## 1 Introduction  
Platelet-rich fibrin and similar biological products are obtained from the plasma portion of one's own blood, exhibiting a platelet concentration higher than that found in the initial blood sample [1]. Platelet-rich fibrin is distinguished from other platelet concentrates, such as platelet-rich plasma and platelet-rich growth factors, by its distinct preparation process and clinical applicability [2]. Platelet-rich fibrin does not require the addition of anticoagulants or thrombin during its preparation when compared with platelet-rich plasma and platelet-rich growth factors [3]. Platelet-rich fibrin has become increasingly popular in recent years due to its remarkable capacity to accelerate the post-surgery wound healing process, reduce inflammation, and promote tissue repair [4, 5]. Platelet-rich fibrin finds extensive applications in dentistry, with dental implantology, oral and maxillofacial surgery, endodontics, and cosmetic dentistry witnessing a surge in its popularity [6]. The use of platelet-rich fibrin, with or without biomaterials, demonstrated superior efficacy compared to open flap debridement [7]. There was a notable enhancement in clinical indications when platelet-rich fibrin was combined with demineralized bone matrix, as opposed to using platelet-rich fibrin alone [7; 8]. Additionally, the group receiving both platelet-rich fibrin and demineralized bone matrix displayed a greater degree of bone fill on radiographs [9]. Platelet-rich fibrin offers the benefit of maintaining a continuous release of growth factors and facilitating cell migration by stimulating the expression of type I collagen and transforming growth factor mRNA [10]. The secretomes of platelet-rich fibrin represent an innovative growth factor-based approach for promoting bone and periodontal regeneration, and differentially expressed proteins have been identified from the platelet-rich fibrin, including key growth factors, cytokines, and components of the extracellular matrix that play crucial roles in the process of wound healing [11]. The proliferation of human gingival fibroblast cells exhibited a direct correlation with the concentration of platelet-rich fibrin, demonstrating a dose-dependent effect [12].  
Hence, the impact of platelet-rich fibrin on periodontal regeneration has remained a topic of continuous discussion. The rationale behind the functioning of platelet-rich fibrin can be elucidated as follows: The reasoning behind the use of platelet-rich fibrin lies in its role as a biomaterial, facilitating the delivery of essential growth factors and cytokines sourced from platelet granules to the specific area of focus, and this process, in turn, fosters tissue regeneration across a range of tissues, including bone regeneration [13]. In addition to utilizing platelet-rich fibrin and graft materials in managing periodontal intrabony defects, a range of other treatment methods, such as targeted delivery of antibiotics, the application of laser therapy, and the use of various medications, can be employed for the treatment of periodontal disease [14; 15]. As a result of its additional benefits, platelet-rich fibrin appears to be a naturally appropriate complement in bone regenerative surgery, leading to positive results with minimal associated risks [16]. Therefore, this study aims to perform a meta-analysis to evaluate the effect of platelet-rich fibrin in mixture form with bone substitute, as a membrane, or in combination. The null hypothesis posited that there would be no noteworthy distinction in the effect of platelet-rich fibrin on periodontal regeneration. The primary goal of this research is to assess the extent of periodontal regeneration that can be attained with platelet-rich fibrin by examining improvements in reductions in periodontal probing, clinical attachment levels, and the attainment of bone fill. Additionally, the secondary objective is to carry out a subgroup analysis that categorizes the findings based on the type of graft material used.