Activity of antimicrobial photodynamic therapy against a cariogenic biofilm composed of a microbial consortium.

SIGNIFICANCE: Dental caries is a polymicrobial condition derived from microbial biofilm. There is a lack of studies addressing antimicrobial photodynamic therapy (aPDT) activity against a cariogenic multispecies biofilm.

AIM: We aim to evaluate the activity of aPDT against a cariogenic biofilm composed of a microbial consortium.

APPROACH: Equal parts of Streptococcus mutans, Lactobacillus rhamnosus, and Candida albicans were used to form a microbial inoculum containing ∼ 10 7 colony-forming units/mL, which was placed on cellulose acetate membranes to form biofilm. After biofilm formation, the seven groups, each containing four membranes, were treated as follows: laser 1 J (G1); laser 4 J (G2); photosensitizer methylene blue (G3); photosensitizer + laser 1 J (G4); photosensitizer + laser 4 J (G5); chlorhexidine as positive control (G6); and distilled water (G7).

RESULTS

The number of viable microbial cells per biofilm varied between 1.40 × 10 8 (G5) and 7.28 × 10 8 (G1), whereas the negative control group (G7) reached 1.38 × 10 9 . Compared with G7, all groups presented a reduction, with the percentage varying from 47.05% (G1) to 89.85% (G5). However, G5 (photosensitizer + laser 4 J) was the only group to present a statistical reduction ( p < 0.05 ).

CONCLUSION

aPDT represents an important antibiofilm adjunct therapy, resulting in a significant reduction in microbial cells within a cariogenic biofilm model.