Dental pulp vascular permeability changes induced by dental bleaching

Aiming to compare the effect of different light sources for dental bleaching on vascular permeability of dental pulps, forty-eight incisors were used. The bleaching agent (35 % hydrogen peroxide) was activated by halogen light; LED (Light Emitting Diode) or LED, followed by laser phototherapy (LPT) (λ = 780 nm; 3 J/cm²). After the bleaching procedures, the animals received an intra-arterial dye injection and one hour later were sacrificed. The teeth were diaphanized and photographed. The amount of blue stain content of each dental pulp was quantified using a computer imaging program. The data was statistically compared (p < 0.05). The results showed a significant higher (p < 0.01) dye content in the groups bleached with halogen light, compared with the control, LED and LED plus LPT groups. Thus, tooth bleaching activated by LED or LED plus LPT induces lesser resulted in increased vascular permeability than halogen light.

Influence of light curing source on microhardness of composite resins of different shades

Introduction: The evolution of light curing units can be noticed by the different systems recently introduced. The technology of LED units promises longer lifetime, without heating and with production of specific light for activation of camphorquinone. However, further studies are still required to check the real curing effectiveness of these units. Purpose: This study evaluated the microhardness of 4 shades (B-0.5, B-1, B-2 and B-3) of composite resin Filtek Z-250 (3M ESPE) after light curing with 4 light sources, being one halogen (Ultralux - Dabi Atlante) and three LED (Ultraled - Dabi Atlante, Ultrablue - DMC and Elipar Freelight - 3M ESPE). Methods: 192 specimens were distributed into 16 groups, and materials were inserted in a single increment in cylindrical templates measuring 4mm x 4mm and light cured as recommended by the manufacturer. Then, they were submitted to microhardness test on the top and bottom aspects of the cylinders. Results: The hardness values achieved were submitted to analysis of variance and to Tukey test at 5% confidence level. It was observed that microhardness of specimens varied according to the shade of the material and light sources employed. The LED appliance emitting greater light intensity provided the highest hardness values with shade B-0.5, allowing the best curing. On the other hand, appliances with low light intensity were the least effective. It was also observed that the bottom of specimens was more sensitive to changes in shade. Conclusion: Light intensity of LED light curing units is fundamental for their good functioning, especially when applied in resins with darker shades.

Degree of conversion of different composite resins photo-activated with light-emitting diode and argon ion laser

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Degree of conversion of different composite resins photo-activated with light-emitting diode and argon ion laser

This study evaluated the degree of conversion (DC%) of one experimental and different brands of composite resins light-cured by two light sources (one LED and one argon laser). The percentage of unreacted C = C was determined from the ratio of absorbance intensities of aliphatic C = C (peak at 1637 cm−1) against internal standards before and after curing: aromatic C–C (peak at 1610 cm−1) except for P90, where %C = C bonds was given for C–O–C (883 cm−1) and C–C (1257 cm−1). ANOVA and Tukey’s test revealed no statistically significant difference among Z350 (67.17), Z250 (69.52) and experimental (66.61 ± 2.03) with LED, just among them and Evolu-X (75.51) and P90 (32.05) that showed higher and lower DC%, respectively. For the argon laser, there were no differences among Z250 (70.67), Z350 (69.60), experimental (65.66) and Evolu-X (73, 37), however a significant difference was observed for P90 (36.80), which showed lowest DC%. The light sources showed similar DC%, however the main difference was observed regarding the composite resins. The lowest DC% was observed for the argon laser. P90 showed the lowest DC% for both light-curing sources.

