Adjunctive use of different lasers Er, Cr: YSGG, femtosecond, potassium titanyl phosphate and photodynamic therapy on radicular disinfection bonded to glass fiber post.

OBJECTIVE: The aim of this study was to evaluate and compare the effect of different laser prototypes [Er, Cr: YSGG laser (ECYL), potassium titanyl phosphate laser (KTP), and Femtosecond laser (FSL)]and curcumin photosensitizer (CP) activated by Photodynamic therapy (PDT) on the bond strength of Pre-fabricated fiber reinforced composite (PFRC) post-bonded to radicular dentin. MATERIALS AND METHODS: A total of fifty mandibular single-rooted closed apex teeth were extracted carefully, assembled, and decoronated up to the cementoenamel junction. The working length of all specimens was determined by using a 10 K patency file and later, were cleaned and shaped with Protaper NiTi system using the crown down approach, dried, and obturated with gutta-percha using an AH Plus sealer. Post space was prepared by guiding peeso-reamer. Based on the method of disinfection, the samples were allocated to five groups (n=10) at random: samples in group 1: curcumin photosensitizer (CP) activated by PDT, samples in group 2 disinfected using 5.25% NaOCl+17% EDTA, samples in group 3 disinfected using 5.25% NaOCl+17% EDTA+FSL, specimens in group 4 sterilized using 5.25% NaOCl+17% EDTA+KTP and samples in group 5 cleaned with 5.25% NaOCl+17% EDTA+ECYL. The fiber post was cemented via self-etch resin cement into the post space. All specimens with posts were dissected perpendicularly into apical, middle, and coronal dentin and subjected to the universal testing machine for push-out bond strength (PBS) testing. Statistical analysis was performed using a One-Way analysis of variance and Post Hoc Tukey multiple comparison tests. RESULTS: The highest PBS was corroborated when the radicular canal was disinfected with 5.25% NaOCl +17% EDTA+ ECYL at all three root levels (coronal, middle, and apical) and the lowest was adjudicated by decontamination with CP activated by PDT at all inspected root levels. Intergroup comparison presented that specimens in group 2: 5.25% NaOCl+17% EDTA (control) and group 4: 5.25% NaOCl+17% EDTA+KTP revealed comparable PBS outcome to group 5 (p>0.05) while samples in group 3 revealed the equivalent PBS values to group 1 (p<0.05) at all three root levels. CONCLUSIONS: Er, Cr: YSGG laser and potassium titanyl phosphate laser when used in combination with the conventional canal disinfection 5.25% NaOCl and 17% EDTA demonstrated the highest push-out bond strength values at coronal, middle, and apical levels of the root.

Disinfection capabilities of a 222 nm wavelength ultraviolet lighting device: a pilot study.

OBJECTIVE: To demonstrate the efficacy of the SafeZone UVC (Ushio Inc., Japan) 222 nm ultraviolet C (UVC) light to reduce bacterial burden in pressure ulcers (PUs) in human patients. This research is the first human clinical trial using 222 nm UVC in eradicating bacteria in human wounds. METHOD: Patients with Stage 2 or 3 (as defined by the revised National Pressure Ulcer Advisory Panel Pressure Injury Staging System) sacral or gluteal pressure ulcers (PUs) were subjected to four sessions of 222 nm UVC light therapy over two weeks. Pre- and post-UVC therapy, wound cultures were taken and quantitative analysis of bacterial colony forming units (CFU) were performed. RESULTS: A total of 68 UV light sessions across 16 different patients were conducted. Of these sessions, 59 (87.0%) sessions showed a reduction in CFU counts, with 20 (29.4%) showing complete eradication of bacteria. Bacteria identified included meticillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella Pneumoniae. The overall median reduction in CFU of the 68 sessions was 78.9%. No adverse events were reported in any of the UV sessions. CONCLUSION: In this study, 222 nm UVC light was safe and effective in reducing bacterial CFU counts in sacral and gluteal PUs across numerous different species of bacteria.

Characterizing the Antimicrobial Properties of 405 nm Light and the Corning® Light-Diffusing Fiber Delivery System.

