Indiana University-Purdue University Indianapolis (IUPUI) / THE EFFECT OF FULL-CONTOUR Y-TZP CERAMIC SURFACE ROUGHNESS ON THE WEAR OF BOVINE ENAMEL AND SYNTHETIC HYDROXYAPATITE: AN IN-VITRO STUDY by Alaa Hussein Aref Sabrah Indiana University School of Dentistry Indianapolis, Indiana Full-contour yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations have been advocated recently in clinical situations where occlusal/palatal space is limited, or to withstand parafunctional activities. The objectives of this in-vitro study were to investigate the effects of different polishing techniques on the surface roughness of Y-TZP (Ardent Dental, Inc.) and to investigate the effects of different polishing techniques on the wear behavior of synthetic hydroxyapatite (HA) and bovine enamel. An in-vitro study was conducted by fabrication of 48 Y-TZP sliders (diameter = 2 mm × 1.5 mm in height) using CAD/CAM technique; then the samples were embedded in acrylic resin using brass holders. Samples were then randomly allocated into four groups according to the finishing/polishing procedure: G1-as-machined (n = 8), G2- glazed (n = 16), G3-diamond bur-finishing (Brasseler, USA) (n = 8) and G4- G3+OptraFine polishing kit (Ivoclar-Vivadent) (n = 16). Thirty-two sintered HA disks (diameter = 11 mm × 2.9 mm in height) and 16 bovine enamel samples with a minimum surface area of 64 mm2 were mounted in brass holders. Baseline surface roughness (Ra and Rq, in μm) were recorded using a non-contact profilometer (Proscan 2000) for all the samples. A two-body pin-on-disk wear test was performed for 25,000 cycles at 1.2 Hz in which the four zirconia groups were tested against HA, and only G2-glazed and G4- G3+OptraFine polishing kit (Ivoclar-Vivadent) were tested against bovine enamel. Vertical substance loss (μm) and volume loss (mm3) of HA were measured (Proscan). Zirconia height loss was measured using a digital micrometer. One-way ANOVA was used for statistical analysis. The results indicated that surface roughness measurements showed significant differences among the surface treatments with G1 (Ra = 0.84, Rq = 1.13 μm) and G3 (Ra = 0.89, Rq = 1.2 μm) being the roughest, and G2 (Ra = 0.42, Rq = 0.63 μm) the smoothest. The glazed group showed the highest vertical loss (35.39 μm) suggesting wear of the glaze layer, while the polished group showed the least vertical loss (6.61 μm). HA antagonist volume loss and vertical height loss for groups (G1, G2 and G3) were similar, while polished group (1.3 mm3, 14.7 μm) showed significant lower (p = 0.0001) values. Antagonist height loss and antagonist volume loss were significantly higher for bovine antagonist than for HA antagonist (197.6 μm/116.2 μm, and 28.5 mm3/17.7 mm3 for bovine against glazed/polished zirconia sliders, respectively) (p < 0.0001). From the results it can be concluded that glazed zirconia provided an initially smooth surface, but a significant increased antagonist wear compared with the polished surface was seen. Bovine enamel showed higher wear compared with HA, which suggested that more studies should be performed to validate the use of bovine enamel as a substitute for human enamel in wear studies.

