Bacteria Filtration Efficiency of Different Face Masks Worn during COVID-19 Pandemic in North-Eastern Tanzania: An In Vitro Study

Increased demand for wearing face masks, lack of surgical masks and N95 respirators during the coronavirus pandemic created alternative needs for cloth masks. Therefore, to determine filtration efficacy, reusability and duration of wearing new and hand washed cloth masks, the bacteria filtration efficacy was tested using Staphylococcus aureus and Escherichia coli. Cotton cloth masks; single layer without pleats and with pleats, double layer with canvas filter in the middle, double layer with stiff filter in the middle, double layer with pleats on both sides and locally made and imported surgical masks and N95 respirators were used. Bacterial suspension was sprayed over outer surface and swabbed from inner surface at 0hrs, 4thhr, 8thhr and 12thhr. Similar procedure was performed to hand washed and ironed cotton cloth masks. After 24 hours of incubation, single layer without pleats and with pleats had no filtration efficacy(0-100%). Double layer with stiff filter in the middle and double layer with pleats on both sides had higher filtration efficacy(99.96-100%), this filtration efficacy remained up to three occasions of hand washing with soap and water, conferring protection up to 12hours. Filtration efficacy of surgical masks made locally, imported and N95 respirators were 90-100%, 99.99-100%, and 99.99-100% respectively.

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Invitro filtration efficiency for selected face masks to bacteria with a size smaller than SARS-CoV-2 respiratory droplet

10.21203/rs.3.rs-28705/v1 ◽

2020 ◽

Author(s):

Maryam Amour ◽

Hussein H. Mwanga ◽

George M. Bwire

Keyword(s):

Escherichia Coli ◽

Double Layer ◽

Ambient Air ◽

Filtration Efficiency ◽

Cotton Cloth ◽

Colony Forming Units ◽

Spread Of Infection ◽

N95 Respirators ◽

And Control ◽

Respiratory Droplets

Abstract Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) can be transmitted between people through respiratory droplets (droplet particles are >5-10 μm in diameter). We conducted an invitro experiment to determine the filtration efficiency for selected face masks (cloth and medical face masks and N95 respirators) to bacteria with a size (0.5-1.5 μm in diameter) smaller than SARS-CoV-2 respiratory droplet. Bacteria suspension was prepared using normal saline (NaCl) and bacteria (Staphylococcus aureus and Escherichia coli) and maintained at a turbidity of 0.5 MacFarland. The suspensions was put in a 100ml plastic spray bottle (with an approximated 250 μl and flow rate of 31.5 ft3/min per spray) and then a single spray was performed to the test masks. Swabbing was done to unsprayed side of the test mask within 0 and after 4 hrs. The swab was streaked on CLED media then incubated for 48 hours at 37oC in ambient air. Bacterial filtration efficiency (BFE) was determined as the proportions of colony forming units (CFUs) between the test and control mask. The selected face masks had BFE of 100% and >99% for medical and double layer cotton cloth masks, respectively. This study supports the use of cotton cloth (at least double layer) face coverings in public settings where other social distancing measures are difficult to maintain to prevent the spread of infection from the wearer.

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Implants With Internal Hexagon and Conical Implant-Abutment Connections: An In Vitro Study of the Bacterial Contamination

Journal of Oral Implantology ◽

10.1563/aaid-joi-d-11-00121 ◽

2014 ◽

Vol 40 (1) ◽

pp. 30-34 ◽

Cited By ~ 14

Author(s):

Simonetta D'Ercole ◽

Antonio Scarano ◽

Vittoria Perrotti ◽

Jorge Mulatinho ◽

Adriano Piattelli ◽

...

Keyword(s):

Bacterial Contamination ◽

In Vitro Study ◽

Vitro Study ◽

Bacterial Suspension ◽

Inflammatory Reactions ◽

Implant Abutment ◽

Group 2 ◽

Group 1 ◽

Internal Connections

Prevention of microbial leakage at the implant-abutment junction is a major challenge for the construction of 2-stage implants in order to minimize inflammatory reactions and to maximize bone stability at the implant neck. The aim of the present in vitro study was an evaluation of the leakage observed over a period of 28 days in Cone Morse taper internal connections and in screwed-abutments connections. In the present study 10 specimens of Cone Morse (Group 1) and 10 of internal hexagon (Group 2) implants were used. The inner parts of 5 implants per group were inoculated with Pseudomonas aeruginosa (PS) suspension and 5 implants per group with Aggregatibacter actinomycetemcomitans (AA). The possible penetration of bacterial suspension into the surrounding solution was determined by the observation of turbidity of the broth. In Group 1, bacterial contamination was found in 3 out of 5 implant-abutment assemblies seeded with the PS and in 2 samples out of 5 in the assemblies seeded with AA, with a total of leaked assemblies in this group of 5 out of 10. In Group 2, bacterial contamination was found in 4 out of 5 implant-abutment assemblies seeded with the PS, and in 4 out of 5 samples seeded with AA, with a total of leaked assemblies of 8 out of 10. The present data confirm the reported high permeability to bacterial leakage of screw-retained abutment connections, and the lower infiltration rates—although not significantly—of Cone Morse taper internal connections.