BACKGROUND AND OBJECTIVES: Hospital-acquired infections (HAIs) and multidrug resistant bacteria pose a significant threat to the U.S. healthcare system. With a dearth of new antibiotic approvals, novel antimicrobial strategies are required to help solve this problem. Violet-blue visible light (400-470 nm) has been shown to elicit strong antimicrobial effects toward many pathogens, including representatives of the ESKAPE bacterial pathogens, which have a high propensity to cause HAIs. However, phototherapeutic solutions to prevention or treating infections are currently limited by efficient and nonobtrusive light-delivery mechanisms. STUDY DESIGN/MATERIALS AND METHODS: Here, we investigate the in vitro antimicrobial properties of flexible Corning® light-diffusing fiber (LDF) toward members of the ESKAPE pathogens in a variety of growth states and in the context of biological materials. Bacteria were grown on agar surfaces, in liquid culture and on abiotic surfaces. We also explored the effects of 405 nm light within the presence of lung surfactant, human serum, and on eukaryotic cells. Pathogens tested include Enterococcus spp, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., Staphylococcus epidermidis, Streptococcus pyogenes, Candida albicans, and Escherichia coli. RESULTS: Overall, the LDF delivery of 405 nm violet-blue light exerted a significant degree of microbicidal activity against a wide range of pathogens under diverse experimental conditions. CONCLUSIONS: The results exemplify the fiber's promise as a non-traditional approach for the prevention and/or therapeutic intervention of HAIs. Lasers Surg. Med. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

The effect of Blephadex™ Eyelid Wipes on Demodex mites, ocular microbiota, bacterial lipase and comfort: a pilot study.

PURPOSE: To investigate the effect of Blephadex™ Eyelid Wipes on Demodex mites, ocular microbiota, bacterial lipase, tear film characteristics and ocular comfort after one month of daily use. METHODS: Twenty subjects were randomly assigned to use the Blephadex™ Eyelid Wipes on either eye once daily for 30 days whilst the contralateral eye was left untreated in this observer-masked, within-subject study. Demodex count, eyelid bacterial colony count, Tearscope Plus non-invasive tear break up time (NITBUT), Lipiview® tear film lipid layer thickness and phenol red thread test tear volume were measured at baseline and 30 days. Bacterial lipase was quantified from single bacterial colonies using a glycerol monolaurate assay. Ocular comfort was assessed at both visits using the Ocular Surface Disease Index (OSDI) questionnaire and visual analogue scales (VAS) to capture monocular symptoms of itching, dryness and overall discomfort. RESULTS: Six males and 14 females, median age 63.5 (range 48-76) completed the study. A statistically significant reduction in Demodex count was observed in treated eyes only (median ±â€¯IQR: treated eyes 2 ±â€¯3 vs. 0 ±â€¯2, ANOVA p = 0.04). Bacterial colony count, lipase production, NITBUT, lipid layer thickness and tear volume remained unchanged (p > 0.05). Overall comfort improved over time in treated eyes only (15 ±â€¯32 vs. 10 ±â€¯16, p = 0.05). Dryness symptoms significantly reduced in both treated and untreated eyes (23 ±â€¯42 vs. 12 ±â€¯21 and 23 ±â€¯41 vs. 10 ±â€¯15, p = 0.02). The OSDI and ocular itch scores remained unchanged (p > 0.05). CONCLUSION: In this pilot study, no changes were observed in ocular microbiota, tear film characteristics or bacterial lipase in eyes treated with Blephadex™ Eyelid Wipes after one month of daily use in this normal healthy population. Although a statistically significant reduction in Demodex count was observed in treated eyes, overall numbers of Demodex were low. A parallel group, placebo-controlled, randomised clinical trial in a population with active blepharitis is warranted to further elucidate these preliminary findings.

In Vitro Effect of Er:YAG Laser on Different Single and Mixed Microorganisms Being Associated with Endodontic Infections.

Objective: The purpose of this in vitro study was to evaluate the antimicrobial effect of activated irrigation with different modes of erbium-doped yttrium aluminum garnet (Er:YAG) laser application on microorganisms related to secondary endodontic infection. Background: Er:YAG laser has been recommended as an adjuvant tool for root canal disinfection during endodontic treatment. Materials and methods: Laser-activated irrigation (LAI) with 300 or 600 µm tips were tested with or without intermittent irrigation with 0.9% sodium chloride (NaCl) solution against different microorganisms (five single strains and dual species (Streptococcus gordonii combined with Actinomyces oris or Fusobacterium nucleatum) in root canals after 3 days of incubation. In a 21-day infection model, LAI was used together with intermittent rinsing with sodium hypochlorite (NaOCl) against the dual-species mixtures; here the incidence of microbial regrowth after up to 7 days was monitored. Results: In the 3-day root infection model, LAI protocols did not show any significant reduction of the microbial load when compared with manual irrigation with saline solution. In the 21-day infection, S. gordonii combined with A. oris were not detectable anymore after applying the LAI protocol with a 600 µm tip (30 mJ/10 pps) up to 7 days after treatment. Conclusions: Application of LAI with a 600 µm tip by using an Er:YAG laser might be advantageous in treatment of endodontic infections.

