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Bast fiber from paper-mulberry (Broussonetia papyrifera) has long been utilized for handmade paper in Asia, serving as a prominent non-wood cellulose material. When restoring paper cultural assets, selecting a similar paper to the original ensures longevity and prevents deterioration issues like warping or tearing. The production of handmade paper involves several processes, including refining, steaming, and bleaching of raw materials. Once formed into sheets, the physical properties of the paper are dictated by these materials and remain unchanged unless the paper is newly made. Handmade paper production is labor-intensive and timeconsuming, emphasizing the need for careful raw material selection to match desired characteristics. This study evaluated the dendrological, morphological, anatomical, and chemical compositions of three papermulberry wood types cultivated in Korea and inferred their suitability as pulp for papermaking or repair of archival paper specimens. Papermulberry wood showed differences in fiber length according to molecular phylogenetic characteristics, but there were no differences in anatomical characteristics owing to the immaturity of the wood. This study investigated the characteristics of the bast fibers from the bark of papermulberry trees with different genetic traits to identify favorable factors likely to affect the pulp and papermaking process and paper quality. [ABSTRACT FROM AUTHOR]

Nanosized composite materials based on BaTiO 3 with 0.5 % and 1 % Fe 2 O 3 were prepared by the sol-gel method and subsequent heat treatment. This work showed that increasing the content of iron(III) oxide in a heterostructured material affects the bleaching of the dye rhodamine B upon irradiation with visible and ultraviolet light. The highest photocatalytic activity was observed on the solid surface of the samples in an air environment under both visible and UV irradiation. The BaTiO 3 /0.5 % Fe 2 O 3 sample was found to be most effective in an air environment when irradiated with an artificial visible light source. The increase in efficiency could be due to the best separation of charge carriers at the interface between the barium titanate and iron(III) oxide structures and the highest concentration of the resulting radical anions. An increase in the mass fraction of Fe 2 O 3 led to a decrease in the efficiency of the nanoscale composite photocatalyst, which was due to a greater recombination of charge carriers. [ABSTRACT FROM AUTHOR]

The pulp bleaching process is mainly responsible for the generation of toxic substances in the whole paper making process. The modification of conventional ECF (elemental chlorine free) bleaching was studied using an oxygen stage, a peracetic acid stage and an oxygen followed by peracetic acid stage in the following bleaching sequences: OD0EOPD, PaaD0EOPD, OPaaD0EOPD and QOPaaD0EOPD. The PaaD0EOPD sequence reduced the COD, BOD, color, TDS and AOX by 36.8, 37.0, 52.4, 39.8 and 53.9%, respectively, in comparison with D0EOPD. Moreover, PaaD0EOPD has better optical effluent properties, compared to the OD0EOPD sequence. OPaaD0EOPD reduced the chlorophenols, chloroguaiacols by 73.3 and 89.3%, and improved the brightness and whiteness by 1.7 and 3.1 units, respectively, in comparison with the D0EOPD bleaching sequence. The QOPaaD0EOPD sequence improved the pulp viscosity by 0.8 units in comparison with OPaaD0EOPD. The amendment of the conventional bleaching sequence was found to be effective for achieving an improvement in optical properties and effluent quality at reduced dose of chlorine dioxide. [ABSTRACT FROM AUTHOR]

The sterilization is a primary step in in-vitro culture. plant breeding through in-vitro culture hinges on the successful effectiveness of the sterilization method in producing sterile plants. This research aims to optimize sterilization methods using a completely randomized factorial design. The first factor is the size of the material (small and large), and the second factor is the graded concentration of the bleach solution. The study revealed that Material sizes do not have a significant effect on contamination level, all the same, large size materials increase the survival rate of sterilized rodent tuber plants. The application of graded bleach solution concentrations at 25%, 20%, and 15% is able to reduce contamination to 0% on small size materials and 5 % on large size materials. Material sizes do not have a significant effect on contamination level, all the same, large size materials increase the survival rate of sterilized rodent tuber plants. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the effects of two different home bleaching agents on color stability and surface roughness of hybrid ceramics. Materials and Methods: Three dental hybrid ceramics (Lava Ultimate, Cerasmart, and Vita Enamic) and two different home bleaching agents (9.5% hydrogen peroxide and 22% carbamide peroxide) were used. Thirty specimens of each material were prepared with dimensions of 12 × 14 × 1 mm. Technical polishing kits were applied to one surface of the specimens for the surface finishing procedure. Color parameters (L*a*b*) of the specimens were measured. Three subgroups were determined: control (C), hydrogen peroxide (HP), and carbamide peroxide (CP) (n = 10 each). After the bleaching procedures, color parameters were remeasured and color differences (ΔE) were calculated. Surface roughness values of the specimens were detected with a profilometer. Surface analysis of one specimen of each group was performed with a scanning electron microscope. Data were analyzed by two-way ANOVA and Tukey honest significant difference tests. Results: There was an interaction between material and bleaching agent type (P < .05). The highest ΔE values were observed in CP groups, and the lowest ΔE values were observed in control groups. For surface roughness, there was not an interaction between material and bleaching agent type (P >.05). Material and bleaching agent factors had a significant effect on surface roughness (P < .05). The highest surface roughness values were detected in HP groups. Conclusion: Home bleaching agents caused clinically acceptable color differences on hybrid ceramic materials. Hydrogen peroxide increased the surface roughness of hybrid ceramics. [ABSTRACT FROM AUTHOR]

The paper presents the new eco-friendly method of bleaching process of the cellulose fibre materials. Cellulose materials were bleached using hydrogen peroxide (both in aqueous solution, vapours, ozone and by the combined action of gaseous hydrogen peroxide and ozone. The method using hydrogen peroxide in aqueous solution presents the standard procedure and was used as the comparison technique. The bleaching processes using gaseous oxidants were carried out in a prototype device for dry, low-temperature treatment of fibrous materials with the use of oxidising agents in the gas phase. The influence of the innovative gas-phase bleaching method on the cotton samples' properties was analysed by Scanning Electron Microscopy (SEM), evaluation of the colour and whiteness, assessment of the polymerisation degree (DP), analysis of the mechanical properties and sorption capacity as well as microbiological assessment against colonies of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The comparison of the obtained results led to the conclusion that the bleaching processes using gas-phase agents—vaporised hydrogen peroxide, ozone or their combination—are non-invasive. The applied bleaching processes resulted in a slightly lower whiteness parameters than standard bath bleaching. After the bleaching processes with ozone and vaporised hydrogen peroxide separately, the decrease in the DP and tensile strength was similar to that observed after the bleaching with aqueous H2O2. When both processes were used together, a higher reduction in DP and tensile strength was noticed. Both oxidising agents showed a strong biocidal effect against bacteria. Gas-phase bleaching procedures, due to the lower temperature (35 °C vs. 98 °C) and minimal water consumption, have economic and environmental advantages, which allows their use in semi-industrial applications. It has been shown that the treatment of cotton fabrics using ozone and hydrogen peroxide in the gas phase allows to simultaneously obtain the bleaching and disinfection effect. [ABSTRACT FROM AUTHOR]

