Table 1.

Classification proposed by Dohan Ehrenfest et al. for platelet concentrates based on their cell content and fibrin architecture [249,250].

Category	Name	Description
I	Pure PRP (P-PRP)	Leukocyte-poor preparations with a low-density fibrin network upon activation.
II	Leukocyte and platelet-rich plasma (L-PRP)	Contains leukocytes and forms a low-density fibrin network upon activation.
III	Pure platelet-rich fibrin (P-PRF)	Leukocyte-poor preparations with a high-density fibrin network. Mixed with an activator and requiring a specific separator gel.
IV	Leukocyte and PRF (L-PRF)	Contains leukocytes and has a high-density fibrin network. Blood is centrifuged immediately after collection without the use of anticoagulants, thrombin, or CaCl2.