scholarly journals Decontamination of Hard Tissue Using a Scanning Pulsed 9.3-µm CO2 Laser

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Ali Badreddine
Keyword(s):  
Laser Beam ◽  
Co2 Laser ◽  
Dental Enamel ◽  
Polarization Microscopy ◽  
Cross Contamination ◽  
Cross Polarization ◽  
Hard Tissue ◽  
Colony Forming Units ◽  
Viable Bacteria

Purpose: The aim of the study was to evaluate the use of a scanning 9.3-µm CO2 laser beam to reduce or eliminate bacteria on hard tissue as a new method of non-specific decontamination to prevent cross-contamination during dental or medical procedures. Methods: A low energy level of a 9.3-μm CO2 laser beam was designed to deliver overall uniform photothermal energy in a 2-mm-diameter beam to eliminate bacteria on the surface of dental enamel without damaging the surface of the tooth. The study was conducted in two parts. The first part consisted of 10 human molars polished to a 1-μm finish and inoculated with S. mutans. The bacteria were stained with methylene blue and imaged through cross-polarization microscopy, and the area of the imaged surface containing bacteria was analyzed using ImageJ. The second part of the study consisted of 20 uncleaned extracted human molars used for evaluating cross-contamination of bacteria by measuring bacteria Colony Forming Units (CFU) ejected during an aerosol-generating procedure in vitro. Tryptic soy agar (TSA) plates were used to collect bacteria while cutting enamel. The TSA plates were incubated at 35o C for 24 hours, after which bacteria colonies were counted. Results: Examination using cross-polarization microscopy and imaging showed that the CO2 laser eliminated >98% of bacteria on the surface without altering the surface of teeth and similarly >98% in the aerosol/splatter from cutting of the enamel. Conclusion: The 9.3-μm CO2 laser resulted in nearly a complete elimination of viable bacteria.

scholarly journals Comparison of Live Bacteria Aerosolization during Removal of Dental Enamel Using a 9.3μm CO2 Laser, a 2.78μm Erbium Laser and a High-Speed Dental Drill

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Ali Badreddine
Keyword(s):  
Co2 Laser ◽  
High Speed ◽  
Dental Enamel ◽  
In Vitro Study ◽  
Vitro Study ◽  
Erbium Laser ◽  
Dental Procedures ◽  
Colony Forming Units ◽  
Live Bacteria

Purpose: To measure the amount of viable pathogens in the aerosol/splatter generated during dental procedures using lasers and high-speed drill. Methods: Three systems were used in this in vitro study: 9.3μm CO2 laser, 2.78μm erbium laser and a high-speed drill. 45 uncleaned human molars were randomly selected to be used for the test groups for the three systems. Bacteria ejected while cutting the buccal or lingual surfaces were collected on tryptic soy agar (TSA) plates in identical conditions for each measurement. On the opposite surface of each tooth, a non-cutting mist spray was applied. Results: The CO2 laser resulted in colony-forming units (CFU) with a mean of 1570 ± 3850 CFU/m3/s, which is statistically different (p < 0.001) relative to both the erbium laser and the drill with a mean of 185,000 ± 182,000 CFU/m3/s and 440,000 ± 496,000 CFU/m3/s, respectively. CFU measured from the non-cutting mist spray on the teeth was higher for the drill than for the lasers. Conclusion: The 9.3μm CO2 laser resulted in the lowest CFU in the aerosol/splatter during enamel removal as compared to that of the 2.78μm erbium laser and the traditional high-speed drill. Furthermore, the CO2 laser was the only system that did not increase aerosolization of bacteria while cutting compared to the non-cutting mist spray.

scholarly journals Cross-Contamination Risk of Dental Tray Adhesives: An In Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6138
Author(s):  
Isabel Paczkowski ◽  
Catalina S. Stingu ◽  
Sebastian Hahnel ◽  
Angelika Rauch ◽  
Oliver Schierz
Keyword(s):  
Staphylococcus Aureus ◽  
Candida Albicans ◽  
Artificial Saliva ◽  
In Vitro Study ◽  
Cross Contamination ◽  
Sabouraud Agar ◽  
Liquid Samples ◽  
Streptococcus Oralis ◽  
Colony Forming Units

