Minimally invasive approach for improving aesthetic in a patient with tetracycline-stained teeth by bleaching:A clinical evaluation

Objective:To compare 16% carbamide peroxide(CP)with a higher concentration of hydrogen peroxide(HP)for bleaching teeth in office or at-home to erase tetracycline stains on teeth.Materials and methods:In a randomized,self-controlled clinical trial,we assigned eligible subjects to group A with 40% HP compared with 16% CP or group B with 45% CP compared with 16% CP on the split maxillary arch and followed the manufacturers’instructions.Tooth color changes were measured with vita 3D-bleached guide and colorimeter at baseline and three-time assessment.Tooth sensitive intensity was evaluated using numeric rating scales,and oral soft and hard tissue examination was recorded.Patient satisfaction survey was conducted at the last tooth color evaluation.Results:There were 20 subjects enrolled.The color changes by the end of the study were A1(40% HP)=8.22,A2(16% CP)=8.20,B1(45% CP)=11.27,B2(16% CP)=8.26 respectively.All groups experienced significant shade reductions by bleaching,the 45% CP group had significantly greatest color changes compared with the other groups(p=0.03).For tooth sensitivity evaluation,significant differences were observed in 40% HP group(p=0.01),but with mild level.None patients suffered oral soft or hard tissue abnormalities before and after treatment.Patients were more in favor of using 45% CP according to the questionnaire results.Conclusion:The 3 whitening agents were effective and safe for the whitening of tetracycline-stained teeth,the 45% CP agent had quicker whitening efficacy with low tooth sensitivity and positive feedback.Clinical significance:45% of high-concentration CP whitener by at-home using,brought faster and superior efficacy to bleaching tetracycline-stained teeth while had the equal intensity of tooth sensitivity.

Evaluating the effectiveness of using ClO_2 bleaching as substitution of traditional Cl_2 on PCDD/F reduction in a non-wood pulp and paper mill using reeds as raw materials

The effectiveness of ClO_2 bleaching as a replacement for conventional Cl_2 bleaching,which is intensively practiced in developing countries,to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in non-wood pulp and paper mills has not been field tested.The first field study was performed to investigate PCDD/F variations when ClO_2 bleaching was used as a substitute for conventional Cl_2 bleaching in a non-wood pulp and paper mill.It was found that the PCDD/F toxic equivalents(TEQs)in solid and effluent samples were approximately 1.3–14.9 times lower when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.2,3,7,8-Substituted tetrachlorinated dibenzofurans(2,3,7,8-TCDF)were the dominant contributors to total PCDD/F TEQs in samples from the investigated mill when using conventional Cl_2 bleaching.The formation amounts of 2,3,7,8-TCDF were reduced from 1.56–2.76 pg TEQ/g to 0.02–0.32 pg TEQ/g in solid samples when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.The replacement of Cl_2 with ClO_2 might decrease the chlorination reactions of dibenzofuran as potential precursors,and thus reduce the formation amounts of 2,3,7,8-TCDF.The results could provide important knowledge for suggesting the best available technique for PCDD/F reduction for non-wood pulp and paper mills in developing countries.

Exhibition of Bleaching Resistance Via Adaptive Bleaching Pattern by Coral Reefs of the Gulf of Mannar during Massive Bleaching Event 2019

Coral reefs in the Gulf of Mannar(GoM)and Palk Bay regions are facing potential threats from climate change,sedimentation and anthropogenic activities.Considerably,coral reefs in these two regions are highly damaged due to frequent bleaching events caused by increased sea surface temperature(SST)recorded over the past two decades.Recently,during February to May 2019,mass bleaching event of corals was documented again in GoM and Palk Bay regions due to increased sea surface temperatures ranged between 32°C to 36°C.Despite of completely bleached corals,some coral colonies of the same bleached coral species have displayed adaptive bleaching pattern(ABP)for survival.This incidence is displayed by the symbiotic zooxanthellae to protect coral polyps from environmental stress such as elevated temperatures.These observations infer that coral colonies with preferential bleaching pattern ability would serve as environmental stress resisting coral colonies which can be used for restoration activities and cryopreservation.Further studies are needed to explain the potential mechanisms or specific environmental drivers responsible for ABP.