Indiana University-Purdue University Indianapolis (IUPUI) / Background: Numerous studies have reported the use of hydrofluoric (HF) acid as one of the most effective methods for the achievement of a durable bond between glass-based ceramics and resin cements. Nevertheless, there is little information available regarding the potential deleterious effect on the ceramic mechanical strength. Objectives: (1) to investigate the effect of HF acid etching regimens on the biaxial flexural strength of a low-fusing nanofluorapatite glass-ceramic (IPS e.max ZirPress, Ivoclar Vivadent), (2) to study the ability of an unfilled resin (UR) to restore the initial (i.e., before etching) mechanical strength, and (3) to evaluate the effect of HF acid etching on the ceramic surface morphology before and after UR treatment via scanning electron microscopy (SEM). Methods: One hundred and forty-four disc-shaped (15 ± 1 mm in diameter and 0.8 ± 0.1 mm in thickness) IPS e.max ZirPress specimens were allocated into 12 groups, as follows: G1-control (no etching), G2-30 s, G3-60 s, G4-90 s, G5-120 s, G6- 60 + 60 s. Meanwhile, groups (G7- G12) were treated in the same fashion as G1-G6, but followed by silane and UR applications. Surface morphology evaluation of non-etched and etched IPS e.max ZirPress (G1-G12) was carried out by scanning electron microscopy (SEM). The flexural strength was determined by biaxial testing as described in ISO 6872. Statistics were performed using two-way ANOVA and the Sidak multiple comparisons (α = 0.05). In addition, the Weibull statistics were estimated. Results: A significant effect of etching time (p=0.0290) on biaxial flexural strength was observed. Indeed, G4 led to a significantly (p=0.0392) higher flexural strength than G1. Correspondingly, G10 revealed a considerably higher flexural strength than G7 (p=0.0392). Furthermore, biaxial flexural strength was significantly higher for G7 – G12 than for G1 – G6 (p<0.0001). For G1 – G6, G4 showed the highest Weibull characteristic strength while the lowest Weibull characteristic strength was seen in G6. In G7 – G12, the highest Weibull characteristic strength was presented in G10 whereas G7 had the lowest. Finally, the SEM data revealed that the HF acid etching affected the surface of IPS e.max ZirPress by generating pores and irregularities and more importantly that the UR was able to penetrate into the ceramic microstructure. Conclusion: Within the limitations of this study, HF acid etching time did not show a damaging effect on the biaxial flexural strength of the IPS e.max ZirPress ceramic. Moreover, the ceramic biaxial flexural strength could be enhanced after UR treatment.

Abstract The aim of the present study was to increase the understanding of how the cell surface properties affect the performance of unit operations used in primary protein purification. In particular, the purpose was to develop, set up and apply methods for studies of cell surface properties and cell interactions. A method for microbial cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Escherichia coli strains were used as model cells. Cell surface fingerprints were generated by registration of the interaction between the cells and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences in fingerprint pattern between some of the strains were observed. The physical properties of the cell surfaces were determined using microelectrophoresis, contact angle measurements and aqueous two-phase partitioning and were compared with the SPR fingerprints. The generated cell surface fingerprints and the physical property data were evaluated with multivariate data analysis that showed that the cells were separated into individual groups in a similar way using principal component analysis plots (PCA). Studies of the behaviour of the model cells on stirred cell filtration and in an interaction test with different expanded bed adsorption (EBA) adsorbents were performed. It could be concluded that especially one of the strains behaved differently. Differences in the properties of the model cells were indicated by microelectrophoresis and aqueous two-phase partitioning which to some extent correlated with observed differences in behaviour during filtration and in an interaction test with EBA adsorbents. The impact of high-pressure homogenisation of E. coli cell extract was examined, with a lab scale and a pilot scale technique. The DNA-fragmentation, visualised with agarose gel electrophoresis, and the resulting change in viscosity was analysed. A short homogenisation time resulted in increased viscosity of the process solution that correlated with increased concentration of released non-fragmented DNA. With longer homogenisation time the viscosity decreased with increasing degree of DNA-fragmentation. The results show that strain dependant cell surface properties of E. coli may have an impact on several primary steps in downstream processing. / QC 20101129

