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Introdução:A sensibilidade dentária é o efeito adverso mais comum relacionado ao clareamento dentário. Na técnica de consultório, o peróxido de carbamida a 37%, surgiu como possibilidade de clarear e não causar sensibilidade.Objetivo:trata-se deum relato de caso, que avaliou a eficácia (mudança de cor) e a presença ou não de sensibilidade dentária quando se fezo uso de um produto àbase de peróxido de hidrogênio a35% e outro de peróxido de carbamida a 37%, na técnica de clareamento dentário de consultório.Relato de caso:Paciente de25 anos, sexo masculino, submetido a estudo de boca dividida, onde no hemiarco esquerdo foi aplicado peróxido de hidrogênio a 35% e no hemiarco direito, peróxido de carbamida a 37%. Foram feitas 3 sessões, sendo Peróxido de Carbamidacom aplicação única de 45 minutos, e Peróxido de Hidrogêniocom 3 aplicações de 15 minutos, em seu respectivo lado de aplicação e intervalo de sete dias entre cada sessão. Os valores de sensibilidade foram analisados antes e depois de cada sessão por meio da escala visual analógica de dor, e a alteração de cor foi avaliada através da Escala Vita, analisando incisivos e caninos superiores, antes de cada sessão.Conclusões:O clareamento dental com o Peróxido de Hidrogênio apresentou melhor eficácia clareadora e o Peróxido de Carbamida apresentou ausência de sensibilidade durante o procedimento clareador. Sugerem-se mais estudos do tipo ensaio clínico, com o Peróxido de Carbamida, para que se possa, com uma amostra maior de pacientes, verificar suas vantagens no quesito sensibilidade, bem como sua efetividade clareadora (AU).

Introduction:Tooth sensitivity is the most common adverse effect related to tooth bleaching. In the in-office technique, 37% carbamide peroxide has emerged as a way of tooth bleaching which does not cause sensitivity.Objective:This paper consists of a case report that evaluated the efficacy (color change) and the presence or absence of tooth sensitivity when using a product based on 35% hydrogen peroxide and another product based on 37% carbamide peroxide in the in-office tooth bleaching technique.Case report:A 25-year-old male patient underwent a split-mouth study in which 35% hydrogen peroxide was applied to the left hemi-arch and 37% carbamide peroxide to the right hemi-arch. Three sessions were carried out, carbamide peroxide with a single 45-minute application, and hydrogen peroxide with three 15-minute applications, on their respective application side and with a seven-day interval between each session. Sensitivity values were analyzed before and after each session using the visual analogue pain scale, and color change was assessed using the Vita Scale, analyzing upper incisors andcanines before each session. Conclusions:Teeth bleaching with hydrogen peroxide showed better bleaching efficacy and carbamide peroxide showed no sensitivity during the bleaching procedure. Further clinical trials with carbamide peroxide are suggested inorder to verify, with a larger sample of patients, its advantages in terms of sensitivity, as well asits bleaching effectiveness (AU).

Introducción: La sensibilidad de la dentina es el efecto adverso más común relacionado con el blanqueamiento dental. En la técnica en clínica, el peróxido de carbamida al 37% ha surgido como una posibilidad de blanqueamiento sin causar sensibilidad.Objetivo: Se tratade un informe de caso que evaluó la eficacia (cambio de color) y la presencia o ausencia de sensibilidad de la denina al utilizar un producto a base de peróxido de hidrógeno al 35% y otro a base de peróxido de carbamida al 37% en la técnica de blanqueamiento dental en clínica.Informe de caso:Un paciente del sexo maculino de 25 años fue sometido a un estudio de boca dividida en el que se aplicó peróxido de hidrógeno al 35% en la hemiarcada izquierda y peróxido de carbamida al 37% en la hemiarcada derecha.Se realizaron tres sesiones, la peróxido de carbamida con una única aplicación de 45 minutos, y la peróxido de hidrógeno con tres aplicaciones de 15 minutos, en sus respectivos lados de aplicación y con un intervalo de siete días entre cada sesión. Se analizaron los valores de sensibilidad antes y después de cada sesión mediante la escala analógica visual del dolor, y se evaluó el cambio de color mediante la Escala Vita, analizando los incisivos superiores y los caninos antes de cada sesión. Conclusiones: El blanqueamiento dental con peróxido de hidrógeno demostró una mayor eficacia blanqueadora y el peróxido de carbamida no manifestó sensibilidad durante el procedimiento de blanqueamiento. Se sugiere realizar más ensayos clínicos con peróxido de carbamidaparapoder utilizar una muestra mayor de pacientes y verificar sus ventajas en términos de sensibilidad, así como su eficacia blanqueadora (AU).

