Curcumin-A Natural Medicament for Root Canal Disinfection: Effects of Irrigation, Drug Release, and Photoactivation

Abstract

Introduction: Curcumin incorporation into polymeric fibers was tested for its antimicrobial properties and potential use in root canal disinfection.

Methods: Curcumin-modified fibers were processed via electrospinning and tested against a 7-day old established Actinomyces naeslundii biofilm. The medicaments tested were as follows: curcumin-modified fibers at 2.5 and 5.0 mg/mL, curcumin-based irrigant at 2.5 and 5.0 mg/mL, saline solution (negative control), and the following positive controls: 2% chlorhexidine, 1% sodium hypochlorite, and triple antibiotic paste (TAP, 1 mg/mL). All medicaments, except for the positive controls, were allocated according to the light exposure protocol (ie, photoactivation with a light-emitting diode every 30 seconds for 4 minutes or without photoactivation). After treatment, the medicaments were removed, and 1 mL saline solution was added; the biofilm was scraped from the well and used to prepare a 1:2000 dilution. Spiral plating was performed using anaerobic blood agar plates. After 24 hours, colony-forming units (colony-forming units/mL, n = 11/group) were counted to determine the antimicrobial effects.

Results: Data exhibited significant antimicrobial effects on the positive control groups followed by the curcumin irrigants and, lastly, the photoactivated curcumin-modified fibers. There was a significant reduction of viable bacteria in curcumin-based irrigants, which was greater than the TAP-treated group. Curcumin-free fibers, saline, and the nonphotoactivated curcumin-modified fibers did not display antimicrobial activity.

Conclusions: Curcumin seems to be a potential alternative to TAP when controlling infection, but it requires a minimal concentration (2.5 mg/mL) to be effective. Photoactivation of curcumin-based medicaments seems to be essential to obtain greater antibiofilm activity.

Keywords: Curcumin; disinfection; electrospinning; endodontics; photodynamic therapy.

Copyright © 2019 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1.

Morphological SEM images illustrating the nanofiber architecture and submicron fiber diameter observation: (A) Curcumin-free PDS nanofiber. (B) PDS nanofibers containing curcumin at 2.5 mg/mL. (C) PDS nanofibers containing curcumin at 5.0 mg/mL. The median fiber diameter (Fd) and the minimum and maximum values for each group was expressed. The curcumin-modified nanofibers presented greater fiber diameter than the curcumin-free nanofibers (p<0.05; Kruskal-Wallis test – α=5%). (D) FTIR spectra confirming the incorporation of curcumin into the PDS fibers. Note the presence of characteristic peaks for curcumin (* and © denote PDS-, and curcumin-related peaks, respectively).

Figure 2.

Antimicrobial effects of different treatments on Actinomyces naeslundii biofilm in CFU/mL (n=11). Similar uppercase letters next to the (±SD) indicate no significant differences at the p 0.05 level. NaOCl exhibited the strongest antimicrobial effect followed by CHX. There was a significant reduction of bacteria between curcumin-based irrigants when compared with TAP. No significant differences were observed between curcumin-free nanofibers, saline, and nonphotoactivated curcumin-modified fibers. There was a slight decrease of bacterial viability obtained with photoactivated curcumin-modified fibers when compared with the non-photoactivated curcumin-modified fiber and negative control groups.