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A formação de coágulos em implantes ósseos produz fatores pró-angiogênicos criando um microam-biente adequado para que ocorra a osteogênese, garantindo o sucesso do implante ósseo. O objetivo deste trabalho foi avaliar o efeito do plasma atmosférico frio (CAP) em superfícies de titânio (Ti) na adesão e ativação plaquetária e no tempo de coagulação. Para isso, foram produzidos discos de titânio tratados por CAP durante 15 minutos na voltagem de 15Kv, frequência de 600Hz e 1 L/min de hélio. A topografia foi avaliada por microscopia de força atômica (AFM), a composição química por espec-troscopia de fotoelétrons de raios X (XPS) e a molhabilidade por teste de gota séssil. Foram coletados 30mL de sangue com citrato de sódio 3,2%. O plasma rico em plaquetas (PRP) foi obtido por centri-fugação a 1000 rpm por 5 min. O tempo de protrombina e tromboplastina parcial foram medidos usando um coagulômetro semiautomático. 800μL de PRP foram distribuídos sobre as amostras e incubados por 60 minutos a 37ºC em atmosfera úmida. Em seguida, as amostras foram lavadas com PBS para remoção de plaquetas não aderidas, fixadas e observadas em microscópio eletrônico de varredura (MEV) e analisadas no software ImageJ. A adesão plaquetária foi determinada pela distân-cia e número de plaquetas aderidas e ativadas. As amostras tratadas por CAP apresentaram maior ativação plaquetária, maior número de plaquetas na superfície e maior distância quando comparadas às polidas, o que resultou em menor tempo de coagulação proporcionando formação mais rápida de coágulos, frequentemente associado a maior biocompatibilidade do implante e melhor osseointegra-ção.

The effects of cold atmospheric plasma (CAP) of dielectric barrier discharges on the wettability, imbibition and germination ofLeucaena leucocephalawere investigated. It was established that CAP treatment markedly hydrophilized the seed coat, especially at longer treatment times. From the profile of the imbibition curve and visual observation, it was possible to verify that there are two resistance barriers to water penetration: integument surface and region of the macrosclereid cell wall (light line). Although the plasma interacts only in the integument, increasing the density of hydrophilic sites increases the capacity of water absorption, producing enough driving force to overcome the second resistance barrier. The existence of these two barriers changes the three-phase pattern generally observed during seed germination. Despite an increase in imbibition, the plasma treatment conditions used in this work, were not enough to overcome completely the dormancy barrier.

The enzymatic oxidation process that causes black spots on shrimp, named melanosis, leads to spoilage and economic losses. Therefore, there is an urgent need for strategies to reduce melan...

Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique that produces ceramic coatings using high voltage discharges. To the present work this technique was applied to treat aluminum surfaces using a pulsed current supply and sodium silicate electrolyte. The effect of the duty cycle and treatment time on the morphology, phase composition and tribo-mechanical properties of the formed layer was investigated. The current density was maintained at 12 A/dm2, with two different duty cycles, 30% and 50%, for total period of 100 μs. For each duty cycle two different treatment times (2 min and 12 min) was used. During each treatment, the voltage was monitored to determine the start of the rupture of the passive oxide layer. It was demonstrated that the increase in the duty cycle from 30% to 50% influenced the thickness and porosity of the film, verified by scanning electron microscopy (SEM) images. Phase γ-Al2O3 was predominant on the surface of the samples treated by PEO, although occurrence of mullite and α-Al2O3 were also observed. There was an inversion in the intensities of the diffraction peaks Al (200) and Al (111) after the formation of the oxide phase, suggesting a preferential oxidation in the Al (111) direction. The PEO process allows tuning of the hardness, yield strength and wear resistance by controlling film thickness, porosity and phases present. Keywords: PEO, Plasma, Duty cycle, Aluminum oxide, Nanohardness, Wear rate