<p dir="ltr">Since the discovery of graphene in 2004, numerous other materials with intriguing electronic, optical, and magnetic properties have been found to be layered and exfoliatable down to atomic thickness. Owing to their weak interlayer coupling, mediated only by van der Waals forces, this new class of 2-dimensional materials, also known as van der Waals (vdW) materials, allows layer-by-layer stacking, overcoming some of the limitations of growth techniques. In particular, the growing inventory of vdW materials has expanded to include magnetic materials, further broadening the possibilities of novel devices based on stacked heterostructures. These magnetic heterostructures can find applications in spintronics and memory devices and may be combined with other vdW materials with optical properties for applications in optoelectronics. In this thesis, we assembled heterostructures via mechanical transfer or growth to modify the magnetism in these vdW materials. We used various optical and electrical techniques to probe the modified magnetism or its effects on the novel heterostructure. Thus, we observed the emergence of the magnetic proximity effect on the topological insulator BiSbTeSe₂ after dry transferring a thin flake of Cr₂Ge₂Te₆ on top, taking steps towards the observation of novel topological phases, such as the quantum Hall insulator. Additionally, we demonstrated an increased Curie temperature and magnetic anisotropy, effectively enhancing the magnetism, in thin flakes of Cr₂Ge₂Te₆ and Cr₂Si₂Te₆ after sputtering NiO or MgO. Finally, noting that the effect of modified magnetism in Cr2Ge2Te6 after sputtering NiO or MgO is induced due to wrinkle formation and strain, we further reproduce similar wrinkle formation on other 2D materials such as hBN, graphite, and 2D antiferromagnets (XPS₃, (X= Mn, Fe, Ni), CrSBr, RuCl₃). We used polarized Raman spectroscopy to characterize the induced biaxial strain in hBN and showed that such wrinkle formation can lead to moderately (up to 1.4% strain) spatially inhomogeneous and anisotropic strain profiles. These efforts demonstrate the versatility of tailoring the properties of these vdW materials.</p>

The application of chemical additives, known as grinding aids (GA), dates back to 1930 in the cement industry. As opposed to the cement industry, where the use of GAs is on the final processing step, it could be one of the first process steps in ore beneficiation. A few investigations addressed the GA applications in ore dressing; therefore, further studies are required to better understand the GA effects on the product properties and downstream separation processes. This thesis undertakes a comparative study on the dry grinding of magnetite and the resulting product characteristics with and without GAs. The main aim is to reduce energy consumption and to address some of the challenges associated with dry processing.  The effects of GAs on the dry batch ball milling of magnetite were examined to analyze the energy consumption (Ec), particle size distribution, flow properties, bulk properties, surface morphology, particle fineness, and surface chemistry of products. Their effects on the ground product were systematically explored by sieve analysis, powder rheology, BET surface measurements, optical microscopy analysis, and zeta potential measurements. Compared with the absence of GAs, the dry grinding efficiency of magnetite increased after using GAs; however, an optimal dosage exists based on the GA type. Among GAs which considered in this investigation (Zalta™ GR20-587 (Commercial GA) and Zalta™ VM1122 (Commercial viscosity aid) as well as sodium hydroxide), Zalta™ VM1122, a polysaccharide-based additive, was the most effective GA where by using this GA; the Ec decreased by 31.1% from 18.0 to 12.4 kWh/t. The PSD became narrower and finer (P80 decreasing from 181 to 142 µm), and the proportion of the particles (38–150 µm) increased from 52.5 to 58.3%. In general, the results reveal that at sufficient GA dosages, they reduce the average particle size, increase the specific surface area, and narrow the particle size distribution. However, an excessive amount of GAs could be detrimental to the grinding performance.  Further studies on powder rheology indicated that the used GAs resulted in improved material flowability compared to grinding without additives (in the examined dosage range). The rheology measurements by the FT4 Powder Rheometer showed strong linear correlations between basic flow energy, specific energy, and the resulting work index when GAs was considered for grinding. There was a strong correlation between the grinding parameters and flow parameters (r &gt; 0.93). These results confirmed the effect of GA on ground particles' flowability. Zalta™ VM1122 showed the best performance with 38.8% reduction of basic flow energy, 20.4 % reduction of specific energy, 24.6% reduction of aerated basic flow energy, and 38.3% reduction of aerated energy. The present investigation showed that the predominant mechanism of GAs is based on the alteration of rheological properties. Further investigation on the surface properties showed that using GAs could increase the surface roughness, which is beneficial for downstream processes such as froth flotation. Zalta™ VM1122 resulted in increased surface roughness and minimum microstructural defects from the optical microscope images. Furthermore, Zalta™ VM1122 (non-ionic) resulted in similar zeta potentials and pH values for the product compared to experiments without GA. These comparable product properties are advantageous as they minimize any potential negative effects on all possible downstream processes. / Kolarctic CBC (KO1030 SEESIMA)

No description available.

