Effect of photodynamic therapy with two photosensitizers on Streptococcus mutants: In vitro study.

BACKGROUND AND OBJECTIVES: Streptococcus mutans (S. mutans) colonizes the oral cavity and causes dental caries and periodontal diseases. Considering the importance of the treatments that decrease pathogenic microorganisms, the aim of the present research was the assessment of the antimicrobial effect of Photodynamic Therapy (PDT) with Methylene Blue (MB) and Indocyanine Green (IG) photosensitizers on S. mutans. MATERIALS AND METHODS: In this In vitro experimental study, Sixty four caries-free first premolars were contaminated with 0.5 McFarland S.mutans suspension and were randomly assigned to 4 groups. The teeth in the first group were impregnated with 2% MB while the teeth in the second group were impregnated with 0.2% IG. The teeth in the first group were irradiated with continuous-wave 660nm dod laser with 40mw output power, energy density of 2.4J/cm2 and 100% duty cycle for 60s, while the teeth in the second group were irradiated with continuous -wave 810nm diode laser with 100mw out power, density energy of 6J/cm2 and 100% duty cycle for 60s in contact mode. In the third group, the teeth were suspended in 0.2% Chlorhexidine for 30s. The fourth group was considered as the control. The teeth were sampled before and after the interventions and the samples were incubated in Blood Agar for 24h. Afterwards, the number of S. mutans colonies were counted. Data were statistically analyzed by Kruskal-Wallis, Dunn's and Friedman tests. RESULTS: In the groups treated with a combination of MB and IG and laser irradiation and also in the Chlorhexidine group, the final number of S. mutans colonies equaled zero. In "MB and IG groups without laser irradiation", although the amount of microorganisms decreased, but the number of colonies did not reach zero. Pair comparisons by Dunn's test showed that there was a significant difference between "MB and IG groups without laser irradiation" and the other experimental groups p=0.03). CONCLUSION: PDT with MB and IG photosensitizers and also Chlorhexidine mouthwash, have the ability to completely eradicate S. mutans bacterial colonies.

Effect of photodynamic therapy with two photosensitizers on Candida albicans.

BACKGROUND AND OBJECTIVES: Oral candidiasis (OC) is an opportunistic infection of the oral cavity most commonly caused by Candida albicans (C. albicans). Considering the drawbacks of standard treatments with antifungal agents, this study sought to assess the efficacy of photodynamic therapy (PDT) with methylene blue (MB) and indocyanine green (ICG) photosensitizers against C. albicans. MATERIALS AND METHODS: In this in-vitro, experimental study, 130 samples of C. albicans standard suspensions were subjected to various combinations of MB and ICG photosensitizers with and without laser irradiation with different exposure parameters, nystatin and chlorhexidine (CHX) in 13 groups of 10. Samples were cultured in microplates containing Sabouraud dextrose agar medium and colony forming units (CFUs) were counted after 24h of incubation at 37°C. Data were analyzed by SPSS version 19.0, one-way ANOVA and Tamhane's test. RESULTS: The maximum number of CFUs was seen in the control group (mean of 214,200CFUs with a log value of 5.32) while the minimum values were noted in the laser (808nm and 100Hz PRR) plus ICG (mean of 13,460CFUs and log value of 4.12) and nystatin (mean of 13,940CFUs and log value of 4.14) groups. CONCLUSION: Within the limitations of this in vitro study, the results revealed that laser application (808nm, 100Hz PRR) plus ICG caused a significant reduction in C. albicans CFUs.