Top PDF Effect of Teeth Bleaching by Hydrogen Peroxide on Enamel Microhardness

Effect of Teeth Bleaching by Hydrogen Peroxide on Enamel Microhardness

Effect of Teeth Bleaching by Hydrogen Peroxide on Enamel Microhardness

Materiał badawczy stanowiło 9 wyrzniętych zębów przedtrzonowych i trzecich trzonowych, usuniętych ze wskazań ortodontycznych u osób obojga płci w wieku 21–26 lat. Na pobranie zębów do badań uzyskano pisemną zgodę pacjentów, a na wykonanie badań zgodę Komisji Bioetycznej. W powiększeniu 10−krotnym oceniano zęby pod kątem braku obecności pęknięć i zmian rozwojo− wych szkliwa. Do czasu przeprowadzenia badania zęby przechowywano w roztworze soli fizjolo− gicznej z tymolem w celu zahamowania rozwoju bakterii i dehydratacji. Po oczyszczeniu za pomo− cą piaskarki profilaktycznej (Prophyflex) wycina− no wargowe powierzchnie zębów, tworząc bloczki o równej podstawie. Bloczek pochodzący z dane− go zęba dzielono na dwie części, uzyskując dwie próby: kontrolną – niewybielaną i badaną – wybie− laną. Powierzchnię próby kontrolnej zabezpieczo− no tzw. „płynnym koferdamem” przed kontaktem z żelem wybielającym i promieniowaniem lasera. Do wybielania zastosowano system LaserSmile Teeth Whitening System ® (Biolase). W skład sy−
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Effect of different peroxide bleaching regimens and subsequent remineralization on the hardness of human enamel

Effect of different peroxide bleaching regimens and subsequent remineralization on the hardness of human enamel

shape of indent obtained in VHN was easy and more accurate to measure. The baseline values of the present study are similar with the earlier studies performed by Ryges and Foley (1961). (Ryge, 1961) The average hardness value for enamel is in the range from 250 to 360 VHN. The results are also consistent with previous studies performed by Lopes et al (2002) (16) and Wongkhantee et al (2006). When paired t-test was applied, the Post-bleach values of all experimental groups showed statistically significant difference as compared to Baseline values of respective groups (Group II to Group IV). This evaluation was in accordance with Chen et al. (2008), Akal et al. (2001) and Rodrigues et al. (2005) who also found significant decrease in microhardness after application of 10% CP bleaching agent. Rodrigues et al. (2005) and Maleki pour (2012) found significant decrease in microhardness for office bleaching agents with 37% and 35% carbamide peroxide respectively. Similarly, Jiang et al. (2008) with 30% hydrogen peroxide, Abreu et al. (2011) and Ulukapi (2007) with 35% hydrogen peroxide reported significant decrease in microhardness. The loss of mineral content and organic matrix decreased enamel microhardness (Pinto et al., 2004). The mean AMH values of subgroups of experimental groups after remineralization were highest for Subgroup C followed by Subgroup B and lowest for Subgroup A in Group II and IV. Whereas, the values were highest for Subgroup B followed by Subgroup C and Subgroup A in Group III. The values were highest for Group I (Control) which was not bleached but kept in artificial saliva for a total of 12 days. When intra-group comparison was done between various Remineralizing agents, Subgroup A showed statistically significant difference as compared to Subgroup B and Subgroup C in each of the 3 experimental groups. No statistically significant difference was found between Subgroup B and Subgroup C. Borges et al (2010) found significant differences of microhardness for bleached groups that received no remineralizing gel but stored in artificial saliva as compared to bleached groups treated with remineralizing gel post-bleaching (Clark, 1993). Post- remineralization mean AMH values compared with baseline & post-bleach mean AMH values for Subgroup II A and III A revealed no statistically significant difference. Like the results of our study, Chen et al (2008) also showed partial recovery of
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The Erosion Properties of Chlorine Dioxide and Hydrogen Peroxide on Bovine Teeth

