## Results
### Biochemical Analysis  
Figure 4 shows the mean content of growth factors and cytokines measured on the surface of the surgical sites (control and L-PRF), on the first and seventh days after the procedure. From the 28 analytes initially assessed, twelve had detectable levels after extraction from the swabs. From those, all growth factors (VEGF, FGF-2, PDGFbb, TGF-\(\beta\)1) and the majority of the inflammatory cytokines (IL-1\(\beta\), IL-4, TNF-\(\alpha\), IL-1 RA, IL-10, and IFN-gamma) were present at significantly higher levels in the L-PRF sites, as compared to Clot at day 1 (\(p\) < 0.05). However, by the end of one week most of the analytes were present at similar levels at the L-PRF and Clot sites, with the exceptions of VEGF, which attained a  
Figure 2: (**A**) Pain evaluation by Visual Analog Scale (VAS) for 1, 2, 3, and 7 days in the postoperative period. (**B**) Comparison of the soft tissue healing, as measured by the Landry ’s index, at seven and 14 days of the postoperative period. Squares indicate the score for the clot site of each participant, while circles indicate the scores for the leukocyte-platelet-rich fibrin (L–PRF) sites. Lines indicate the mean \(\pm\) SD. Connecting lines indicate statistical difference (\(p\) value indicated on the figure). two-fold increase as compared to control, and the anti-inflammatory cytokines IL-10 and IL-1 RA, which were around 1.5 \(\times\) increased at the L-PRF sites (\(p<0.05\)). In order to observe if the content of growth factors and cytokines could correlate with hematological parameters (WBC and platelets) of each participant, an analysis was  
Figure 4: Heatmap of the cytokines extracted from swabs of the L–PRF and Clot sites at 1 and 7 days after surgery. The intensity of the blue color indicates the mean concentration (n = 20) of each analyte, as detected by flow luminometry. An asterisk indicates a significant difference between L–PRF and Clot at the same experimental time (\(p<0.05\)). Figure 3: (**A**) L–PRF placed at the dental socket; (**B**) Immediate postoperative area, after suturing; (**C**) Evaluation of soft tissue healing after seven days, socket showing good healing (Landry’s Index 3) (**D**) After 14 th day with excellent healing (Landry’s Index 5) of soft tissues. performed with blood samples collected before the production of L-PRF. The hematological analysis showed that the WBC (6.99 \(\pm\) 1.30) and platelets (262.7 \(\pm\) 14.90). The WBC count (\(\times\)103/microL) were within normal ranges in all participants. A Spearman's rank correlation test was performed between the WBC and platelet contents, and the values of analytes detected for each participant (Table 2). From all interactions, a significant positive correlation was detected between the blood platelet count of the participants and the surface concentration of VEGF (\(p\) = 0.04, rho = 0.769). TGF-\(\beta\)1 presented a coefficient comparable to a moderate correlation with platelet content, even with a non-significant borderline \(p\) value (\(p\) = 0.05, rho = 0.634). In order to identify relationships between the outcome measurements and the detected biological mediators, several multiple regression analyses were performed, as shown in Table 3 for the control group and Table 4 for the L-PRF sites. The multiple \(r^{2}\) from the tests varied from 0.596 to 0.741, and the residuals passed normality in all tests (\(p\) < 0.05). However, no significant association was identified between any pain or cicatrization index and the concentrations of growth factors and cytokines in both surgical sites (\(p\) > 0.05).