The effect of cold-light-activated bleaching treatment on enamel surfaces in vitro

This in vitrostudy aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal （Group LP）, disto-buccal （Group P）, mesio-lingual （Group NP） and disto-lingual （Group L） specimens. These four groups were treated using the standard cold-light bleaching procedure, a bleaching agent, a peroxide-free bleaching agent and cold-light, respectively. Before and after treatment, all specimens were analyzed by high-resolution, micro-area X-ray diffraction and scanning electron microscopy. Using a spectrometer, tooth color of all specimens was measured before and after treatment. The phase of the enamel crystals was identified as hydroxyapatite and carbonated hydroxyapatite. After treatment, specimens in Groups LP and P showed significantly weaker X-ray diffraction peaks, significant reduction in crystal size and crystallinity, significant increase in L~ but decrease in a＊ and b＊, and obvious alterations in the surface morphology. However, specimens in Groups NP and L did not show any significant changes. The cold-light bleaching treatment leads to demineralization in the enamel surface. The acidic peroxide-containing bleaching agent was the major cause of demineralization, whereas cold-light did not exhibit significant increase or decrease effect on this demineralization.

Recovery of oil and free fatty acids from spent bleaching earth using sub-critical water technology supported with kinetic and thermodynamic study

This work represents the extraction of oil with high free fatty acid content from spent bleaching earth using sub-critical water technology as a greener production pathway. The extraction efficiencies under different conditions were investigated. The studied parameters include temperatures in the range of 180 to 270°C, the feed to solventfeed-to-solvent (in this case water) ratio (1:1, 1:2, 1:3, 1:4 and 1:5) and extraction times in the range of 5-60 minutes. The results showed that the optimum temperature, feed to solventfeed-to-solvent ratio, and extraction time were 270°C, 1:3, and 20 minutes, respectively. In another experiment, the extracted free fatty acids were converted into mono-, di-, and triglycerides through esterification with glycerol to increase the value added of the extracted products. The kinetics of the extraction process was found to be corresponding to an irreversible consecutive unimolecular-type first order reaction, consisting of the extraction step followed by the decomposition reaction step. Both reaction rates of extraction and decomposition were estimated using the reaction rate equations utilizing the nonlinear regression method. The apparent activation energy was calculated to be 46.1 kJ·mol-1. This result indicates a diffusion controlled reaction. For more exploration and deep understanding of the extraction mechanism, other thermodynamic parameters were also calculated and analyzed including,ΔH#, ΔS#, and ΔG# of the extraction step.

Adsorption Behavior of Acid-Leached Clays in Bleaching of Oil

The available data have shown that acid-leached clays had sites for adsorption of impurities in oils. Data obtained on residual impurities in cotton and sunflower-seed oils bleached with the same clay materials produced linear Langmuir and Freundlich isotherms. The increase in constant, k with increase in both temperature of thermal activation and concentration of acid used to leach the clay, suggests that bleaching efficiency increased. The value of n decreased with increase in temperature of activation and concentration of acid used to leach the clay suggesting that bleaching capacity increased. The mineral compositions of the clays influenced their surface, structural and bleaching properties.

Bleaching of Black Human Hair

Bleaching of black human hair has been studied systematically. On the basis of experimental data the technology of human hair bleaching through five processes was established. The optimum technology of improving the whiteness and reducing damage on fibers has been found. The technology can provide good luster,smooth handle and relatively high strength retention to human hair used for wigs or drama articles, meeting the needs of people better. Moreover, it also has important reference value to bleaching of other colored fibers.

Effects of Mg-based Alkaline Peroxide Bleaching on Physical Properties of Poplar Bleached Chemi-thermomechanical Pulp and Its Influence Mechanism

In this study,Mg O was partially used as an alkali source in the peroxide bleaching process of bleached chemi-thermomechanical pulp(BCTMP).The effects of substitution percentage of Mg O for Na OH on the bulk,optical,and physical properties of bleached pulp,and the main effluent characteristics were analyzed.In addition,the influencing mechanism of Mgbased alkali on the strength properties of the BCTMP was further investigated.Strength properties of the BCTMPs were investigated as a function of charge characteristics,fiber morphology,surface lignin content,relative bonding area,and hydrogen bonds of the BCTMP.The results showed that cationic demand(CD) and chemical oxygen demand(COD_(Cr)) of the bleaching effluent decreased as the substitution percentage of Mg O for Na OH increased; meanwhile,the bulk and optical properties of the BCTMP increased.Nevertheless,the strength properties(tensile,tear,and burst indices) of the bleached pulp decreased as the substitution percentage of Mg O for Na OH increased.The decrease in the fiber charge density and increase in the surface lignin content affected the fiber swelling,resulting in a decline in pulp interfibers bonding strength and further loss of the tensile and burst indices.