The Erosion Properties of Chlorine Dioxide and Hydrogen Peroxide on Bovine Teeth

Investigations on the effects of pH on dental enamel suggested that low pH and high acid concentrations can cause enamel ero- sion [4]. In addition, possible alterations in the enamel organic ma- trix promoted by nonspecific and potentially reactive free radicals might result in decreased fracture toughness [3]. Chlorine dioxide tooth whitening* (Frontier Pharmaceutical Incorporation, New York, USA) has been considered as a ‘safer’ method for whitening teeth in shorter periods thereby avoiding the adverse effects usu- ally associated with the use of peroxides [5]. Chlorine dioxide was first used in the form of Labarraque solution for bleaching non - vital teeth [6]. Currently, it is been used by non - dental establish- ments to whiten teeth.
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Effect of a Combined Bleaching Regimen on the Microhardness of a Sealed Methacrylate-based and a Silorane-based Composite

Effect of a Combined Bleaching Regimen on the Microhardness of a Sealed Methacrylate-based and a Silorane-based Composite

The high peroxide concentrations used in the cur- rent study may facilitate the cumulative softening ef- fects of the whitening agents, in-office and at-home agents. The importance of peroxide concentration and pH of bleaching agents in having the adverse effects on restorations has been noticed [18, 39-40]. The greater hydrogen peroxide release from higher concentration of the carbamide peroxide gel and a resultant lowered mi- crohardness value was reported for the Charisma (He- raeus; Kulzer, Germany) and Vitremer (3M ESPE, USA) [39]. The same effect was demonstrated for Spec- trum TPH (Dentsply; USA) and Fuji II LC (GC; Tokyo, Japan) treated with Opalescence Xtra (Ultradent; USA, 35% hydrogen peroxide) compared to Opalescence Quick (Ultradent; USA, 35% carbamide peroxide). The former had a low pH (3.67) and the latter had a high pH (6.53) [14]. However, in that study [14], no significant difference was reported between the control and bleached groups for the tested materials. The pH of most bleaching products is approximately neutral. The pH of Opalescence Boost after mixing and Opalescence PF used in the present study was 6.6-7.6 and 6.5, re- spectively. However, a rise in the pH value of Opales- cence PF used in the present can occur following de- composition of carbamide peroxide into hydrogen pe- roxide and urea because urea decomposes into CO 2 and
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Erosion and abrasion on dental structures undergoing at-home bleaching

Erosion and abrasion on dental structures undergoing at-home bleaching

In summary, most of the studies have shown that at- home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant harmful effects on enamel and dentin surface morphology, microhardness, roughness, or calcium loss. The few studies that showed alterations in enamel or dentin surfaces all had limitations in their in vitro methodology or used highly acidic bleaching agents. In addition, these harmful effects on tooth substrates were generally transitory, and were not significant when remineralization periods were allowed.
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Shear Bond Strength of Resin Bonded to Bleached Enamel Using Different Modified 35% Hydrogen Peroxides

Shear Bond Strength of Resin Bonded to Bleached Enamel Using Different Modified 35% Hydrogen Peroxides

