European Journal of Cardiovascular Medicine

Effectively reducing the microbial burden inside the root canal complex is said to be essential to the outcome of endodontic therapy.¹ It is advised to use a combination strategy that includes irrigation, instrumentation, and intracanal medicine because simply shaping the canal is not enough to completely eradicate bacteria.² According to studies, even after being irrigated with sodium hypochlorite, a sizable percentage—between 40% and 60%—of cultivable bacteria are still present in the root canals.³

The main microbial cause of apical periodontitis was recently found to be Enterococcus faecalis. Known for its resilience, this Gram-positive microbe often recurs in subsequent root canal disease. Interestingly, E. faecalis has the unusual ability to form a single-species biofilm inside the root canal on its own without interacting with other microorganisms. It has shown increased resistance to other treatments used during root canal therapy as well as chemo-mechanical disinfection.3. Intracanal medications are essential for improving the disinfectant regimen when used in tandem with root canal disinfection.⁴

In order to avoid tissue damage from bacteria or their byproducts leaking into the periapical area, the root canal complex must be optimally disinfected. Numerous intracanal medications, including antibiotics, calcium hydroxide (CH), pastes comprising iodoform, steroids, and chlorhexidine (CHX), are used in endodontics.²

The purpose of this study was to compare the antibacterial activity of chlorhexidine, metronidazole, and calcium hydroxide mixed with different vehicles against bacterial species commonly isolated from infected root canals.

The investigation was conducted at the DY Patil Dental College's Department of Endodontics and Conservative Dentistry in Pune. Among the medications are (a) calcium hydroxide powder combined with distilled water; (b) calcium hydroxide powder combined with CPMC (3.5:6.5); (c) calcium hydroxide powder combined with glycerin; (d) difluconatc chlorhexidine (0.12% gel); and (e) metronidazole 1% gel. The following calcium hydroxide combinations were prepared to a toothpaste uniformity: Actinomyces Israelii, Fusobacterium nucleatum, Propionibaclerium, Campylobacter reclus (clinical isolate), Porphyromonas endodontalis, and Porphyromonas gingivalis. Staphylococcus aureus, Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius (clinical isolate), Enterococcus Jüecalis, and Actinomyces viscosus were the facultative anaerobes that were employed. Facultative anaerobes were maintained in brain heart infusion (BHI) broth, and obligate anaerobic bacteria were maintained in produced anaerobically sterilized BHI supplemented with hemin (5 mg/L) and menadione (0.5 mg/L). Turbidity of the inoculum, prepared in BHI, was adjusted to the turbidity of a 0.5 McFarland Standard (1.5 >< 10⁸ bacteria/ml).

They employed the agar diffusion test. The bacteria to be examined were added into petri plates comprising BHI agar fortified with haemin and menadione using sterile cotton-tipped applicators that were brushed across the medium. The medications to be evaluated were put into wells that were punched in agar plates, measuring 5 mm in depth and 6 mm in diameter. Exclusively obligate anaerobic bacteria have been investigated with metronidazole. Bacteria streaking was done on positive control plates without the use of medication.

Anaerobic containers were used to hold the bacteria agar plates. The evacuation-replacement process, which uses a vacuum machine to eliminate air from the container and substitute it with a solution of 10% H2 and 1% C02 in nitrogen, created an anaerobic state. For seven days, the sealed containers underwent incubation at 37.0°C. Then, for every substance examined, the dimension of zones of bacterial inhibition were calculated and documented, with a minimum threshold of 6 mm. Every bacterial strain was evaluated on two agar plates.

Tables I and 2 show the averages of the zones of bacterial inhibition for each medication. When combined with CPMC, the presence of calcium hydroxide demonstrated broad zones of inhibition against every tested bacterial strain. All strains were inhibited by chlorhexidine (0.12%), although overall, it was no more effective than calcium hydroxide combined with CPMC. Metronidazole worked well against every obligatory anaerobe that was examined. It was more effective than calcium hydroxide/CPMC paste, albeit, only against F. nucleatum and P. endodontalis. All of the bacterial strains employed in this experiment were not affected by calcium hydroxide combined with distilled water or glycerin.

TABLE 1. Means of the diameters of the zones of inhibition against anaerobic bacteria (in millimeters)

TABLE 2. Means of the diameters of the zones of inhibition against facultative bacteria (in millimeters)

Glycerin or calcium hydroxide combined with distilled water did not work versus any of the germs in our investigation. These results conflicted with the results of earlier research.^4,5 This discrepancy can result from the various approaches taken. The antibacterial activity of endodontic materials is frequently assessed using the agar diffusion examination. Nevertheless, caution must be used when interpreting the outcomes of in vitro research. The harmful effects of a medication against the tested microorganisms and its diffusibility in the medium being utilised will determine its zones of inhibition. Additionally, the artificial media's buffering capacity may change the actions of compounds that react with high pH levels, such as bases or acids.

It takes a long time to alkalinise the culture medium since calcium hydroxide cannot diffuse effectively due to its low solubility. The buffering properties of blood, tissue fluids, and dentin, however, may have similar effects in a therapeutic setting. Large zones of attenuation were demonstrated by the calcium hydroxide/CPMC paste against every bacterial strain employed in the present research. The release of CPMC from the paste, the rise in calcium hydroxide diffusibility when linked to CPMC, or both could have contributed to this discovery. Calcium paramonochlorophenolate, a weak salt that gradually releases paramonochlorophenol (PMC) and hydroxyl ions into the surrounding media, is created when calcium hydroxide and CPMC are combined^.6 Released PMC may be responsible for the zones of bacterial inhibition seen in this study. Phenolic compounds have a lower surface tension than distilled water.⁷ This property determines the higher penetra bility and spreading of these drugs. When associated with CPMC, calcium hydroxide may have a higher agar diffusibility than when associated with distilled water.⁸

Based on our data, it seemed that calcium hydroxide/CPMC paste was as good in its antibacterial activity as other medicaments tested. It should be noted that the present study was performed under in vitro conditions, and direct extrapolation of a clinical situation must be done with caution.

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