Safety and efficacy of wiping lid margins with lid hygiene shampoo using the "eye brush", a novel lid hygiene item, in healthy subjects: a pilot study.

BACKGROUND: To evaluate the safety and efficacy of using a lid hygiene brush prototype to wipe the lid margins with lid hygiene shampoo in subjects with normal meibomian glands. METHODS: Twelve eyes of 6 subjects were all evaluated just before and after wiping lid margins using 1) tap water alone, 2) Eye Shampoo, 3) Eye Brush, or 4) both products, each during a different week. The results after using both products twice daily for 1 month were also evaluated. Wiping efficacy was determined by post-wiping scores for the remaining fluorescein-stained 0.3% Tarivid ointment fully applied to eyelids and lid margins under microscopic view illuminated by blue light just after performing each of the four lid hygiene methods described above. RESULTS: No significant deterioration in ocular conditions occurred. Eyestrain, eye discharge, and dryness decreased with tap water (P = 0.020), Eye Shampoo (P = 0.036), and Eye Brush (P = 0.014), respectively. Sensations of eye discharge increased after 1 month of using both products (P = 0.042). The wiping efficacy of Eye Brush, Eye Shampoo or both was significantly greater than that of tap water alone (two-sided test, P = 0.003, 0.003, 0.002), and using both significantly increased efficacy above Eye Shampoo use alone (one-sided test, P = 0.009). CONCLUSIONS: Wiping lid margins using Eye Brush enhanced the cleansing power of Eye Shampoo. A daily healthcare routine using both products could be a safe and effective option for daily lid hygiene. TRIAL REGISTRATION: UMIN000016905 . Registration date: March 24, 2015; the study was prospectively registered.

Manual Operated Ultraviolet Surface Decontamination for Healthcare Environments.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a new handheld equipment based on a mercury low-pressure vapor lamp. The Surface UV® device was tested in Staphylococcus aureus, Streptococcus mutans, Streptococcus pneumoniae, two strains of Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and other clinical microorganisms isolated from different surfaces of a public health hospital. BACKGROUND DATA: The incidence of hospital infections has increased in recent years. Despite the variety of available chemicals to reduce the microorganisms, the search for antimicrobial agents and the characterization of novel targets are a continued need. Also, the minimization of chemical procedures is a constant need, and the use of ultraviolet (UV) light as a germicidal device for microorganisms' inactivation has been an alternative and one possible approach for the reduction of contamination. MATERIALS AND METHODS: The in vitro decontamination was performed by application of Surface UV in different species of microorganisms (study 1). The surface decontamination was carried out by application of Surface UV on each surface of hospital environment (study 2). The device presents ultraviolet C (UV-C) light at 254 nm and produces an irradiance of 13 mW/cm2 at a distance of 1 cm of the surfaces. The light dose was 0.78 J/cm2 for 60 sec of application in both studies. RESULTS: The results for in vitro decontamination indicated a log10 reduction factor of 6.5 for S. aureus, 6.7 for S. mutans, 6.2 for S. pneumoniae, 5.4 for E. coli, 5.2 for E. coli (ATCC 8739), 5.4 for P. aeruginosa, and 6.7 for C. albicans. The hospital level of microorganisms decreases more by 75% after the procedure. CONCLUSIONS: The study highlights the development and successful application of a new portable device that can reduce the risk of contamination in health settings. Our results suggest that Surface UV is efficient and may be an alternative decontamination method.

Efficacy and safety of a therapeutic apparatus using hydrogen peroxide photolysis to treat dental and periodontal infectious diseases.