Vital tooth bleaching which is a routine treatment in modern dental practice is accomplished by either an at-home technique or in-office procedures with high-concentration bleaching agents [1,2]. Although the clinical effectiveness of tooth bleaching has been demonstrated extensively [3], there are some concerns about potential complications. Whitening agents have adverse effects on the dental pulp [4,5] may decrease micro-hardness of the bleached substrate [6], and have deleterious effect on bond strength of the resin materials [7,8]. One of the theories regarding the deleterious effect of bleaching on the bond strength of resin materials is related to the decrease in bond strength with the free radicals from oxygen that remain in the dental tissues released by the bleaching agents. After an adhesive system application, the oxygen responds to the closures of the forming polymeric chains, finishing the polymeric extension, lessening the level of transformation of the adhesive system and resin composites and declining the bond quality [9]. The use of bleaching techniques modified by a remineralizing agent called CPP-ACP (casein phosphopeptide amorphous calcium phosphate) has been suggested in an attempt to recover minerals that are lost during bleaching [10]. A recent study revealed that the associative utilization of CPP- ACP and high concentration hydrogen peroxide may be a fruitful strategy for diminishing tooth sensitivity and restricting changes in the enamel morphology during in-office bleaching [11]. Another modification is using fluoride with bleaching agents to prevent either hypersensitivity or demineralization accompanying tooth-whitening therapy. The addition of sodium fluoride to the bleaching agent was found to generate fluoridated hydroxyapatite and calcium fluoride crystals on the enamel surfaces, which potentially accelerated the remineralization of the bleached enamel [12]. But there is inadequate evidence on the influence of hydrogen peroxide and CPP-ACP on composite-enamel bonding. Additionally, despite profound scientific suggestions which support the remineralization capability of fluoride [13], the impact of fluoride on resin–enamel holding is dubious. Decreased resin bond strength has been reported for fluoride-treated enamel, particularly
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BIOLOGICAL CONSIDERATIONS IN IN-OFFICE VITAL BLEACHING PROCEDURE – A SYSTEMATIC REVIEW

BIOLOGICAL CONSIDERATIONS IN IN-OFFICE VITAL BLEACHING PROCEDURE – A SYSTEMATIC REVIEW

Qasem Alomari and Ehsan Al Daraa evaluated the effect of four in-office dental bleaching methods on shade change, color stability, patient satisfaction and postoperative sensitivity. Forty patients were randomly divided into four groups (n=10) according to the method of in-office bleaching used: Group A—35% hydrogen peroxide (HP); Group B—35% HP plus BriteSmile and a blue curing light; Group C—35% HP plus QuickSmile and an LED curing light; Group D—35% HP and a Zoom2 metal halide curing light. [4] For all groups, there was only one session of bleaching with three 20-minute applications of bleaching gel. Tooth sensitivity was evaluated by blowing air from air-water syringe of the dental unit over the labial surfaces of the upper anterior teeth for 5 seconds. The degree of sensitivity was recorded according to the following criteria: 0-no sensitivity 1-slight sensitivity 2-moderate sensitivity 3- severe sensitivity. Immediate postoperative sensitivity was the least in Group A and the highest for Group B. This sensitivity typically was mild in severity and transient in nature, and often resolved after active treatment. About 70% of the patients had tooth sensitivity immediately after bleaching. The sensitivity was mild and tolerable in all of the participants and disappeared within one month following treatment in all of the groups. Chemical bleaching alone caused less sensitivity.
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<p>Influence of Erosion/Abrasion and the Dentifrice Abrasiveness Concomitant with Bleaching Procedures</p>

<p>Influence of Erosion/Abrasion and the Dentifrice Abrasiveness Concomitant with Bleaching Procedures</p>

Purpose: The aim of this study was to evaluate the effect of erosive/abrasive cycles and two different levels of abrasiveness of dentifrices over enamel and dentin subjected to bleaching. Methods: Enamel and dentin bovine specimens were prepared and submitted to an at-home bleaching treatment using 9.5% hydrogen peroxide gel, which was applied daily (30 min/14 days). Concomitant with bleaching, an erosive cycle was performed using citric acid (0.3%, pH 3.8, 5 mins, 3×/day), followed by immersions in arti fi cial saliva for remineralization (30 mins). Abrasion was done with two (high and low abrasiveness) dentifrices (2×/day, 120 seconds) after the fi rst and third erosive immersion each day. Enamel and dentin softening were assessed by microhardness and erosive tooth wear by optical pro fi lometry. Data were submitted to repeated measures ANOVA, followed by the Tukey ’ s test with a signi fi cance level of 5%.
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Effect of Bleaching on Shear Bond Strength of Composite Resins to Bovine Enamel Using Three Bonding Agents

