Photodynamic effects of toluidine blue on human oral keratinocytes and fibroblasts and Streptococcus sanguis evaluated in vitro.

BACKGROUND AND OBJECTIVE

Some oral bacteria are susceptible to killing by red light after their sensitization with toluidine blue O (TBO). The photochemotherapy of periodontal disease in vivo would require a therapeutic window where bacteria could be killed without adjacent normal tissue damage.

STUDY DESIGN/MATERIALS AND METHODS: The laser-induced effects of TBO on normal human gingival keratinocytes and fibroblasts have been studied in vitro. For the assessment of viability, the CellTiter 96TM AQueous Non-Radioactive Cell Proliferation Assay was used.

RESULTS

TBO was cytotoxic at low concentrations (5.0 micrograms/ml). Sensitization of keratinocytes and fibroblasts with 2 and 5.0 micrograms/ml TBO, respectively, for 5 min and exposure to light from a 7.3 mW Helium/Neon (HeNe) laser for up to 2 min (0.876J) did not reduce cell viability. However, killing of Streptococcus sanguis was achieved following exposure to HeNe light for 75 sec (0.547J) in the presence of TBO at a concentration of 2.5 micrograms/ml.

CONCLUSION

The development of a system for the lethal photosensitization of bacteria responsible for periodontal disease may be possible.