Photoactivation of curcumin and sodium hypochlorite to enhance antibiofilm efficacy in root canal dentin

Abstract

Background: To test the effect of ultrasonic or light activated curcumin and sodium hypochlorite against Enterococcus faecalis biofilms in vitro.

Methods: E. faecalis biofilms were grown within root canals (n=175) and divided into 7 groups (n=25). Group 1, sterile saline; group 2, 3% sodium hypochlorite; group 3, 3% sodium hypochlorite activated with ultrasonic files (30s cycles for 4min); group 4, 3% sodium hypochlorite irradiated with blue light (1200mw/cm(2) for 4min); group 5, curcumin (2.5mg/mL); group 6, curcumin (2.5mg/mL) activated with ultrasonic files (30s cycles for 4min); group 7, curcumin (2.5mg/mL) irradiated with blue light. The biofilms' ultrastructure was examined using scanning electron microscopy. Bacterial viability was assessed by confocal microscopy. Data were analyzed by one-way ANOVA and Student-Newman-Keuls test (P=0.05). The quantitative analysis of the colony-forming units was carried out from dentinal shaving and analyzed by One-way ANOVA and Tukey multiple comparison test (P=0.05).

Results: All treatment groups showed a significantly higher percentage of dead bacteria than the saline control (P<0.05). The percentage of dead bacteria was significantly higher when light activated curcumin was used (P<0.05). At both depths (200 and 400 microns), light activated curcumin showed no growth of bacteria.

Conclusions: Light activation produced significantly higher antibacterial efficacy than ultrasonic agitation, with light activated curcumin producing the maximum elimination of biofilm bacteria within the root canal lumen and dentinal tubules.

Keywords: Biofilm; Confocal microscopy; Curcumin; Enterococcus faecalis; Photosensitizer; Sodium hypochlorite.