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Filter paper inhibits in vitro protocorm-like body formation in hybrid Cymbidium and reduces synseed germination, but buffers the negative impact of antibiotics

Biological Letters ◽

10.1515/biolet-2015-0005 ◽

2014 ◽

Vol 51 (1) ◽

pp. 47-54

Author(s):

JAIME A. TEIXEIRA DA SILVA

Keyword(s):

Double Layer ◽

Filter Paper ◽

Negative Impact ◽

Single Layer ◽

Negative Effects ◽

Cell Layers ◽

Single Sheet ◽

Plant Hybrid ◽

The Impact

Abstract Only few studies in the plant tissue culture literature have examined the impact of filter paper on in vitro plant organogenesis. In this study, using a model plant, hybrid Cymbidium Twilight Moon ‘Day Light’, the impact of a single or double layer of Advantec #2 or Whatman #1 filter paper on new protocorm-like body (neo-PLB) formation on Teixeira Cymbidium (TC) medium was examined for half-PLBs (transgenic and non-transgenic), PLB-derived transverse thin cell layers (tTCLs), and PLB synseeds. In addition, the response of half-PLBs or tTCLs to two antibiotics (kanamycin and cefotaxime, commonly used in plant genetic transformation studies) was investigated either directly on gelled medium or on filter paper-overlaid medium. Filter paper negatively affected most growth and developmental parameters of all the explants tested, both transgenic and non-transgenic. A double sheet of filter paper had a significantly (P ≤ 0.05) more negative impact than a single sheet, relative to the control values (i.e., no filter paper). Kanamycin inhibited neo-PLB formation on TC medium, the negative impact being greater on a single layer than on a double layer of filter paper, i.e., filter paper buffered the growth-inhibiting characteristics of kanamycin. Up to 100 mg/l, cefotaxime showed no apparent negative effects on neo-PLBs formation and growth, although hyperhydricity was observed when filter paper was not used.

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Adherence of Streptococcus mutans to Nanoceramic and Nanohybrid Resin Composites: An In vitro Study

Journal of Pharmaceutical Research International ◽

10.9734/jpri/2020/v32i2530831 ◽

2020 ◽

pp. 128-133

Author(s):

Krishnakanth Jaju ◽

Iffat Nasim

Keyword(s):

Streptococcus Mutans ◽

Bacterial Adhesion ◽

Resin Composite ◽

In Vitro Study ◽

Bacterial Suspension ◽

Resin Composites ◽

Colony Forming Units ◽

Significant Difference ◽

Test Control

Streptococcus mutans (S. mutans) is one of the cariogenic microorganisms. The restorative materials which harbor a biofilm with high number of S. mutans can accelerate the occurrence of dental caries. The purpose of this study was to evaluate the adherence of S. mutans to nanoceramic and nanohybrid resin composites. Fifteen discs of each material (Nanohybrid resin composite, Nanoceramic resin composite) were prepared, polished, and sterilized in a gamma radiation chamber. Specimens were exposed to the S. mutans bacterial suspension (0.5 McFarland) and were incubated for 4 hours. Specimens were rinsed and sonicated in normal saline, 10 μl of the obtained suspension was cultured in a sterile blood agar medium. After 24 hours, the number of colony forming units of S. mutans was counted. A sterility test control was considered for each group of materials. The data was analyzed by Independent t test. The means and standard deviations of the logarithmic counts of the colonies on the surfaces of nanohybrid resin composites and nanoceramic resin composite were equal to 3.2±0.87 and 2.8±0.324 respectively. Ceram X Universal did not show any significant difference in the bacterial adhesion compared to Filtek Z350XT. Both composites showed similar behaviour in terms of S. mutans colonization in a simple biofilm formation model.

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Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols

10.1101/2020.10.05.20207241 ◽

2020 ◽

Author(s):

William G. Lindsley ◽

Francoise M. Blachere ◽

Brandon F. Law ◽

Donald H. Beezhold ◽

John D. Noti

Keyword(s):

Double Layer ◽

Aerosol Particles ◽

Single Layer ◽

Face Mask ◽

Cotton Cloth ◽

Source Control ◽

The Face ◽

Community Transmission ◽

Small Aerosol ◽

Control Devices

AbstractFace masks are recommended to reduce community transmission of SARS-CoV-2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields and neck gaiters have been proposed as an alternative to face masks, but information about face shields and neck gaiters as source control devices is limited. We used a cough aerosol simulator with a pliable skin headform to propel small aerosol particles (0 to 7 µm) into different face coverings. An N95 respirator blocked 99% of the cough aerosol, a medical grade procedure mask blocked 59%, a 3-ply cotton cloth face mask blocked 51%, and a polyester neck gaiter blocked 47% as a single layer and 60% when folded into a double layer. In contrast, the face shield blocked 2% of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols.

