Evaluation of Circadian Variation in Growth Factors of Platelet-Rich Fibrin: A Pilot Study

Platelet-rich fibrin (PRF) has extensive clinical applications in dentistry, particularly in the regeneration of soft and hard tissues, extraction socket healing, treatment of periodontal defects, sinus augmentation, and mucogingival procedures. PRF is a platelet-derived, growth factor-rich biomaterial prepared via a single-step centrifugation protocol. This study aimed to evaluate whether PRF-derived growth factors exhibit circadian variation between morning and evening hours. Twenty healthy volunteers participated, each providing six venous blood samples, three at 08:00 and three at 20:00. From each time point, one tube was used for complete blood count, one for serum cortisol analysis, and one for PRF preparation (centrifuged at 708 x gfor 12 min). Growth factors (IGF-1, PDGF, FGFR, VEGF, TGFβ-1) in PRF were measured at 24 h and 72 h using ELISA. Their levels were compared between time points and correlated with serum cortisol levels. FGFR levels were significantly higher at 72 h than at 24 h in evening samples. However, no significant differences were found for IGF-1, PDGF, VEGF, or TGFβ-1 between morning and evening. Cortisol levels were negatively correlated with PDGF at 72 h in morning samples and with IGF-1 at 72 h in evening samples; however, no other significant correlations were observed. These findings suggest that the timing of blood collection does not significantly influence PRF growth factor content, indicating flexibility in clinical protocols regarding sample timing.