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Texto completo SciELO Brasil
Texto completo
Id: biblio-1287090
Autor: Ahmed, Mushtaq; Khan, Shahan Zeb; Sher, Naila; Rehman, Zia Ur; Mushtaq, Nadia; Khan, Rahmat Ali.
Título: Kinetic and toxicological effects of synthesized palladium(II) complex on snake venom (Bungarus sindanus) acetylcholinesterase
Fonte: J. venom. anim. toxins incl. trop. dis;27:e20200047, 2021. tab, graf.
Idioma: en.
Projeto: higher education commission of Pakistan.
Resumo: The venom of the krait (Bungarus sindanus), an Elapidae snake, is highly toxic to humans and contains a great amount of acetylcholinesterase (AChE). The enzyme AChE provokes the hydrolysis of substrate acetylcholine (ACh) in the nervous system and terminates nerve impulse. Different inhibitors inactivate AChE and lead to ACh accumulation and disrupted neurotransmission. Methods: The present study was designed to evaluate the effect of palladium(II) complex as antivenom against krait venom AChE using kinetics methods. Results: Statistical analysis showed that krait venom AChE inhibition decreases with the increase of Pd(II) complex (0.025-0.05 µM) and exerted 61% inhibition against the AChE at a fixed concentration (0.5 mM) of ACh. Kinetic analysis using the Lineweaver Burk plot showed that Pd(II) caused a competitive inhibition. The compound Pd(II) complex binds at the active site of the enzyme. It was observed that K m (Michaelis-Menten constant of AChE-ACh into AChE and product) increased from 0.108 to 0.310 mM (45.74 to 318.35%) and V max remained constant with an increase of Pd(II) complex concentrations. In AChE K Iapp was found to increase from 0.0912 to 0.025 µM (29.82-72.58%) and did not affect the V maxapp with an increase of ACh from (0.05-1 mM). K i (inhibitory constant) was estimated to be 0.029µM for snake venom; while the K m was estimated to be 0.4 mM. The calculated IC50 for Pd(II) complex was found to be 0.043 µM at constant ACh concentration (0.5 mM). Conclusions: The results show that the Pd(II) complex can be deliberated as an inhibitor of AChE.(AU)
Descritores: Bungarus
Venenos Elapídicos/toxicidade
Biologia Sintética
-Paládio
Acetilcolinesterase
Limites: Animais
Responsável: BR68.1 - Biblioteca Virginie Buff D'Ápice


  2 / 23 LILACS  
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Rubo, José Henrique
Texto completo
Id: lil-779907
Autor: SUEDAM, Valdey; MORETTI NETO, Rafael Tobias; SOUSA, Edson Antonio Capello; RUBO, José Henrique.
Título: Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures
Fonte: J. appl. oral sci;24(2):114-120, Mar.-Apr. 2016. tab, graf.
Idioma: en.
Projeto: São Paulo Research Foundation; . São Paulo Research Foundation.
Resumo: ABSTRACT Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm) was used. Six groups were formed according to the alloy’s framework (CoCr or PdAg) and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm). A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05) between the groups. Pearson correlation test (p<0.05) was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm.
Descritores: Ligas de Cromo/química
Prótese Dentária Fixada por Implante/métodos
Ligas Dentárias/química
Análise do Estresse Dentário
-Paládio/química
Valores de Referência
Prata/química
Estresse Mecânico
Teste de Materiais
Reprodutibilidade dos Testes
Análise de Variância
Planejamento de Prótese Dentária
Força Compressiva
Torque
Prótese Parcial Fixa
Módulo de Elasticidade
Responsável: BR1.1 - BIREME


  3 / 23 LILACS  
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Pulcinelli, Sandra Helena
Id: biblio-872190
Autor: Almeida, Rossana Pereira de; Pulcinelli, Sandra Helena; Panzeri, Heitor; Antunes, Ricardo de Souza; Volta, Edson.
Título: Estudo de propriedades físicas de ligas experimentais do sistema prata-paládio e prata-cobre. Parte II: análise microestrutural e microdureza Vickers / Study of physical properties of experimental alloys of silver-palladium and silver-copper systems. Part II: microstructural analysis and Vickers microhardness
Fonte: Rev. odontol. Univ. Säo Paulo;6(3/4):127-32, jul.-dez. 1992. tab, ilus.
Idioma: pt.
Resumo: Num estudo seqüencial sobre aspectos metalúrgicos de ligas à base de prata, foram desenvolvidas três ligas experimentais. Este trabalho tem como objetivo o estudo dessas ligas por difração de raios X para determinar-se a presença de defeitos microestruturais que pudessem afetar as propriedades das mesmas. Foram feitos, também, estudos relacionados à microdureza VICKERS. Concluiu-se que, embora tenham ocorrido alterações microestruturais, estas não comprometeram os valores de microdureza das ligas
Descritores: Cobre
Ligas Dentárias/análise
Paládio
Prata
Tipo de Publ: Artigo de Revista
Responsável: BR97.1 - Serviço de Documentação Odontológica