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A highly efficient cloth facemask

10.21203/rs.3.rs-322107/v3 ◽

2021 ◽

Author(s):

Christopher Cappa ◽

The San Francisco Opera Costume Department ◽

William Ristenpart ◽

Santiago Barreda ◽

Nicole Bouvier ◽

...

Keyword(s):

High Efficiency ◽

Separation Distance ◽

Filtration Efficiency ◽

Ambient Aerosols ◽

The Public ◽

Professional Singers ◽

Surgical Masks ◽

Mask Design ◽

N95 Respirators ◽

Better Than

Abstract Wearing masks and face coverings helps reduce transmission of respiratory diseases. Much prior research on mask filtration efficiency has focused on fabric type, with less consideration given to mask design and shape. Here, we present evidence that increasing the mouth-mask separation distance engenders an increase in the mask-fabric filtration efficiency towards expiratory aerosols emitted via vocalization, which we attribute to a decrease in the expiratory jet velocity and expansion of the breath-mask contact area. We further assess the performance of a new reusable cloth facemask design, originally made for, but not exclusive to, professional singers and having a large mouth-mask separation distance. With proper fitting, these masks achieve overall filtering efficiencies of >93% for both exhaled expiratory aerosols >0.5 microns in diameter from singing and speaking and for inhaled ambient aerosols, better than surgical masks and approaching N95 respirators. Air exchange between the mask deadspace and the ambient environment limits the extent of CO2 buildup and in inhaled air and maintains O2 levels near ambient. The mask design also provides for less inhibited mouth and jaw movement and lower relative humidity, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.

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Evaluation of bactericidal effects of ultraviolet light C irradiation on cariogenic bacteria: An in vitro study

BMC Oral Health ◽

10.1186/s12903-021-01767-x ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Moayyad Alharbi ◽

Fahad Bakitian ◽

Ali Alenezi

Keyword(s):

Streptococcus Mutans ◽

Ultraviolet Light ◽

Single Layer ◽

In Vitro Study ◽

Bactericidal Effect ◽

Oral Bacteria ◽

Solid Surfaces ◽

Limited Effect ◽

Bactericidal Effects

Abstract Backgrounds Ultraviolet light C (UVL-C) irradiation has demonstrated an antimicrobial action against various pathogens. This study aimed to evaluate the bactericidal effect of UVL-C irradiation against cariogenic oral bacteria (Streptococcus mutans) in single layers and colonies grown on solid surfaces. Methods Two different experiments were performed. In the first experiment, a single layer of Streptococcus mutans bacteria on agar plates was exposed to UVL-C irradiation at energies from 0 to 21 mWs/cm2. The second experiment was conducted to inhibit viability of bacterial colonies on solid surfaces. The samples were derived from saliva from a patient where bacteria were grown on plastic strips and then exposed to UVL-C. The highest energy was 1050 mWs/cm2. Results Exposure to 21 mWs/cm2 was bactericidal in single layers of Streptococcus mutans. The result for bacterial colonies on solid surfaces indicated only a bacteriostatic effect, even at energies of 1050 mWs/cm2. Conclusions Ultraviolet light C exhibits bactericidal effects on single layers of Streptococcus mutans but has a limited effect on bacterial colonies in a biofilm. It is a matter of debate whether these in vitro results would have the same effect in clinical setting.

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Stress relaxation properties of four orthodontic aligner materials: A 24-hour in vitro study

The Angle Orthodontist ◽

10.2319/113015-813.1 ◽

2016 ◽

Vol 87 (1) ◽

pp. 11-18 ◽

Cited By ~ 28

Author(s):

Luca Lombardo ◽

Elisa Martines ◽

Valentina Mazzanti ◽

Angela Arreghini ◽

Francesco Mollica ◽

...