The present study aimed to evaluate the acute locally injurious property of our most current hydroxyl radical generation system by hydrogen peroxide (H2O2) photolysis. This system, which releases 3% H2O2 with a 405-nm laser, was developed in our laboratory for the treatment of dental and periodontal infectious diseases. First, the hydroxyl radical yield generated by H2O2 photolysis was examined by applying an electron spin resonance-spin trapping technique. Second, the bactericidal effect of the device was examined under a simulant condition in which Streptococcus mutans, a pathogenic bacterial species that causes caries, was irrigated with running 3% H2O2 concomitantly with laser irradiation. Finally, the acute topical effect of the model apparatus on rat palatal mucosa was evaluated by histological examination. We found that the hydroxyl radical yield was dependent upon laser output power. The bacterial count was substantially reduced within as little as 3 min. No abnormal findings were observed in the palatal mucosa, even when rats received three treatments of 3% H2O2 with laser irradiation at an output power of 40 mW. These results suggest that our apparatus has the ability to kill bacteria via hydroxyl radical generation and is safe to use at the lesion site of dental and periodontal infectious diseases.

COD, nutrient removal and disinfection efficiency of a combined subsurface and surface flow constructed wetland: A case study.

A constructed wetland system composed of a subsurface flow wetland, a surface flow wetland and a facultative pond was studied from July 2008 until May 2012. It was created to treat the domestic sewage produced by a hamlet of 150 inhabitants. Monthly physicochemical and microbiological analyses were carried out in order to evaluate the removal efficiency of each stage of the process and of the total treatment system. Pair-wise Student's t-tests showed that the mean removal of each considered parameter was significantly different (α = 0.05) between the various treatment phases. Two-way ANOVA and Tukey's HSD tests were used to find significant differences between wetland types and seasons in the removal efficiency of the considered water quality parameters. Significant differences in percent removal efficiency between the treatment phases were observed for total phosphorus, total nitrogen, ammonia nitrogen and organic load (expressed as Chemical Oxygen Demand). In general, the wastewater treatment was carried by the sub-superficial flow phase mainly, both in growing season and in quiescence season. Escherichia coli removal ranged from 98% in quiescence season to >99% in growing season (approximately 2-3 orders of magnitude). The inactivation of fecal bacteria was not influenced by the season, but only by the treatment phase.

Hydrophilic, bactericidal nanoheater-enabled reverse osmosis membranes to improve fouling resistance.

Polyamide (PA) semipermeable membranes typically used for reverse osmosis water treatment processes are prone to fouling, which reduces the amount and quality of water produced. By synergistically coupling the photothermal and bactericidal properties of graphene oxide (GO) nanosheets, gold nanostars (AuNS), and hydrophilic polyethylene glycol (PEG) on PA reverse osmosis membrane surfaces, we have dramatically improved fouling resistance of these membranes. Batch fouling experiments from three classes of fouling are presented: mineral scaling (CaCO3 and CaSO4), organic fouling (humic acid), and biofouling (Escherichia coli). Systematic analyses and a variety of complementary techniques were used to elucidate fouling resistance mechanisms from each layer of modification on the membrane surface. Both mineral scaling and organic fouling were significantly reduced in PA-GO-AuNS-PEG membranes compared to other membranes. The PA-GO-AuNS-PEG membrane was also effective in killing all near-surface bacteria compared to PA membranes. In the PA-GO-AuNS-PEG membrane, the GO nanosheets act as templates for in situ AuNS growth, which then facilitated localized heating upon irradiation by an 808 nm laser inactivating bacteria on the membrane surface. Furthermore, AuNS in the membrane assisted PEG in preventing mineral scaling on the membrane surface. In flow-through flux and foulant rejection tests, PA-GO-AuNS-PEG membranes performed better than PA membranes in the presence of CaSO4 and humic acid model foulants. Therefore, the newly suggested membrane surface modifications will not only reduce fouling from RO feeds, but can improve overall membrane performance. Our innovative membrane design reported in this study can significantly extend the lifetime and water treatment efficacy of reverse osmosis membranes to alleviate escalating global water shortage from rising energy demands.