RESUMO Cera de carnaúba é utilizada, com sucesso, em revestimento de frutos por formar uma barreira contra a perda de umidade, troca de gases e ação antimicrobiana. No presente trabalho, pretende-se melhorar esta última propriedade através do tratamento por plasma. Plasma produzido por descarga de barreira dielétrica (DBD), usando pulsos de voltagem de 45 kV, repetidos na frequência de 405 Hz, durante 9 min, foi aplicado diretamente sobre esporos de fungo Colletotrichum brevisporum (4x104 conidia.cm-1) ou sobre superfície dos revestimentos de cera. Verificou-se que o revestimento, após tratado por plasma, apresentou resistência antifúngica equivalente àquela existente quando aplicada diretamente sobre os fungos. Este resultado foi justificado com base na literatura, em que o tratamento com plasma em lipídios estimula a oxidação das cadeias lipídicas, resultando na formação de compostos carboxílicos, que possuem propriedades antimicrobianas. ABSTRACT Carnauba wax is successfully used in fruit coating to produce a barrier against moisture loss, gas exchange and microbial action. The present study aims to improve this latter property by plasma treatment. Plasma produced by dielectric barrier discharge (DBD), using voltage pulses of 45 kV, repeated at the frequency of 405 Hz, for 9 min, was applied directly to spores of the fungus Colletotrichum brevisporum (4x104 conidia.cm-1) or on the surface of wax coatings. It was found that the coating, after being treated by plasma, presented antifungal resistance equivalent to that existing when applied directly to the fungi. This result was justified based on the literature, in which plasma treatment with lipids stimulates the oxidation of lipid chains, resulting in the formation of carboxylic compounds, which have antimicrobial properties.

Desalination plant and saltwork production currently produce large quantities of by-product, in the form of bitterns, which is generally regarded as waste. Up to now methods to discard this waste are unsustainable and restricted by high capital costs and non-universal application. Cold atmospheric plasma over liquids has led to various established industrial implementations, as well as promising applications, including chemical analysis, nanomaterials synthesis and plasma medicine. In this study interaction plasma – hypersaline water using cathodic or anodic polarization was investigated. Pulses of 2.3 kV, repeated at a frequency of 1 kHz, were applied to produce a pulsed corona discharge (PCD) over hypersaline water (HSW) surface. It was observed that in cathode polarization, considerable number of metallic cations can be extracted from the solution in the form of precipitate salts, while in anodic configuration, despite having a higher spectral intensity for Na (589.5 nm), it was less efficient in the salt precipitation. The findings of this study suggest that changing polarization also changes the mechanism of plasma interaction, indicating to be an interesting technique to explore selective saline water chemical extraction.

Sob condicoes ainda desconhecidas, cristais denominados de flor de sal, ou fleur de sel, como e comumente conhecido, pode ser formado na superficie de uma salmoura supersaturada durante a evaporacao da agua do mar nas salinas. Visando produzir flor de sal de uma maneira controlada e fazer melhor uso da solucao residual de salinas, denominada de agua-mae, o presente trabalho foi proposto. O mecanismo de crescimento, morfologia, microestrutura e composicao quimica dos sais obtidos foram estudados durante a evaporacao da agua-mae, cuja densidade variou de 1,230 g/cm³ para 1,244 g/cm³, mantendo fixos o gradiente termico e umidade relativa do ar. Analises quimicas, microestruturais e morfologicas foram usadas para caracterizacao. Cristais cubicos ocos foram obtidos cujas concentracoes ionicas foram dependents da densidade da solucao. O tamanho e massa dos cristais tambem foram dependentes da densidade da solucao. As amostras apresentaram fases contendo sulfatos como NaK3(SO4)2, Mg (SO4). (H2O) e K2SO4, cuja porcentagem aumentou levemente com o aumento da densidade. Mesmo assim, as porcentagens de NaCl foram acima de 90% para todas as amostras, mostrando que e possivel extrair flor de sal de alta pureza a partir de uma solucao residual hipersalina. Palavras chaves: flor de sal, agua-mae, crescimento de cristais, mecanismo, salina.

Up to now, plasma electrolytic oxidation (PEO) has been either produced direct current or ultra-low frequency (< 1 kHz) pulsed discharge using high concentration alkaline-silicate electrolytic (Na2SiO3 > 8 g.L-1 with presence of KOH). In order to contribute to these studies, the effect of current pulse width and time duration was investigated using diluted silicate electrolytic (Na2SiO3 2 g.L-1) and high pulse frequencies (> 1 kHz). The PEO process was performed on pure aluminum to try to explain how the phases composing the coatings are formed and distributed over the treatment time. For this, was made in situ monitoring using optical emission spectroscopy (OES) coupled with CCD camera. The crystalline phases evolution in the sample surface was investigated using grazing incidence X-ray diffraction (GIXRD). Regarding the evolution of ceramic phases, it is possible to verify that, internally, the predominant phase is rhombohedral α-Al2O3 but, superficially, the predominant phase is cubic γ-Al2O3. It was verified the presence of Si on the borders of the pores or in proximity to cracks, especially in the treatments with higher pulse width. SEM analysis shows a reduction of the superficial porosity and an increase in coating thickness with pulse width and treatment time.

