Enhanced photodynamic therapy using light fractionation against Streptococcus mutans biofilm: type I and type II mechanism.

Aim: The objective of the study was to look the efficacy of fractionated light against Streptococcus mutans biofilm.

Materials & Methods: Antibiofilm assays (crystal violet, congo red), electron microscopic, confocal and spectroscopic studies were performed to check the effect of fractionated light.

Results: 6-6.5 log reduction of planktonic and 3.6-4.2 log reduction in biofilm were observed after irradiation with fractionated as compared with continuous light. Increased permeability to propidium iodide and leakage of cellular constituent validate the greater antibiofilm effect of fractionated light. Spectroscopic studies confirmed the relative contribution of type I and type II photochemistry.

Conclusion: Phenothiazinium dyes have a potential against bacterial biofilm in combination with light fractionation and it offers new opportunities to explore its clinical implication.