Laser Doppler evaluation of gingival and pulpal microcirculation after impacted mandibular third molar surgery: A retrospective comparison of L-PRF and T-PRF

Objective: The aim of this study was to compare the effects of leukocyte- and platelet-rich fibrin (L-PRF) and titanium-prepared platelet-rich fibrin (T-PRF), placed into extraction sockets after impacted mandibular third molar surgery, on the gingival and pulpal microcirculation of the adjacent mandibular second molar. Methods: This retrospective comparative clinical study included 60 patients aged 20–30 years with fully impacted mesioangular mandibular third molars. Patients were divided into two groups according to the platelet concentrate used during surgery: L-PRF (n=30) and T-PRF (n=30). Gingival blood flow in the mucoperiosteal flap and pulpal blood flow in the adjacent mandibular second molar were measured with laser Doppler flowmetry, a well-established noninvasive method. Measurements were performed preoperatively and on postoperative day 7. Perfusion values were recorded as perfusion units (PU) and analyzed using non-parametric statistical methods with Bonferroni correction applied for multiple comparisons. Results: Both the L-PRF and T-PRF groups demonstrated significant increases in pulpal and gingival perfusion values on postoperative day 7 compared with baseline measurements (all Bonferroni-adjusted p<0.001). In the T-PRF group, pulpal perfusion increased by 8.10 PU and gingival perfusion increased by 11.09 PU, whereas the corresponding increases in the L-PRF group were 6.52 PU and 6.81 PU, respectively. Direct intergroup comparison of change scores (postoperative − preoperative) revealed that the increase in both pulpal blood flow (U=759.0; Z=4.568; p<0.001; r=0.590) and gingival blood flow (U=814.0; Z=5.382; p<0.001; r=0.695) was significantly greater in the T-PRF group. Intergroup comparisons further demonstrated higher postoperative perfusion values in the T-PRF group. The largest between-group difference was observed for gingival perfusion (U=900.0; Z=6.653; p<0.001; r=0.859), representing a very large effect size. A moderate effect size was observed for postoperative pulpal perfusion(r=0.332). Conclusion: Both platelet-rich fibrin protocols were associated with increased gingival and pulpal perfusion during the early postoperative healing period. T-PRF was associated with higher postoperative perfusion measurements, particularly in gingival tissues; this finding may indicate a more pronounced early microcirculatory response. However, because clinical healing outcomes were not directly evaluated and no untreated control group was included, the clinical significance of the observed perfusion differences remains uncertain and should be confirmed by prospective randomized controlled studies.