<p>Uvođenje nanočestica u stomatolo&scaron;ke kompozitne materijale predstavlja poku&scaron;aj da se odgovori univerzalnim zahtevima za kvalitetom direktnog zubnog ispuna, i da se stvori materijal koji kombinuje visoku mehaničku otpornost sa dobrim estetskim karakteristikama i zadovoljavajućim kvalitetom poliranja. Cilj sprovedene studije je bio da se ispita uticaj nanočestica, i soft-start metode svetlosne indukcije polimerizacije na mehanička i povr&scaron;inska svojstva savremenih stomatolo&scaron;kih nanokompozita, dostupnih na trži&scaron;tu. Ispitana su četiri stomatolo&scaron;ka nanostrukturisana kompozitna materijala na bazi smola i jedan univerzalni mikrohibridni kompozit, kao referentni materijal (Filtek Z250, 3M ESPE). Kori&scaron;ćena su po dva reprezentativna materijala iz dve podgrupe nanokompozita: nanopunjenih (Filtek Ultimate Body, 3M ESPE i Filtek Ultimate Translucent, 3M ESPE) i nanohibridnih kompozita (Filtek Z550, 3M ESPE i Tetric EvoCeram, Ivoclar Vivadent - TEC). Uzorci su polimerizovani nakon svetlosne aktivacije polimerizacije, uz kori&scaron;ćenje dva svetlosna režima: konvencionalnog i soft start režima. Pritisna i zatezna čvrstoća (dobijena poprečnim sabijanjem valjka, engl. diametral tensile strength) testirane su na Univerzalnoj ma&scaron;ini, kidalici. Tvrdoća uzoraka merena je testom za određivanje tvrdoće po Vickersu. Povr&scaron;inska tekstura i parametri hrapavosti određeni su skeniranjem povr&scaron;ine mikroskopom atomskih sila. Uop&scaron;teno, TEC je pokazao najniže vrednosti pritisne i zatezne čvrstoće, i tvrdoće, i statistićki je značajno bio slabiji od drugih testiranih materijala kroz sve mehaničke testove. Suprotno, TEC je imao najniže vrednosti parametara hrapavosti među testiranim materijalima. Spoj prepolimerizovanog punioca i polimerne baze u ovom materijalu pokazao se kao njegova slaba tačka. Navedeni materijal je iz tog razloga pokazao značajno slabiju otpornost od ostalih na razvijene napone izazvane dejstvom mehaničkih sila. Čestice nanodimenzija u sastavu stomatolo&scaron;kih polimernih kompozita, samostalno, nisu imale značajan uticaj na pobolj&scaron;anje mehaničkih i povr&scaron;inskih svojstava testiranih kompozita. Zaključeno je i da se procentualna zastupljenost neorganskih čestica u polimernoj bazi ne može smatrati apsolutnim kriterijumom kvaliteta kompozita, u pogledu njihovih mehaničkih svojstava. Samo srodni materijali, izrađeni istim tehnolo&scaron;kim postupkom, koji imaju veoma sličan ili isti hemijski sastav, pokazali su se kao mehanički superiorniji ukoliko su sadržali veći procenat neorganske komponente u svom sastavu. Nano prefiks u nazivu klase materijala ne garantuje sigurnu prednost stomatolo&scaron;kih nanokompozita nad univerzalnim mikrohibridnim kompozitima.</p> / <p>The introduction of nanoparticles in dental composite materials was an attempt to respond to the universal quality requirements for a direct dental restoration, and to create a material that meets the needs of high mechanical resistance, good aesthetic characteristics and surface properties of tooth restoratives. The aim of this study was to investigate the effect of nanoparticles in materials composition, and the soft start photoactivation method on the mechanical and surface properties of contemporary dental nanocomposites, available in the market. Four dental resin based nanostructured composites were tested along with a universal microhybrid one, as reference material (Filtek Z250, 3M ESPE). Two representative materials from the two classification subgroups were tested, nanofilled (Filtek Ultimate Body, 3M ESPE and Filtek Ultimate Translucent, 3M ESPE) and nanohybrid composites (Filtek Z550, 3M ESPE and Tetric EvoCeram, Ivoclar Vivadent, TEC). Polymerization of the samples was light activated using two light modes: conventional and soft start. Compressive and diametral tensile strength were tested on the Universal testing machine. The Vickers hardness was also determined. Surface texture and roughness parameters were examined by atomic force microscopy. Generally, TEC showed the lowest values of compression, tensile strength and hardness, and was statistically different from the other tested materials throughout all mechanical tests. In contrast, TEC had the lowest values of roughness parameters among the tested materials. In this material, contact zone of