Effect of Bleaching on Shear Bond Strength of Composite Resins to Bovine Enamel Using Three Bonding Agents

site to the tooth reduced 24 hours after bleaching, which is in agreement with results found in this study [13]. Perdigo et al. point out in their studies that loss of calcium, reduction in microhardness, and changes in organic component can be impor- tant factors in reducing the bond strength to enamel after bleaching [14]. Van der Vyver P.J, Titley K.C, Dishman M.V, and Ghavam in separate stu- dies have shown that the reduction in bond strength could be due to permeation of hydrogen peroxide into enamel and formation of free-radicals, which inhibit the initiation of polymerization and forma- tion of resin tags, which concurs with the results of this study [9, 15, 12, 16]. Zho et al. in 2000 showed that peroxide ions can replace free radicals in the apatite hydroxide network, and thus, produce apatite peroxide, causing destruction of the enamel prisms structure [17]. Several methods have been proposed for prevention from the clinical problems associated with reduced bond strength after bleach- ing: the most common is delaying application of bonding agent (any type) after bleaching [16]. Shimahara M.S et al. and Van Der Vyver et al. in 2004 reported that the best time for restoration of enamel and dentin is two weeks after bleaching, since the resin bond strength to enamel be im- proved [12-18]. Bulucu et al. also found that in the samples restored two weeks after bleaching, the difference in bond strength, compared to control group was insignificant. They also stated that the type of light cure system did not affect bond strength [19]. Other studies have shown that stor- ing the samples in distilled water or in artificial saliva after bleaching and before bonding can im- prove resin bond strength by removing layer of Bonding Bleach Number Mean Standard deviation Standard error
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Effect of surface removal following bleaching on the bond strength of enamel

Effect of surface removal following bleaching on the bond strength of enamel

still not clear, the reduced bond strength of bleached enamel has been related to the presence of residual free radicals due to the breakdown of hydrogen peroxide [14, 18] and alter- ations in the enamel composition and structure [6, 19] fol- lowing the bleaching treatment. The residual oxygen in the interprismatic spaces can hamper resin infiltration and in- hibit resin polymerization [20]. Moreover, morphological and compositional changes (e.g., porosity, loss of enamel prismatic form, loss of calcium, and changes in organic sub- stances) in the enamel may weaken the adhesive interface and compromise bond strength [21, 22]. Therefore, bonding procedures should not be performed immediately after bleaching treatment [23]. A waiting period of 1–3 weeks has been advocated by various researchers [21, 24, 25]. In addition to the delayed bonding procedure, the application of antioxidant agents (e.g., sodium ascorbate, sodium bi- carbonate, and grape seed extract) [18, 26, 27] and laser ir- radiation [28, 29] have been proposed to restore the compromised bond strength of bleached enamel. By neu- tralizing residual free radicals [30] and promoting micro-retentions in the enamel surface [28], antioxidant agents and laser irradiation have been shown to reverse the reduced bond strength between the composite resin and bleached enamel. However, it is important to point out that most of the above-mentioned studies measured the bond strength without thermocycling [24–29]. Ther- mocycling is the in vitro process of subjecting a restor- ation and tooth to temperature limits similar to those experienced in the oral cavity [31]. It would be of interest to investigate the effects of thermocycling on the bond strength between the composite resins and the bleached enamel.
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DEVELOPMENT, CHARACTERIZATION AND STABILITY STUDY OF NANOMETRIC SYSTEMS CONTAINING HYDROGEN PEROXIDE FOR DENTAL BLEACHING

DEVELOPMENT, CHARACTERIZATION AND STABILITY STUDY OF NANOMETRIC SYSTEMS CONTAINING HYDROGEN PEROXIDE FOR DENTAL BLEACHING

