O hexametafosfato de sódio é eficaz na prevenção de danos de metal em próteses removíveis imersas em produtos de limpeza de hipoclorito?

The aim of this study was to evaluate if sodium hexametaphosphate (NaPO3)n is effective in preventing surface changes in Co-Cr-Mo alloy when immersed in cleansing solutions of 0.5% sodium hypochlorite (NaOCl). Thirty samples were randomly divided in to three groups (n=10) according to immersion solution: G1- distilled water (control), G2- 0.5% NaOCl, and G3- 0.5% NaOCl solution containing (NaPO3)n. Samples were evaluated before immersion (T0), 10 minutes (T1), 20 minutes (T2), and 60 minutes after immersion (T3) through Scanning Electron Microscopy (SEM) and rugosimeter. SEM showed little surface alteration in G1, dark stains in G2 and stains suggestive of a thin white film deposition in G3. The roughness analysis showed statistical significance between G1 and G2 (P≤0.05). There was also an increase in roughness in T2 and T3 (P≤0.05). (NaPO3)n protected the alloy from the harmful effects of 0.5% NaOCl, which caused surface alteration and increased roughness. O objetivo deste estudo foi determinar a citotoxicidade induzida por mini-implantes ortodônticos conforme recebidos pelo fabricante, após a exposição a fluoretos, e após a exposição ao meio bucal. Oitenta e quatro mini-implantes de fabricantes brasileiros (SIN, INP e Neodent) foram divididos em sete grupos (n = 12): G1 - SIN como recebido do fabricante; G2 - SIN imerso durante quinze dias em NaF 0,05%; G3 - SIN exposto ao meiobucal; G4 - INP como recebido do fabricante; G5 - INP imerso durante quinze dias em NaF 0,05%; G6 - Neodent como recebido do fabricante; G7 - Neodent imerso por quinze dias em NaF 0,05%. Sua citotoxicidade foi avaliada por testes de exposição direta e indireta usando a levedura S. cerevisiae. O estresse oxidativo também foi avaliada por meio de teste de coloração de colônias. Os resultados mostraram não haver redução significativa da viabilidade celular sobre a exposição direta ou indireta a mini-implantes

Translucency and masking ability of a translucent zirconia with different thicknesses over dark backgrounds

ABSTRACT Objectives: To evaluate the translucency, contrast ratio and masking ability of a translucent zirconia with different thicknesses. Methods: Disc shaped specimens (n= 3) with 10 mm (Ø) x 1.5 mm, 1 mm and 0.7 mm (thickness) were manufactured simulating all-ceramic simplified restorations. Substrate discs (n= 2; Ø: 10 mm; thickness: 2 mm) were simulated with composite resin shades: A2 (positive control) and C4; and metal alloys: silver (Ni-Cr) and golden (Cu-Al). Optical properties of the 9 translucent zirconia specimens placed on the 3 different substrates were analyzed by a spectrophotometer. The color variation (ΔE00) between each ceramic structure over the positive control substrate (A2) and over the dark backgrounds (C4, silvery, golden) were obtained as to their ceramic masking ability and subjected to non-parametric Kruskal Wallis test (5%). The translucency parameter (TP00) and contrast ratio (CR) of the different thicknesses of the ceramic discs were also collected and analyzed by one-way ANOVA and the Tukey test (5%). Results: The translucent zirconia showed greater opacity in the thickness of 1.5 mm, although it was not statistically different between 0.7 and 1.0 mm. All dark backgrounds significantly affected the final color of the simplified restoration in all evaluated thicknesses. However, the increase in ceramic thickness showed a decrease in ΔE00 values for all substrates. Conclusion: The translucent zirconia was not able to mask the dark substrates, independent of the evaluated thickness

Efeito da espessura oclusal do cimento e da sua união à cerâmica na resistência à fratura de coroas CAD/CAM: método de elementos finitos e testes monotônicos

