The Effectiveness of Cold Atmospheric Plasma (CAP) on Bacterial Reduction in Dental Implants: A Systematic Review.

BACKGROUND: The emergence of dental implants has revolutionized the management of tooth loss. However, the placement of clinical implants exposes them to complex oral environment and numerous microscopic entities, such as bacteria. Cold atmospheric plasma (CAP) is often used to treat the surfaces of dental implants, which alters morphological features and effectively reduces bacterial load. PURPOSE: This systematic review aims to assess the existing literature on the bactericidal properties of CAP when used on various kinds of dental implant surfaces. REVIEW METHOD: An in-depth examination of MEDLINE/PubMed and EMBASE was performed to identify relevant studies, with the most recent search conducted in May 2023. Studies were selected based on their exploration of CAP's effects on dental implants compared to control groups, focusing on CAP's bactericidal efficacy. However, studies that lacked a control group or that failed to measure bactericidal effects were excluded. RESULTS: After applying the selection criteria, 15 studies were ultimately included in the systematic review. The collected data suggest that CAP can effectively reduce bacterial loads on dental implant surfaces, including pathogens like Streptococcus mitis and Staphylococcus aureus. Furthermore, CAP appears to combat biofilms and plaques that are key contributors to periimplantitis. CONCLUSION: CAP emerges as a promising treatment option, exhibiting significant bactericidal activity on dental implant surfaces. CAP can decrease the rates of bacterial biofilm and plaque formation, leading to improved outcomes for dental implant patients.

Characterization and evaluation of cold atmospheric plasma as seedborne fungal disinfectant and promoting mediator for physico-chemical characteristics of Moringa oleifera seedlings.

Non-thermal atmospheric pressure plasmas are a powerful tool to impact seed germination and microbial decontamination. Air large volume atmospheric pressure glow discharge plasma was developed and investigated to improve the biological activities of Moringa oleifera seeds. Ninty ns magnetic pulse compression high voltage system was used to generate the plasma. The plasma discharges current increases with increasing applied voltage and it decreases with increasing discharge gap. There was a steady reduction in the count of seedborne fungi on the application of air cold plasma with complete elimination of fungi at ≥ 10.94 mJ per pulse. The low doses of plasma (2.46 and 4.35 mJ) induced an increase in the seed germination, a significant increase in chlorophyll content (chl a and chl b) and antioxidant activities of the seedlings emerged from soaked or wet seeds rather than dry seeds. At lower plasma doses (2.46 and 4.35 mJ) there was a significant increase in leaf area and chlorophyll content (chl a and chl b) of the seedlings that emerged from H2O2 soaked seeds rather than that of free from H2O2. The plasma was harmful when applied at higher doses (≥ 10.94 mJ) and more harmful to the wet seeds compared to the dry ones.

Enhancement of the antidermatophytic activity of silver nanoparticles by Q-switched Nd:YAG laser and monoclonal antibody conjugation.

The objective of this research was to investigate the effect of silver nanoparticles (AgNPs), free or conjugated with monoclonal antibody and mediated by Q-switched Nd:YAG laser on five dermatophytes. The laser was applied for 45 s at 532 nm and 0.8 J/cm2. The application of AgNPs combined with laser caused an increase in fungal susceptibility compared to application of AgNPs alone. The MIC50 and MIC100 recorded 3 and 9 µg/ml in the case of E. floccosum (the most susceptible species), 10 and 19 µg/ml for T. rubrum (the most tolerant species), respectively. A decrease in keratinase activity reaching 76.1, 67.1, and 62.4% was attained in the case of M. gypseum, T. rubrum, and T. mentagrophyte, respectively, on application of 10 µg/ml AgNPs combined with Nd:YAG laser. Under the same conditions of application, a steady increase in leaked materials coupled with reduction in ergosterol synthesis was reached. The structural alterations occurred to the fungus were more observed on the application of AgNPs in combination with laser where the conidia and hyphae lost their cellular integrity, become flaccid, permanently destructed, and completely killed. The monoclonal antibody conjugated AgNPs did not result in significant variation in in vitro experiments compared with that produced by nonconjugated nanoparticles. However, the conjugates achieved significantly more curing of M. canis-inoculated guinea pigs compared with nonconjugated nanoparticles.

Design of Thermochromic Polynorbornene Bearing Spiropyran Chromophore Moieties: Synthesis, Thermal Behavior and Dielectric Barrier Discharge Plasma Treatment.

A new class of thermochromic polynorbornene with pendent spiropyran moieties has been synthesized. Functionalization of norbornene monomers with spirobenzopyran moieties has been achieved using Steglich esterification. These new monomeric materials were polymerized via Ring Opening Metathesis Polymerization (ROMP). In spite of their poor solubility, polynorbornenes with spirobenzopyran exhibited thermochromic behavior due to the conversion of their closed spiropyran moieties to the open merocyanine form. Moreover, these polymers displayed bathochromic shifts in their optical response, which was attributed to the J-aggregation of the attached merocyanine moieties that were associated with their high concentration in the polymeric chain. The surface of the obtained polymers was exposed to atmospheric pressure air Dielectric Barrier Discharge (DBD) plasma system, which resulted in the reduction of the surface porosity and converted some surface area into completely non-porous regions. Moreover, the plasma system created some areas with highly ordered J-aggregates of the merocyanine form in thread-like structures. This modification of the polymers' morphology may alter their applications and allow for these materials to be potential candidates for new applications, such as non-porous membranes for reverse osmosis, nanofiltration, or molecular separation in the gas phase.

