,7]. The periodononium is likely to heal completely after a successful root canal treatment [7]. An unfavorable outcome was noticed in a study where endodontic-periodontal lesions were treated without using an accompanying regenerative procedure, with a score of success ranging from 27% to 37% [32]. In addition to the endodontic and periodontal treatment, regenerative procedures are also needed for the regeneration of the damaged tissue [8]. Platelet-rich fibrin is an innovative material that can be used in regenerative therapy to stimulate healing in bone and soft tissue [9,10]. It is a fibrin matrix which contains platelets, leukocytes, cytokines, circulating stem cells [11], and macrophages [12]. The most important growth factors found in PRF [12, 13, 14] are: platelet derived growth factors (PDGFs), transforming growth factor-1 (TGF-81), Insulin-like growth factors (IGFs), vascular endothelial growth factor (VEGF). As the resorption of the fibrin matrix goes, growth factors are released progressively over a period of time, leading to favorable healing course [33]. The beneficial impact of PRF on bone healing can be explained by its components action. Macrophages stimulate the osteogenesis and support the bone formation process [34, 35, 36, 37]. After the activation of platelets and leukocytes, cytokines are released which stimulate bone healing [13]. TGF-81 stimulates the synthesis of collagen, one of the components of the bone and fibronectin, which is responsible for the adhesion and migration of the cells and also promotes the osteogenic differentiation [38,39]. VEGF has an angiogenic effect [40]. PDGFs and IGF-I have a proliferative and differentiating effect on the osteoblasts [41,42]. There are a series of patients related factors that may affect PRF's characteristics: age, systemic diseases (diabetes, thrombocytopenia), diet, environmental changes, ethnic differences, the immune system and the genetics [43]. In one study conducted by [PERSON] and coworkers [44], it was concluded that the fibrous proteins found in PRF modified with age, with a reduction in the number of platelets and leukocytes. In the studies included, all the patients were reported as systemically healthy, and this factor might not interfere with the results.