This technique has been notable with several publications attesting its bleaching efficacy and biological safety 13, 27, 14 . In this case, carbamide peroxide or hydrogen peroxide is used 29, 30 . When that desired color is reached, the treatment can be interrupted or continued for another week, the most recommended to stabilizing the color 14 . Hydrogen peroxide can diffuse through the tooth enamel to reach the junction of the dentin and regions of the dentin itself 30, 31 . This substance is considered a potent oxidizing agent, since it presents a great concentration of liberated oxygen, facilitating its penetration through interprismatic spaces and dentinal tubules, promoting the bleaching effect 27 . Allied to the aesthetic exigency from patients, Dental Science was driven to seek a continuous improvement of the knowledge in search of new techniques and materials 32 . Among the used structures and materials for product placement we can highlight nanotechnology scale dimensions. Today, nanotechnology is one of the main focuses of research, development and innovation activities in industrialized countries. Investments in this industry surpass every year and its development has been touted as a technological revolution. It is known, therefore, that material properties contained in this atomic or subatomic level can differ significantly from properties of same materials in a larger size. Hence, nanotechnology emerges as an alternative that guarantees to products greater stability and efficacy 33, 34 .
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N-acetyl cysteine prevents pain and hypersensitivity of bleaching agents without affecting their aesthetic appeal; evidence from in vitro to animal studies and to human clinical trials

N-acetyl cysteine prevents pain and hypersensitivity of bleaching agents without affecting their aesthetic appeal; evidence from in vitro to animal studies and to human clinical trials

Teeth-bleaching is a widely used procedure in general aesthetic dentistry and it has become significantly more popular in recent years. To achieve whitening, highly oxidant compounds, such as carbamide and hydrogen peroxides are applied to teeth as bleaching agents [1]. The application of these whitening agents on the outer layer of the tooth, the enamel, leads to a significant de- crease in calcium and phosphorous content and increase in surface roughness and porosity. The new surface top- ography allows the whitening agents to penetrate the tooth and promote the oxidation and consequent break- down of staining compounds, which with time accumu- late in the teeth [2]. There are two main methods of whitening: in-office peroxide-containing gels and white strips for application at home. In-office whitening gels contain higher concentrations of hydrogen peroxide (be- tween 25 and 40%) and can be applied through deep bleaching in a single visit of 1 hour treatment or through the usage of take-home personalized trays containing peroxide gels. In-home white strips are composed of 3 to 15% hydrogen peroxide or carbamide peroxide, and are required to be used twice a day for 2 weeks to reach optimal efficacy [3].
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Effect of waiting time for placing resin composite restorations after bleaching on enamel bond strength

Effect of waiting time for placing resin composite restorations after bleaching on enamel bond strength

This study investigated the influence of the waiting time for placing resin composite (RC) restorations after dental bleaching on the shear bond strength (SBS) to enamel. Seventy bovine incisors were obtained, of which 60 were stained in coffee solution for 1 week and then bleached with the whitening agent Lase Peroxide Sensy (DMC Equipments, Brazil), following the manufacturer directions of use. Next, all teeth were allocated into seven groups (n = 10) according to the waiting time after bleaching for placing the RC: immediately (0 h), 24 h, 3, 7, 14 and 28 days (d). Ten teeth were not bleached to serve as control. The specimens were prepared for SBS test and also for failure mode analysis. Scanning electron microscopy images were taken in non- bleached and bleached specimens. Data was analyzed by one-way ANOVA and Tukey’s test (α = 0.05). The SBS means (standard deviations), in MPa, were: control = 8.5 b (5.8);
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International Journal of Dentistry and Oral Health Open Access