Keyword(s):

Tooth Movement ◽

Single Layer ◽

In Vitro Study ◽

Constant Load ◽

Strength Testing ◽

Stress Release ◽

Materials Used ◽

F22 Aligner ◽

Over Time

ABSTRACT Objective: To investigate the stress release properties of four thermoplastic materials used to make orthodontic aligners when subjected to 24 consecutive hours of deflection. Materials and Methods: Four types of aligner materials (two single and two double layered) were selected. After initial yield strength testing to characterize the materials, each sample was subjected to a constant load for 24 hours in a moist, temperature-regulated environment, and the stress release over time was measured. The test was performed three times on each type of material. Results: All polymers analyzed released a significant amount of stress during the 24-hour period. Stress release was greater during the first 8 hours, reaching a plateau that generally remained constant. The single-layer materials, F22 Aligner polyurethane (Sweden & Martina, Due Carrare, Padova, Italy) and Duran polyethylene terephthalate glycol-modified (SCHEU, Iserlohn, Germany), exhibited the greatest values for both absolute stress and stress decay speed. The double-layer materials, Erkoloc-Pro (Erkodent, Pfalzgrafenweiler, Germany) and Durasoft (SCHEU), exhibited very constant stress release, but at absolute values up to four times lower than the single-layer samples tested. Conclusions: Orthodontic aligner performance is strongly influenced by the material of their construction. Stress release, which may exceed 50% of the initial stress value in the early hours of wear, may cause significant changes in the behavior of the polymers at 24 hours from the application of orthodontic loads, which may influence programmed tooth movement.

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THE EFFECT OF CURCUMA XANTHORRHIZA - ETHANOL EXTRACT TO BIOFILM FORMATION OF STREPTOCOCCUS MUTANS AND AGGREGATIBACTER ACTINOMYCETEMCOMITANS (DENTAL BIOFILM RESEARCH: IN VITRO STUDY)

International Journal of Applied Pharmaceutics ◽

10.22159/ijap.2017.v9s1.14_16 ◽

2017 ◽

Vol 9 ◽

pp. 20

Author(s):

Fidhianissa . . ◽

Hedijanti Joenoes ◽

Ariadna A Djais

Keyword(s):

Streptococcus Mutans ◽

Biofilm Formation ◽

In Vitro Study ◽

Ethanol Extract ◽

Single Species ◽

Vitro Study ◽

Bacterial Suspension ◽

Dental Biofilm ◽

Curcuma Xanthorrhiza

Objective: This in vitro study aimed to analyze the mass ratio of single- and dual-species Streptococcus mutans and Aggregatibacteractinomycetemcomitans biofilm after exposure to Curcuma xanthorrhiza ethanol extract (Xan).Methods: A bacterial suspension in brain heart infusion medium, enriched with 0.2% sucrose, was exposed to the Xan, incubated for 18 hrs, andanalyzed using a crystal violet assay.Results: This research concluded that the minimum inhibitory concentration of ethanol-temulawak extract against S. mutans was 5%, while theminimum bactericidal concentration was 15%.Conclusions: Xan prevented biofilm formation of single-species S. mutans and dual-species S. mutans and A. actinomycetemcomitans more effectivelythan it did single-species A. actinomycetemcomitans.

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Effect of Double-layer Application on Dentin Bond Durability of One-step Self-etch Adhesives

Operative Dentistry ◽

10.2341/13-168-l ◽

2014 ◽

Vol 39 (4) ◽

pp. 416-426 ◽

Cited By ~ 19

Author(s):

M Taschner ◽

M Kümmerling ◽

U Lohbauer ◽

L Breschi ◽

A Petschelt ◽

...

Keyword(s):

Bond Strength ◽

Double Layer ◽

Artificial Saliva ◽

In Vitro Study ◽

Adhesive Systems ◽

Microtensile Bond Strength ◽

Application Technique ◽

One Step ◽

Self Etch

SUMMARY Purpose The aim of this in vitro study was 1) to analyze the influence of a double-layer application technique of four one-step self-etch adhesive systems on dentin and 2) to determine its effect on the stability of the adhesive interfaces stored under different conditions. Materials and Methods Four different one-step self-etch adhesives were selected for the study (iBondSE, Clearfil S3 Bond, XenoV+, and Scotchbond Universal). Adhesives were applied according to manufacturers' instructions or with a double-layer application technique (without light curing of the first layer). After bonding, resin-dentin specimens were sectioned for microtensile bond strength testing in accordance with the nontrimming technique and divided into 3 subgroups of storage: a) 24 hours (immediate bond strength, T0), b) six months (T6) in artificial saliva at 37°C, or c) five hours in 10 % NaOCl at room temperature. After storage, specimens were stressed to failure. Fracture mode was assessed under a light microscope. Results At T0, iBond SE showed a significant increase in microtensile bond strength when the double-application technique was applied. All adhesive systems showed reduced bond strengths after six months of storage in artificial saliva and after storage in 10% NaOCl for five hours; however at T6, iBond SE, Clearfil S3 Bond, and XenoV+ showed significantly higher microtensile bond strength results for the double-application technique compared with the single-application technique. Scotchbond Universal showed no difference between single- or double-application, irrespective of the storage conditions. Conclusion The results of this study show that improvements in bond strength of one-step self-etch adhesives by using the double-application technique are adhesive dependent.

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