The Effect of Photodynamic Therapy on the Viability of Streptococcus Mutans Isolated From Oral Cavity

Abstract

Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizer by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. The aim of this study was to evaluate the effect of PDT on Streptococcus mutans in planktonic conditions, previously treated with different photosensitive concentrations of erythrosine, using halogen and LED curing unit as a light source. And we compared the effects of PDT on six strains of S. mutans isolated from oral cavity and reference strain.As a result, S. mutans was susceptible to the combination of hand held photopolymerizer (HHP) and erythrosine. The higher concentration of erythrosine in the presence of light irradiation induced greater effects in reduction of viability of S. mutans. Isolated S. mutans showed a significant reduction in bacterial counts of the groups submitted to PDT compared to the control groups. And they appeared to be similar or slightly lower antimicrobial effect compared with reference strain. However, the difference was not significant (p < 0.05).In conclusion, PDT using erythrosine as a photosensitizing agent and HHP as a light source could be an efficient option for diseases caused by S. mutans.

Recovery of Streptococcus Mutans Biofilm after Photodynamic Therapy with Erythrosine and LED Light Source

“…The CFU counts immediately after treatment were significantly lower in Group II (PDT) than in Group I (negative control), thus verifying the antimicrobial ability of erythrosinemediated PDT on S. mutans. This is consistent with the results of previous studies [9,[11][12][13][14][15]. The American Society of Microbiology defines antimicrobial activity as a ≥3 log CFU/mL reduction from the starting inoculum [16].…”

“…Studies have reported the use of erythrosine as a photosensitizer in PDT to exert antimicrobial effects against S. mutans cells in suspensions or biofilms [9,[11][12][13][14][15]. After antimicrobial treatment, residual bacteria induce the recovery of biofilm growth and CFU counts, indicating the possibility of reinfection.…”

“…Group II underwent PDT treatment. For PDT, cells were treated with 40 μM erythrosine for 3 minutes, followed by irradiation at an energy density of 18 J/cm 2 [11,12]. Group III was a positive control, treated with 0.12% chlorhexidine (CHX) (Hexamedine, Bukwang Pharmaceutical, Seoul, South Korea).…”

Antimicrobial Effect on <italic>Streptococcus mutans</italic> in Photodynamic Therapy using Different Light Source

“…However, disadvantages of a halogen curing unit is the de- been widely used [25]. A study on PDT using halogen as a light source and erythrosine as a photosensitizer for planktonic S. mutans reported an effective reduction in viability [26].…”

“…Due to the differences in the amount of energy irradiated, the LEDs failed to show the results of effective photodynamic therapy [24]. Others conducted a study on PDT using 600 mW/cm 2 of halogen and 900 mW/cm 2 of LED, and irradiated 18 J/cm 2 and 27 J/cm 2 respectively [26]. Both light sources were effective.…”