International Journal of Dentistry and Oral Health Open Access

treatments, there have been studies published that raise concerns about possible harmful effects of some bleaching agents on the pulp [50-54]. Glucose metabolism and protein synthesis, especially collagen synthesis, are the two most central metabolic processes occurring in the pulp. These metabolic reactions are catalyzed by enzymes that are sensitive to changes in environmental conditions [54]. Bowles and Thompson examined combined effects of heat and hydrogen peroxide on pulpal enzymes and found that most of the enzymes were relatively resistant to the effects of heat up to 50°C [52]. However, nearly every enzyme tested was inhibited to some degree by hydrogen peroxide. At concentrations as low as 5% some enzymes were completely inactivated. Results indicated that a combination of heat and hydrogen peroxide might increase the permeability of the pulp and potentiate the effects of hydrogen peroxide on the pulp. While the pulp appears to be quite resilient, there is concern for patients who may apply bleaching agents for longer periods of time or more frequently than recommended in order to hasten the achievement of whiter teeth. The long-term effects of frequent or prolonged use of bleaching agents on pulps are unknown [51-54]. The reasons for tooth sensitivity during vital tooth bleaching are not clear. Studies are inconclusive regarding the pulpal considerations of vital tooth bleaching. What is clear, however, is that case selection is critical. Considerations prior to initiating tooth whitening procedures should include assessment of the condition of existing restorations, cervical erosion, enamel cracks, and the estimated duration and repetition of bleaching required to obtain and maintain the desired effect [55].
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IN VITRO ANTIOXIDANT AND PHYTOCHEMICAL SCREENING OF METHANOLIC EXTRACT OF AGARICUS BISPOROUS (BUTTON MUSHROOM)

IN VITRO ANTIOXIDANT AND PHYTOCHEMICAL SCREENING OF METHANOLIC EXTRACT OF AGARICUS BISPOROUS (BUTTON MUSHROOM)

Objective: The present study was carried out to evaluate the qualitative and In vitro antioxidant activities of methanolic extract of Agaricus bisporous (button mushroom) Materials And Methods: Agaricus bisporous was extracted with three solvents like methanol,ethanol and chloroform. Three extracts of Agaricus bisporous were tested for different phytoconstituents and the In vitro antioxidant activity of the methanolic extract was studied by using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, Reducing power activity, hydrogen peroxide scavenging activity, Superoxide scavenging activity and nitric oxide scavenging activity. Results: The yield of phytochemicals is in the order of methanol extract > ethanol extract >chloroform extract were obtained. Finally, methanolic extract was selected for further investigation. Highest free radical scavenging activity of DPPH assay, reducing power scavenging activity,
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THE EFFECT OF THE AMOUNT OF PEROXIDE CONCENTRATION ON TANNING PROCESS TOWARDS PHYSICAL AND ORGANOLEPTIC CHARACTERISTICS OF PANGASIUS SKIN

THE EFFECT OF THE AMOUNT OF PEROXIDE CONCENTRATION ON TANNING PROCESS TOWARDS PHYSICAL AND ORGANOLEPTIC CHARACTERISTICS OF PANGASIUS SKIN

The research is divided into two stages, The first stage is the process of pangasius skin tanning, and the second stage is the chracteristic test which included physical, and chemical character and tested in the laboratory of Balai Kulit Karet dan Plastik Yogyakarta. The tools used in this research are plastic buckets, knives, brushes, weighing instrument, funnels, plywood boards, rulers, rotating drums, cutters, thicness gauges, and tensile testing machine (Zwick and Roell brand). The material used in this research includes the main ingredients is, 5 kg of pangasius fish skin obtained from PT. Hayati Seafood, H2O2 (hydrogen peroxide), Na2S (sodi- um sulfide), Ca (OH) 2 (calcium hydroxide), (NH4) SO4 (ammonium sulfate), Pancerol (oropon), NaCl (kitchen salt ), HCOOH (formic acid), H2SO4 (sulfuric acid), Cr2O3 (chrome tanner), Na2CO3 (Sodium carbonate), H2O (water), and synthetic tanning agent (soft syntan).
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The Influence of Storage, Heat Treatment and Solids Composition on the Bleaching of Cheddar Whey with Hydrogen Peroxide.