Neste estudo avaliou-se a influência da espessura oclusal do cimento e de sua união à cerâmica na resistência à fratura de coroas CAD/CAM. O software COMSOL Multiphysics® foi utilizado para análise de elementos finitos (AEF) em modelos axi-simétricos bidimensionais de coroas de cerâmica vítrea estilizadas, com espessura oclusal de 1,5 mm, cimentadas à troqueis de material análogo à dentina quanto ao módulo elástico e potencial de união à resina composta (NEMA G-10 International Paper, USA). Variou-se as espessuras oclusais de cimento resinoso de 50 a 500 μm. Uma carga de 500 N foi aplicada com um pistão de extremidade circular plana (2 mm de diâmetro) sobre as coroas. A contração de polimerização do cimento foi simulada através de contração térmica. O contato entre cimento e cerâmica foi configurado para “união” e “ausência de união”. O contato cimento-troquel foi sempre do tipo “união”. As tensões dadas pela AEF foram utilizadas para o cálculo de cargas para fratura, levando-se em conta os efeitos deletérios da usinagem e do condicionamento ácido relatados na literatura. As coroas (Mark II, Vita Zhanfabrik, Germany) foram usinadas (CEREC InLab, Sirona, Germany), condicionadas e cimentadas (Multilink Automix, Ivoclar, Lietchstein) à troqueis de NEMA G-10 (n=6). Para a produção de corpos-de-prova na condição “ausência de união”, aplicou-se uma fina película de poli(dimetilsiloxano) 30,000 cSt na superfície interna das coroas. As coroas foram submetidas à carregamento de 5N/s, com pistão de NEMA G-10, de extremidade plana e 2 mm de diâmetro. As fraturas radiais foram detectadas por sensor acústico. A magnitude das tensões resultantes da contração de polimerização dependeram da condição de união à cerâmica e da espessura oclusal de cimento. As cargas médias para fratura (N) de coroas com “união” ao cimento foram...In this study the influence of the occlusal cement thickness and its bonding to ceramic on the stresses and failure-loads of CAD/CAM crowns were evaluated. The software used for finite element analysis (FEA) was COMSOL Multiphysics®. Bi-dimensional axially symmetric models simulated stylized feldspathic crowns (1.5 mm occlusal thickness) with resin cement layers of 50 μm, 100 μm, 300 μm and 500 μm on dentin analog (NEMA G-10, International Paper, USA) under 500 N loading (2 mm diameter piston). Polymerization shrinkage of the cement layer was simulated as thermal contraction. Ceramic-cement interface was either bonded or not; cement-dentin was always bonded. Stress data were used for load-to-fracture predictions, using literature strengths accounting for milling and acid etching. Mark II® (Vita Zahnfabrik) crowns were milled (Cerec InLab®, Sirona), etched and cemented (Multilink Automix®, Ivoclar) to dentin analogs (NEMA G-10) (n=6). Non-bonding was achieved by applying a thin layer of 30,000 cSt poly(dimethylsiloxane) on the internal surface of the crowns. Crowns were loaded (5N/s) beneath a 2mm flat G-10 piston and radial cracks were detected acoustically. Stress magnitude resulting after cement shrinkage and loading depended on the bonding condition and on the cement thickness. Average failure loads (N) of bonded crowns were: 673.5 N for 50μm-cement thickness and 300.6 N for 500 μm. For non-bonded crowns, failure loads were 308,3 N, for 50 μm cement thickness and 233,3 N, for 500 μm. Bonded crowns presented failure loads at least two times higher than non-bonded, for 50 μm cement thickness, both experimentally and by FEA-based predictions. The benefit of bonding was lost when the cement was thicker than 500 μm. The resistance to fracture decreased with the cement thickness. Calculated loads based on FEA stresses and experimental data were comparable for the evaluate... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Effect of machining, bur adjustments and hydrofluoric acid etching on the roughness and on the flexural strength of CAD/CAM glass-ceramics: a systematic review and meta-analyses

Systematic review and meta-analyses of in vitro studies of CAD/CAM glass-ceramic

Meiotic behavior of Adesmia DC. (Leguminosae-Faboideae) species native to Rio Grande do Sul, Brazil