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OBJECTIVE: To compare the color change, the risk and intensity of tooth sensitivity (TS), and gingival irritation (GI) of at-home bleaching applied on the buccal surface only or the buccal and lingual surfaces. MATERIALS AND METHODS: Sixty patients with canines A2 or darker were selected and their superior arches were randomized in two groups: at-home bleaching on the buccal-only or on the buccal and lingual surfaces, with 7.5% hydrogen peroxide, for 1 h daily/2 weeks. The color change was evaluated at baseline, 7, 14 days, and 1 month after bleaching using shade guides scales (ΔSGU) and a spectrophotometer (ΔEAB, ΔE00, and ΔWID). Risk and intensity of TS and GI were recorded daily using visual analogic scale (0-10). Patient satisfaction was evaluated with the orofacial esthetics. Paired t-test, McNemar's, and Wilcoxon signed-rank test were used for data analysis (α = 5%). RESULTS: Neither the color change nor the risk/intensity of TS was statistically different between groups (p > 0.05). Patient satisfaction increased after bleaching for both groups (p < 0.05). CONCLUSION: The addition of one contact surface does not result in an increased whitening degree compared to bleaching applied solely on the buccal surface. CLINICAL SIGNIFICANCE: Understanding the influence of surfaces interacting with the bleaching agent is crucial for comprehending the bleaching mechanism and avoiding unnecessary material expenses. Notably, employing the buccal-only technique is sufficient to achieve the desired efficacy.

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Monoxenous trypanosomatid Strigomonas culicis harbors an endosymbiotic bacterium, which enables the protozoa to survive without heme supplementation. The impact of H2O2 resistance and symbiont elimination on intracellular heme and Fe2+ availability was analyzed through a comparison of WT strain with both WT H2O2-resistant (WTR) and aposymbiotic (Apo) protozoa. The relative quantification of the heme biosynthetic pathway through label-free parallel reaction monitoring targeted mass spectrometry revealed that H2O2 resistance does not influence the abundance of tryptic peptides. However, the Apo strain showed increased coproporphyrinogen III oxidase and ferrochelatase levels. A putative ferrous iron transporter, homologous to LIT1 and TcIT from Leishmania major and Trypanosoma cruzi, was identified for the first time. Label-free parallel reaction monitoring targeted mass spectrometry also showed that S. culicis Iron Transporter (ScIT) increased 1.6- and 16.4-fold in WTR and Apo strains compared to WT. Accordingly, antibody-mediated blockage of ScIT decreased by 28.0% and 40.0% intracellular Fe2+concentration in both WTR and Apo strains, whereas no effect was detected in WT. In a heme-depleted medium, adding 10 µM hemin decreased ScIT transcript levels in Apo, whereas 10 µM PPIX, the substrate of ferrochelatase, increased intracellular Fe2+ concentration and ferric iron reduction. Overall, the data suggest mechanisms dependent on de novo heme synthesis (and its substrates) in the Apo strain to overcome reduced heme availability. Given the importance of heme and Fe2+ as cofactors in metabolic pathways, including oxidative phosphorylation and antioxidant systems, this study provides novel mechanistic insights associated with H2O2 resistance in S. culicis.

