Smear Layer Removal from Root Canal Dentin and Antimicrobial Effect of Citric Acid-modified Chlorhexidine

Abstract

Objective: To study the effectiveness of various concentrations of citric acid (CA) added to 2% chlorhexidine (CHX) on smear layer removal from the root canal wall and antimicrobial efficacy against Enterococcus faecalis ( E. faecalis ) and Candida albicans ( C. albicans ). Methods: Fifty-three single-rooted mandibular premolars were decoronate and the root canals underwent mechanical instrumentation using MTwo rotary files to size 40/0.06. The samples were then randomly divided into 5 groups according to the root canal irrigants to be used: 17% ethylenediaminetetraacetic acid (EDTA), 2% CHX, 1%, 6%, and 10% citric acid-modified 2% chlorhexidine (CAmCHX). Three teeth irrigated with phosphate-buffered saline (PBS) were used as a negative control. The smear layer removal effectiveness was evaluated under scanning electron microscopy (SEM). Images were randomly taken at the apical, middle, and coronal third level. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests. Disc diffusion and direct exposure tests were performed along with three additional control groups consisting of 1%, 6%, and 10% CA groups to assess and compare the antimicrobial efficacy of irrigants against E. faecalis and C. albicans . Statistical analysis was conducted using one-way ANOVA and Dunnett’s T3 tests. Results: Smear layer removal effectiveness in 17% EDTA group and 6% and 10% CAmCHX groups were not significantly different in the coronal and apical third of the root canal (P>0.05), however at the middle third of the root canal, the 10% CAmCHX group had significantly less remaining smear layer than all of the other experimental groups (P<0.05). There was significantly more smear layer remnant in the CHX group (P<0.01). For antimicrobial efficacy, the largest growth inhibition zone against E. faecalis was recorded in the 10% CAmCHX group (P<0.05). For planktonic E. faecalis , 1%, 6%, and 10% CAmCHX demonstrated an insignificant difference in antimicrobial efficacy compared to CHX (P>0.05). CA demonstrated no antifungal effect against C. albicans . Whereas, 6% and 10% CAmCHX resulted in the largest growth inhibition zone. Also, adding CA to CHX resulted in an insignificant difference in antifungal effect against planktonic C. albicans compared to CHX (P>0.05). Conclusion: When CA was added into CHX, the mixed irrigant demonstrated smear layer removal ability. Additionally, its antimicrobial effect remained the same.

CHX and a Face Shield Cannot Prevent Contamination of Surgical Masks

“…Chlorhexidine is a broad-spectrum antiseptic effective against Gram-positive and negative bacteria, furthermore fungi. It is used in dentistry to control dental biofilms' growth and treat periodontitis or root canals, especially Enterococcus faecalis ( 18 , 19 ). At the latest since the COVID-19 pandemic, a pre-procedural mouth rinse with CHX is widely accepted in dentistry, although an antiviral effect in the oral cavity was unproven so far ( 20 ).…”

Efficacy of preheated chelating agents on calcium ion removal from instrumented root canals

“…( 27 ). In addition to this, after removing the smear layer by using a chelating agent, it is reasonable to irrigate the canal again with another disinfecting solution to attack the bacteria remaining in the dentin tubules ( 28 ). However, when NaOCl is used as a final disinfectant for this purpose, it shows the corrosive effect on the dentin microstructure.…”

“…However, when NaOCl is used as a final disinfectant for this purpose, it shows the corrosive effect on the dentin microstructure. Therefore, using QMix as a single final solution and thus reducing disinfection steps can provide optimal final irrigation without dentin erosion caused by NaOCl ( 1 , 28 ).…”

Evaluation of the Caries Removal Efficacy of Several Organic Acid Reagents

“…Similar to Carisolv treatment, the smear layer was not removed completely from the cavity surface after citric acid and tartaric acid treatment, and smear layer and closed dentin microtubules were observed in several areas of the cavity surface. Previous papers suggested that root canal irrigation with 10% of citric acid enabled efficient removal of smear layer in root canal walls [23][24][25]. However, both 10% citric acid reagent and 10% tartaric acid reagent could not remove the smear layer completely.…”