Platelet-rich plasma (PRP) was originally demonstrated to be effective in the operation of alveolar ridge augmentation and immediately spread to the fields of periodontal and oral maxillofacial surgery [1]. This clinical application was endorsed by evidence that several major growth factors are contained at high levels in PRP preparations. However, for some reasons, such as low handling efficiency, addition of animal-derived thrombin for clotting, and fundamental individual differences, it has been indicated that it is difficult to reproducibly control the quality of PRP preparations at similar levels [1]. To overcome these drawbacks, Anitua developed plasma rich in growth factors (PRGF) by modifying the procedure of PRP preparation [2]. It simplified the preparation protocol and replaced animal-derived thrombin with calcium for clotting.

Platelet-rich fibrin (PRF), a self-clotted preparation of PRP derivative, also overcame these matters. Blood samples collected in the absence of anticoagulants are immediately centrifuged to form fibrin clots. This simple preparation procedure has been widely accepted in various medical fields and spread worldwide. Choukroun, a developer of PRF, further modified it to an advanced form (A-PRF), which is expected to contain a relatively greater number of white blood cells (WBC) [3]. Because of low-speed centrifugation, this fibrin clot is softer than that of the original PRF. On the other hand, concentrated growth factors (CGF), another modified form of PRF, are prepared by repeatedly switching the centrifugation speed and are characterized as a relatively stiffer fibrin clot [4]. Therefore, it has been anticipated that the difference in mechanical characteristics may produce a difference in the growth factor content.

The aim of this study was to address the question as to whether growth factors are equally or more concentrated in A-PRF or CGF preparations and whether these preparations function like a reservoir of major platelet-derived growth factors as do PRP and PRGF preparations to facilitate wound healing and tissue regeneration. Thus, we evaluated the levels of the selected major growth factors and pro-inflammatory cytokines in A-PRF and CGF extracts and compared the data with those of PRP and PRGF preparations. To reduce the individual-dependent differences in the growth factor levels, we collected sufficient volumes of peripheral blood samples from the same donors both in the presence or absence of anticoagulants and immediately prepared four types of platelet concentrates.