Use of hand held photopolymerizer to photoinactivate Streptococcus mutans

Summary Objectives: The main focus of this research was to investigate the photodynamic therapy (PDT), in vitro, acting on Streptococcus mutans and fibroblasts. A hand held photopolymerizer (HHP) and a classical photosensitizer (Rose Bengal) were used to induce photodynamic response. Methods: S. mutans and fibroblast were treated with different concentrations of Rose Bengal (0–50 μM) irradiated with light (400–500 nm) for different time periods (0–40 s) and then cell viability was evaluated. Results: It was observed that the light (per se) is not toxic and in the dark Rose Bengal is toxic to the cells tested only at concentrations above 2.5 μM. Under light exposure concentrations of Rose Bengal above 0.5 μM all S. mutans were killed with no cytotoxic effects to fibroblasts. Conclusions: For the purpose of this work, the photoactivation of Rose Bengal, using the HHP, inactivated the bacteria without affecting the fibroblast viability.