Eficacia antimicrobiana de la terapia fotodinámica en la desinfección de los conductos radiculares: estudio ex vivo / Antimicrobial efficacy of photodynamic therapy in the disinfection of root canal: ex vivo study

Objetivo: Evaluar la eficacia antimicrobiana de la terapia fotodinámica (TFD) mediante el empleo de una solución colorante azul de ortotoluidina (AOT) y una luz emitida por un diodo (LED), en dientes humanos ex vivo, inoculados con Enterococcus faecalis. Meterial y método: Se utilizaron 34 piezas dentarias humanas unirradiculares que fueron preparadas biomecánicamente y esterilizadas. Las muestras fueron divididas al azar en cinco grupos experimentales: I (n = 2) control positivo, II (n = 10) NaOCL 2,5% + NaOCL 2,5%, III (n = 10) NaOCL 2,5% + AOT + LED, IV (n = 10) NaCOL 2,5% + AOT y V (n = 2) control negativo. Todos los grupos, excepto el grupo V (control de esterilidad), fueron inoculados con 30 μl de Enterococcus faecalis e incubados por 24 horas, previo sellado de la superficie externa. Luego de realizar los tratamientos correspondientes se tomaron muestras, por duplicado, para ser procesadas microbiológicamente y efectuar el recuento de unidades formadoras de colonias (UFC). Los resultados fueron evaluados mediante la prueba de Chi cuadrado (X2). Resultados: En el grupo I hubo desarrollo de UFC/ml (2,85 x 107) y se empleó para comparar los otros grupos. Los grupos II, III y V no presentaron desarrollo bacteriano, sin diferencias significativas en sus resultados (p > 0,05). Sin embargo, hubo diferencias entre estos y los grupos I y IV (1,25 x 107). Conclusión: En las condiciones de este estudio la terapia fotodinámica (TFD) con AOT y LED demostró tener potencial antimicrobiano para su uso como coadyuvante en la preparación biomecánica de los conductos radiculares

Aim: To evaluate the antimicrobial efficacy of photodynamic therapy by employing a solution of ortho toluidine blue dye (AOT) and a light emitting-diode (LED), human teeth ex vivo, were inoculated with Enterococcus faecalis. Materials and methods: We used 34 single-rooted human teeth, which were biomechanically prepared and sterilized. Samples were divided randomly into 5 experimental groups: I (n = 2) positive control, II (n = 10) 2.5% NaOCl + 2.5% NaOCl, III (n = 10) 2.5% NaOCl + AOT + LED, IV (n = 10) 2.5% NACOL + AOT and V (n = 2) negative control. All groups except group V (sterility control) were inoculated with 30 μl of Enterococcus faecalis, and incubated for 24 hours before sealing the outer surface. After performing appropriate treatments, samples were taken, in duplicate, to be processed microbiologically and for the determination of colony forming units (CFU). The Chi-square test was used to evaluate the results of this study. Results: The results showed the development of UFC/ml (2.85 x 107) in Group I and served to compare the other groups. Groups II and III showed no statistically significant differences in the results (p > 0.05) between them and respect to Group V (negative control). However, there were differences between them and Groups I and IV (1.25 x 107). Conclusion: Under the conditions of this study, photodynamic therapy with AOT/LED shown to have antimicrobial potential for use as an adjunct in the biomechanical preparation of root Canals

Biogenic nanosilver incorporated reverse osmosis membrane for antibacterial and antifungal activities against selected pathogenic strains: an enhanced eco-friendly water disinfection approach.

Reverse osmosis (RO) membranes have been used extensively in water desalination plants, waste water treatment in industries, agricultural farms and drinking water production applications. The objective of this work is to impart antibacterial and antifungal activities to commercially available RO membrane used in water purification systems by incorporating biogenic silver nanoparticles(AgNPs) synthesized using Rosa indica wichuriana hybrid leaf extract. The morphology and surface topography of uncoated and AgNPs-coated RO membrane were studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Elemental composition of the AgNPs-coated RO membrane was analyzed by energy-dispersive X-ray spectroscopy (EDAX). The functional groups were identified by Fourier Transform Infrared spectroscopy (FT-IR). Hydrophilicity of the uncoated and AgNPs-coated RO membrane was analyzed using water contact angle measurements. The thermal properties were studied by thermogravimetric analysis (TGA). The AgNPs incorporated RO membrane exhibited good antibacterial and antifungal activities against pathogenic bacterial strains such as E. coli, S. aureus, M. luteus, K. pneumoniae, and P. aeruginosa and fungal strains such as Candida tropicalis, C. krusei, C. glabrata, and C. albicans.

The efficiency of root canal disinfection using a diode laser: in vitro study.