FT-IR Microspectroscopic Imaging of Cross-Sectioned Human Hair during a Bleaching Process

We investigated bleached human hair by FT-IR microspectroscopy and chemical imaging. The cross sectioned hair is approximately 90 μm in diameter, showed cuticle and cortex in chemical imaging. Differential amide I/II absorbance ratio and broadening amide I band between in the cortex and cuticle were confirmed in FT-IR microspectroscopy and chemical imaging. The cystine monoxide band from the products of disulfide oxidation of the amino acid cystine is associated with hair damaging during bleaching process. With increase bleaching time, the band for cystine monoxide shows more intense and larger area in chemical image. The spatially chemical change was investigated in detail by FT-IR microspectroscopy and chemical imaging during the bleached process.

Effect of Different Bleaching Applications on the Surface Properties and Staining Susceptibility of Dental Composites

The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide （Opalescence PF） or 35% hydrogen peroxide （Beyond Max 5） and subsequently immersed in four different staining solutions （coffee, tea, red wine, and cola）. Distilled water was used as a control. Color measurements were performed with a spectrophotometer. Vickers micro hardness and roughness data were analyzed with two- way analysis of variance for repeated measures. The analysis of variance was used to compare the color change values. Duncan＇s multiple comparison test was applied to compare the results （a = 5%）. AE~＂ values over 3.3 were considered clinically unacceptable. Micro hardness and surface roughness values of the tested composites were decreased significantly after bleaching applications. Red wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process.

APPLICATIONS OF FLOCCULANT IN BLEACHING AND WASHING OF KAOLIN

The difficulties of washing during the dressing of kaolin ore have been analyzed, the multistep intermittent washing model has been deduced, and effective methods for dealing with the difficulties were put forward. Experimental results show that the bleaching and washing process was enhanced, the washing time was shortened and the consumption of water was reduced by means of adding flocculant.

Treatment of pulpless coloured anterior tooth by bleaching the interior of pulp cavity and filling the cavity with composite

A method of treating pulpless coloured anterior tooth is presented.Most part ofthe coloured dentin of the labial crown was removed and the dental structure was bleachedwith 30% hydrogen peroxide for 5min.The pulp cavity was then filled with whitephoto-curing composite.The result of the treatment is quite satisfactory.With our treatment,the intact contour of the crown and the hardness and gloss of the enamel are preserved.SEM proved that the composite was tightly bound with the enamel of the medial wall of thepulp cavity,forming an entity with the tooth,thus guaranteeing the strength of the crown.

Applications of Enzyme-simulating Copper Complex Catalyst in Low-temperature Scouring/Bleaching of Cotton Knits

An enzyme-stimulating catalyst( PTL) with copper ions( Cu^(2+)) as the activation center and aminophosphonate as ligand was developed and applied in low-temperature scouring/bleaching of cotton knits. The optimal weight ratio of Cu^(2+) to aminophosphonate was 1 ∶75. Via orthodox and single-factor experiments,the most efficient formula for low-temperature scouring/bleaching was composed of 0. 4 g/L high-efficiency degreaser DM-1130,1. 5 g/L PTL,2. 0 g/L sodium hydroxide( NaOH),and 7. 0 g/L 30% hydrogen peroxide( H_2O_2). The PTL could not only increase the whiteness of cotton knits,but also remove pectin to enhance capillary effect.