Objective: To review the efficacy and safety of PS neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for the removal of cosmetic tattoos of the eyebrows. Method: This was a retrospective review from January 2022 to August 2023 of patients who underwent cosmetic tattoo removal of the eyebrows with PS Nd:YAG laser. Results: A total of 24 patients were included in the review. 70% of patients were rated as “very much improved” (75-100% of the tattoo removed) and 30% of patients were rated “much improved” (50-75% of the tattoo removed). 1064-nm was the 1st wavelength used in all the cases. The average number of sessions required to obtain satisfactory results was 3. Four patients experienced unexpected change in their primary color of the eyebrow tattoos after the 1st treatment, which was successfully treated with 532-nm wavelength. None of the patients experienced dyspigmentation, scarring, or damage/bleaching of hairs of the eyebrows. Conclusion: PS Nd:YAG garnet laser is an effective and safe treatment for the removal of cosmetic tattoos of the eyebrows. [ABSTRACT FROM AUTHOR]

Recent advances in bleaching technology, such as bleaching ingredients, have accelerated the development of tooth whitening materials to change the color of natural teeth toward a lighter or whiter shade. Some bleaching materials are used for patients in combination with auxiliary medical devices to activate the bleaching materials by a light or heat source. Bleaching ingredients can be a poisonous and deleterious substance. Some bleaching materials are used in dental offices and the others at home. In clinical development of bleaching materials, appropriate evaluation of safety and efficacy is required according to the intended use. For appropriate and swift approval of the emerging bleaching materials, guideline on evaluation of dental whitening materials was discussed in a commissioned project by the Ministry of Health, Labour and Welfare of Japan for FY2021. Here, we summarize the current principles of the premarketing evaluation of the safety and efficacy. [ABSTRACT FROM AUTHOR]

Background and objectives: Pulp bleaching is a concern of many conservationists. Research has been conducted with the aim of evaluating some traditional bleaching materials used in the preservation of documents and books, such as hydrogen peroxide and sodium borohydride, which shows that these materials do not significantly improve the mechanical properties of historical papers. Also, investigating the effect of reducing agents on oxidized papers has shown the effectiveness of tert-butylamine borane complex. In another study, five dyeing processes with oxidizers (calcium hypochlorite, hydrogen peroxide in two concentrations, light bleaching and potassium permanganate) and two dyeing processes with reducing agents (sodium borohydride and tert-butylamine borane) were compared. Their effect on alfa cellulose (Whatman filter paper) and two different historical papers have been investigated. The results indicate that all the tested dye removal methods have led to a clear increase. Due to the differences of opinion, in this research, the effectiveness of two reducing agent sodium borohydride and sodium dithionite on the appearance and structural characteristics of paper is investigated. Methodology: In this research, Whatman Filter Paper No. 1 (Whatman Filter Paper No. 1) made in England with a thickness of 180 microns, diameter of 11 cm, basis weight of 87 grams per square meter and ash content of 0.06% was used. . Chemical reagents including potassium persulfate, sodium borohydride and sodium dithionite reagent grade were prepared in a laboratory from Merck, Germany.Three solutions including potassium persulfate (2% by weight/volume), sodium borohydride (1% by weight/volume), sodium dithionite (1% by weight/volume) in distilled water (distilled water, pH; 7), to perform tests on zinc. Paper samples have been used by immersion. Whatman filter paper samples were subjected to oxidation in 2% peta persulfate in distilled water for 2 days (48 hours) and then the samples were immersed. Next, the identified samples were modified by two solutions of sodium borohydride and sodium dithionite 1% in distilled water for 1 to 5 hours and then purified in distilled water. Also, the samples were subjected to accelerated aging according to ASTM standard number D4714-96 at a temperature of 90±2 centigrade and a relative humidity of 50±2% for 384 hours. Test methods include potentiostat, colorimetry, tensile strength, pH measurement, scanning electron microscope and infrared examination. Results: The results show that potassium persulfate is the most neutralizing solution among the three solutions used on the first day, and it also indicates the reducing power of two solutions of sodium dithionite and sodium borohydride, which according to the test results, sodium borohydride is the reducing power compared to sodium dithionite. The sample prepared with pH 3.92, after accelerated aging, was accompanied by an increase of several units of pH after modification with two reducing substances. Examining the data obtained from the tensile strength test shows that in comparison with the tested samples with a tensile index of 1.06, the samples modified with sodium borohydride and sodium dithionite increased the index in all five modified periods. The infrared spectrometry investigation of the samples modified with sodium borohydride and sodium dithione shows that this old material improves the structure of cellulose after aging by changing the C=O bonds to C-O and reducing the area of 1640 cm-1.. The reduction of the absorption band in the region of 1640 cm-1 has been opened in almost all time cases with this material compared to the modified sample. Based on the data, samples modified with sodium borohydride and sodium dithionite had a significant increase (approximately 25 units) in the Lfactor (light-darkness) after aging, indicating that two substances have increased the brightness of the sample by reviving the color compounds. In the microscopic examination of the surface of the fibers, in the samples identified with potassium persulfate, local separation of the fibers is observed. In the samples modified with sodium borohydride and sodium dithionite, fibers with higher consistency and entanglement are observed. Conclusion: Double bonds and carbon groups in paper samples formed with potassium persulfate have been the main responsible for the yellowness and darkness of the paper. The reducing agents, sodium borohydride and sodium dithionite reduce this aldehyde and ketone to hydrocarbon. With the loss of multiple conjugates, the light absorption of the paper is reduced and this causes the paper to brighten. The double bonds and their regeneration also cause rearrangement of the cellulose chain, which has resulted in increasing the mechanical resistance and strength of the paper samples. [ABSTRACT FROM AUTHOR]

Using different bleaching materials to eliminate or reduce organic volatiles in deteriorated olive oils will positively affect its characteristics. This study aims to identify the volatiles of oxidized olive oil after physical bleaching using selected immobilized adsorbents. Oxidized olive oil was eluted using open-column chromatography packed with silica gel, bentonite, resin, Arabic gum, and charcoal at a 1:5 eluent system (w/v, adsorbent: oxidized olive oil). The smoke point was determined. The collected distilled vapor was injected into GC-MS to identify the volatiles eluted after partial refining with each of these bleaching compounds. The results showed that volatile compounds were quantitatively and qualitatively affected by the type of adsorbents used for the elution of olive oil and the smoking points of eluted oils. The most prominent detected volatile compounds were limonene (14.53%), piperitone (10.35%), isopropyl-5-methyl-(2E)-hexenal (8.6%), methyl octadecenoate (6.57%), and citronellyl acetate (5.87%). Both bentonite and resin were superior in decreasing the ratio of volatile compounds compared with other bleaching materials used. Resin immobilized medium was significantly affected (p < 0.05), raising the smoke point. These results highlighted some information regarding the characteristics of volatile compounds that result after the physical elution of olive oil through selected adsorbents. [ABSTRACT FROM AUTHOR]

