How Adding Chlorhexidine or Metallic Nanoparticles Affects the Antimicrobial Performance of Calcium Hydroxide Paste as an Intracanal Medication: An In Vitro Study

The aim of our study was to explore the potential value of metallic (Ag, Cu, and Zn) salts, polymer/metallic nanoparticles, and chlorhexidine (CHX) for improving the antimicrobial activity of calcium hydroxide (CH) against E. faecalis and C. albicans, associated with persistent endodontic infections. A first screening was performed by determining minimum inhibitory/bactericidal concentrations (MIC/MBC).

Antimicrobial activity of the CH paste mixed with metallic salts, chitosan or cyclodextrin polymer metallic nanoparticles was compared to the antimicrobial activity of CH paste alone and CH + CHX using a time-kill kinetics assay. The effect of the antimicrobials on the rheological and the key mechanical properties were also examined. Copper and zinc were discarded because of their MIC/MBC values and silver because of its kill time curve profile. Except for a slower setting time after 24 h and a higher weight loss after 1 week of incubation, the mechanical behavior of the CH paste was unaffected by the addition of CHX.

Polymeric/metallic nanoparticles failed to potentiate the antimicrobial effect of CH. By contrast, CHX increased this effect and thus could help eradicate E. faecalis associated with persistent root canal infections without altering the desired key physical properties of the CH paste.

Download the full article as a PDF here or read it here

Materials: Preparation of Antimicrobial Agents: The antimicrobials were tested in the form of solutions: chlorhexidine digluconate (Evonik, Hanau, Germany), silver sulfate (Ag₂SO₄) (Sigma-Aldrich^®, Saint-Quentin Fallavier, France), copper (II) sulfate anhydrous (CuSO₄) (Alfa Aesar^®, Kandel, Germany), and zinc chloride anhydrous (ZnCl₂) (Alfa Aesar^®). Metallic ions (silver (Ag), copper (Cu), and zinc (Zn) were also tested in the form of PMNPs and were formulated with (i) low molecular weight chitosan (CHT) (MW: 140 kg mol⁻¹; DD: 77%) (Sigma-Aldrich^®) to produce chitosan/metallic nanoparticles (CHT/MNPs) and were named, respectively, CHT/Ag, CHT/Cu, and CHT/Zn or (ii) with cyclodextrin polymer (Kleptose^®, Roquette, Lestrem, France) to produce cyclodextrin polymer/metallic nanoparticles (CDP/MNPs) named, respectively, CDP/Ag, CDP/Cu, and CDP/Zn, as previously described [33,36].

Article information: Sy, K.; Agossa, K.; Maton, M.; Chijcheapaza-Flores, H.; Martel, B.; Siepmann, F.; Deveaux, E.; Blanchemain, N.; Neut, C. How Adding Chlorhexidine or Metallic Nanoparticles Affects the Antimicrobial Performance of Calcium Hydroxide Paste as an Intracanal Medication: An In Vitro Study. Antibiotics 2021, 10, 1352. https://doi.org/10.3390/antibiotics10111352