Fig. 1.

Preparation of PRP. Active PRP is prepared immediately before use by a 2-step procedure. Step 1: two centrifugations, the first(A1) designed to eliminate red blood cells, the second (A2) to enrich plasma with platelets (minimum 1 × 10 6/μl to get clinical efficacy). Step 2: Plasma rich in platelets (B1) can be used immediately (C1) or activated with the addition of thrombin or calcium chloride (B2),resulting in fibrin polymerization and production of a gelatinousplatelet gel applied to the surgical site (C2) (Maffulli, 2016).