Influence of Bleaching Powder on the Quality of Giant Freshwater Prawn (<i>Macrobrachium rosenbergii</i>)

Calcium hypochlorite commercially known as bleaching powder is used as a bleaching agent in shrimp processing industries in many countries and known to effect biochemical alteration in shrimp muscle. Studies were, therefore, undertaken to determine their effect in different concentrations viz., 10, 20, 30, 40 and 50 ppm with different time intervals on the quality of head-on, headless shell-on and peeled giant freshwater prawn (Macrobrachium rosenbergii) by determining biochemical and organoleptic aspects. Myofibrillar protein solubility of fresh head-on, headless shell-on and peeled samples were 90.5%, 90% and 88%, respectively indicating a gradual decrease in protein solubility with increasing concentration of bleaching powder. Decrease in protein solubility was also higher in samples kept at longer duration in different concentration of bleaching powder. At a given concentration of 50 ppm for 30 min treatment, the loss of myofibrillar protein was higher (26.14%) in peeled samples than those of head-on and headless shell-on samples (20.44% and 21.11%). Shelf life of bleaching powder treated prawn samples was found to be reduced to 4 - 5 days in iced condition compared to 6 - 7 days for control samples. Peeled samples were also found to be more susceptible to bleaching powder than that of head-on and headless shell-on samples.

Effects of Temperature, pH, Ammonia Nitrogen Content and Salinity on Coral (Acropora millepora ＆ Palythoa sp. ) Bleaching

This study was conducted to investigate the effects of temperature, pH, ammonia nitrogen content and salinity on the bleaching of Acropora millepora and Palythoa sp. This study included two experiments ： Experiment 1 was designed to test the effects of different gradients of temperature, pH, ammonia nitrogen con- tent and salinity at a time point （6h） on Palythoa sp. breeding; and Experiment 2 tested the effects of different levels of temperature, pH, ammonia nitrogen con- tent and salinity at three time points （24, 48 and 72h） on A. millepora bleaching. Before the experiments, A. millepora and Palythoa sp. were washed with filtered seawater （0.45 p,m microporous membrane filtration） and then reared in interior seawater aquurium cylinder. The experiments were carried out when the coral ten- tacles extended and the growth condition were good. The results showed that under high temperature （32 -40 ~C ） , both A. millepora and Palythoa sp. showed drastic reactions in the course of time, reflecting considerably significant stress responses. The number of releasing zooxanthellae increased with increase or de- creaseof the pH value （pH 0, 4, 6, 10, 12） over time. Meanwhile, a relatively thick layer of mucus was found on the upper zone of the seawater and the corals started to bleach. As the concentration of ammonia nitrogen （ NH4 , 0 mmool/L） increased in the course of time, the number of zooxanthellae floating on A. millepo- ra and Palythoa sp. had the tendency to rise. When the salinity level were at 15%o and 40%o for A. miUepora and below 34‰ for Palythoa sp. , a considerable number of zuoxanthellae floated out and had rising trend in their number over time at 24 -72 h and 6 h, respectively. In this occasion, the corals stopped growing and started to bleach. In conclusion, it revealed that temperature, pH, ammonia nitrogen content and salinity are the potential impact factors on coral breeding. It is suggested that, as temperature, pH value and salinity decrease or increase, as well as anmlonia nitrogen content rises, the quantity of phycobiont would be raised, and the bleaching would be more severe.

TCF Bleaching of Populus tomentosa Kraft Pulps with H_2O_2 Pretreatment un-der Acid Condition

The process of peroxide bleaching of Populus tomentosa kraft pulp with H2O2 pretreatment under acid condition was studied. The variations of pulp characteristics such as brightness, Kappa number and viscosity during the peroxide bleaching process were discussed and the concept of the A/B value was presented for the first time. The results show that acid pretreatment with H2O2 is essential to improve pulp brightness and avoid viscosity loss. The conclusion is reached that the A/B value has great influence on pulp properties when the total amount of peroxide used in the bleaching process is 2%-5%. Pulp with a high viscosity and brightness can be obtained when A/B is about 0.15.

Baseline Levels of <i>Siderastrea siderea</i>Bleaching under Normal Environmental Conditions in Little Cayman

This study describes the health status of Siderastrea siderea in Little Cayman before, during, and after the 2015 Caribbean-wide elevated temperature anomaly. Colony color was used as a proxy for health during snorkel and scuba surveys of shallow (°C, S. siderea were early indicators of reef stress and among the first corals to bleach. Depth and site resilience did not significantly impact temperature susceptibility;however, smaller colonies (2 surface area) were more likely to change color than the larger size classes. Little Cayman’s S. siderea were capable of surviving large-scale (>80%) bleaching: mortality was observed for only one colony. Resilience rates varied considerably: one-third of the impacted population returned to the normal brown color within two months, one-third required 3 - 9 months to recover, and the fates of the remaining one-third remain to be determined. If the return to normal color is indicative of resistance to reef disturbances, S. siderea may be among the “winning” coral species following elevated temperature anomalies which are predicted to occur with increasing frequency and severity as a result of climate change.