Objectives: Surface reaction-type pre-reacted glass-ionomer (S-PRG) filler releases six types of ions with a neutralizing ability. This study evaluated the effect of S-PRG filler incorporation in an H2O2-based bleaching material on the bleaching efficacy, pH, and reaction state. Materials and methods: The experimental bleaching material was formulated by the addition of 5% or 10% S-PRG fillers to the powder part. The stained bovine teeth were treated with the prepared bleaching paste. Commission internationale de l'éclairage (CIE) L*a*b* color space values were recorded before and after bleaching, and the color difference (ΔE) and whiteness index (WID) were calculated. Moreover, the used bleaching formulations were assessed for their pH values and reaction state by evaluating the oxidation state of manganese (Mn+2) using electron spin resonance (ESR). Results: The results of ΔE and WID showed that the addition of S-PRG filler increased the bleaching effect, but there was no significant difference between the groups with 5% and 10% S-PRG filler. A significant increase in pH in S-PRG filler groups (5% pH 6.7, 10% pH 6.8) was found compared to the 0% group (pH 4.8). ESR measurements showed that the signal emitted from Mn+2 decreased over time. The S-PRG filler groups showed a significantly higher reduction in Mn+2 compared to the 0% group, with no significant difference between the 5% and 10% S-PRG groups. Conclusions: S-PRG filler addition resulted in improved bleaching efficacy, higher reaction rate, and pH values that are close to neutral. Clinical relevance: S-PRG filler addition may be effective on the bleaching outcome of H2O2-based materials. [ABSTRACT FROM AUTHOR]

The article is a continuation of the book chapter entitled Recent Advances in Antioxidant Capacity Assays published by IntechOpen in 2021. The various methods for determining antioxidant capacity in a variety of materials (plant extracts, biological material, foods, etc.) are discussed, with a special emphasis on articles published in recent years and especially on reviews. Both chemical methods for determining antioxidant capacity and cellular antioxidant capacity assays were presented. In addition to the review published in 2021, the following methods for the determination of antioxidant capacity were presented: crocin bleaching assay, Briggs-Rauscher reaction inhibition assay, ferricyanide-Prussian blue assay, cerric reducing antioxidant capacity assay and Anti Oxidant Power 1 (AOP1) assay. Several applications of the cellular antioxidant capacity assay were also presented in tabular form. [ABSTRACT FROM AUTHOR]

Optical gain and resistance against photo-bleaching are key material parameters for practical applications in microlasers and microphotonics. Here, we present studies of optical amplification and photo-bleaching in a wide range of optical gain materials, including fluorescent dyes, quantum dots and rods, organic and inorganic room temperature polaritons, and nanodiamonds with emission range from 430 to 680 nm. We used amplified spontaneous emission (ASE) for each material to measure the optical gain. Robustness against photo-bleaching was determined by measuring the intensity of spontaneous emission of the material as a function of the number of excitation femtosecond pulses (106–1010) at various excitation energy densities. We show that pyrromethene laser dyes are the best organic emitters in terms of low excitation energy and good optical gain, whereas solid-state polariton materials are better in terms of high optical gain and stability. We found that all organic and inorganic optical gain materials bleach completely after 106–109 illumination pulses with typical 0.1–0.6 GW/cm2 peak power density, with an exception of nanodiamonds. We show that nanodiamonds are the only optical gain material that shows no photo-bleaching beyond the 1010 excitation pulses of 300 fs pulse duration and with 0.16 GW/cm2 peak power density. [ABSTRACT FROM AUTHOR]

The most frequently used bleaching materials are hydrogen and carbamide peroxide materials with specific concentration and techniques. The disadvantages of these materials range of sensitivity to bone inflammation and resorption processes. Therefore, it is desirable to employ alternative natural materials with little to no negative effects on the enamel, pulp and oral mucosa. This article reviews recently developing materials like papain, bromelain, chlorine dioxide, sodium chloride and sodium bicarbonate and a combination of peroxide and natural substances. In studies employing bromelain and papain in comparison to peroxide bleaching materials, the peroxide materials evolved to show better stain removal than the natural alternatives. It is worth mentioning that the concentrations of natural materials used were 20 times lesser compared to the peroxide materials. Chlorine dioxide was found to improve bleaching efficacy by virtue of the warmth that was created on application of light, leading to dryness of teeth. This material needs further research and improvement to match its conventional alternatives in efficacy. The newer alternatives considered in this line-up are sodium chloride and sodium bicarbonate. There was no slod scientific support to back this material's efficacy to conclusively compare it against peroxide materials. Finally, combination materials including lactoperoxidase along with hydrogen and carbamide peroxide showed to increase after 8 hours of contact than the system without lactoperoxidase. It can be concluded by saying that further research is required to find better alternatives to peroxide materials with better efficacy. Nanoparticles, off late, have found extensive purpose in modern day dentistry. The application of nanoparticles in bleaching is through hydroxyapatite nanoparticles. These nanoparticles concentration dependent whitening in comparison with carbamide peroxide. Recent developments including reduced graphene oxide has also been tried as an alternative to conventional bleaching methods. This material provided significant results and prove to be promising alternatives to peroxide tooth bleaching materials. This article reviews the developments and efficacy of non-peroxide bleaching materials. [ABSTRACT FROM AUTHOR]