Background: The aim of this study was to investigate the risk of cross-contamination in dental tray adhesives with reusable brush systems. Methods: Four dental tray adhesives with different disinfectant components were examined for risk as a potential transmission medium for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus oralis, and Candida albicans. Bacterial and fungal strains were mixed with artificial saliva. The contaminated saliva was intentionally added to tray adhesive liquid samples. At baseline and up to 60 min, 100 microliters of each sample were collected and cultivated aerobically on Columbia and Sabouraud agar for 24 or 48 h, respectively. Results: At baseline, contamination with Staphylococcus aureus and Candida albicans could be identified in three out of four adhesives. In the subsequent samples, low counts of up to 20 colony-forming units per milliliter could be observed for Staphylococcus aureus. All other strains did not form colonies at baseline or subsequently. Adhesives with isopropanol or ethyl acetate as disinfectant additives were most effective in preventing contamination, while adhesives with hydrogen chloride or acetone as a disinfectant additive were the least effective. Conclusion: Within 15 min, the tested adhesives appeared to be sufficiently bactericidal and fungicidal against all microorganisms tested.

CO2 laser irradiation enhances CaF2 formation and inhibits lesion progression on demineralized dental enamel—in vitro study

2016 ◽  
Vol 31 (3) ◽  
pp. 539-547 ◽  
Author(s):  
Bruna R. Zancopé ◽  
Lívia P. Rodrigues ◽  
Thais M. Parisotto ◽  
Carolina Steiner-Oliveira ◽  
Lidiany K. A. Rodrigues ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Co2 Laser ◽  
Dental Enamel ◽  
In Vitro Study ◽  
Vitro Study

SEM Evaluation of Fluoride Pretreatment Effects on Acid-Etching of Caries-Like Enamel Lesions In Vitro

1981 ◽  
Vol 39 ◽  
pp. 474-475
Author(s):  
M. John Hicks
Keyword(s):  
Dental Enamel ◽  
Preventive Measure ◽  
Acid Etching ◽  
Distilled Water ◽  
Adhesive Resin ◽  
Fluoride Treatment ◽  
Treatment Groups ◽  
Pretreatment Effects ◽  
Preparation Techniques

Acid-etching of enamel surfaces has been performed routinely to bond adhesive resin materials to sound dental enamel as a caries-preventive measure. The effect of fluoride pretreatment on acid-etching of enamel has been reported to produce inconsistent and unsatisfactory etching patterns. The failure to obtain an adequate etch has been postulated to be due to fluoride precipitation products deposited on the enamel surface. The purpose of this study was to evaluate the effects of fluoride pretreatment on acid-etching of carieslike lesions of human dental enamel.Caries-like lesions of enamel were created in vitro on human molar and premolar teeth. The teeth were divided into two fluoride treatment groups. The specimens were exposed for 4 minutes to either a 2% Sodium Fluoride (NaF) solution or a 10% Stannous Fluoride (SnF2) solution. The specimens were then washed in deionized-distilled water. Each tooth was sectioned into four test regions. This was carried out to compare the effects of various time exposures (0 to 2 minutes) and differing concentrations (10 to 60% w/w) of phosphoric acid (H3PO4) on etching of caries-like lesions. Standard preparation techniques for SEM were performed on the specimens.

