Request Proposal. Contact Us. Useful Links. Facebook-f Instagram Twitter Linkedin. Copyright — Q Laboratories. All rights reserved. Share via. The remaining bacterial precipitate was viable and maintained as stock. Then, the concentration was adjusted by spectrophotometer to an optical density of 0. The standard broth dilution method CLSI MA8 was used to study the antimicrobial efficacy of silver nanoparticles by evaluating the visible growth of microorganisms in the agar broth.
The MIC endpoint is the lowest concentration of silver nanoparticles where no visible growth is seen in the tubes. The visual turbidity of the tubes was noted, both before and after incubation to confirm the MIC value. When This was done by observing pre and post-incubated agar plates for the presence or absence of bacteria. Whereas in concentrations of 0. The suspension from the tubes of 0.
The antibacterial effects of drugs are routinely assessed by agar diffusion and MIC test. The advantage of direct contact tests over the agar diffusion method is that it is independent of the diffusion properties of the tested material and media [ 11 ]. Serial dilutions of a solution are used for MIC to determine the lowest concentration of material that would still show antibacterial properties.
Staphylococcus aureus , a facultative anaerobic gram-positive coccus, has been recovered from several oral sites [ 12 ]. It was selected for use in this study because it is one of the facultative bacteria found in failed root canal cases and recurrent apical periodontitis [ 13 ] and it can develop resistance to antimicrobial agents.
The antimicrobial effects of silver are mostly attributed to silver ions [ 14 , 15 ]. Silver nanoparticles continuously release silver ions in an aqueous microenvironment [ 16 ]. Because of the bigger surface area of silver nanoparticles, they show a stronger and better bactericidal effect [ 17 ]. The main reasons for bactericidal properties of silver nanoparticles are interfering with the integrity of the bacterial cell by binding to essential cellular structural [ 18 ], particularly to their SH-groups [ 19 , 20 ].
Silver nanoparticles also generate reactive oxygen species ROS and free radicals which damage the bacterial cell wall and inhibit the respiratory enzymes [ 21 ]. Silver nanoparticles disturb the DNA replication and terminate the bacteria. Silver nanoparticles are biocidal to various gram-positive and gram-negative bacteria [ 22 ].
The ultrafine particle size causes its action at lower concentration. Humberto et al. Various studies have concluded that silver nanoparticles possess antimicrobial effect against many bacteria and fungi, including S.
Generally, the tendency to develop bacterial resistance is low towards noble metals [ 27 ]. Ellis et al. Hosny et al. Results from Kaweeteerawat et al. It is worth noting, however, that most of the studies are related to exogenous and endogenous silver ion resistance. The release of silver ions by silver nanoparticles is only one of the forms by which silver nanoparticles act as an antimicrobial, as discussed earlier [ 31 ].
One side effect of silver is argyria, an irreversible pigmentation of the skin that is mostly an aesthetic concern [ 32 ]. Silver nanoparticles also display substantial toxicity against fibroblasts, hepatocytes, osteoblasts or bone-marrow cells [ 33 ]. An important limitation of this study is that it was done on planktonic bacteria. The dental infections are mostly polymicrobial, consisting of Enterococcus, Streptococci, Provotella, Porphyromonas and many more bacteria.
They present different properties in biofilm. Further study is required to assess the antimicrobial effect of silver nanoparticles on dental biofilm. Most of the time, in-vitro results do not correlate with in-vivo activity. The results obtained from this study suggest that the effective bactericidal concentration of silver nanoparticles against S.
The use of silver nanoparticles as an antimicrobial agent against S. Silver nanoparticles can be incorporated into the intra-canal medicaments, root canal sealers and also in irrigating solution to eradicate S. Further in vivo studies are needed to imply this effectively. Future scope of antimicrobial silver nanoparticles in contemporary dentistry includes wide ranges of applications in restorative dentistry, endodontics, implantology, dental prostheses, orthodontics and other dental fields.
No potential conflict of interest was reported by the author s. National Center for Biotechnology Information , U. Journal List Biomater Investig Dent v.
Biomater Investig Dent. Thus, the test truly does determine the minimum concentration needed to kill the test organism, since all other parameters are conducive to biocidal effect. The MBC test can be a good and relatively inexpensive tool to rank a great number of antimicrobial agents by potency, for screening purposes. The MBC test can be used to evaluate formulation problems wherein the formulator suspects that the active ingredient is being "bound up" by other ingredients.
The theory is that the MBC will be worse for a formula that has a portion of its active ingredient chemically combined with other ingredients, thus not available to kill microorganisms in the suspension.
The test parameters for the MBC are easy to control in the laboratory, so comparisons can be made fairly easily between various antimicrobial agents tested under the same conditions and their respective effects on specific microorganisms.
Weaknesses of the Minimum Bactericidal Concentration Test An MBC must be determined for each microorganism individually as the antimicrobial will likely have different MBC values for different test microorganisms. MBC testing results will not determine the concentration of the antimicrobial needed to disinfect or sanitize microorganisms at a short contact time, such as 10 minutes. Mueller Hinton Broth is the recommended broth for this method.
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