Objectives: The development of new bleaching agents with minimum concentration of hydrogen peroxide (HP), without adverse effects, and with bleaching effectiveness, has great clinical relevance. The aim of this study was to evaluate the bleaching efficacy and cytotoxicity of a new niobium-based bleaching gel, compared to already available HP-based gels. Materials and methods: For the bleaching efficacy analysis, 40 bovine incisors were randomly divided into 4 groups according to the established bleaching protocol: control, untreated; 35HP, 35% HP bleaching gel; 6HP, 6% HP bleaching gel; NbHP, niobium gel associated with 3% HP gel. The color variation was measured in a spectrophotometer and the values of ΔL, Δa, Δb, and ΔE obtained. For the cell viability assay by MTT, MC3T3 cells were exposed to bleaching gel extracts (1:500, 1:250, 1:125 dilutions; immediately and 24 h). Statistical tests were performed (P < 0.05). Results: The color alteration for all bleaching gels was significant compared to control (P < 0.05), but the NbHP gel showed a significant ΔE than other gels, with expressive color alteration at 14 days (P < 0.05). The 35HP showed high cytotoxicity regarding control and the most groups in all periods and extracts analyzed (P < 0.05), while the NbHP showed greater cell viability than control in the immediate period, dilution of the 1:500 and superior to 6HP in the most extracts at 24 h. Conclusion: The new experimental niobium-based gel has bleaching efficacy similar to that of gels with a high concentration of HP, and it has high cytocompatibility. Clinical relevance: The use of this new generation of niobium-based whitening gel associated with a low concentration of hydrogen peroxide represents the possibility of a tooth whitening with lower dentin sensitivity. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of in-office bleaching on enamel microshear bond strength (μSBS) of two self-etch adhesives (SEA). Materials and Methods: For the bleaching group, bovine enamel surfaces were treated with a bleaching agent and divided into two main groups: one in which adhesive was applied immediately after bleaching and another in which adhesive was applied after one week. Enamel was bonded using the following procedures: group 1: application of a two-step SEA (Clearfil SE Bond 2, SE2, Kuraray Noritake); group 2: etching with 40% phosphoric acid (PA) and application of SE2;.group 3: application of a one-step SEA (G-Premio Bond, GP, GC); group 4: etching with PA and application of GP. Resin composite was placed and μSBS was measured at 24 h (immediately) and 1 week after bleaching. Acid-base resistant zones (ABRZ) were observed under SEM. Three-way ANOVA was used for data analysis. Results: Bleaching significantly decreased the μSBSs even after PA etching with both SE2 and GP (p ≤ 0.005). However, there were no significant differences in μSBS between groups with and without PA etching, except for SE2 without bleaching, in which the μSBS significantly increased with PA etching (p < 0.005). Thick ABRZs were found in SE2 and GP after bleaching, which exhibited an irregular wave-like shape for PA-treated specimens. Conclusion: The enamel μSBSs were adversely affected by in-office bleaching. Thick ABRZs were created with bleaching and PA treatment. [ABSTRACT FROM AUTHOR]

Aim and Objective: The aim of the study was to evaluate and compare the surface microhardness of bleached enamel subjected to erosion after using Remin Pro and NovaMin. Methodology: Thirty human maxillary premolars were selected and decoronated. Enamel blocks were obtained from these teeth and subjected to three phases of treatment: bleaching phase, remineralizing phase, and erosive phase. Samples were divided into four groups with 15 samples each. Group I: subjected to erosion without application of bleaching and remineralizing agent, Group II: treatment with 35% carbamide peroxide without application of remineralizing agent, Group III: treatment with 35% carbamide peroxide, followed by application of Remin Pro, and Group IV: treatment with 35% carbamide peroxide followed by application of NovaMin. Initial and final surface microhardness was analyzed using Vickers microhardness. Results: There was a statistically significant difference between control and experimental groups. The percentage of surface hardness loss (%SHL) value was significantly higher in Group II in comparison with the other groups of treatment. However, Group IV and Group III showed the lowest %SHL compared to GI. Conclusion: Within the limitations of this present in vitro study, NovaMin has better-remineralizing potential than Remin Pro and demonstrated increased microhardness of bleached enamel. [ABSTRACT FROM AUTHOR]

Background and Objectives. White spot lesions (WSLs) are a common problem that can be conservatively managed by resin infiltration. Consumption of dark beverages such as coffee causes staining of dental hard tissues, which can deteriorate the esthetic qualities of treated WSLs. The aims of this study were to investigate the effect of dark coffee heavy consumption on ICONR resin infiltrated WSLs and the influence of bleaching on them after staining. Methods. Twenty surfaces from sound human extracted third molars were used in the study. Two square-shaped buccal and lingual window areas had artificially created WSLs (received buccal resin infiltration afterward). Using VITA Easyshade, the baseline ΔE was recorded. Espresso coffee was used to immerse all surfaces for 8 days. The color coordinates according to CIE LAB were recorded for all surfaces at 2, 4, 6, and 8 days of immersion, and ΔE was calculated at each timepoint. After 8 days, in-office bleaching was applied to all surfaces according to the manufacturer's instructions and the color. Coordinates and ΔE were recorded. For statistical analysis, an independent sample t - test was used to compare each group. A general linear mixed model (GLMM) repeated measure ANOVA was applied for statistical analysis of L* and changes due to staining over time. Results. Analysis of time as a main effect on the L values of surfaces was statistically highly significant (p < 0.01). The interaction of time with surfaces under investigation and type of surface (test vs. control) as a main effect were non-significant (p = 0.47 and p = 0.35, respectively). Bleaching showed a significant difference in color lightness in both test and control surfaces compared to the mean L value at 8 days of staining (p < 0.01). Conclusion. Capsule-coffee consumption gradually influences the esthetic of resin infiltration on treated teeth. However, bleaching materials might restore an esthetic shade. [ABSTRACT FROM AUTHOR]

Using different bleaching materials to eliminate or reduce organic volatiles in deteriorated olive oils will positively affect its characteristics. This study aims to identify the volatiles of oxidized olive oil after physical bleaching using selected immobilized adsorbents. Oxidized olive oil was eluted using open-column chromatography packed with silica gel, bentonite, resin, Arabic gum, and charcoal at a 1:5 eluent system (w/v, adsorbent: oxidized olive oil). The smoke point was determined. The collected distilled vapor was injected into GC-MS to identify the volatiles eluted after partial refining with each of these bleaching compounds. The results showed that volatile compounds were quantitatively and qualitatively affected by the type of adsorbents used for the elution of olive oil and the smoking points of eluted oils. The most prominent detected volatile compounds were limonene (14.53%), piperitone (10.35%), isopropyl-5-methyl-(2E)-hexenal (8.6%), methyl octadecenoate (6.57%), and citronellyl acetate (5.87%). Both bentonite and resin were superior in decreasing the ratio of volatile compounds compared with other bleaching materials used. Resin immobilized medium was significantly affected (p < 0.05), raising the smoke point. These results highlighted some information regarding the characteristics of volatile compounds that result after the physical elution of olive oil through selected adsorbents.