Knoop Microhardness and FT-Raman Spectroscopic Evaluation of a Resin-Based Dental Material Light-Cured by an Argon Ion Laser and Halogen Lamp: An in Vitro Study

Objective: The purpose of this study was to evaluate in vitro the Knoop microhardness (Knoop hardness number [KHN]) and the degree of conversion using FT-Raman spectroscopy of a light-cured microhybrid resin composite (Z350-3M-ESPE) Vita shade A3 photopolymerized with a halogen lamp or an argon ion laser. Background Data: Optimal polymerization of resin-based dental materials is important for longevity of restorations in dentistry. Materials and Methods: Thirty specimens were prepared and inserted into a disc-shaped polytetrafluoroethylene mold that was 2.0 mm thick and 3 mm in diameter. The specimens were divided into three groups (n = 10 each). Group 1 (G1) was light-cured for 20 sec with an Optilux 501 halogen light with an intensity of 1000 mW/cm(2). Group 2 (G2) was photopolymerized with an argon laser with a power of 150 mW for 10 sec, and group 3 (G3) was photopolymerized with an argon laser at 200 mW of power for 10 sec. All specimens were stored in distilled water for 24 h at 37 degrees C and kept in lightproof containers. For the KHN test five indentations were made and a depth of 100 mu m was maintained in each specimen. One hundred and fifty readings were obtained using a 25-g load for 45 sec. The degree of conversion values were measured by Raman spectroscopy. KHN and degree of conversion values were obtained on opposite sides of the irradiated surface. KHN and degree of conversion data were analyzed by one-way ANOVA and Tukey tests with statistical significance set at p < 0.05. Results: The results of KHN testing were G1 = 37.428 +/- 4.765; G2 = 23.588 +/- 6.269; and G3 = 21.652 +/- 4.393. The calculated degrees of conversion (DC%) were G1 = 48.57 +/- 2.11; G2 = 43.71 +/- 3.93; and G3 = 44.19 +/- 2.71. Conclusions: Polymerization with the halogen lamp ( G1) attained higher microhardness values than polymerization with the argon laser at power levels of 150 and 200 mW; there was no difference in hardness between the two argon laser groups. The results showed no statistically significant different degrees of conversion for the polymerization of composite samples with the two light sources tested.

Molecular screening of 246 Portuguese Aspergillus isolates among different clinical and environmental sources

Clinical and environmental samples from Portugal were screened for the presence of Aspergillus and the distributions of the species complexes were determined in order to understand how their distributions differ based on their source. Fifty-seven Aspergillus isolates from clinical samples were collected from 10 health institutions. Six species complexes were detected by internal transcribed spacer sequencing; Fumigati, Flavi, and Nigri were found most frequently (50.9%, 21.0%, and 15.8%, respectively). β-tubulin and calmodulin sequencing resulted in seven cryptic species (A. awamorii, A. brasiliensis, A. fructus, A. lentulus, A. sydowii, A. tubingensis, Emericella echinulata) being identified among the 57 isolates. Thirty-nine isolates of Aspergillus were recovered from beach sand and poultry farms, 31 from swine farms, and 80 from hospital environments, for a total 189 isolates. Eleven species complexes were found in these 189 isolates, and those belonging to the Versicolores species complex were found most frequently (23.8%). There was a significant association between the different environmental sources and distribution of the species complexes; the hospital environment had greater variability of species complexes than other environmental locations. A high prevalence of cryptic species within the Circumdati complex was detected in several environments; from the isolates analyzed, at least four cryptic species were identified, most of them growing at 37ºC. Because Aspergillus species complexes have different susceptibilities to antifungals, knowing the species-complex epidemiology for each setting, as well as the identification of cryptic species among the collected clinical isolates, is important. This may allow preventive and corrective measures to be taken, which may result in decreased exposure to those organisms and a better prognosis.

WATER FROM DIFFERENT SOURCES USED FOR THE IRRIGATION OF VEGETABLES TO BE MARKETED: RESEARCH ON Cryptosporidium spp., Giardia spp., AND COLIFORMS IN PARANA, BRAZIL