prepolimeryzed filler and polymer matrix appeared to be a weak point. For this reason, this material showed significantly lower resistance than the others on mechanically developed stresses. Nanosized particles within the dental polymer composites, individually, did not have a significant influence on improving the mechanical and surface properties of tested composites. It is concluded that the inorganic volume fraction in composites cannot be considered as an absolute criterion of their quality, regarding their mechanical properties. Only similar materials, made using the same technological process, which have very similar or the same chemical composition, and similar technological method of synthesis and optimization of organic and inorganic components, showed improved mechanical strength, if they contained a higher percentage of inorganic components in their composition. Nano prefix in the name of material&rsquo;s class does not guarantee the pure advantage of dental nanocomposites in comparison with the universal microhybrid composites.</p>

Le protocole pour le greffage irréversible du copolymère amphiphile polystyrène-b-poly (acrylate de sodium) PS-b-PANa, sur un substrat de mica et de silice hydrophobe a été développé, en utilisant la méthode de greffage à partir de solution. Les propriétés de surface du bloc chargé ont été évaluées. L’effet de la force ionique sur le gonflement des chaînes a été investigué par ellipsométrie. Les forces d’interaction entre les surfaces recouvertes du copolymère ont été évaluées par la technique SFA. Les profils de force ont démontré être stables et nettement répulsifs en compression et décompression, montrant l’irréversibilité du greffage. Les forces de frottement entre les brosses de PANa sont élevées, mais aucune évidence d’endommagement de la surface n’a été observée. La comparaison entre le comportement à la surface des chaînes de l’acide polyacrylique PAA et celles du PANa, obtenues par deux méthodes de greffage différentes, est également investiguée. / A protocol for irreversibly grafting of amphiphilic copolymer polystyrene-b-poly (sodium acrylate) PS-b-PANa onto hydrophobized mica and silica was developed, using the grafting to approach. Surface properties of charge block were evaluated. The swelling of chains and force ionic effect were studied by ellipsometry. The interaction forces and frictional forces were evaluated by SFA technique. Forces profiles were stable and clearly repulsive in loading and receding, indicating an irreversible grafting. High friction forces onto PANa brushes were determinate without evidence of damage at the surface. The comparison between solution behavior of polyacrylic acid, PAA and PANa brushes, obtained via different grafting methods, was equally investigated.

Made available in DSpace on 2017-07-24T19:22:01Z (GMT). No. of bitstreams: 1 Rosana Marques Silva Figueroa.pdf: 3807885 bytes, checksum: 3650be97bf0d582c6f9fac01fcff5ea1 (MD5) Previous issue date: 2016-02-12 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / The aim of this study was to determine a microwave polymerization cycle that resulted in adequate physicomechanical and biological properties for the denture base acrylic resins polymerized in water bath (Vipi Cril-VC, VIPI®) or processed by microwave energy (Vipi Wave-VW, VIPI®). The evaluated polymerization cycles were: 1) WB (water bath) = (65ºC during 90 min + boiling during 90 min), recommended cycle for the VC resin; 2) M630/25 = 10 min at 270 W + 5 min at 0 W + 10 min at 360 W, recommended cycle for VW resin; 3) M650/5 = 5 min at 650 W; 4) M550/3 = 3 min at 550 W. The following properties were evaluated: degree of conversion (n=6), cytotoxicity (n=9), porosity (n=10), water sorption and solubility (n=10), and surface roughness and color stability (n=5) after immersion in potential colorant beverages and simulated toothbrushing. Data were submitted to analysis of variance ANOVA-2 way followed by Bonferroni’s test for degree of conversion and color stability, ANOVA-2 way for porosity and cytotoxicity, ANOVA-2 way followed by HSD Tukey’s test for water sorption and solubility, and ANOVA-3 way followed by Bonferroni’s test for surface roughness (α=0.05). For VC resin, there was no significant difference among the groups for degree of conversion. For VW resin, the lowest degree of conversion values appeared