The efficiency of chemoinformatics methods based on a fragment approach for the analysis of relationships between the chemical structure of textile dyes and colour fastness of the dyeings have been shown by examining a large set of properties, including the light fastness of acid dyes on wool and polyamide fibres, the sensitivity of acid dyes on wool to oxygen bleaching, the wash fastness of acid dyes on wool, the adsorption of direct dyes on cotton, and the photodegradation of azo dyes in solution. An analysis of the developed regression models depicted the contribution of ten substructural molecular fragments for each indicator of the colour fastness properties of acid and direct azo dyes on textile materials. The similarity of several individual multi-atomic fragments for acid and direct azo dyes was found for wool, polyamide, and cotton fibres, which indicates the coinciding mechanisms of the physicochemical processes that accompany the destruction of dyes while testing the light fastness and sensitivity of the dyeings to oxygen bleaching, as well as their adsorption/desorption with the wash fastness and dyeability of wool and cotton. [ABSTRACT FROM AUTHOR]

The present study aimed to determine the effectiveness of Trigona spp. propolis as an antioxidant to reduce residual peroxide after intra-coronal bleaching treatments. Thirty-five maxillary central incisors were divided into seven groups: five samples without antioxidants; sodium ascorbate 10% combined with Tween 80 0.2%; and Trigona spp. propolis 10%. The lengths of the application time were 1 h, 24 h, and 48 h. Each application time consisted of five samples. Root resection followed by artificial discoloration was performed in the samples. Then, intra-coronal bleaching using 35% hydrogen peroxide was applied. After the tooth color changed, the bleaching material was cleared, and this was followed by the applications of sodium ascorbate 10% combined with Tween 80 0.2% and Trigona spp. propolis 10%. The peroxide residue was measured by assessing dissolved oxygen using a titration analysis with either the Winkler or iodometric method. Data were analyzed using the ANOVA test and Tukey's HSD test. The lowest peroxide residue amount was found with the application of antioxidants for 48 h after the intra-coronal bleaching treatment using 35% hydrogen peroxide. However, there was no significant difference between sodium ascorbate 10% combined with Tween 80 0.2% and Trigona spp. propolis 10% to reduce peroxide residues after the intra-coronal bleaching treatment (p > 0.05). Therefore, these findings indicate that Trigona spp. propolis 10% effectively reduces peroxide residues after intra-coronal bleaching treatments, which can interfere with the bond of the composite to the tooth surface and shorten the wait time for composite restorations after bleaching treatments. [ABSTRACT FROM AUTHOR]

The bleaching process is an important stage in the edible oil refining operation, and is carried out by using acid-activated bleaching earths. The aim of this study was to evaluate the efficiency of coconut fiber ash, shell ash, acid-activated fiber ash and acid-activated shell ash as compared to the commercial bleaching earth in the bleaching of neutralized soybean oil. Bleaching materials were added to neutralized oil at the concentration of 1% (w/v) with agitation under vacuum at 110 °C for 30 minutes. The values for red and yellow colors, carotenoids, chlorophylls, peroxide value, p-anisidine value, free fatty acid contents, copper and iron levels of the bleached samples were determined. The results indicated that all coconut-based adsorbents have been significantly more effective than commercial bleaching earth in reducing color and the greatest reductions in carotenoid (84.25%) and chlorophyll (82.30%) contents were obtained by using acid-activated fiber ash. The peroxide value for all treatments decreased. The amounts of iron and copper as peroxide compounds decreased considerably (44.59% and 23.53%) by using acid-activated fiber ash and acid-activated shell ash, respectively. Therefore, coconut fiber and shell as agricultural wastes which have been ignored in the past might be employed as effective agents to bleach crude oils, particularly soybean oil, in refining operations. [ABSTRACT FROM AUTHOR]

Changes in the color of teeth to become darker are a lot of complaints by the public. Bleaching is a whitening treatment for teeth that have changed color. Home bleaching is a bleaching that can be done at home under the supervision of a dentist using 10% carbamide peroxide for a period of more than 2 weeks. The purpose of this study was to determine the effectiveness of 10% carbamide peroxide as a home bleaching agent with an extended period of time against tooth discoloration. This type of research is Literature Review using Google Scholar, Web of Science, and Pubmed using keywords that have been carried out, obtaining 9 articles that match the research criteria. The results showed that 10% carbamide peroxide with an application of more than 2 weeks gave effective and stable results, but the effect was also greater. The use of 10% carbamide peroxide as a home bleaching agent with an additional effective time for discoloration was seen based on a literature review. [ABSTRACT FROM AUTHOR]

Objectives: The current tooth bleaching materials are associated with adverse effect. Photodynamic method based on a novel photosensitizer alone, without combining with peroxides, is evaluated for tooth bleaching application. Materials and methods: Teeth samples were randomly divided into 3 groups with different treatment schemes, including negative control group (group A, physiological saline), experimental group (group B, ZnPc(Lys)5), and the positive control group (group C, hydrogen peroxide). Tooth color, surface microhardness, and roughness were determined at baseline, right after the first and second phase of bleaching, as well as 1 week and 1 month post-bleaching. Four samples in each group was randomly selected to evaluate the changes in surface morphology using the scanning electron microscope. Results: The color change values (ΔE) in group B (7.10 ± 1.03) and C (12.22 ± 2.35) were significantly higher than that in group A (0.93 ± 0.30, P < 0.05). Additionally, surface microhardness and roughness were significantly affected in group C, but not in the group A and B. Furthermore, the scanning electron microscope images showed no adverse effect of enamel in the group A and B while the group C demonstrated corrosive changes. Conclusions: ZnPc(Lys)5 had a satisfactory bleaching effect and is promising to be a new type of tooth bleaching agent. Clinical relevance: The current tooth bleaching materials give a satisfactory clinical outcome and long-term stability, but associated with some adverse reactions. Photosenstizer ZnPc(Lys)5 eliminated the main side effects observed in hydrogen peroxide-based agents on the enamel, and also had a satisfactory bleaching effect and provide a novel selective bleaching scheme for clinical use. [ABSTRACT FROM AUTHOR]

This study evaluated the alterations of surface topography of the bovine enamel caused by different pH of in-office bleaching agents. 23% H2O2 with pH 5.5, 7.0 and 8.5 were applied on the bovine tooth specimens (n=10) and photo-irradiated for 10 min. The bleaching procedure was repeated three times and specimens were subjected to linear surface roughness (Ra) and Vickers microhardness test (VHN) at baseline and after three consecutive applications. The morphological alterations were observed before and after third bleaching application. Data were analyzed by two-way ANOVA followed by Tukey's HSD. The pH of the bleaching agent significantly affects the Ra and VHN (p<0.05). Low pH yielded a significant increase in Ra and decrease in VHN. All the groups showed morphological alterations and profound effect was found in pH 5.5 group. It was concluded that the pH of the bleaching agent can affect Ra, VHN and surface morphology. [ABSTRACT FROM AUTHOR]

The purpose is to evaluate the effect of photo-thermal acceleration on in-office bleaching efficiency using a bleaching agent without photocatalysts in vitro. Artificially discolored bovine lower incisors were prepared, and the mixed in-office bleaching material contained hydrogen peroxide 23% was applied by following treatment for 10 min: high-(HI group) and low-intensity LED lights (LI group), oven at 38 °C (OV group), and room temperature at 23 °C (RT group). Color was measured before and after bleaching and color difference (∆E*) was calculated. The data were statistically analyzed using a two-way ANOVA and Tukey's post hoc test. The temperature change (∆T) of applied bleaching agent in HI and LI groups was measured using a thermography and was analyzed using a T test. The bleaching procedures were repeated 6 times. Irradiation in the HI group resulted in the highest ΔE, followed by the LI group whose ΔE was significantly lower. Both irradiated modes exhibited higher ΔE compared to non-irradiated OV and RT groups which were not significantly different from each other. The average temperature rise of bleaching agents in HI and LI groups after 10 min irradiation was 15.00 °C and 11.80 °C, respectively. The effect of photo-thermal acceleration was proved for an in-office bleaching agent without photocatalysts in vitro. [ABSTRACT FROM AUTHOR]

