Effect of simultaneous application of low-level diode laser and leukocyte platelet-rich fibrin on gingival tissue healing: an in vitro investigation

The aim of the present in vitro study was to assess the simultaneous effect of low-level laser therapy (LLLT) and leucocyte platelet-rich fibrin (L-PRF) as adjunctive therapy on gingival tissue healing. Human gingival fibroblasts (HGFs) were cultured and subjected to different concentrations of L-PRF (100%, 50%, 25%, 12.5%, and 6.25%) and 915 nm diode laser with different energy densities (2, 3, and 4 J/cm 2 ). Cell viability, proliferation, and migration were assessed via MTT, flow cytometry, and scratch assay, respectively. The expression of connective tissue healing-related biomarkers (MMP1, ANG1, and COL1A1) was assessed via reverse transcription quantitative polymerase chain reaction (RT-qPCR). Each condition was performed in six biological replicates (n = 6). Simultaneous application of 3 J/cm 2 diode laser and L-PRF resulted in the highest cell viability and proliferation ( p < 0.01). The solitary application of L-PRF showed the highest cell migration ( p < 0.026). While the solitary application of L-PRF yielded the highest MMP1 expression, the simultaneous application of L-PRF and 3 J/cm 2 laser resulted in the highest expression of ANG1 and COL1A1 ( p < 0.01). The discrete application of 915 nm diode laser and L-PRF increased cell viability, proliferation, migration, and expression of gingival tissue healing-related biomarkers. However, within the limitations of this in-vitro study, the combined application of L-PRF with diode laser at 3 J/cm 2 resulted in the highest bio-stimulatory effects on HGFs.