Adhesion and Proliferation of Human Gingival Fibroblasts on Root Surfaces following Photodynamic Therapy: An In Vitro Study

Background and Aim: Previous studies have shown that some dyes used in photodynamic therapy (PDT) have a low pH and may cause root demineralization and remove the smear layer. This study aimed to assess and compare the effects of root biomodification with citric acid and PDT on the adhesion and proliferation of human gingival fibroblasts (HGFs). Materials and Methods: In this in vitro experimental study, 75 single-rooted teeth extracted due to periodontal disease were assigned to the following treatment groups: (I) Scaling and root planing (SRP) alone; (II) SRP + citric acid (pH=1, 60 s); (III) PDT with toluidine blue (TB; 635 nm laser,150 mW for 30 s); (IV) PDT with methylene blue (MB; 660 nm laser, 150 mW for 30 s) and (V) PDT with indocyanine green (ICG; 810 nm laser, 150 mW for 30 s). Fibroblasts were then cultured in Dulbecco’s modified Eagle’s medium along with the treated root pieces. Adhesion and proliferation of fibroblasts were quantified using the methyl thiazolyl tetrazolium (MTT) assay at 24, 48 and 72 hours. Data were analyzed using SPSS version 22 by repeated measures ANOVA. Pairwise comparisons were performed by the LSD test. Results: Adhesion and proliferation of HGFs significantly increased in all groups from 24 to 72 hours (P=0.0001). There was no significant difference in this respect among the groups at the three time points (P=0.143). Conclusion: PDT did not have any adverse effect on the adhesion and proliferation of HGFs on dentin, which confirms the safety of this treatment modality.