Effect of Photodynamic Therapy With Two Different Photosensitizers on the Viability of Human Dental Pulp Stem Cells

Introduction: Photodynamic therapy(PDT)is a minimally invasive technique increasingly used in dentistry for its antimicrobial properties. This research aimed to evaluate the influence of photodynamic therapy (PDT) on the viability of dental pulp stem cells (DPSCs). Methods: In this laboratory-based, experimental study, DPSCs were cultured in Dulbecco's modified Eagle's medium and maintained at 37 °C. The cells were separated into five groups: Toluidine blue (TBO) at concentration of 0.1 mg/mL and 0.5 mg/mL, as well as methylene blue (MB) at concentrations of 0.01 mg/mL and 0.05 mg/mL were added to the wells in groups 1 to 4. The fifth group served as the control group. After 5 minutes of incubation, the experimental groups were irradiated with Fotosan® light-emitting diode (LED) for one minute. Cell viability was assessed after 8, 24, 48, and 72 hours using the methyl thiazolyl tetrazolium (MTT) assay. Results: Time (P<0.000), photosensitizer type/concentration (P<0.0001), and their interaction effect (P<0.000) on cell viability were all significant. Viability in both MB groups was considerably higher than that in the control group at 8 hours (P<0.001). At 24 hours, no significant difference was observed between the experimental groups and the control (P>0.05). At 48 and 72 hours, cell viability in the TBO groups was markedly lower compared to the control group (P<0.01). Conclusion: PDT with MB at the tested concentrations had no adverse effect on DPSCs even in the long- term (48 and 72 hours).