Evolução da terapia com Fibrina Rica em Plaquetas (PRF) na prática odontológica: tubos plásticos sem aditivos como alternativa na produção de PRF, biofuncionalização de hidroxiapatita sintética com Protocolo Progressivo PRO-PRF e uma série de casos

Abstract

Platelet-Rich Fibrin (PRF) has emerged as a promising autologous biomaterial in tissue engineering and the biofunctionalization of synthetic materials, particularly in regenerative bone procedures. This thesis aimed to investigate key aspects related to the preparation, characterization, and clinical application of PRF, with emphasis on the use of plastic tubes without additives and the biofunctionalization of synthetic hydroxyapatite (HA) using the third-generation Progressive PRF (PRO-PRF) protocol. In Chapter 1, the density of the fibrin network, platelet aggregates, and cellular morphology of three PRF protocols obtained in glass or plastic tubes, with or without silica coating, were evaluated. Eight volunteers (n = 8) participated in the study, from whom nine blood samples were collected per individual. The samples were divided into three groups according to tube material and centrifuged using the following protocols: Leukocyte- and Platelet-Rich Fibrin (L-PRF – 700 g/12 min), Advanced Platelet-Rich Fibrin (A-PRF – 200 g/14 min), and Advanced Platelet-Rich Fibrin Plus (A-PRF+ – 200 g/8 min). The membranes were analyzed by light microscopy (LM) to assess fibrin and platelet density and by transmission electron microscopy (TEM) for qualitative evaluation of cellular morphology. Membranes obtained from plastic tubes without additives exhibited significantly lower fibrin network density in the L-PRF (p < 0.019) and A-PRF (p < 0.001) protocols. A significantly higher percentage of platelets was observed in membranes produced in plastic tubes without additives, regardless of the protocol used (p < 0.005). Ultrastructural morphology and cellular integrity were preserved in all groups. In Chapter 2, the distribution pattern of HA biofunctionalized with three protocols was investigated: L-PRF, GM350, and PRO-PRF. The study included eight participants (n = 8), with approximately 48 mL of blood collected in six plastic tubes without additives at three different time points. The tubes were divided into three groups according to the centrifugation protocol: L-PRF, GM350 (350 g/15 min), and PRO-PRF (60 g/5 min, 200 g/5 min, and 700 g/5 min). The fluid material was aspirated and transferred to glass containers (5 mL) containing 0.25 g of HA. After polymerization, the clots were compressed to form blocks. Density analysis by micro-computed tomography revealed no significant differences among L-PRF (37.95 ± 0.40), GM350 (39.13 ± 2.29), and PRO-PRF (34.62 ± 4.05; p = 0.132). The PRF/HA ratio, assessed by LM, was significantly lower in PRO-PRF compared with L-PRF (55.14 ± 1.65; p = 0.033) and GM350 (57.10 ± 4.66; p = 0.014). Scanning electron microscopy (SEM) revealed a dense three-dimensional fibrin network integrated with HA. Chapter 3 described a series of four clinical cases involving the application of HA biofunctionalized with PRO-PRF in maxillary sinus floor elevation procedures. Preliminary clinical and tomographic outcomes demonstrated significant vertical bone gain after 120 days (mean: 8.07 mm), and no postoperative complications observed, suggesting that HA biofunctionalization with PRO-PRF represents a safe and promising strategy to enhance tissue repair.