Deterioration to extinction of wastewater bacteria by non-thermal atmospheric pressure air plasma as assessed by 16S rDNA-DGGE fingerprinting.

The use of cold plasma jets for inactivation of a variety of microorganisms has recently been evaluated via culture-based methods. Accordingly, elucidation of the role of cold plasma in decontamination would be inaccurate because most microbial populations within a system remain unexplored owing to the high amount of yet uncultured bacteria. The impact of cold atmospheric plasma on the bacterial community structure of wastewater from two different industries was investigated by metagenomic-based polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) utilizing 16S rRNA genes. Three doses of atmospheric pressure dielectric barrier discharge plasma were applied to wastewater samples on different time scales. DGGE revealed that the bacterial community gradually changed and overall abundance decreased to extinction upon plasma treatment. The bacterial community in food processing wastewater contained 11 key operational taxonomic units that remained almost completely unchanged when exposed to plasma irradiation at 75.5 mA for 30 or 60 s. However, when exposure time was extended to 90 s, only Escherichia coli, Coliforms, Aeromonas sp., Vibrio sp., and Pseudomonas putida survived. Only E. coli, Aeromonas sp., Vibrio sp., and P. putida survived treatment at 81.94 mA for 90 s. Conversely, all bacterial groups were completely eliminated by treatment at 85.34 mA for either 60 or 90 s. Dominant bacterial groups in leather processing wastewater also changed greatly upon exposure to plasma at 75.5 mA for 30 or 60 s, with Enterobacter aerogenes, Klebsiella sp., Pseudomonas stutzeri, and Acidithiobacillus ferrooxidans being sensitive to and eliminated from the community. At 90 s of exposure, all groups were affected except for Pseudomonas sp. and Citrobacter freundii. The same trend was observed for treatment at 81.94 mA. The variability in bacterial community response to different plasma treatment protocols revealed that plasma had a selective impact on bacterial community structure at lower doses and potential bactericidal effects at higher doses.

Inhibitory effect of silver nanoparticles mediated by atmospheric pressure air cold plasma jet against dermatophyte fungi.

In an in vitro study with five clinical isolates of dermatophytes, the MIC(50) and MIC(100) values of silver nanoparticles (AgNPs) ranged from 5 to 16 and from 15 to 32 µg ml(- 1), respectively. The combined treatment of AgNPs with atmospheric pressure-air cold plasma (APACP) induced a drop in the MIC(50) and MIC100 values of AgNPs reaching 3-11 and 12-23 µg ml(- 1), respectively, according to the examined species. Epidermophyton floccosum was the most sensitive fungus to AgNPs, while Trichophyton rubrum was the most tolerant. AgNPs induced significant reduction in keratinase activity and an increase in the mycelium permeability that was greater when applied combined with plasma treatment. Scanning electron microscopy showed electroporation of the cell walls and the accumulation of AgNPs on the cell wall and inside the cells, particularly when AgNPs were combined with APACP treatment. An in vivo experiment with dermatophyte-inoculated guinea pigs indicated that the application of AgNPs combined with APACP was more efficacious in healing and suppressing disease symptoms of skin as compared with the application of AgNPs alone. The recovery from the infection reached 91.7 % in the case of Microsporum canis-inoculated guinea pigs treated with 13 µg ml(- 1) AgNPs combined with APACP treatment delivered for 2  min. The emission spectra indicated that the efficacy of APACP was mainly due to generation of NO radicals and excited nitrogen molecules. These reactive species interact and block the activity of the fungal spores in vitro and in the skin lesions of the guinea pigs. The results achieved are promising compared with fluconazole as reference antifungal drug.

Inhibitory effect of double atmospheric pressure argon cold plasma on spores and mycotoxin production of Aspergillus niger contaminating date palm fruits.

BACKGROUND: Aspergillus niger has been reported as a potentially dangerous pathogen of date-palm fruits in Saudi Arabia due to the production of fumonisin B2 (FB2 ) and ochratoxin A (OTA). In a trial to disinfect this product, a double atmospheric pressure argon cold plasma (DAPACP) jet system was set up and evaluated against spore germination and mycotoxin production of the pathogen. RESULTS: The plasma jets were characterised photographically, electrically and spectroscopically. DAPACP jet length increases with the increase of argon flow rate, with optimum rate at 3.5 L min(-1) . The viability of A. niger spores, inoculated onto sterilised date palm fruit discs, progressively decreases with extension of the exposure time of DAPACP due to the more quantitative amount of OH and O radicals interacting with the examined samples. There was a progressive reduction of the amount of FB2 and OTA detected in date palm discs on extension of the exposure time of the plasma-treated inoculums at flow rate of 3.5 L min(-1) . FB2 was not detected in the discs inoculated with 6-min plasma-treated A. niger, while OTA was completely absent when the fungus was treated for 7.5 min. CONCLUSION: DAPACP showed promising results in dry fruit decontamination and in inhibition of mycotoxin release by A. niger contaminating the fruits. The progress in the commercial application of cold plasma needs further investigation concerning the ideal width of the plasma output to enable it to cover wider surfaces of the sample and consequently inducing greater plasma performance.