In this study, we analyzed seed wettability as well as imbibition and germination after treatment with atmospheric pressure cold plasma (APCP) using dielectric barrier discharge (DBD) in seeds that have very low germination rates. To aid industrial applications, several seeds were simultaneously treated with plasma within a space between two coaxial glass tubes sandwiched by two metal mesh screens that produced high-voltage pulses at 17.5 kV with a frequency of 990 Hz. Three treatment times (3 min, 9 min and 15 min) as well as untreated seeds were used to conduct the wettability, imbibition and germination tests. The wettability and imbibition were found to be directly related to the treatment duration, but saturation of the imbibition was found for treatment durations greater than 9 min. Plasma treatment was also effective in improving germination, but shorter treatment duration presented greater germination. This apparent contradiction is explained by the cell damage caused by the increased exposure to plasma, as observed in other studies. The results suggest that there must be an optimal wettability and imbibition condition that ensures that excessive moisture does not harm the germination process.

Discharge of dielectric barriers significantly reduced microbial populations. Treatments resulted in improvement in physical characteristics during storage. Nonthermal plasma provided a 43% (4-day) increase in sample lifetime.

Direct current (DC) plasma nitriding offers some disadvantages, especially in parts with complex geometries, where the presence of edges is significant, such as gears, molds, and needle punched parts are strongly affected by this effect, leading to irregular formation of nitrided layers and high variation in surface hardness. To solve these problems two techniques were developed as alternatives, namely: pulsed plasma nitriding and cathodic cage nitriding. In this work, these three nitriding techniques were compared using AISI 1045 steel as substrate. Steel discs were nitrided with the purpose of evaluating the influence of these different plasma configurations on the characteristics of the nitrided layer. The treatments in the three techniques were carried out at the same pressure, temperature, time and gas atmosphere. The samples were characterized for the microstructure, microhardness and crystalline phases present. X-ray diffraction with grazing incidence was used to verify the order of the nitrites formed and to estimate the thickness of the single-phase layers. Differences between the configurations with respect to the occurrence of restriction rings, total thickness (xe + xγ') and relative (xe/xγ') compound layers were observed. Keywords: Plasma DC; cathodic cage; pulsed plasma; nitriding; GIXRD.

Objectives To evaluate the effects of the surface modification of 316L stainless steel (SS) by lowtemperature plasma nitriding on endothelial cells for stent applications. Results X-ray diffraction (XRD) confirmed the incorporation of nitrogen into the treated steel. The surface treatment significantly increased SS roughness and hydrophilic characteristics. After 4 h the cells adhered to the nitride surfaces and formed clusters. During the 24 h incubation period, cell viability on the nitrided surface was higher compared to the polished surface. Nitriding reduced late apoptosis of rabbit aorta endothelial cell (RAEC) on the SS surface. Conclusion Low temperature plasma nitriding improved the biocompatible of stainless steel for use in stents.

Biomedical devices introduced in the human body interact initially with blood cells, their success being dependent on the result of this interaction. This work aimed to obtain optimum biocompatibility and hemocompatibility of the titanium by plasma treatment. For this, discs of commercially pure titanium (CP) were subjected to plasma nitriding using different mixture of nitrogen and hydrogen; the effect of addition of hydrogen to the nitriding plasma was investigated. Before and after treatment, samples were evaluated in terms of topography and wettability using atomic force microscopy and sessile drop tests, respectively. The titanium biological response was evaluated in vitro through the application of platelet-rich plasma (PRP) on the surfaces modified and analysis of their behaviour from the point of view of surface tension and cell adhesion. Surface properties, such as roughness and wettability, were sensitive to the hydrogen/nitrogen ratio in the nitriding plasma, suggesting a strategy for producing different surfaces of biomedical devices. Results showed to be possible to obtain surfaces with different response to the adhesion of platelets, covering different applications.