in the M630/25 and M650/5 cycles (P<0.05). Degree of conversion values ranged from 66.9 to 85.9%. There was no difference between the materials and experimental groups for cytotoxicity and all conditions resulted in non-cytotoxic effects. Porosity mean values below 1.52% with no significant difference among groups for both materials were observed. Resins showed water sorption and solubility values without a significant difference. The highest water sorption (2.43%) and solubility (0.13%) values were obtained for WB and M550/3, respectively (P<0.05). After immersion in coffee, M550/3 and WB groups of VC resin showed the highest and the lowest roughness values, respectively (P<0.05). There was also an increase in roughness of M550/3 group after immersion in wine (P<0.05). For VW resin, M650/5 group presented rougher surface after immersion in coffee (P<0.05). There was no difference in color among cycles for VW resin and VC resin showed more changes (P<0.05). All medium values were classified as acceptable, exception for VW resin (M630/25 group) which presented NBS=4.88 after immersion in wine. Vipi Cril conventional resin can be polymerized in microwave without impairment to the evaluated properties. According to the obtained results, the better experimental condition was the microwave polymerization at 650 W for 5 min for Vipi Cril. / O objetivo deste estudo foi determinar um ciclo de polimerização em micro-ondas que resultasse em propriedades físico-químicas e biológicas satisfatórias para resinas acrílicas termopolimerizáveis para base de prótese processadas em banho de água (Vipi Cril-VC, VIPI®) ou por energia de micro-ondas (Vipi Wave-VW, VIPI®). Os ciclos de polimerização avaliados foram: 1) BA (banho de água) = (65ºC por 90 min + 90 min em ebulição), ciclo recomendado para a resina VC; 2) M630/25 = 10 min a 270 W + 5 min a 0 W + 10 min a 360 W, ciclo recomendado para a resina VW; 3) M650/5 = 5 min a 650 W; 4) M550/3 = 3 min a 550 W. Foram avaliadas as seguintes propriedades: grau de conversão (n=6), citotoxicidade (n=9), porosidade (n=10), sorção de água e solubilidade (n=10) e rugosidade de superfície e estabilidade de cor (n=5) após imersão em líquidos potencialmente corantes e escovação simulada. Os resultados obtidos foram submetidos à análise de variância ANOVA-2 fatores seguida pelo teste de Bonferroni para grau de conversão e estabilidade de cor, ANOVA-2 fatores para porosidade e citotoxicidade, ANOVA-2 fatores seguida pelo teste de Tukey HSD para sorção de água e solubilidade e ANOVA-3 fatores seguida pelo teste de Bonferroni para rugosidade de superfície (α=0,05). Não houve diferença significante entre os grupos para os resultados de grau de conversão da resina VC. Para a resina VW, os valores mais baixos de grau de conversão foram obtidos nos ciclos M630/25 e M650/5 (P<0,05). Os valores médios de grau de conversão foram entre 66,9% e 85,9%. Não houve diferença entre os materiais e os grupos experimentais para os resultados de citotoxicidade e todas as condições resultaram em efeitos não citotóxicos. Foram observados valores médios de porosidade inferiores a 1,52%, sem diferença significante entre os grupos para ambos os materiais. As resinas apresentaram valores de sorção de água e solubilidade sem diferença estatisticamente significante entre elas. Os valores mais altos de sorção de água (2,43%) e de solubilidade (0,13%) foram obtidos nos grupos BA e M550/3, respectivamente (P<0,05). Com a imersão em café, os grupos M550/3 e BA da resina VC apresentaram os maiores e os menores valores de rugosidade de superfície, respectivamente (P<0,05). Também houve aumento da rugosidade do grupo M550/3 após imersão no vinho tinto (P<0,05). Para a resina VW, o grupo M650/5 demonstrou superfície mais rugosa após imersão em café (P<0,05). Não houve diferença de cor entre os ciclos para a resina VW e a resina VC apresentou mais alterações (P<0,05). Todos os valores médios de estabilidade de cor foram classificados como aceitáveis, exceto para a resina VW (grupo M630/25) que apresentou NBS=4,88 após imersão em vinho tinto. A resina Vipi Cril formulada para polimerização convencional pôde ser polimerizada em micro-ondas sem prejuízo às suas propriedades avaliadas. De acordo com os resultados obtidos, a melhor condição experimental foi a polimerização da resina Vipi Cril em micro-ondas a 650 W por 5 min.

