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Scripta Scientifica Medicinae Dentalis

Effect of APDT on human dental biofilm isolated streptococci species with 2 photosensitizers - In Vitro study

Maya Doychinova, Vesselin Kussovski, Slavcho Dimitrov


AIM: The aim of this study is to evaluate and compare the in vitro antimicrobial effect of 2 photosensitiz­ers: FotoSan®medium and ZnPcMe on a biofilm isolate of clinical strain of Streptococci species .

MATERIALS AND METHODS: Twelve patients were instructed to stop using any kind of oral hygiene care for 24 hours. Plaque was collected with sterile dental floss, placed in vial containing 3ml of BFS. Ten-fold dilution of the suspension was made. Samples of 0.1ml were plated on Mitis Salivarius agar. Bacte­ria were Gram-stained as well and underwent morphological identification. A bacterial suspension at a density of 106 cells/ml was used. An incubation mixture of 1 ml bacterial suspension (106 CFU/ml) and the corresponding photosensitizer were prepared, achieving a different final concentration of PS. LED light source with a wavelength of 643 nm was used for irradiation. Samples and controls for each tested PS after 24h incubation at 37ºC were reported.

RESULTS: The control samples in dark showed a minor antimicrobial effect. Samples of bacterial suspen­sion + PS + light irradiation expressed statistically relevant antibacterial effect on Streptococci species with small differences in the different concentrations and irradiation time used.

CONCLUSION: The clinical strain of Streptococci species was susceptible to photodynamic inactivation by the used photosensitizers: FotoSan®medium and ZnPcMe. Full photoinactivation was not observed. Dark toxicity was to be neglected. ZnPcMe should undergo further trials and given the positive photodynamic ef­fect in vitro, be licensed for clinical use. FotoSan®medium should undergo further in vivo and in vitro ex­periments in order to establish an alternative protocol for caries prevention.


dental biofilm, photosensitizers

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About The Authors

Maya Doychinova
Medical University of Varna

Department of Conservative Dental Treatment and Oral Pathology, Faculty of Dental Medicine

Vesselin Kussovski
Bulgarian Academy of Sciences

Slavcho Dimitrov
Bulgarian Academy of Sciences

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