SUMMARY The aim of this work was to compare, from a parasitological ( Cryptosporidiumspp. and Giardia duodenalis), bacteriological (total and thermotolerants coliforms) and physicochemical perspective, water sources used for drinking and irrigation of vegetables intended to be sold for human consumption. From January 2010 to May 2011, samples of different water sources from vegetable producing properties were collected; 100 liters for parasitological analysis, 200 mL for bacteriological analysis, and five liters for physicochemical analysis. Water samples were filtered under vacuum with a kit containing a cellulose acetate membrane filter, 1.2 µm (Millipore(r), Barueri, SP, Brazil). The material retained on the membrane was mechanically extracted and analyzed by direct immunofluorescence (Merifluor(r)kit). From 20 rural properties investigated, 10 had artesian wells (40 samples), 10 had common wells (40 samples), and one had a mine (four samples), the latter contaminated by Cryptosporidiumspp. In samples from artesian wells, 90 to 130 meters depth, 42.5% were positive for total coliforms and 5.0% were identified to have abnormal coloration. From the samples of common wells, 14 to 37 meters depth, 87.5% were contaminated with total coliforms, 82.5% were positive for thermotolerant coliforms, and 12.5% had color abnormalities. We did not detect the presence of Giardiaspp. or Cryptosporidiumspp. in artesian and common wells. The use of artesian or common wells is an important step in the control of the spreading of zoonoses, particularly Cryptosporidiumspp. and Giardiaspp., as well as artesian wells for coliform control in local production of vegetables to be marketed.

Light-emitting diodes (LED) for domestic lighting: any risks for the eye?

Light-emitting diodes (LEDs) are taking an increasing place in the market of domestic lighting because they produce light with low energy consumption. In the EU, by 2016, no traditional incandescent light sources will be available and LEDs may become the major domestic light sources. Due to specific spectral and energetic characteristics of white LEDs as compared to other domestic light sources, some concerns have been raised regarding their safety for human health and particularly potential harmful risks for the eye. To conduct a health risk assessment on systems using LEDs, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES), a public body reporting to the French Ministers for ecology, for health and for employment, has organized a task group. This group consisted physicists, lighting and metrology specialists, retinal biologist and ophthalmologist who have worked together for a year. Part of this work has comprised the evaluation of group risks of different white LEDs commercialized on the French market, according to the standards and found that some of these lights belonged to the group risk 1 or 2. This paper gives a comprehensive analysis of the potential risks of white LEDs, taking into account pre-clinical knowledge as well as epidemiologic studies and reports the French Agency's recommendations to avoid potential retinal hazards.

TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

In this work, TiO2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB), facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, and Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m-2) and black-light lamps (BLL UV intensity: 17-20 W m-2). Samples were taken after each treatment stage. Results indicate that bacterial photocatalytic inactivation is affected by characteristics of the effluent, including turbidity, concentration of organic matter, and bacterial concentration, which depend of the type of biological pretreatment previously used.

Effects of different ammoniacal nitrogen sources on N-metabolism of the atmospheric bromeliad Tillandsia pohliana Mez

Increasing levels of atmospheric ammonia from anthropogenic sources have become a serious problem for natural vegetation. Short-term effects of different ammoniacal sources on the N metabolism of Tillandsia pohliana, an atmospheric bromeliad, were investigated. One-year-old, aseptically grown plants were transferred to a modified Knudson medium lacking N for three weeks. Plants were subsequently transferred to Knudson media supplemented with 0.5, 1.0, or 1.5 mM of N in the forms of NH3 or NH4+ as the sole N source. The activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH-NADH) were determined after 40 h. The GS activity was stimulated significantly by increasing the levels of the gaseous form. The GDH-NADH activity increased significantly under increasing N concentrations with NH3, while no significant differences were observed with NH4+ as a N source. These results may reflect a faster NH3 absorption by T. pohliana compared to NH4+ uptake. The increased activity of GDH-NADH in NH3 treatment may play a role in protecting the cells from the toxic effects of increased endogenous level of free ammonium. A raise in the concentration of N, especially in the form of NH3, greatly increased the content of free amino acids and soluble proteins. A possible utilisation of T. pohliana to evaluate the changes of atmospheric gaseous ammonia is proposed.