Crystallization of salts in droplets of hypersaline solution placed on a glass slide was monitored and evaluated under controlled conditions of temperature and humidity. Pulsed corona discharge (PCD) was applied over sessil droplets on a glass surface, and its effect in the crystallization is demonstrated for the first time. These results were compared with natural evaporation. Under natural evaporation, crystals are firstly formed on surface, near edges of the drop and grow towards the center, eventually acquiring a pyramidal morphology. Under PCD, a Taylor cone is formed between electrode and droplet surface and then, 4 s after the beginning of the discharge, small crystals were formed on the cone besides a dense crystal film around the discharge incidence point in the droplet. These results are discussed considering existing knowledge about plasma–liquid interaction (PLI) and dynamical of crystal growth. This paper explores an interesting aspect of PLIs, which has both fundamental and practical usefulness, for understanding desalination processes, salt crystallization on water surface and biomedical science for advances in electrosurgical methods.

We evaluated the effects of titanium plasma nitriding and oxidation on live endothelial cell viscoelasticity. For this, mechanically polished titanium surfaces and two surfaces treated by planar cathode discharge in nitriding (36N2 and 24H2) and oxidant (36O2 and 24H2). Surfaces were characterized regarding wettability, roughness and chemical composition. Rabbit aortic endothelial cells (RAECs) were cultured on the titanium surfaces. Cell morphology, viability and viscoelasticity were evaluated by scanning electron microscopy (SEM), methyl thiazolyl tetrazolium (MTT) assay and atomic force microscopy (AFM), respectively. Grazing Incidence X-ray Diffraction confirmed the presence of TiN0,26 on the surface (grazing angle theta 1°) of the nitrided samples, decreasing with depth. On the oxidized surface had the formation of TiO3 on the material surface (Theta 1°) and in the deeper layers was noted, with a marked presence of Ti (Theta 3°). Both plasma treatments increased surface roughness and they are hydrophilic (angle < 90°). However, oxidation led to a more hydrophilic titanium surface (66.59° ± 3.65 vs. 76.88° ± 2.68; p = 0.001) due to titanium oxide films in their stoichiometric varieties (Ti3O, TiO2, Ti6O), especially Ti3O. Despite focal adhesion on the surfaces, viability was different after 24 h, as cell viability on the oxidized surface was higher than on the nitrided surface (9.1 × 103 vs. 4.5 × 103cells; p < 0.05). This can be explained by analyzing the viscoelastic property of the cellular cytoskeleton (nuclear and peripheral) by AFM. Surface oxidation significantly increased RAECs viscoelasticity at cell periphery, in comparison to the nucleus (2.36 ± 0.3 vs. 1.5 ± 0.4; p < 0.05), and to the RAECs periphery in contact with nitrided surfaces (1.36 ± 0.7; p < 0.05) and polished surfaces (1.55 ± 0.6; p < 0.05). Taken together, our results have shown that titanium plasma treatment directly increased cell viscoelasticity via surface oxidation, and this mechanobiological property subsequently increased biocompatibility.

RESUMO No Brasil, estudos sobre pigmentos cerâmicos ainda são bastante escassos. Por esta razão, grande parte dos pigmentos consumidos pela indústria cerâmica são importados dos países europeus. Outra parte destes pigmentos são obtidos pela rota cerâmica, entretanto, esta rota de síntese resulta em pigmentos com propriedades bastante heterogêneas, reduzindo a qualidade do revestimento. Por esta razão, vários são os estudos no sentido de desenvolver rotas de síntese que resultem em pigmentos com propriedades mais homogêneas, sendo ambientalmente adequados e economicamente viáveis. Nesse contexto, este trabalho teve como objetivo sintetizar óxidos com estrutura tipo perovskita de composição LaAl1-xCrxO3 (x=0,1; x=0,05) pelo método gelatina, visando sua aplicação como pigmento para colorir esmalte transparentes brilhante. Os pós resultantes do processo de síntese foram calcinados a 800 e 1000 °C. Em seguida, foram caracterizados por análise termogravimétrica, difração de raios-x, espectroscopia na região do Uv-Visível e colorimetria. As perovskitas sintetizadas foram usadas para a preparação de esmaltes cerâmicos pela adição de 2% em peso de pigmentos em esmalte transparentes brilhantes. Os difratogramas de raios-x revelaram que os pós são monofásicos com estrutura perovskita trigonal. A cor das amostras variou em função do teor de substituinte, e a tonalidade mais avermelhada foi obtida para as perovskitas com menor substituição do íon Cr3+ e calcinadas em temperaturas maiores. Não foram observadas alterações na cor do pigmento quando introduzido no esmalte transparente brilhante. ABSTRACT In Brazil, studies on ceramic pigments are still very scarce. For this reason, most of the pigments consumed by the ceramic industry are imported to European countries. Another part of these pigments is obtained by the ceramic route, however, this route of synthesis results in pigments with very heterogeneous properties, reducing the quality of the coating. For this reason, several studies are aimed at developing synthetic routes that result in pigments with more homogenous properties, being environmentally friendly and economically viable. In context, the aim of this work was to synthesize oxides with perovskite structure of LaAl1-xCrxO3 composition (x = 0.1; x = 0.05) by the gelatin method, aiming its application as pigment for color transparent glazes. The powders resulting from the synthesis process were calcined at 800 and 1000 °C. Then they were characterized using thermal analysis, X-ray diffraction, UV–visible diffuse reflectance spectroscopy and CIElab colorimetry. The perovskite was used for the preparation of ceramic glazes by addition of 2 wt.% pigments on transparent glazes. X-ray patterns revealed single-phase powders with trigonal perovskite structure. The color of the samples varied as a function of the substituent content. The reddish hue was observed in the perovskites obtained with lower substitution of the Cr3+ ion and calcined at higher temperatures. No changes in the pigment color when introduced into transparent glazes were observed.

