Exopolysaccharide dispelled by calcium hydroxide with volatile vehicles related to bactericidal effect for root canal medication

Abstract

Objective: Enterococcus faecalis is the dominant microbial species responsible for persistent apical periodontitis with ability to deeply penetrate into the dentin. Exopolysaccharides (EPS) contribute to the pathogenicity and antibiotic resistance of E. faecalis. Our aim was to investigate the antimicrobial activity of calcium hydroxide (CH), camphorated parachlorophenol (CMCP), and chlorhexidine (CHX) against E. faecalis in dentinal tubules.Material and Methods:Decoronated single-canal human teeth and semicylindrical dentin blocks were incubated with E. faecalis for 3 weeks. Samples were randomly assigned to six medication groups for 1 week (n=10 per group): CH + 40% glycerin-water solution (1:1, wt/vol); CMCP; 2% CHX; CH + CMCP (1:1, wt/vol); CH + CMCP (2:3, wt/vol); and saline. Bacterial samples were collected and assayed for colony-forming units. After dentin blocks were split longitudinally, confocal laser scanning microscopy was used to assess the proportion of viable bacteria and EPS production in dentin.Results:CMCP exhibited the best antimicrobial activity, while CH was the least sensitive against E. faecalis (p<0.05). CHX showed similar antimicrobial properties to CH + CMCP (1:1, wt/vol) (p>0.05). CH combined with CMCP inhibited EPS synthesis by E. faecalis, which sensitized biofilms to antibacterial substances. Moreover, increasing concentrations of CMCP decreased EPS matrix formation, which effectively sensitized biofilms to disinfection agents.Conclusion:The EPS matrix dispelled by CH paste with CMCP may be related to its bactericidal effect; the visualization and analysis of EPS formation and microbial colonization in dentin may be a useful approach to verify medicaments for antimicrobial therapy.

The Pathogenicity and Transcriptome Analysis of Methicillin-Resistant Staphylococcus aureus in Response to Water Extract of Galla chinensis

“…The biofilm samples were washed twice in PBS and imaged with a scanning electron microscope (SEM, Inspect Hillsboro) following our previous procedures [5, 18]. The samples were serially dehydrated with ethanol solutions (30%, 50%, 70%, 95%, and 100%), dried in air, and coated with gold for imaging.…”

“…The bacterial cells in the biofilm were labeled with SYTO9 (Invitrogen, Carlsbad, CA, USA). Confocal laser scanning microscopy (CLSM, TSP SP2; Leica, Solms, Germany) was then performed [18]. For the fluorescence microscopy, the live and dead cells in the biofilms grown on the glass coverslips were distinguished with LIVE/DEAD BacLight™ Bacterial Viability Kit reagent (Invitrogen, Waltham, MA) and labeled in accordance with the manufacturer's instructions to assess the proportion of vital bacteria [18].…”

Nano-graphene oxide with antisense <i>vicR</i> RNA reduced exopolysaccharide synthesis and biofilm aggregation for <i>Streptococcus mutans </i>

“…A three-dimensional reconstruction was conducted and analyzed by a software program (Imaris 7.0.0, Bitplane, Zurich, Switzerland). All procedures were repeated in triplicate 19) . We rinsed S. mutans biofilms twice with PBS buffer and dried at room temperature.…”

Optimizing Antimicrobial Agents in Endodontics

“…Ca(OH) 2 can be added to phenolic products to make them more effective antimicrobial agents, as this disrupts the biofilm matrix [88]. The contact between hydrophobic phenolic agents and the walls of the root canal can be enhanced by formulating these into a water base containing surfactants or by using water-miscible solvents such as low molecular weight forms of PEG.…”