Platelet-rich plasma has antimicrobial activity against dental plaque in vitro

Objectives: Platelet-rich plasma (PRP) contains concentrated platelets and has been used successfully in periodontal regeneration. As platelets play a key role in antimicrobial host defense, we hypothesized that PRP might have antimicrobial activity against dental plaque. This study was designed to assess the levels of two predominant platelet antimicrobial peptides in PRP and the antimicrobial activity of PRP against supragingival plaque in vitro. Methods: PRP was obtained from 20 healthy donors. The levels of platelet factor 4 (PF-4) and connective tissue activating peptide 3 (CTAP-3) in PRP, serum and plasma were measured by a sandwich enzyme-linked immunosorbent assay. Ten supragingival plaque samples were obtained from 10 periodontitis patients. Each sample was divided into 8 aliquots and treated with physiologic saline solution (negative control), chlorhexidine (positive control), PRP and serum from 3 donors, respectively. The vitality of plaque (vital flora %) was evaluated by a vital fluorescence technique. Results: Mean PF-4 and CTAP-3 levels in PRP were 30.07±9.76IU/ml and 402.47±140.72ng/ml, respectively, significantly greater than those in serum or plasma (P<0.001). Plaque treated with saline solution showed a mean vitality of 62.15±1.73%. The plaque vitality in 3 PRP-treated groups showed significantly reduced compared with negative control group: 22.05±2.07%, 25.05±1.38%, and 27.40±2.03%, respectively (P<0.001). They were also lower than that of corresponding serum-treated groups (P<0.001). The reduction of plaque vitality treated by PRP or serum showed strong positive correlations with PF-4 and CTAP-3 levels in them. Spearman rank correlation coefficient (rs) was 0.926 for CTAP-3 (P<0.01) and 0.703 for PF-4 (P<0.01). Conclusions: It is indicated that PRP exerted antimicrobial activity against supragingival plaque in vitro, and the antimicrobial activity of PRP had significantly strong positive correlations with PF-4 and CTAP-3 levels in it. This might be another explanation for the positive impact of PRP on periodontal regeneration.