Plasma technology is a fast, cost-effective, and pollution-free method that can be used in place of conventional methods to overcome seed dormancy. The goal of the present study was to determine the effect of different application times of atmospheric plasma on soaking and germination of Hybanthus calceolaria seeds in order to accelerate these processes. Helium plasma jet produced by dielectric barrier discharge was used to treat H. calceolaria seeds with applications of 1, 5, and 10 minutes. The treated seeds were characterized considering their weight variation during soaking, changes in electrical conductivity, and pH. It was found that germination depended on the plasma application time. The treatment of H. calceolaria seeds with atmospheric plasma for 1 minute provided 3.5 times greater germination in comparison to untreated seeds. Atmospheric plasma technology obtained by dielectric barrier discharge had potential of being used as a germination accelerant in H. calceolaria seeds. The treatment of H. calceolaria seeds using atmospheric plasma for 1 minute favored germination. A tecnologia de plasma constitui-se em um método rápido, econômico e livre de poluição que pode ser utilizada na superação de dormência de sementes em substituição aos métodos convencionais. O objetivo com esse estudo foi verificar o efeito do tempo de aplicação de plasma atmosférico sobre a embebição e germinação de sementes de Hybanthus calceolaria visando à aceleração destes processos. Jato de plasma de gás hélio, produzido por descarga em barreira dielétrica (DBD), foi utilizado para tratar as sementes de H. calceolaria por 1, 5 e 10 minutos de aplicação. As sementes tratadas foram caracterizadas quanto à variação de peso durante a embebição, variações da condutividade elétrica e pH. Verificou-se que a germinação depende do tempo de aplicação do plasma. O tratamento de sementes de H. calceolaria com plasma atmosférico por 1 min. proporcionou incremento na germinação de 3,5 vezes em comparação com as não tratadas. A tecnologia de plasma atmosférico, obtido por barreira dielétrica, apresenta potencial de utilização como acelerador da germinação de sementes de H. calceolaria. O tratamento de sementes de H. calceolaria à plasma atmosférico durante 1 minuto favorece a germinação.

Electrical discharges in liquids are currently used to synthesize nanoparticles. The plasma-liquid interaction is complex, where parameters such as electric field, ion charges and other species present are important. In order to understand the mechanism of crystallization, mother liquor (saturated solution of NaCl, MgCl2 and KCl) was used to study the effectiveness and selectivity of the crystallization caused by the application of plasma. Discharge was applied with the solution at room temperature or during cooling. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and chemical analysis was used to evaluate the structure and composition effects on crystal structure and composition. It was observed that the discharge induces selectively crystallization, and when compared to crystals obtained conventionally by cooling, were smaller and more uniform. We therefore confirm that plasma in liquid can also be used to selectively crystallize materials in atmospheric pressure, where the sizes of the crystals must be dependent on the parameters used.