The Influence of Storage, Heat Treatment and Solids Composition on the Bleaching of Cheddar Whey with Hydrogen Peroxide.

L* increased after HP bleaching in 34% and 80% (w/w) protein retentates, which indicated that HP bleaching increased brightness (Table 2). Similar results were observed in experiments I and II (results not shown). L* value is associated with white and black color and the higher positive value represents whiter color. Croissant et al. (2009) stated that HP bleaching of liquid whey resulted in a whiter whey protein product (WPC70) compared to control unbleached WPC70. However, Listiyani et al. (2011) reported that L* values of HP bleached WPC34 were not different from unbleached WPC34. The whey protein products in Croissant et al. (2009) (WPC70 bleached at liquid whey) and Listiyani et al. (2011) (WPC34 bleached during ultrafiltration) had different protein content and bleaching conditions, which may cause the different results. b* value is associated with blue and yellow, a higher positive value represents a more yellow color. b* values of liquid HP bleached samples decreased compared to liquid unbleached controls (Figure 4, 5, Table 3). Listiyani et al. (2011) also demonstrated decreased b* values of HP bleached liquid wheys compared to control liquid wheys. The b* values of HP bleached rehydrated WPC80 were not different from control WPC80. Miao and Roos (2004) reported that Maillard browning occurred during the spray drying of dairy products. In addition to the low bleaching efficacy of rehydrated spray-dried WPC80, this may be the reason why differences in b* values were not observed. It is possible that Maillard browning also occurred in the spray drying of WPC34, but b* value differences were still observed because of the higher bleaching efficacy of rehydrated spray-dried
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Application of Response Surface Methodology for Optimization of Reactive Azo Dye Degradation Process by Fenton’s Oxidation

Application of Response Surface Methodology for Optimization of Reactive Azo Dye Degradation Process by Fenton’s Oxidation

In this work, the removal of the model dye RBO3RID from aqueous solutions by Fenton’s reagent has been studied. Based on experimental results, an empirical relationship between the response and independent variables is obtained and expressed by the second-order polynomial equation. Effect of experimental parameters on COD removal efficiency of RBO3RID was established by the response surface and contour plots of the model-predicted responses. High COD removal (78.56%) was obtained under optimal value of process parameters for dye solutions in the 93 min of the removal process. Analysis of variance showed a high coefficient of determination value (R 2 =0.997, adj
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Prediction of whiteness index of cotton using bleaching process variables by fuzzy inference system

Prediction of whiteness index of cotton using bleaching process variables by fuzzy inference system

A similar phenomenon is observed from Fig. 9 for t and PC on WI. The figure shows that WI increases progressively with the increase of t. The effect of PC on WI is found very little here again. Lastly, from Fig.  10, it is observed that both T and t have almost similar influence on WI. Whiteness index increases smoothly with the increase of tem- perature and time. The rate of increase is initially sharp but slows down later on. For instance, WI increases around 17.65% for raising temperature from 78 to 88  °C, but it increases only about 6.12% for raising temperature from 88 to 108 °C. Similarly WI increases around 19.95% for increasing time from 20 to 30 min, but it increases only
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 OVERVIEW OF IN-OFFICE BLEACHING OF VITAL TEETH

 OVERVIEW OF IN-OFFICE BLEACHING OF VITAL TEETH

The importance of tooth whitening for patients has shown a dramatic increase in the number of products and procedures over recent years. Vital tooth bleaching refers to chair-side clinical application of a chemical solution to a tooth surface in order to achieve whitening effect of the teeth. Vital bleaching have found to be very effective but they also have their the drawbacks. The current article gives knowledge of vital tooth whitening with respect to external bleaching methods. the external bleaching of vital teeth focuses on patient selection, mechanisms, bleaching procedure and various in-office bleaching systems and techniques and their disadvantages
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