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

• Published in: Lasers in surgery and medicine Vol. 18; no. 3; pp. 253 - 259
• Main Authors: Soukos, Nikolaos S., Wilson, Michael, Burns, Tracy, Speight, Paul M.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 1996; Wiley-Liss
• Subjects: bacteria; Biological and medical sciences; Dose-Response Relationship, Drug; Fibroblasts - drug effects; Gingiva - drug effects; Gingiva - microbiology; Humans; In Vitro Techniques; Keratinocytes - drug effects; lasers; lethal photosensitization; Medical sciences; periodontal disease; Photochemotherapy; Photoradiation therapy and photosensitizing agent; Streptococcus sanguis - drug effects; Tolonium Chloride - pharmacology; Treatment with physical agents; Treatment. General aspects; Tumors; Human; Streptococcaceae; Toluidine; Bacteria; Micrococcales; Keratinocyte; Streptococcus sanguis; Fibroblast; In vitro; Photosensitizer; Phototherapy
• ISSN: 0196-8092; 1096-9101
• DOI: 10.1002/(SICI)1096-9101(1996)18:3<253::AID-LSM6>3.0.CO;2-R

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 96™ AQueous Non‐Radioactive Cell Proliferation Assay was used.
Results
TBO was cytotoxic at low concentrations (5.0 μg/ml). Sensitization of keratinocytes and fibroblasts with 2 and 5.0 μg/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 μg/ml.
Conclusion
The development of a system for the lethal photosensitization of bacteria responsible for periodontal disease may be possible. © 1996 Wiley‐Liss, Inc.