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Three 2,4-diarylpyrroles were synthesized starting from 4-nitrobutanones and the crystal structures of two derivatives were analysed. These are 4-(4-methoxyphenyl)-2-(thiophen-2-yl)-1H-pyrrole, C15H13NOS, and 3-(4-bromophenyl)-2-nitroso-5-phenyl-1H-pyrrole, C16H11BrN2O. Although pyrroles without substituents at the α-position with respect to the N atom are very air sensitive and tend to polymerize, we succeeded in growing an adequate crystal for X-ray diffraction analysis. Further derivatization using sodium nitrite afforded a nitrosyl pyrrole derivative, which crystallized in the triclinic space group P-1 with Z = 6. Thus, herein we report the first crystal structure of a nitrosyl pyrrole. Interestingly, the co-operative hydrogen bonds in this NO-substituted pyrrole lead to a trimeric structure with bifurcated halogen bonds at the ends, forming a two-dimensional (2D) layer with interstitial voids having a radius of 5 Å, similar to some reported macrocyclic porphyrins.

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The synthesis and structural characterization of four novel supramolecular hydrogen-bonded arrangements based on self-assembly from molecular `[Cu(2,2'-biimidazole)]' modules and malonate anions are presented, namely, tetrakis(2,2'-biimidazole)di-µ-chlorido-dimalonatotricopper(II) pentahydrate, [Cu3(C3H2O4)2Cl2(C6H6N4)4]·5H2O or [Cu(H2biim)2(µ-Cl)Cu0.5(mal)]2·5H2O, aqua(2,2'-biimidazole)malonatocopper(II) dihydrate, [Cu(C3H2O4)(C6H6N4)(H2O)]·2H2O or [Cu(H2biim)(mal)(H2O)]·2H2O, bis[aquabis(2,2'-biimidazole)copper(II)] dimalonatodiperchloratocopper(II) 2.2-hydrate, [Cu(C6H6N4)2(H2O)]2[Cu(C3H2O4)(ClO4)2]·2.2H2O or [Cu(H2biim)2(H2O)]2[Cu(mal)2(ClO4)2]·2.2H2O, and bis(2,2'-biimidazole)copper(II) bis[bis(2,2'-biimidazole)(2-carboxyacetato)malonatocopper(II)] tridecahydrate, [Cu(C6H6N4)2][Cu(C3H2O4)(C3H3O4)(C6H6N4)2]·13H2O or [Cu(H2biim)2][Cu(H2biim)2(Hmal)(mal)]2·13H2O. These assemblies are characterized by self-complementary donor-acceptor molecular interactions, demonstrating a recurrent and distinctive pattern of hydrogen-bonding preferences among the carboxylate, carboxylic acid and N-H groups of the coordinated 2,2'-biimidazole and malonate ligands. Additionally, coordination of the carboxylate group with the metallic centre helps sustain remarkable supramolecular assemblies, such as layers, helices, double helix columns or 3D channeled architectures, including mixed-metal complexes, into a single structure.

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Hydrogen peroxide (H2O2) transport by aquaporins is a critical feature for cellular redox signaling. However, the H2O2 permeation mechanism through these channels remains poorly understood. Through functional assays, two Plasma membrane Intrinsic Protein (PIP) aquaporins from Medicago truncatula, MtPIP2;2 and MtPIP2;3 have been identified as pH-gated channels capable of facilitating the permeation of both water (H2O) and H2O2. Employing a combination of unbiased and enhanced sampling molecular dynamics simulations, we investigated the key barriers and translocation mechanisms governing H2O2 permeation through these aquaporins in both open and closed conformational states. Our findings reveal that both H2Oand H2O2 encounter their primary permeation barrier within the selectivity filter (SF) region of MtPIP2;3. In addition to the SF barrier, a second energetic barrier at the NPA (asparagine-proline-alanine) region that is more restrictive for the passage of H2O2 than for H2O, was found. This behavior can be attributed to a dissimilar geometric arrangement and hydrogen bonding profile between both molecules in this area. Collectively, these findings suggest mechanistic heterogeneity in H2Oand H2O2 permeation through PIPs.