AIMS: The aim of this study is to verify the disinfection of diode laser, following chemo-mechanical procedures against Enterococcus fecalis. MATERIALS AND METHODS: Crowns of 30 extracted premolar teeth were sectioned at the cemento- enamel junction. The canals were shaped using step-back technique to K-file #40. The teeth were randomly assigned to three groups and placed into nutrient broth containing bacterial suspension of Enterococcus fecalis. Group A received no laser radiation. Specimens of group B and C were treated with diode laser (Sirona) with energy set at 1.5 and 3 W, respectively. After laser irradiation, the teeth were placed in vials, which contained 2 mL of the nutrient broth. The vials were incubated at 37°C for 24 h. Grown colonies were identified by standard methods. STATISTICAL ANALYSIS USED: Statistical analysis used was the nonparametric Kruskal-Wallis test, with comparison using the Bonferroni methods of means. RESULTS: Higher mean CFU/mL is recorded in Group A (without laser disinfection) followed by Group B (with 1.5 W laser disinfection) and Group C (with 3 W laser disinfection), respectively. The difference in CFU/mL between the three groups is found to be statistically significant ( P < 0.001). CONCLUSIONS: The results of this research show that the 980 nm diode laser can eliminate bacteria that has immigrated into dentin, thus being able to increase the success rate in endodontic therapy.

Investigation of the mutagenic potential of cold atmospheric plasma at bactericidal dosages.

In the past few years, cold atmospheric plasma (CAP) has evolved into a new tool in the fight against nosocomial infections and antibiotic-resistant microorganisms. The products generated by the plasma-electrons, ions, reactive species and UV light-represent a 'lethal cocktail' for different kinds of pathogen, which opens up possible applications in hygiene and medicine. Nevertheless, to ensure the safe usage of CAP on skin (e.g., to treat wounds or skin diseases) several pre-clinical in vitro studies have to be performed before implementing clinical trials on humans. In the study presented here, inactivation experiments with Escherichia coli were carried out to identify the necessary plasma dosage for a 5 log reduction: with a small hand-held battery-operated CAP device, these disinfection properties were achieved after application during 30s. This and higher plasma dosages were then used to analyze the mutagenicity induced in V79 Chinese hamster cells-to furthermore define a 'safe application window'-with the HPRT (hypoxanthine-guanine phosphoribosyl transferase) mutation assay. The results show that a CAP treatment of up to 240 s and repeated treatments of 30s every 12h did not induce mutagenicity at the Hprt locus beyond naturally occurring spontaneous mutations.

Disinfection of root canals with photon-initiated photoacoustic streaming.

INTRODUCTION: This study set out to compare the efficacy of laser-activated and ultrasonically activated root canal disinfection with conventional irrigation, specifically its ability to remove bacterial film formed on root canal walls. METHODS: Seventy human premolars were shaped to an apical size #20, taper .07, sterilized, and contaminated in situ with oral bacteria for 1 week and incubated for 2 more weeks. Irrigation was done with 6% NaOCl (group 1), NaOCl ultrasonically activated with blunt inserts (group 2), or a pulsed erbium:YAG laser at nonablative settings (group 3) for a total of 60 seconds each. Positive and negative controls were also included. Aerobic bacterial sampling was performed, and the incidence of positive samples after 24 and 48 hours as well as bacterial counts (colony-forming units) were determined. Fixed and demineralized sections 1 mm and 4 mm off the apex were Brown-Brenn stained and assessed for remaining intracanal bacteria/biofilm and dentinal tubule penetration. RESULTS: All 3 canal disinfection protocols significantly reduced bacterial counts (P < .001). None of the 3 techniques predictably generated negative samples, but laser-activated disinfection was superior to the other 2 techniques in this aspect (P < .05). Histologic sections showed variable remaining bacterial presence in dentinal tubules at the 4-mm level and significantly less bacterial biofilm/necrotic tissue remaining at the 1-mm level after laser-activated irrigation (P < .05). CONCLUSIONS: Under the conditions of this combined in situ/in vitro study, activated disinfection did not completely remove bacteria from the apical root canal third and infected dentinal tubules. However, the fact that laser activation generated more negative bacterial samples and left less apical bacteria/biofilm than ultrasonic activation warrants further investigation.

Disinfection of Pseudomonas aeruginosa biofilm contaminated tube lumens with ultraviolet C light emitting diodes.