Meiotic behavior in Adesmia DC. is described for the first time. The study encompassed twelve populations of seven Adesmia DC. species native to Rio Grande do Sul, Brazil. Populations with 2n = 2x = 20 are A. securigerifolia 9615, A. riograndensis 9590 (subnudae), A. latifolia 1568, 1775, 15025, A. bicolor JB-UFSM, A. incana var. incana 9636, 10288, A. punctata var. hilariana 6885, 10812, and A. tristis 10757. A. incana var. incana 9637 is a tetraploid with 2n = 4x = 40. The material was stained with 1% acetic orcein. The meiotic behavior of the populations studied was considered normal. The meiotic index (MI) and the estimates of pollen grain viability were above 95%, except for A. latifolia 1568 (MI = 89%). The present data indicate that these plants are meiotically stable and potentially fertile, apparently with no problems for use in programs of selection, crossing and viable seed production

Estudos citogenéticos em cinco espécies de Adesmia DC. (Leguminosae-Faboideae) nativas no Rio Grande do Sul Citogenetics studies in five native species of Adesmia DC. (Leguminosae-Faboideae) in the Rio Grande do Sul, Brazil

Populações de espécies de Adesmia DC. das séries bicolores e psoraleoides, nativas do Rio Grande do Sul, Brasil, foram estudadas para determinação do número cromossômico (11 populações de 5 espécies) e também quanto aos cariótipos (5 populações de 4 espécies). Todas as espécies estudadas quanto ao número cromossômico são diplóides (2n=2x=20), mas em A. incana var. incana foram encontradas duas populações diplóides e uma tetraplóide (2n=4x=40). A. incana não é uma espécie unicamente tetraplóide, como vinha sendo considerada até agora. A. bicolor 9614 parece ser a mais antiga entre as populações analisadas devido a sua alta simetria cariotípica e A. tristis 10814 parece ser a mais recente, devido ao seu cariótipo mais assimétrico.Populations of Adesmia DC. species bicolores and psoraleoides series, nativo from Rio Grande do Sul, Brazil, were studied to determine the chromosome numbers (in 11 populations of 5 species) and Karyotypes (in 5 of these population in 4 species). All species studied regarding to the chromosome numbers were diploid (2n=2x=20) and in A. incana var. incana besides two diploid races there was one tetraploid race (2n=4x=40). A. incana should not be considered as a tetraploid species, as has been considered in the literature. A. bicolor 9614 seemed to be more ancient among the analized populations due to the high Karyotype symmetry. A. tristis seemed be more recent among the analysed populations due to the karyotype was highly asymmetry

Implant-abutment gap versus microbial colonization:Clinical significance based on a literature review

<p>Microorganisms from the oral cavity may settle at the implant-abutment interface (IAI). As a result, tissue inflammation could occur around these structures. The databases MEDLINE/PubMed and PubMed Central were used to identify articles published from 1981 through 2012 related to the microbial colonization in the implant-abutment gap and its consequence in terms of crest bone loss and osseointegration. The following considerations could be put forward, with respect to the clinical importance of IAI: (a) the space present at the IAI seems to allow bacterial leakage to occur, in spite of the size of this space; (b) bacterial leakage seems to occur at the IAI, irrespective of the type of connection. More studies are necessary to clarify the relationship between leakage at IAI and abutment connection designs; (c) losses at the peri-implant bone crests cannot be related to the IAI size, since few studies have shown no relationship. Also, the microbial leakage at the IAI cannot be related to the bone crest loss, since there are no articles reporting this relationship; remains controversial the influence of the IAI position on the bone crest losses. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 1321-1328, 2013.</p>

Surface change assessment of Co-Cr alloy subjected to immersion in denture cleansers

