Mara Simões Pedro*1; Nuno Bernardo Malta dos Santos1; Pedro Maria B. P. Senos Tróia1; António Completo2; Gustavo Vicentis de Oliveira Fernandes1

1Universidade Católica Portuguesa Viseu - Faculdade de Medicina Dentaria, Viseu; 2TEMA, Universidade de Aveiro - Mechanical Technology and Automation, Aveiro, Portugal

Background: PRF is a 2nd generation of platelet concentrates that has suffered modifications in the original high centrifugation protocol (L-PRF),giving rise to new derivates: A-PRF by reducing centrifugation speed and recently A-PRF+ by time reduction. This autologous 3D scaffold is applicable in various medical and dental procedures owing to their rapid angiogenic stimulation and vast potential for bone and tissue regeneration. Resistance is a key factor in membranes behavior to direct cell differentiation.

Aim/Hypothesis: Compare the tensile strength and structural organization of the membranes produced by PRF derivatives (L-PRF, A-PRF, and A-PRF +),in order to suggest the membrane with better mechanical properties to be sutured, proper handled, and biologically spaced to enhance growth factors release.

Material and Methods: Peripheral blood was drawn from an healthy donor, with no history of anticoagulants or immunosuppressors use. Trials were conducted over 4 days, spaced one week apart from D1 to D2 and one month later D3 and D4. It was collected 8 tubes (9mL silica coated tubes, BD Vacutainer®, UK) and immediately centrifuged for each standardized protocols: L-PRF 2700RPM,12min; A-PRF 1500RPM, 14min, and A-PRF+ 1500RPM, 8min (Intra-Spin, IntraLock®, FL, USA). Traction test was performed in all specimens with the Shimadzu MMT-101N equipment after being cut in a glass-mold (10x15 mm). For scanning electron microscopy (SEM) analysis, samples of equal length (5x5 mm) were fixed with 2.5% neutralized glutaraldehyde (2h, 4˚C), 0.2 M sodium cacodylate buffer solution and 1% osmium tetroxide (2h, 4˚C), dehydrated in ethanol series (70 to 100%) and hexamethyldisilane. The materials were metallized with silver and observed at a voltage acceleration of 15kV using Hitachi SEM S4100.

Results: For maximum traction were obtained 0.0020 for A-PRF, 0.0022 for A-PRF+ and 0.0010 for L-PRF. Regarding the average traction, A-PRF scored 0.0012, 0.0007 L-PRF while A-PRF+ obtained 0.0015 (P = 0.01). Surface morphology observations with SEM, showed some similarities between A-PRF and A-PRF+ composed of thin and elongated fibers, porosity is also present with large interfibrillar spaces in A-PRF but appears to be more evident the amount of porous in A-PRF+ with a high density of fibers cross-linking, more auspicious to undergo slow lysis by the fibrinolitic system. At lower magnification can be seen the A-PRF+ matrix irregularity with exophytic portions and preserved cells adhered to the surface. Noticeable differences are shown in high centrifugation protocol (L-PRF), formed of thick fibers demonstrating polymerization maturity but very limited interfibrous space for microvascularization and presenting visible severe destruction of red blood cells and leukocytes.

Conclusion and Clinical implications: This study allowed us to conclude that A-PRF+ is able to produce membranes with superior viscoelastic resistance and a more favorable architecture to cell encapsulation and increased growth factors release or other adhered particles with pharmacokinetic potential. As mechanical deformation occurs in layers, these findings also suggest gradual degradation. It is, therefore, a promising option in treatment of complex and delicate defects.

Disclosure of Interest: None Declared.

Keywords: biomaterial, biomechanical stability, osseointegration