Purpose: Bleaching agents are commonly used to make the natural dentition look more attractive. Currently, in addition to products from reputable manufacturers, products of not fully known origin are available for purchase. The aim of the study was to investigate whether products of this type have a destructive influence on the mechanical and aesthetic properties of the dental restorative nanocomposite. Design/methodology/approach: Four bleaching agents were used, two recognized brands, and two products were purchased from Chinese websites (their manufacturer is unknown). Two gels and two types of whitening strips were used. One composite nanomaterial was used. Microhardness, diametral tensile strength, compressive strength and colour measurements were tested. Findings: For some bleaching agents, studies have shown a relatively small effect on mechanical properties and an acceptable effect on colour changes. Regardless of the observed changes, the use of bleaching agents qualified for the experiment should be considered safe for composites. Research limitations/implications: The number of blenching agents used as well as dental composites in this study was limited. In future studies, increasing the number of cycles in the bleaching process should be considered. Practical implications: A popular method of improving the aesthetic properties of teeth is the use of a wide range of blenching agents. Most patients who use teeth whitening procedures are also users of composite fillings. The use of bleaching agents may have a different effect on the mechanical and aesthetic restorative composites. For economic reasons, many people decide to import cheap bleaching agents of unknown or dubious origin via Internet services to perform the bleaching process on their own. In this study, it was investigated whether products of this type have an influence on the mechanical and aesthetic properties of the dental restorative nanocomposite. Originality/value: Until now, no comparison of the safety of the use of bleaching agents of recognized manufacturers and of unknown origin in terms of the effect on composite materials has been presented, despite their high social importance. [ABSTRACT FROM AUTHOR]

More than 70 % bleached chemical pulp is produced in India through elemental chlorine-free bleaching in which chlorine-based compounds like chlorine dioxide is a dominant chemical which generates chlorinated organic toxins harmful to the environment. Present studies demonstrate short sequence of bleaching combined with acid treatment, followed by pressurized oxygen delignification. It was found that efficiency of oxygen improved by adding hydrogen peroxide as an additive in oxygen delignification with subsequent treatment with ozone or chlorine dioxide as bleaching agents. It was observed that by using additive in ODL process, pulp can achieve 70±1 (%ISO) brightness. Reduction attains in kappa number 65–70 % as compared to 45–50 % in control oxygen delignification stage. Through AOpZ and AOpD bleaching sequences, full brightness achieved 84–85 (%ISO) without considerable loss in mechanical strength properties compared to DEpD sequence. A potential reduction in COD, color, and AOX was 28, 53.3, and 88 % respectively were observed in AOpZ short bleaching sequence compared to DEpD bleaching. [ABSTRACT FROM AUTHOR]

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In order to investigate the influences of hair dyeing on the distribution shapes of drugs in hair, different hair dyeing processes ("semi-permanent coloring without bleaching" and "permanent coloring with bleaching") were performed in vitro on black hair specimens collected from two subjects (Asians) who took a single dose of zolpidem (ZP, 10 mg of ZP tartrate) or methoxyphenamine (MOP, 50 mg of MOP hydrochloride). Under the following three different dyeing conditions, (1) semi-permanent coloring, (2) permanent coloring (once), (3) permanent coloring (twice), drug distributions in single hair specimens were investigated using a 2-mm segmental analysis by liquid chromatography-tandem mass spectrometry. Distribution shapes of drugs changed significantly only under the permanent coloring (twice) condition, resulting in reduced peak concentration and extended distribution width. There was, however, no significant difference in the amounts of drugs in hair between non-treated and dyed specimens, suggesting the drugs hardly leaked out of hair or were only slightly degraded during dyeing. In addition, while assuming contact with aqueous environment such as daily hair washing after dyeing, dyed hair specimens were individually immersed in ultrapure water for 20 hours, then the outflow of drugs in ultrapure water as well as the distribution shapes of drugs remaining in hair were determined. The drug outflow after permanent coloring (once and twice) was significantly larger than those after semi-permanent coloring, and the outflow ratios, [outflow]/([outflow] + [amount remaining in hair]), ranged over 9.8–24% (n = 3) for ZP and 68–71% (n = 3) for MOP after permanent coloring (once), and 54–72% (n = 3) for ZP and 86–91% (n = 3) for MOP after permanent coloring (twice). The distribution shapes of drugs after 20 h of immersion tended to flatten as outflow ratios increased, resulting in no change in the shapes after semi-permanent coloring, and complete collapse of their shapes after permanent coloring (twice). Thus, the present results indicated that hair dyeing involving bleaching and subsequent contact with aqueous environment after dyeing could significantly influence distribution shapes of drugs in hair. [Display omitted] • Permanent coloring could influence the distribution shapes of drugs in hair. • Semi-permanent coloring hardly influence the distribution shapes of drugs in hair. • Permanent coloring promotes leakage of drugs out of hair. • Dyeing and contact with water could make it difficult to estimate drug use history. • It could be possible to estimate drug use history even after dyeing. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the influence of different bleaching gels on the masking and caries-arresting effects of infiltrated and non-infiltrated stained artificial enamel caries lesions. Materials and methods: Bovine enamel specimens (n = 240) with each two sound areas (SI and SC) and each two lesions (DI and DC) were infiltrated (DI and SI), stained (1:1 red wine-coffee mixture,70 days), and randomly distributed in six groups to be bleached with the following materials: 6%HP (HP-6), 16%CP (CP-16), 35%HP (HP-35), 40%HP (HP-40), and no bleaching (NBl,NBl-NBr). Subsequently, specimens were pH-cycled (28 days, 6 × 60 min demineralization/day) and all groups except NBl-NBr were brushed with toothpaste slurry (1.100 ppm, 2×/day, 10 s). Differences in colorimetric values (ΔL, ΔE) and integrated mineral loss (ΔΔZ) between baseline, infiltration, staining, bleaching, and pH cycling were calculated using photographic and transversal microradiographic images. Results: At baseline, significant visible color differences between DI and SC were observed (ΔEbaseline = 12.2; p < 0.001; ANCOVA). After infiltration, these differences decreased significantly (ΔEinfiltration = 3.8; p < 0.001). Staining decreased and bleaching increased ΔL values significantly (p ≤ 0.001). No significant difference in ΔΔE was observed between before staining and after bleaching (ΔEbleaching = 4.3; p = 0.308) and between the bleaching agents (p = 1.000; ANCOVA). pH-cycling did not affect colorimetric values (ΔEpH-cycling = 4.0; p = 1.000). For DI, no significant change in ΔZ during in vitro period was observed (p ≥ 0.063; paired t test). Conclusions: Under the conditions chosen, the tested materials could satisfactorily bleach infiltrated and non-infiltrated stained enamel. Furthermore, bleaching did not affect the caries-arresting effect of the infiltration. Clinical relevance: The present study indicates that bleaching is a viable way to satisfactorily recover the appearance of discolored sound enamel and infiltrated lesions. [ABSTRACT FROM AUTHOR]