g the right chemical cleanser for removable partial dentures is a challenge, because they present an acrylic and a metallic portion, which should be cleaned and not damaged. Aim: The aim of this study was to assess surface changes of cobalt chromium alloys immersed in diferente cleaners solutions: 0.05% sodium hypochlorite, 4.2% acetic acid, 0.05% sodium salicylate, sodium perborate (Corega Tabs®) and 0.2% peracetic acid. Material and Methods: One hundred and twenty circular specimens (10 mm in diameter) of two commercial available Co-Cr alloys were tested: GM 800 ® (Dentaurum) and Co-Cr® (DeguDent). The samples were randomly divided into tem experimental groups (n=10), according to the trend mark of alloy and cleaners solutions in which they were immersed, and two control groups, in which the samples of the two alloys were immersed in distilled water. Evaluations were performed through roughness measurement (rugosimeter Surftest 211, Mitutoyo), visual evaluation with stereomicroscope (Stereo Discovery 20, Carl Zeiss) and scanning electron microscope surface (JSM, 6360 SEM, JEOL), at experimental times T0 before immersions, T1 - after one immersion, and T2 - after 90 immersions. Intergroup comparison for the effect of immersion in the different cleanser agents was evaluated through ANOVA/Tukey tests (p&#8804;0.05). The effect of the time in the immersion of each alloy was evaluated by t-pared test (p&#8804;0.05). The two alloys were compared using the t-Student test. Results: The analysis of roughness and microscopy showed that surface changes were significantly greater in groups submitted to 0.05% sodium hypochlorite after 90 immersions (T2). When comparing the two alloys, a similar behavior of roughness was observed for the cleaning agents. However, alloy GM 800® showed significant statistical difference for roughness variations in experimental times (&#916;1 and &#916;2), when immersed in sodium 0.05% hypochlorite. The number of exposures of the alloys to the cleaning agents showed a negative influence when using sodium hypochlorite solution. Conclusions: It is possible to conclude that 0.05% sodium hypochlorite has caused the greatest apparent damage to alloy surface

Impact of machining on the flexural fatigue strength of glass and polycrystalline CAD/CAM ceramics

Made available in DSpace on 2019-09-12T16:53:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2017Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Objectives. To assess the effect of machining on the flexural fatigue strength and on the surface roughness of different computer-aided design, computer-aided manufacturing (CAD/CAM) ceramics by comparing machined and polished after machining specimens. Methods. Disc-shaped specimens of yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP), leucite-, and lithium disilicate-based glass ceramics were prepared by CAD/CAM machining, and divided into two groups: machining (M) and machining followed by polishing (MP). The surface roughness was measured and the flexural fatigue strength was evaluated by the step-test method (n = 20). The initial load and the load increment for each ceramic material were based on a monotonic test (n = 5). A maximum of 10,000 cycles was applied in each load step, at 1.4 Hz. Weibull probability statistics was used for the analysis of the flexural fatigue strength, and Mann-Whitney test (alpha = 5%) to compare roughness between the M and MP conditions. Results. Machining resulted in lower values of characteristic flexural fatigue strength than machining followed by polishing. The greatest reduction in flexural fatigue strength from MP to M was observed for Y-TZP (40%; M = 536.48 MPa; MP = 894.50 MPa), followed by lithium disilicate (33%; M = 187.71 MPa; MP = 278.93 MPa) and leucite (29%; M = 72.61 MPa; MP = 102.55 MPa). Significantly higher values of roughness (Ra) were observed for M compared to MP (leucite: M = 1.59 mu m and MP = 0.08 mu m; lithium disilicate: M = 1.84 mu m and MP = 0.13 mu m; Y-TZP: M = 1.79 mu m and MP = 0.18 mu m). Significance. Machining negatively affected the flexural fatigue strength of CAD/CAM ceramics, indicating that machining of partially or fully sintered ceramics is deleterious to fatigue strength. (C) 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.[Fraga, Sara] Univ Fed Santa Maria, Postgrad Program Dent Sci, Santa Maria, RS, Brazil[Amaral, Marina] Universidade de Taubaté (Unitau), Postgrad Program Dent[Bottino, Marco Antonio] Sao Paulo State Univ, Dept Dent Mat & Prosthodont, Sao Jose Dos Campos, SP, Brazil[Valandro, Luiz Felipe; May, Liliana Gressler] Univ Fed Santa Maria, Dept Restorat Dent, Santa Maria, RS, Brazil[Kleverlaan, Cornelis Johannes] Univ Amsterdam, Acad Ctr Dent Amsterdam ACTA, Dept Dent Mat, Amsterdam, Netherlands[Kleverlaan, Cornelis Johannes] Vrije Univ Amsterdam, Amsterdam, Netherland