In vitro efficacy of photodynamic therapy with toluidine blue for decontamination of resorbable membranes inoculated with Streptococcus mutans

Objectives

This study assessed the efficacy of antimicrobial photodynamic therapy (aPDT) with toluidine blue (TB) for decontamination of resorbable membranes inoculated with Streptococcus mutans (S. mutans).

Materials and Methods

In this in vitro study, Mucoderm and Jason resorbable membranes were cut into 15 pieces each, and were inoculated with S. mutans at 10⁵ colony forming units (CFUs)/mL concentration. The membranes were subsequently assigned to 3 subgroups each (n = 5), for decontamination with TB (100 µg/mL) activated by 635 nm laser (60 s) as the experimental group (aPDT), 0.12 % chlorhexidine (CHX) as the positive control, and phosphate buffered saline (PBS) as the negative control. Changes in colony count after the interventions were calculated. Data were analyzed by the Kruskal-Wallis and Dunn's tests (alpha=0.05).

Results

In both membrane types, the difference in colony count was significant among the three subgroups (P = 0.002). The lowest colony count was noted in the CHX subgroup, and the highest was recorded in the PBS subgroup. aPDT caused a significant reduction in colony count compared with the negative control group (P = 0.002). Significant differences were found between all three groups in pairwise comparisons (P < 0.05). The efficacy of aPDT was not significantly different for decontamination of the two membrane types (P = 635).

Conclusion

aPDT with 635 nm diode laser and TB had optimal efficacy (although inferior to CHX) for decontamination of both Jason and Mucoderm resorbable membranes inoculated with S. mutans.