Advances in separation methods for the use of platelet-rich fibrin in tissue repair: an integrative review.

Plasma preparations originating from the centrifugation of blood samples, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), have proven useful for the treatment of gingival recession due to their rich concentration of cells and cytokines fundamental in the mechanisms of both soft tissue and hard tissue repair. Depending on the preparation method used to generate PRP and PRF, different concentrations of plasma elements and physicochemical characteristics can be obtained. This study sought to perform an integrative literature review to compile the available data on different protocols for generating plasma preparations and their indications, benefits, and results. A descriptive research method was adopted for assessing the literature on processes for obtaining PRF, and articles indexed in the MEDLINE database were searched. The literature review showed that changes in the PRF protocols for obtaining blood concentrates have led to better isolation of cells and growth factors and more promising results in tissue repair. The evolution in protocols has resulted in various forms of PRF with different components: (1) a membrane that aggregates platelets and leukocytes (L-PRF); (2) a PRF rich in growth factors and cytokines, known as advanced PRF (A-PRF); (3) a liquid phase called injectable PRF (I-PRF) that shows greater cell accumulation than L-PRF; (4) A-PRF plus (A-PDF+), which improved the release of growth factors for a period of 10 days; and (5) concentrated PRF (C-PRF) obtained by progressive pipetting, which has the greatest cell accumulation among all of the types of platelet aggregates. Subsequently, the observation that the speed of centrifugation influenced the acquisition of specific cells resulted in the development of the low-speed centrifugation concept. Then, it was determined that reduction of the relative centrifugation forces significantly increased the number of platelets, leukocytes, and growth factors. Recently, evaluation of the centrifugation angle revealed greater entrapment of large cells, such as red blood cells, when centrifugation was changed from a fixed to a horizontal angle. Tissue bioengineering studies are allowing for significant advances in the process of obtaining blood components and enabling their use for tissue repair with greater predictability and less morbidity.