FROM BENCH TO CHAIRSIDE: EVALUATION OF BIOLOGICAL EFFECTS OF PLATELET CONCENTRATES THROUGH AN IN-VITRO STUDY AND A RANDOMIZED CLINICAL TRIAL

Autologous platelet concentrates are widely used in a variety of medical application with the aim of enhancing the regeneration of hard and soft tissue. The rationale of this clinical use lies in their enriched content of growth factors and other key molecules involved in promoting tissue healing. This thesis is composed of two different studies having as a common objective the evaluation of the biological properties of a platelet concentrate, Pure-Platelet Rich Plasma. The first part of the thesis was a pre-clinical in vitro study focused on evaluating the stimulating activity of P-PRP on human osteoblasts (hObs) and human dermal fibroblasts (hDFs). hObs and hDFs were grown in a serum-free medium supplemented by P-PRP obtained from three different donors. hObs and hDFs proliferation was assessed by cell counting and vitality through MTT assays up to 12 days of incubation. hObs osteo-differentiation was tested after 7- and 14- days of incubation by alkaline phosphatase assay. Results showed that cells maintained in the presence of P-PRP display an increased proliferation rate at 12 days of culture, compared to the standard condition. The increased vitality of hObs, induced by P-PRP, noticed after 12 days of culture, was comparable of that of control. In contrast, an increased vitality of hDFs, in comparison to the control, was observed at 12 days of culture. The addition of P-PRP did not further stimulate the enzyme activity either at day 7 and 14. The second part of the thesis was a randomized clinical trial that focused on clinical and radiographic evaluation of the adjunct of P-PRP in the management of edentulous posterior maxillae with a reduced height needing an implant rehabilitation. Clinical and radiographic outcomes of two different approaches were compared up to 3 years after loading: fixed prosthesis supported by 5 to 8.5 mm-long implants which were humidified with P-PRP versus fixed prosthesis supported by 10-mm or longer implants bioactivated with P-PRP and placed following maxillary sinus augmentation with deproteinized bovine bone mixed with P-PRP. Results showed that both procedures were safe and successful, with comparable outcomes. The use of P-PRP did not shift the balance toward one technique over the other one, but it may have contributed to make these procedures similar in term of clinical and radiographic outcomes. Since similar outcomes were reported for both approaches, the most cost-effective treatment appears the appropriate and should be advocated. Therefore, when there is an alternative for restoring the lost dentition, avoidance of a demanding surgical procedure like maxillary sinus augmentation should be considered and recommended. In conclusion, results coming from the in vitro study and the randomized clinical trial may support the clinical use of P-PRP. It may be beneficial in those situations requiring a successful bone and soft tissue regeneration at the site of surgery.