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This study presents the potential role of deep eutectic solvents (DESs) in a lipase-catalyzed hydrolysis reaction as a co-solvent in an aqueous solution given by a phosphate buffer. Ammonium salts, such as choline chloride, were paired with hydrogen bond donors, such as urea, 1,2,3-propanetriol, and 1,2 propanediol. The hydrolysis of p-nitrophenyl laureate was carried out with the lipase Candida antarctica Lipase B (CALB) as a reaction model to evaluate the solvent effect and tested in different DES/buffer phosphate mixtures at different % w/w. The results showed that two mixtures of different DES at 25 % w/w were the most promising solvents, as this percentage enhanced the activities of CALB, as evidenced by its higher catalytic efficiency (kcatKM). The solvent analysis shows that the enzymatic reaction requires a reaction media rich in water molecules to enable hydrogen-bond formation from the reaction media toward the enzymatic reaction, suggesting a better interaction between the substrate and the enzyme-active site. This interaction could be attributed to high degrees of freedom influencing the enzyme conformation given by the reaction media, suggesting that CALB acquires a more restrictive structure in the presence of DES or the stabilized network given by the hydrogen bond from water molecules in the mixture improves the enzymatic activity, conferring conformational stability by solvent effects. This study offers a promising approach for applications and further perspectives on genuinely green industrial solvents.

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The (R,R)-Teth-TsDPEN-Ru(II) complex promoted the one-pot double C=O reduction of α-alkyl-ß-ketoaldehydes through asymmetric transfer hydrogenation/dynamic kinetic resolution (ATH-DKR) under mild conditions. In this process, ten anti-2-benzyl-1-phenylpropane-1,3-diols (85:15 to 92:8 dr) were obtained in good yields (41-87%) and excellent enantioselectivities (>99% ee for all compounds). Notably, the preferential reduction of the aldehyde moiety led to the in situ formation of 2-benzyl-3-hydroxy-1-phenylpropan-1-one intermediates. These intermediates played a crucial role in enhancing both reactivity and stereoselectivity through hydrogen bonding.

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This study evaluated the photoactivation of hydrogen peroxide gels at different concentrations using blue or violet LED in terms of whitening efficacy and tooth sensitivity. Forty patients were randomly divided into 4 groups: HP6V (violet LED and 6% hydrogen peroxide), HP6B (blue LED and 6% hydrogen peroxide), HP35V (violet LED and 35% hydrogen peroxide), and HP35B (blue LED and 35% hydrogen peroxide). The L*, a* and b* values were measured before, 1 week and 3 months after treatment, and the ΔE and ΔWID values were calculated. Tooth sensitivity was measured using a visual analogue scale (VAS) before, immediately after, and 24 h after bleaching. The ΔE, ΔWID and bleaching sensitivity values were subjected to the ANOVA test and Bonferroni post-test. HP35V and HP35B showed higher whitening efficacy than HP6VL, while HP6V did not show statistical differences compared to the other groups. Regarding bleaching-related sensitivity, the HP6V and HP6B groups presented the lowest values when compared to HP35V and HP35B. HP6V showed whitening efficacy comparable to HP35V and HP35B but with reduced tooth sensitivity. TRIAL REGISTRATION NUMBER: NCT06165458; registration date: 12/09/2023.

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Using a 1:1 cocrystal of (E)-N-(3,4-difluorophenyl)-1-(pyridin-4-yl)methanimine with acetic acid, C12H8F2N2·C2H4O2, we investigate the influence of F atoms introduced to the aromatic ring on promoting π-π interactions. The cocrystal crystallizes in the triclinic space group P1. Through crystallographic analysis and computational studies, we reveal the molecular arrangement within this cocrystal, demonstrating the presence of hydrogen bonding between the acetic acid molecule and the pyridyl group, along with π-π interactions between the aromatic rings. Our findings highlight the importance of F atoms in promoting π-π interactions without necessitating full halogenation of the aromatic ring.