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

Abstract

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.

Therapeutic Potential of Chlorhexidine-Loaded Calcium Hydroxide-Based Intracanal Medications in Endo-Periodontal Lesions: An Ex Vivo and In Vitro Study

“…In this study, a dose-dependent potentiation of the antimicrobial action of CH on P. gingivalis is observed, which is found in both the root canal and the periodontal pocket and is not susceptible to CH alone. In a previous publication, our group reported similar results with E. faecalis [ 28 ]. The dosage used in the bacterial culture medium in contact with the ICMs confirmed that CHX is released at a concentration of 2.25 mg/L after 24 h, which is close to the MICs of these bacteria [ 28 ].…”

“…In a previous publication, our group reported similar results with E. faecalis [ 28 ]. The dosage used in the bacterial culture medium in contact with the ICMs confirmed that CHX is released at a concentration of 2.25 mg/L after 24 h, which is close to the MICs of these bacteria [ 28 ]. CH and two combinations of CH + CHX were both effective in inhibiting biofilm formation and eradicating mature biofilms.…”

“…The MICs/MBCs of CHX for E. faecalis and P. gingivalis were determined, and the time–kill effect of CH + CHX mixtures on these bacteria was evaluated. The MICs/MBCs and time–kill curves for E. faecalis were reported in a previous publication by our group [ 28 ]. The MIC of P. gingivalis could not be determined because of the turbidity of the blood-supplemented medium.…”

“…Chlorhexidine (CHX) has also been proposed as an intracanal medication because of its strong antimicrobial properties and its affinity for dental tissues that allows for prolonged drug release [ 26 , 27 ]. Our group recently confirmed that a mixture of CH and CHX is effective against microorganisms such as E. faecalis , which is frequently considered as non-susceptible to CH alone [ 28 ].…”

Present status and future directions of intracanal medicaments

“…Another effective antimicrobial agent as an intracanal medication is the use of nanoparticles, including metal, polymeric and ceramic nanoparticles. These nanoparticles are commonly mixed in the calcium hydroxide paste as additives to enhance the antimicrobial potency of calcium hydroxide (Sy Agossa et al, 2021). One of the most studied metal nanoparticles against E. faecalis is silver nanoparticle (AgNP) due to its broad‐spectrum antimicrobial activity and simple fabrication procedures (Afkhami et al, 2015; Halkai et al, 2018; Noronha et al, 2017; Wu et al, 2014; Zheng et al, 2018).…”