Bacterial biofilms on long-term catheters are a major source of infection. Exposure to ultraviolet C (UVC - 265 nm) light was shown in an earlier study to reduce the number of bacteria substantially on ex vivo treated urinary patient catheters. Very large doses (long treatment times) should, however, be applied to obtain 99.9% disinfection rates. The major reason was that besides cells the mature biofilm contained absorbing and scattering particulates, which made the biofilm opaque. The potential of UVC light emitting diodes (LED) for disinfection purposes in catheter-like tubes contaminated with biofilm was investigated. It was shown that UVC light propagation was possible through both Teflon and catheter tubes (silicone). The disinfection efficiency of the diodes was demonstrated on tubes contaminated artificially with a Pseudomonas aeruginosa biofilm. The tubes were connected to a flow system and biofilms were produced during a 3 day period. Tubes in lengths of 10 (Teflon, silicone) and 20 cm (Teflon) were contaminated. Tubes for control and for UVC treatment were contaminated in parallel. Biofilms were sampled from the total inner surface of the tubes. Colony counts on the control samples were in the range of 5 x 10(5)-1.3 x 10(9) CFU ml(-1), with disinfection rates in the range 96-100%. The applied UVC doses corresponded to treatment times between 15 and 300 min. Disinfection (100%) was obtained in 10 cm Teflon tubes exposed for 30 min (detection limit <5 CFU ml(-1)). The same result was obtained for a 20 cm Teflon tube exposed for 300 min. The disinfection rate was 96% for the 20 cm tube if the dose was reduced to 30 min. A disinfection rate of 99.99% was observed for a 10 cm peritoneal dialysis catheter tube (silicone) exposed for 300 min. Differences between the tubes were dependent on the differences in length and the type of the material. The UVC light was transmitted six times more efficiently in Teflon than in silicone tubes of equal length (10 cm). The germicidal effect to obtain a 99.99% killing rate for the biofilm ( approximately 78 J m(-2)) is comparable to that for the planktonic bacterium. It is concluded that there is potential for LED UVC light sources if they are used for disinfection of thin biofilms.

Development of an ecologically sustainable wastewater treatment system.

The present study aimed mainly for the development of a wastewater treatment system incorporating enhanced primary treatment, anaerobic digestion of coagulated organics, biofilm aerobic process for the removal of soluble organics and disinfection of treated water. An attempt was also made to study the reuse potential of treated water for irrigation and use of digested sludge as soil conditioner by growing marigold plants. Ferric chloride dose of 30 mg/l was found to be the optimum dose for enhanced primary treatment with removals of COD and BOD to the extent of 60% and 77%, respectively. Efficient anaerobic digestion of ferric coagulated sludge was performed at 7 days hydraulic retention time (HRT). Upflow aerobic fixed film reactor (UAFFR) was very efficient in removals of COD/BOD in the organic loading rate (OLR) range of 0.25 to 3 kg COD/m(3)/day with COD and BOD removals in the range 65-90 and 82-96, respectively. Photo-oxidation followed by disinfection saved 50% of chlorine dose required for disinfection of treated effluent and treated water was found to be suitable for irrigation. The result also indicated that anaerobically digested sludge may be an excellent soil conditioner. From the results of this study, it is possible to conclude that the developed wastewater treatment system is an attractive ecologically sustainable alternative for sewage treatment from institutional/industrial/residential campuses.

High-power diode laser in the disinfection in depth of the root canal dentin.

OBJECTIVE: The objective of this study was to evaluate the disinfection degree of dentine caused by the use of diode laser after biomechanical procedures. STUDY DESIGN: Thirty teeth were sectioned and roots were autoclaved and incubated for 4 weeks with a suspension of Enterococcus faecalis. The specimens were randomly divided into 3 groups (n = 10): G1, instrumented with rotary files, irrigated with 0.5% sodium hypochlorite and 17% EDTA-T, and then irradiated by 830-nm diode laser at 3 W; G2, the same procedures as G1 but without laser irradiation; and G3, irrigation with saline solution (control). Dentin samples of each third were collected with carbide burs and aliquots were sowed to count viable cells. RESULTS: The disinfection degree achieved was 100% in G1 and 98.39% in G2, when compared to the control group (G3). CONCLUSION: Diode laser irradiation provided increased disinfection of the deep radicular dentin in the parameters and samples tested.