Direct biological effects of fractional ultrapulsed CO2 laser irradiation on keratinocytes and fibroblasts in human organotypic full-thickness 3D skin models

Cornea thermal damage due to incidental continuous wave CO2 laser irradiation is studied numerically based on bio-heat equation. The interaction of laser with tissue leads to a rapid temperature increased in target and the nearby tissue. As the temperature of the eye surface reaches 44?C, a sensation of pain will cause aversion response of the reflex blink and/or shifting away from the source of pain. The aim of the work is to predict numerically the threshold limit of incidental laser power that causes damage to the anterior part of the cornea, which can be healed within 2-5 days as long as damage is not exceeding the outer part of the eye (epithelium). A finite element analysis is used to predict temperature distribution through the cornea where the necroses region can be obtained using thermal dose equation. The thermal dose that required for damaging the cornea is predicted from previously published experimental data on rhesus monkeys and used later as a limit for shrinkage to human cornea. The result of this work is compared by international standard of safety and a good nearby result is obtained which verified the result of this work.

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Microleakage of "Bulk-Fill" Composite Resin for Class II Restorations Pretreated With CO2 Laser in Deciduous Molars: An In Vitro Study

Journal of lasers in medical sciences ◽

10.15171/jlms.2019.49 ◽

2019 ◽

Vol 10 (4) ◽

pp. 304-309

Author(s):

Larissa Costa Santos ◽

Ravana Angelini Sfalcin ◽

Eugenio José Garcia ◽

Fátima Antônia Aparecida Zanin ◽

Aldo Brugnera Junior ◽

...

Keyword(s):

Phosphoric Acid ◽

Laser Irradiation ◽

Co2 Laser ◽

Class Ii ◽

Composite Resins ◽

Acid Etching ◽

Dentin Hypersensitivity ◽

Significant Difference ◽

Acid Gel

Introduction: Microleakage has been reported to cause dentin hypersensitivity because of the passage of bacteria and their products through the restoration-tooth interface and is one of the main reasons for replacement of restorations. CO2 laser can be used for treatment of dentin hypersensitivity. Thus, this study aimed to evaluate in vitro the microleakage in composite restorations following surface pretreatment with acid etching and CO2 laser. Methods: Twelve human caries-free primary molars were selected. Class II cavities were prepared on occlusal mesial and occlusal distal surfaces. Specimens were randomly divided into four groups (n=6): Group 1 (G1) – 37% phosphoric acid gel etching + Beautiful-Bulk Restorative – Giomer (Shofu Inc); Group 2 (G2) – 37% phosphoric acid gel etching + SDR Bulk-Fill Flow (Dentsply); Group 3 (G3) – CO2 laser irradiation + Beautiful-Bulk Restorative – Giomer (Shofu Inc); Group 4 (G4) – CO2 laser irradiation + SDR Bulk-Fill Flow (Dentsply). Surfaces were restored with bonding agent (Natural Bond DE, DFL). Specimens were cut longitudinally and immersed in 0.5% methylene blue solution for 4 hours. Microleakage scores were assessed under a magnifying glass at x3,5 and qualitatively analyzed by scanning electron microscope (SEM). Data were analyzed using nonparametric Wilcoxon test (P < 0.05). Results: Scores prevailed between 0 and 2, however, no statistically significant difference was found among the groups (P= 0.05). Conclusion: It could be concluded that all composite resins bulk fill did not show significant difference among them regarding microleakage using either CO2 laser or 37% phosphoric acid etching.

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The Bactericidal Effect of CO2 Laser on Pseudomonas aeruginosa Isolated from Wound and Burn Infections, In-Vitro

Baghdad Science Journal ◽

10.21123/bsj.12.3.485-495 ◽

2015 ◽

Vol 12 (3) ◽

pp. 485-495

Author(s):

Baghdad Science Journal

Keyword(s):

Pseudomonas Aeruginosa ◽

Laser Irradiation ◽

Virulence Factors ◽

Co2 Laser ◽

Exposure Time ◽

Antibiotic Susceptibility ◽

Bactericidal Effect ◽

Bacteriological Diagnosis ◽

The Mean ◽

Power Densities

A total of 60 cotton swabs are collected from patients suffering from burn wound and surgical site infections admitted to Baghdad Teaching Hospital and Burn Specialist Hospital in Baghdad city during 9/2013 to 11/2013. All cotton swabs are cultured initially on blood agar and MacConkey agar and subjected for standard bacteriological procedures for bacteriological diagnosis. Twenty samples out of sixty are identified as Pseudomonas aeruginosa by conventional methods. The results of antibiotic susceptibility test illustrate that the antibiotics resistance rate of Pseudomonas aeruginosa isolates is as follows:100% (2020) for ceftriaxone, cefepime and carbencillin, 70% (14/20) for amikacin, 65%(13/20) for tobramycin, ceftazidim and gentamycin, 55% (11/20) for ciprofloxacin and norfloxacin, 50% (10/20) for piperacillin and impeneme, 30% (6/20) for aztreonam. All Pseudomonas aeruginosa isolates are investigated for detection of some virulence factors (haemolysin, protease, lipase enzymes, and extracellular pigments) and biofilm formation. The results of virulence factors reveal that all the isolates are haemolysin, protease, lipase enzymes and extracellular pigments producer, while 95% of the isolates are biofilm producer. Six isolates are selected to irradiation by using CO2 laser according to the results of antibiotic susceptibility and virulence factors at power densities (2000, 2500, and 3000) W/cm2 with exposure time (60 and 90) second. The results of CO2 laser irradiation illustrate that CO2 laser irradiation lead to a reduction in the mean value of the viable number CFU/ml of Pseudomonas aeruginosa isolates with the increase of the power density and exposure time. The results of the statistical analysis by using analysis of variance (ANOVA) one way and least significant differences-LSD show that there are statistical significant differences in the mean of the viable number CFU/ml between different power densities and different exposure times. After irradiation, antibiotic susceptibility and virulence factors tests of the irradiated strains are performed. The current study concludes that CO2 laser has bactericidal effect on P. aeruginosa isolates without any effect on its antibiotics susceptibility and virulence factors.

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