Production of phycobiliproteins by Arthrospira platensis under different lightconditions for application in food products

There has been an increase in investment in research on new sources of natural pigments for food application. Some cyanobacteria can change the structures responsible for light harvesting and cellular processes according to the wavelength and light intensity. This phenomenon has been described as complementary chromatic adaptation. The present study aimed to investigate the growth of Arthrospira platensis using different light qualities, irradiance, and wavelength by evaluating the production of biomass, proteins, and phycobiliproteins. The occurrence of the chromatic adaptation phenomenon in this cyanobacterium was also investigated. The microorganism used in this study, A. platensis, was grown in a Zarrouk medium under three irradiance levels, 50, 100, and 150 μmol fotons.m–2.s–1 with illumination provided by white and green fluorescent lamps. The condition of 150 µmol fotons.m–2.s–1 white light was the one that promoted the highest biomass production of A. platensis cultures (2115.24 mg.L–1). There was no difference in the production of total protein and total phycobiliproteins under the studied conditions. It is likely that the large supply of nitrogen in the Zarrouk medium was sufficient for cell growth and maintenance, and it supplied the production of accessory pigments composed of protein. Finally, there was no evidence of the complementary chromatic adaptation phenomenon in A. platensis cultivated under green light. Moreover, this condition did not increase phycocyanin production.

Comparison of Botryosphaeran production by the ascomyceteous fungus Botryosphaeria sp., grown on different carbohydrate carbon sources, and their partial structural features

The influence of glucose concentration and other carbohydrates (monosaccharides: fructose, galactose, mannose; polyols: mannitol and sorbitol; disaccharides: lactose, sucrose and commercial sucrose; and industrial sugarcane molasses) were compared as sole carbon sources for the production of Botryosphaeran, an exopolysaccharide (EPS) produced by Botryosphaeria sp. The optimum glucose concentration for EPS production was 50 g 1(-1). With the exception of mannitol, the fungus produced EPS on all carbon sources studied, with highest yields occurring with sucrose followed by glucose. All EPS showed exclusively glucose after acid hydrolysis and monosaccharide analysis. FTIR spectroscopy demonstrated the presence of beta-anomers indicating that all the EPS produced by Botryosphaeria sp. on the different carbon sources were essentially of the beta-D-glucan type.

Clinical Evaluation of the Effectiveness of Different Bleaching Therapies in Vital Teeth

The aims of this in vivo study were to compare the effectiveness and color stability of at-home and in-office bleaching techniques and to evaluate whether the use of light sources can alter bleaching results. According to preestablished criteria, 40 patients were selected and randomly divided into four groups according to bleaching treatment: (1) at-home bleaching with 10% carbamide peroxide, (2) in-office bleaching with 35% hydrogen peroxide (HP) without a light source, (3) in-office bleaching with 35% HP with quartz-tungsten-halogen light, and (4) in-office bleaching with 35% HP with a light-emitting diode/laser. Tooth shade was evaluated using the VITA Classical Shade Guide before bleaching as well as after the first and third weeks of bleaching. Tooth shade was evaluated again using the same guide 1 and 6 months after the completion of treatment. The shade guide was arranged to yield scores that were used for statistical comparison. Statistical analysis using the Kruskal-Wallis test showed no significant differences among the groups for any time point (P > .01). There was no color rebound in any of the groups. The bleaching techniques tested were equally effective. Light sources are unnecessary to bleach teeth. (Int J Periodontics Restorative Dent 2012;32:303-309.)

Color alteration in teeth subjected to different bleaching techniques

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electron scattering and effects of sources of light on photoconductivity of SnO2 coatings prepared by sol-gel

Electro-optical properties of sol-gel derived 2 mol% antimony or niobium doped tin dioxide films have been measured. The electron density has been calculated considering all the relevant scattering mechanisms and experimental conductivity data measured in the range -197 to 25 degrees C. The results support the hypothesis that both ionised impurity scattering and grain boundary scattering have comparable effects in the resistivity of coatings, for free electron density congruent to 5 x 10(18) cm(-3). We have measured variation of photoconductivity excitation with wavelength using xenon and deuterium lamp as light sources. Results show that the main band in the photoconductivity spectrum is dependent on the spectral light source emission, the excitation peak reaching 5 eV (deuterium lamp). This band is due to the recombination process involving oxygen species and photogenerated electron-hole pairs. (C) 1999 Elsevier B.V. B.V. All rights reserved.