Mechanical properties and fatigue behavior of CO2 laser beam welded armor steel joints

2020 ◽  
Vol 62 (7) ◽  
pp. 689-697
Author(s):  
Zulkuf Balalan ◽  
Furkan Sarsilmaz ◽  
Omer Ekinci
Keyword(s):  
Mechanical Properties ◽  
Laser Beam ◽  
Co2 Laser ◽  
Fatigue Behavior ◽  
Armor Steel ◽  
Steel Joints

Density and morphological characterization of bacteria in integrated and exclusive production systems

2020 ◽  
Vol 13 (11) ◽  
pp. 1
Author(s):  
A. R. B. Zanco ◽  
A. Ferreira ◽  
G. C. M. Berber ◽  
E. N. Gonzaga ◽  
D. C. C. Sabino
Keyword(s):  
Bacterial Community ◽  
Rainy Season ◽  
Production Systems ◽  
Cropping System ◽  
Morphological Characterization ◽  
Native Forest ◽  
Exclusive Production ◽  
Colony Forming Units

The different integrated production systems can directly interfere with its bacterial community. The present study aimed to assess density, bacterial diversity and the influence of dry and rainy season in different integrated and an exclusive production system. The fallow and a native forest area was assessed to. Samples were collected in 2012 March and September. The isolation were carried out into Petri dishes containing DYGS medium. The number of colony forming units (CFU) was counted after 48 hours and. The bacterial density ranged between 106 and 107 CFU g-1 soil. The crop system affected the dynamics of the bacterial community only in the rainy season. The rainy season showed greater density of total bacteria when compared to the dry period regardless of the cropping system. The dendrograms with 80 % similarity showed thirteen and fourteen groups in the rainy and dry seasons. Isolates with the capacity to solubilize phosphate in vitro were obtained from all areas in the two seasons, but this feature has been prevalent in bacteria isolated during the rainy season

High-Pressure Homogenization Alters Physicochemical Properties and In Vitro Digestibility of Chinese Yam (Dioscorea Opposita Thunb.) Starch

2018 ◽  
Vol 18 (1) ◽  
pp. 10-15
Author(s):  
Wang Yi-Wei ◽  
He Yong-Zhao ◽  
An Feng-Ping ◽  
Huang Qun ◽  
Zeng Feng ◽  
...  
Keyword(s):  
High Pressure ◽  
Physicochemical Properties ◽  
Starch Content ◽  
In Vitro Digestibility ◽  
High Pressure Homogenization ◽  
Starch Granules ◽  
Cross Polarization ◽  
Chinese Yam ◽  
Crystal Type

In this study, Chinese yam starch-water suspension (8%) were subjected to high-pressure homogenization (HPH) at 100 MPa for increasing cycle numbers, and its effect of on the physicochemical properties of the starch was investigated. Results of the polarizing microscope observations showed that the starch granules were disrupted (i.e. greater breakdown value) after HPH treatment, followed by a decrease in cross polarization. After three HPH cycles, the crystallinity of starch decreased, while the crystal type remained unaltered. Meanwhile, the contents of rapidly digestible starch and slowly digestible starch were increased. On the contrary, resistant starch content was decreased. Our results indicate that HPH treatment resulted in reduction of starch crystallinity and increase of starch digestibility.

scholarly journals Fetal erythropoiesis in steel mutant mice. III. Defect in differentiation from BFU-E to CFU-E during early development

Blood ◽  
1978 ◽  
Vol 51 (3) ◽  
pp. 539-547 ◽  
Author(s):  
DH Chui ◽  
SK Liao ◽  
K Walker
Keyword(s):  
Progenitor Cells ◽  
Early Development ◽  
The Other ◽  
Mutant Mice ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells ◽  
Other Hand ◽  
Colony Forming Units ◽  
Fetal Erythropoiesis

Abstract Erythroid progenitor cells in +/+ and Sl/Sld fetal livers manifested as burst-forming units-erythroid (BFU-E) and colony-forming units- erythroid (CFU-E) were assayed in vitro during early development. The proportion of BFU-E was higher as mutant than in normal fetal livers. On the other hand, the proportion of CFU-E was less in the mutant than in the normal. These results suggest that the defect in Sl/Sld fetal hepatic erythropoiesis is expressed at the steps of differentiation that effect the transition from BFU-E to CFU-E.

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