Purpose: To assess the influence of adhesive restorations on hydrogen peroxide (H2O2) diffusion through enamel and dentin and its cytotoxicity to pulp (MDPC-23) cells. Materials and Methods: Sound and resin-restored enamel/dentin disks were stored in water for 24 h or 6 months and adapted to artificial pulp chambers. Bleaching gels with 20% or 35% H2O2 were applied to the enamel surface for 45 min, and a culture medium in direct contact with the dentin surface (extract) was applied for 1 h to the MDPC-23 cells. Cell metabolism (MTT assay) and cell morphology (SEM) were assessed. The amount of H2O2 in the extracts was also quantified (peroxidase/leuco-crystal violet reaction). Results: A significant reduction in cell metabolism was observed between the group bleached with the 35% gel and the control group (sound, nonbleached) (p < 0.05). The H2O2 diffusion was directly related to its concentration in the bleaching gel. The variables "presence of restoration" and "time of water storage" did not significantly influence H2O2 diffusion or cell metabolism for either of the bleaching gels (p > 0.05). All bleached groups presented alterations in cell morphology related to the concentration of H2O2 in the bleaching gel. Conclusion: The reduction in cell metabolism and the changes in cell morphology were H2O2-concentration dependent, having no relationship with the presence of either new or aged adhesive restorations on teeth subjected to bleaching therapies. [ABSTRACT FROM AUTHOR]

Background: Using remineralizing agents during and after bleaching procedures could maintain enamel surface, decreasing its erosive susceptibility. This study evaluated the efficacy of an in-office and at-home bleaching materials with amorphous calcium phosphate (ACP) on the susceptibility of the enamel to erosion. Forty-five bovine specimens were separated into three groups. Group A: no bleaching (control). Group B: Zoom 2 bleaching followed by ACP application. Group C: Nite White ACP. All specimens in all groups were subjected to an erosive challenge for five days. Using Energy Dispersive X-ray all specimens were subjected to elemental analysis and were examined for morphological changes under Scanning Electron Microscope (SEM). Results: Group B showed the highest mean calcium, phosphorus and sodium weight percent (wt%). Both Groups B and C showed statistically significant difference. While, there was no statistically significant difference between both Groups A and B.The sodium mean wt% showed a statistically significant difference in all groups. The magnesium mean wt% showed no statistically significant difference in all groups. SEM photomicrograph revealed hollowing of prism cores with intact prisms peripheries for group A. Group B showed relativity smooth surface with minor pores, while Group C showed an increase in the depth of surface irregularities and depressions. Conclusions: Enamel susceptibility to erosion after bleaching procedure was material dependent. Zoom 2 bleaching agent followed by ACP application did not increase the susceptibility of the enamel surface to erosion. Adding ACP to Nite White bleaching agent had no benefit on reducing enamel susceptibility to erosion. [ABSTRACT FROM AUTHOR]

Adsorptive bleaching potentials of activated animal bone on palm oil was investigated. Palm oil was obtained locally from the mesocarp of oil palm fruits. The obtained palm oil was degummed, neutralized, and subjected to proximate analysis before bleaching. The animal bone–based activated carbon used as a bleaching material was locally prepared by cleaning, drying, carbonization, and chemical activation process. The prepared activated carbon (CBAC) was characterized using Fourier transform infrared, scanning electron microscopy, Braummer–Emmett–Teller, and x‐ray diffraction (XRD) methods. Bleaching of the prepared palm oil on CBAC was done at different process conditions. The characterization results of BET analysis show that CBAC has a surface area of 593.270 m2/g, micropore surface area 595.56 m2/g, micropore volume 0.212 cm3/g, Langmuir surface area 1.38e+04 m2/g, and adsorption energy 3.998 KJ/mol. XRD analysis indicates gypsum as the dominant mineral in the activated carbon sample. The CBAC efficiency of 75.14% was obtained for time/temperature interactions at 50 min/120°C while at 25 g/50 min dosage/time interactions an efficiency of 75.17% was obtained. [ABSTRACT FROM AUTHOR]

Textiles represent promising support materials for enzymes. The goal of the present work was to investigate the immobilization of commercial peroxidase on a polyester needle felt and the repeated use in the gentle degradation of norbixin in whey from dairy cheese as a practical application. High enzyme loads were obtained by a 2-step immobilization procedure. First, the number of functional groups on the textile surface was increased by a modification with amino-functional polyvinylamine. Second, the enzyme was immobilized by using 2 types of crosslinking agents. Due to the iron content of peroxidase, inductively coupled plasma–optical emission spectrometry was used for the quantitative determination of the enzyme load on the textile. The enzyme activity was evaluated using common 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulfonic acid) assay for peroxidases. By the variation of enzyme input and crosslinker concentration, a maximal enzyme load of 80 mg/g of textile was achieved, and a maximum specific activity of 57 U/g of textile. For the visualization of the enzyme on the fiber surface, fluorescence microscopy as well as scanning probe microscopy were used. The immobilized peroxidase showed significant activity, even after 50 reuse cycles. In addition, the potential of the new support and enzyme combination in commercial whey bleaching was demonstrated successfully on a 10-L scale. [ABSTRACT FROM AUTHOR]

Background. Internal bleaching is a choice of treatment in discolored endodontically treated teeth. Cervical root resorption is one of the important complications of this treatment. A suggested procedure to prevent this type of resorption is using a coronal barrier under the bleaching materials. The aim of the study was to compare the microleakage of mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) cement, and Biodentine. Materials and Methods. In this in vitro study, a total of 60 single canal incisors were included. They were randomly divided into three experimental groups (n = 16), one positive control group (n = 6), and one negative control group (n = 6). Coronal portion of the canals in the experimental groups was sealed with 3 mm of MTA, CEM cement, or Biodentine as a coronal barrier. After 3 days, specimens were bleached. A fresh Enterococcus faecalis suspension was added to the samples. The culture tubes were observed for 45 days, and the daily turbidity was recorded. Statistical analysis was accomplished by the Kaplan–Meier test and SPSS 22. Results. All positive samples showed turbidity, whereas none of the negative samples allowed bacterial leakage. Results showed no significant difference between MTA, CEM cement, and Biodentine groups. (P value = 0.304, 0.695, and 0.217). The bacterial microleakage for the two groups also did not show significant differences. Conclusions. CEM cement and Biodentine showed promising results as coronal plug, and clinical studies are needed to test these materials with MTA for avoiding microleakage in internal bleaching treatment. [ABSTRACT FROM AUTHOR]

