Photodynamic antimicrobial
chemotherapy (PACT) is proposed as a potential candidate to inactivate pathogens in localized
infections due to the rapid evolution of bacterial resistance. The treatment modality utilizes nontoxic agents called
photosensitizers and harmless visible light to generate
reactive oxygen species which result in microbial cells' killing.
Hematoporphyrin monomethyl ether (HMME) as a novel and affordable
photosensitizer has been used in treating various clinical diseases for years, but few applications in
infection. In this report, we studied the bactericidal effects of the HMME-mediated photodynamic reaction on the pathogenic microbes in supragingival plaque which can lead to many oral
infectious diseases such as caries,
gingivitis, and so on. Our findings demonstrated that HMME promoted an effective action in bacterial reduction with the application of
laser energy. Moreover, the antimicrobial activities were dramatically enhanced as the HMME concentration and exposure time were increased, but reached a plateau when matched the appropriate agent concentration and illumination. It was found that the survival fraction of microorganisms is exponentially dependent on the product of HMME concentration and irradiation time. These promising results suggest the HMME may be an excellently cost-effective
photosensitizing agent for mediating PACT in the treatment of supragingival plaque-related diseases. An optimized HMME concentration and irradiation time has been found to achieve the best results under our experimental conditions. The high HMME concentration matching short curative time, or vice versa, can achieve the similar
therapeutic effect, which may provide more flexible treatment plans according to specific conditions.