The effect of plasma applied to mulungu (Erythrina velutina) seeds was studied to verify its influence on the germination, water absorption, wettability and structure of the seeds. The plasma jet used in this study was produced by dielectric barrier discharge (DBD) in a helium gas flow of 0.03 L/s at a distance of 13 mm for 60 s. The plasma treatment significantly affected the seed germination rate, which was approximately 5% higher than that of the untreated group. Micropyle and hilum contributed a greater proportion to uptake. When sealed in the hilar or micropyle regions the amount of water absorbed into the seed decreased approximately 75% compared to the unsealed seed. This difference suggests that these two regions together act cooperatively in the water absorption. However, when plasma treated seed was blocked in the micropyle region, water absorption was higher higher than in seeds blocked hilum. This difference suggests that the plasma treatment changed the wettability of the hilum more effectively than it changed the micropyle. These results indicate that plasma can significantly change the hydrophilicity, water absorption and percentage of seed germination in E. velutina.

One of the great challenges of the oil extraction is the amount of water produced in the process, which creates a great investment for the treatment of the effluent aimed at its disposal in the environment. The phenol component is in significant concentrations in this production water as mentioned by Milhome et al. in 2009. Phenol is a highly toxic chemical that if ingested, inhaled or absorbed through the skin can be fatal to the living organism. The present study aimed to investigate an alternative to the reduction of the phenol concentration in an aqueous solution of phenol by treatment by advanced oxidation processes using heterogeneous photocatalysis and TiO2 as a catalyst. The photocatalysis was carried out in a reactor containing a UV lamp with power of 30 W at the wavelength of 254 nm. The influence of the treated solution volume and volume change was investigated using volumes of 200 ml and 500 ml of solution with 100 mg/L of phenol and 1 g/L TiO2 and duration of radiation 2 hours. The results showed that the variation of the volume of the solution during treatment has an influence on the photocatalytic degradation efficiency of phenol where the tests with 200 ml and withdrawing 10 ml of the solution every 10 min, the degradation was 61.46%, since the tests with 200 ml volume shows no withdrawal, there was a 20.21% efficiency apparent degradation.

Background. This study evaluated the impact of bleaching teeth using blends of a CPP-ACP paste (MI Paste; MI) and carbamide/hydrogen peroxides in different proportions on surface properties of bleached enamel. Methods. Ninety bovine incisors were bleached with 7.5% hydrogen peroxide (HP), 16% carbamide peroxide (CP), MI and blends of HP or CP:MI at three proportions (1:1, 2:1, 1:2). Hardness and roughness were measured at baseline and after bleaching. Enamel morphology was evaluated by Scanning Electron Microscopy (SEM). The data were analyzed by two-way ANOVA for repeated measurements and Tukey’s test. Results. Most of the samples bleached with MI in combination with peroxides presented increased hardness and roughness which were associated to mineral deposition, as observed by SEM images. Blends with higher fractions of MI did not offer superior benefits. Conclusions. The use of a CPP-ACP paste mixed to carbamide/ hydrogen peroxides can decrease adverse side-effects from tooth bleaching on an enamel surface.

OBJECTIVES: The aim of this in vitro study was to investigate the efficacy of in-office bleaching technique combined with the application of a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (MI Paste–MI) at different moments and its influence on enamel surface properties. METHODS: Eighty bovine dental crowns were randomly allocated into eight groups (n = 10), and bleached with either 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP). Four different protocols of application of MI were considered: without MI, MI applied before bleaching, MI applied after bleaching, and MI applied both before and after bleaching. Bleaching effectiveness was measured by the VITA EasyShade spectrophotometer utilizing the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*). Color readings were measured at baseline, 7, 14, and 21 days. Hardness and roughness were measured at baseline (T0) and immediately after bleaching (T14). Data were subjected to the two-way ANOVA for repeated measurements and Tukey's test at 5%. RESULTS: HP groups achieved the greatest color change. The application of a CPP-ACP paste did not reduce the efficacy of bleaching peroxides. Samples bleached with CP showed decreased hardness at T14. Samples bleached with HP that received the application of MI before and before/after bleaching did not present hardness decrease at T14. Samples bleached with peroxides only and received MI after bleaching showed increased roughness at T14. CONCLUSIONS: The use of CPP-ACP was able to prevent negative changes in roughness and hardness of bovine enamel when associated to hydrogen peroxide, and might be applied before/after the bleaching protocol. Microsc. Res. Tech. 75:1019–1025, 2012. © 2012 Wiley Periodicals, Inc.