Optimization of Bleaching Process of Crude Palm Oil by Activated Plantain (<i>Musa paradisiaca</i>) Peel Ash Using Response Surface Methodology

The bleaching of crude palm oil using activated plantain peel ash (APPA) was studied in this work. Historical data design (HDD) in response surface methodology (RSM) experimental design was employed to optimize and correlate the process operating parameters (temperature, time and adsorbent dosage) to the percentage bleaching efficiency. The analysis of the results showed that the quadratic effects of the operating parameters were significant. The optimum condition for the maximum adsorption efficiency of 70.04% was obtained at 160&#176;C temperature, 60 minutes reaction time, and 4 g adsorbent dosage. The predicted bleaching efficiency of 74% was in good agreement with the optimum experimental yield. This study has revealed that APPA is a good source of adsorbent for palm oil bleaching.

The Use of Bleaching Creams among Central Sudan Students, 2010

The aim of this study was to examine the use of bleaching creams containing hydroquinone, corticosteroids and mercury for skin lightening among higher secondary school students in central Sudan. A cross-sectional epidemiological study was conducted at 19 different girls’ schools. A total of 1187 young students aged 16 - 19 years old were randomly selected and approached, using a well-structured questionnaire. The main outcome measure was a number of epidemiological factors per abusers. Results revealed that, 55.4% of the respondents misused this product, whilst 51.6% of girls used cosmetics to lighten their skin for 1 - 3 years with skin irritations prevalence of 3.3%, and the face was reported as main application site (35.4%). In conclusion, the lack of health awareness and ignorance was the main causative factor, whilst education, competent authorities awareness and prescriptions restrictions were highly recommended.

Dimethylsulfide and Coral Bleaching: Links to Solar Radiation, Low Level Cloud and the Regulation of Seawater Temperatures and Climate in the Great Barrier Reef

Coral reefs produce atmospheric dimethylsulfide (DMSa) which oxidises to non-sea-salt (nss) sulfate aerosols, precursors of cloud condensation nuclei (CCN) and low level cloud (LLC), reducing solar radiation and regulating sea surface temperatures (SSTs). Here we report measurements of solar radiation, SST, LLC, DMS flux, , and rainfall before, during and after a major coral bleaching event at Magnetic Island in the central Great Barrier Reef (GBR). Measurements are compared with those made at the nearby fringing reef of Or-pheus Island where coral bleaching did not occur. Extreme solar radiation levels occurred from November to late January and could have reflected cloud radiative effects that increased downwelling of solar radiation. High levels of LLC often coincided with high periodic fluxes of DMS from the unbleached coral reef at Orpheus Island (e.g. 14 - 20 μmol·m-2·d-1), in direct contrast to the very low fluxes of DMS that were emitted from the bleached, human-impacted Magnetic Island fringing reef (nd-0.8 μmol·m-2·d-1) when SSTs were >30°C. Continuous SSTs measurements at the Magnetic Island reef revealed various heating and cooling periods, interspersed with stable SSTs. Cooling periods (negative climate feedback) ranged from -1°C to -3°C (7 day mean -1.6°C), and often seemed to occur during low tides, periodic pulses of DMS flux and LLC, keeping SSTs °C. In contrast warming periods of +1°C to +3°C (positive climate feedback, 7 day mean +1.52°C), seemed to occur during increasing tides, decreasing DMS flux and low to medium levels of LLC which increased solar radiation and caused SSTs over 30°C and corals to bleach. Alternation between these two states or types of feedback is indicated in this research and may be a function of enhanced scattering of solar radiation from nss-sulfate aerosols that originate from oxidation of DMSa produced from the coral reefs in the GBR. The net radiative forcing from clouds can be as high as four times as large as the radiative forcing from a doubling of CO2 levels in the atmosphere, which needs to be taken into account when ascribing coral bleaching events in the GBR solely to GHG warming. Further studies are needed to more critically assess the importance of this GBR coral reef-cloud feedback to the climate of northern Australia and the western Pacific, where the greatest biomass of coral reefs occurs.