O presente estudo in vitro analisou o efeito de 3 sucos de fruta com baixo pH (suco de cupuaçu, taperebá e laranja), e saliva artificial (controle) sobre materiais restauradores indicados em lesões cervicais não cariosas: resina composta nanoparticulada (Filtek Z350 XT), cimento de ionômero de vidro resino modificado (Vitremer) e um cimento de ionômero de vidro convencional (Fuji II). Os materiais foram avaliados, quantitativamente, quanto à alteração de: peso, rugosidade superficial e microdureza superficial, e qualitativamente, por microscopia eletrônica de varredura (MEV). Foram confeccionados 144 corpos de prova para cada teste quantitativo (n=12) e 45 para o MEV (n=3), de (8mm de diâmetro x 2mm de altura). Os corpos de prova foram preparados, mantidos em saliva artificial por 24 h à 37º C, receberam acabamento em politriz, e em seguida foram realizadas as leituras iniciais. Durante um período de 10 dias consecutivos, os corpos de prova foram submetidos ao desafio erosivo (nos respectivos sucos de frutas) durante 30 minutos três vezes ao dia, totalizando 90 minutos/dia e mantidos em saliva artificial entre os intervalos. Após o período de ciclagem erosiva, foram realizadas as leituras finais. Os resultados obtidos foram submetidos ao teste t, ANOVA e Tukey. As médias de alteração entre os valores de peso finais e iniciais demonstraram diferença significativa (p<0,01) nos materiais estudados e em todos os sucos estudados, com exceção do Vitremer quando imerso no suco de taperebá (p>0,01). As médias de alteração entre os valores de rugosidade superficial final e inicial demonstraram diferença significativa (p<0,01) para todos os materiais estudados em todos os sucos, exceto a Filtek Z350 XT no grupo controle que não apresentou diferença significativa (p>0,01). A comparação entre os valores de microdureza final e inicial demonstrou diferença significativa (p<0,01) na microdureza dos materiais estudados em todos os meios de imersão, inclusive no grupo controle. De um modo geral o suco de taperebá foi o que provocou a maior alteração na superfície dos materiais restauradores quanto ao peso, rugosidade, microdureza e na microscopia eletrônica de varredura. A resina composta Filtek Z350 XT foi o material restaurador que menos sofreu alterações de superfície. Concluiu-se que os sucos das frutas estudados são capazes de alterar os materiais restauradores, sendo que a resina composta foi o material que sofreu menor alteração. / This in vitro study examined the effects of 3 fruit juices with low pH (cupuaçu, taperebá and orange) and artificial saliva (control) upon restorative materials indicated in noncarious cervical lesions: nanoparticle composite resin (Filtek Z350 XT), resin-modified glass ionomer cement (Vitremer) and a glass ionomer cement (Fuji II). The materials were evaluated quantitatively as for alterations in weight, surface roughness and surface microhardness, and qualitatively by scanning electronic microscopy (SEM). 144 specimens were prepared for each quantitative test (n = 12) and 45 for the SEM (n = 3), of (8mm diameter x 2mm height). The specimens were prepared, stored in artificial saliva for 24 hours at 37º C, were finished in a polishing machine, and then the initial readings were performed. During a period of 10 consecutive days, the specimens were subjected to erosive challenge (in the respective juices) for 30 minutes, three times a day, and totaling 90 minutes/day and kept in artificial saliva between intervals. After the erosive cycling period, the final readings were taken. The data were analyzed using t test, ANOVA and Tukey.Test The average alterations between the values of initial and final weight showed significant difference (p < 0.01) in the material studied and all the juices studied, except for Vitremer when immersed in taperebá juice (p > 0.01). The average alterations between the values of initial and final surface roughness showed a significant difference (p < 0.01) for all materials studied in all juices, except for Filtek Z350 XT, in the control group, that showed no significant differences (p > 0.01). The comparison between the values of initial and final microhardness showed a significant difference (p < 0.01) in microhardness of the materials studied in all immersion means, including the control group. In general, taperebá juice was the one that caused the biggest alterations in the surface of restorative materials with respect to weight, roughness, hardness and scanning electronic microscopy. The composite resin Filtek Z350 XT was the restorative material that suffered less surface alterations. It was concluded that the fruit juices studied are capable of altering the restorative materials, and composite resin was the material that has undergone minor changes.