Introduction:Post bleaching treatment, patients often require additional interventions for aesthetics such as replacement of previous restorations or veneer lamination. The adhesion of composite restorations after inoffice bleaching treatment with 25-40% hydrogen peroxide (H2O2) cannot be done immediately, because of the residual free radicals as a result of oxidation of the bleaching material, it is recommended to delay adhesive treatment for 1-3 weeks. If the adhesive action is taken immediately, the shear bond strength of the restoration can be reduced. Free radicals can interfere with resin infiltration and inhibit complete polymerization. The use of antioxidants as an alternative treatment that effectively eliminates residual free radicals and improves the shear bond strength of post-bleaching restorations. Sodium ascorbate is an antioxidant that has been known wide to scavenge free radicals, so adhesive restoration can be taken immediately after bleaching. Natural resources being developed like pomegranate peel (punica granatum) which is rich in antioxidants. Objective: This study aims to compare the differences of antioxidant sodium ascorbate and pomegranate peel extract 5% and 7.5% concentrations which can increase the shear bond strength of nanofilled composite restorations in teeth after bleaching with 25% and 40% H2O2. Materials and Methods: Thirty-two human incisors were divided into eight groups. The sample was treated with bleaching, then labial veneer preparation. In groups A and D 10% sodium ascorbate antioxidant was applied, groups B and E with 5% pomegranate peel extract and groups C and F with 7.5% pomegranate peel extract for 10 minutes. Groups G and H are groups without antioxidants. Then all samples were restored with nanofilled composites. The shear bond strength of the composite resins was tested with universal testing machine. Results: The highest shear bond strength of the composite resin was in the bleaching group of 40% hydrogen peroxide and using 7.5% antioxidant pomegranate peel extract, while the lowest was in the control group bleaching using 40% hydrogen peroxide and immediate restoration without antioxidants. Conclusion:In conclusion, application of 7.5% pomegranate peel extractas as an oantioxidant of post bleaching treatment with 40% H2O2is effective in giving benefit to achieve higher shear bond strength of composite nanofilled restoration than the other groups. [ABSTRACT FROM AUTHOR]

Background: Bleaching methods have been developed using peroxide compounds as bleaching material. The process of bleaching agent such as hydrogen peroxide works by forming unpaired electrons or what is called Reactive Oxygen Species (ROS). Purpose: to determine the effect of cocoa bean extract containing theobromine in inhibiting the decrease in microhardness that occurs after the application of bleaching material. Methods: This type of research is experimental laboratories using the Experimental Pre and Posttest Only Group Design. The sample of this study was 27 bovine incisive tooth enamel taken from the abattoir. The data obtained were analyzed by repaired ANOVA test and continued with Turkey's HSD test. Result: The value of the average difference in enamel surface hardness between the control and treatment concentrations of 15% was 10.99; between the control group and the extract of the cocoa beans (Theobroma cacao) concentration of 25% is equal to 31.94. Conclusion: this research is the extract of cocoa (Theobroma cacao) concentrations of 15%, 25% and 35% can increase enamel hardness after the bleaching process. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of in‐office and at‐home bleaching agents on color changes (ΔE00), translucency (TP00), whiteness (WID), surface roughness (Ra), and surface topography (Rsk and Rku) of a resin nano‐ceramic and a polymer‐infiltrated ceramic network CAD/CAM material. Materials and Methods: Sixty specimens (6 mm × 7 mm × 1.3 mm) were prepared from Lava Ultimate (LU) and Vita Enamic (VE). The specimens were divided into 6 groups according to the bleaching agents applied (n = 10/group): control, Perfect Bleach Office + (PBO), Opalescence Boost (OB), Perfect Bleach (PB) with 10% and 16% carbamide peroxide and Whiteness Perfect (WP). ΔE00 values were calculated before and after bleaching procedures with a spectrophotometer using the CIEDE2000 formula. ΔTP00 and ΔWID values were calculated for each material. Ra, Rsk, and Rku values of the specimens were evaluated with an Atomic Force Microscope. Two‐way ANOVA was used for statistical analyses of the parameters measured after bleaching. For pairwise comparisons, Tukey test was performed. Results: For LU, no statistically significant difference among the ΔE00 values of the groups was observed (p = 1.000). For VE, only WP group presented significantly higher values (2.12 ± 2.66) than the other groups (p < 0.001). For both materials; ΔTP00 values of at‐home bleaching groups were significantly higher than in‐office bleaching groups and control group (p < 0.001). For VE, ΔWID values did not demonstrate statistically significant difference (p = 1.000); however, for LU, PBO applied group showed statistically higher ΔWID values (3.00 ± 2.38) (p = 0.010) and WP applied group showed lower ΔWID values (0.47 ± 0.31) than the other groups (p = 0.030). For both LU and VE, there was no statistically significant difference among the groups regarding Ra (F = 4.544), Rsk (F = 2.369), and Rku values (F = 2.391) (p = 1.000). All of the VE groups presented Ra values higher than 0.2 µm. Conclusions: The optical properties of LU and VE after bleaching applications were affected by the contact time with bleaching agents rather than concentration. Bleaching procedure had no effect on the surface properties of these materials. [ABSTRACT FROM AUTHOR]

Bleaching refers to tooth whitening through the application of chemicals to the tooth surface, to oxidize organic pigmentation. This method has become a favored treatment in the community, to support the appearance of teeth. However, the use of chemicals during the bleaching process can result in reductions in tooth enamel hardness due to demineralization. The aim of the present study to determine the effects of hydroxyapatite (HA) paste, synthesized from chicken eggshells, on the microhardness of tooth enamel after the application of external bleaching materials. This study was conducted using 24 permanent maxillary central incisors, which were divided into four groups. Group 1 received sequential at-home bleaching and HA paste; group 2 received sequential at-home bleaching and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste; group 3 received sequential in-office bleaching and HA paste; and group 4 received sequential in-office bleaching and CPP-ACP paste. Enamel hardness tests were performed using a Universal Hardness Tester tool. Statistical analysis was performed using the Wilcoxon signed-rank test. The results show that the applications of HA paste, synthesized from eggshells, after the application of in-office bleaching, resulted in significant (p<0.05) increases in tooth enamel microhardness. In contrast, no significant effect was observed after the application of at-home bleaching. In conclusion, HA paste derived from eggshells can increase the microhardness of tooth enamel after the application of external bleaching materials. [ABSTRACT FROM AUTHOR]