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Pulcinelli, Sandra Helena
Id: biblio-872188
Autor: Almeida, Rossana Pereira de; Pulcinelli, Sandra Helena; Panzeri, Heitor; Antunes, Ricardo de Souza; Volta, Edson.
Título: Estudo de algumas propriedades físicas de ligas do sistema prata-paládio e prata-cobre. Parte I: elaboração das ligas e análise química por fluorescência de raios x / Study of some physical properties of experimental alloys of silver-palladium and silver-copper systems. Part I: alloy development and chemical analysis by x-ray fluorescence
Fonte: Rev. odontol. Univ. Säo Paulo;6(3/4):115-9, jul.-dez. 1992. tab, ilus.
Idioma: pt.
Resumo: Com o aumento no preço do ouro, novos sistemas de ligas têm surgido na tentativa de substituí-lo e, muitas vezes, sem estudos aprofundados. Com o objetivo de aprofundar os estudos nessa área de metalurgia, foram desenvolvidas três ligas experimentais, à base de prata, que estão sendo estudadas física e mecanicamente. Este trabalho discorre sobre a análise química qualitativa das ligas através da fluorescência de raios X. Conclui-se que, após as sucessivas fusões, não ocorreram perdas ou contaminações
Descritores: Cobre
Ligas Dentárias/análise
Paládio
Prata
Tipo de Publ: Artigo de Revista
Responsável: BR97.1 - Serviço de Documentação Odontológica


  5 / 23 LILACS  
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Texto completo SciELO Brasil
Texto completo
Id: lil-723961
Autor: Strom, Tobin J.; Hutchinson, Sean Z.; Shrinath, Kushagra; Cruz, Alex A.; Figura, Nicholas B.; Nethers, Kevin; Biagioli, Matthew C.; Fernandez, Daniel C.; Heysek, Randy V.; Wilder, Richard B..
Título: External beam radiation therapy and a low-dose-rate brachytherapy boost without or with androgen deprivation therapy for prostate cancer
Fonte: Int. braz. j. urol;40(4):474-483, Jul-Aug/2014. tab, graf.
Idioma: en.
Resumo: Purpose To assess outcomes with external beam radiation therapy (EBRT) and a low-dose-rate (LDR) brachytherapy boost without or with androgen deprivation therapy (ADT) for prostate cancer. Materials and Methods From January 2001 through August 2011, 120 intermediate-risk or high-risk prostate cancer patients were treated with EBRT to a total dose of 4,500 cGy in 25 daily fractions and a palladium-103 LDR brachytherapy boost of 10,000 cGy (n = 90) or an iodine-125 LDR brachytherapy boost of 11,000 cGy (n = 30). ADT, consisting of a gonadotropin-releasing hormone agonist ± an anti-androgen, was administered to 29/92 (32%) intermediate-risk patients for a median duration of 4 months and 26/28 (93%) high-risk patients for a median duration of 28 months. Results Median follow-up was 5.2 years (range, 1.1-12.8 years). There was no statistically-significant difference in biochemical disease-free survival (bDFS), distant metastasis-free survival (DMFS), or overall survival (OS) without or with ADT. Also, there was no statistically-significant difference in bDFS, DMFS, or OS with a palladium-103 vs. an iodine-125 LDR brachytherapy boost. Conclusions There was no statistically-significant difference in outcomes with the addition of ADT, though the power of the current study was limited. The Radiation Therapy Oncology Group 0815 and 0924 phase III trials, which have accrual targets of more than 1,500 men, will help to clarify the role ADT in locally-advanced prostate cancer patients treated with EBRT and a brachytherapy boost. Palladium-103 and iodine-125 provide similar bDFS, DMFS, and OS. .
Descritores: Antagonistas de Androgênios/uso terapêutico
Braquiterapia/métodos
Neoplasias da Próstata/tratamento farmacológico
Neoplasias da Próstata/radioterapia
Radioterapia Conformacional/métodos
-Intervalo Livre de Doença
Seguimentos
Radioisótopos do Iodo/uso terapêutico
Paládio/uso terapêutico
Dosagem Radioterapêutica
Estudos Retrospectivos
Fatores de Risco
Estatísticas não Paramétricas
Fatores de Tempo
Resultado do Tratamento
Limites: Idoso
Idoso de 80 Anos ou mais
Humanos
Masculino
Pessoa de Meia-Idade
Responsável: BR1.1 - BIREME


  6 / 23 LILACS  
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Rubo, José Henrique
Texto completo
Id: lil-711709
Autor: GRANDO, Antônio Francisco; REZENDE, Carlos Eduardo Edwards; SOUSA, Edson Antônio Capello; RUBO, José Henrique.
Título: Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework
Fonte: J. appl. oral sci;22(3):209-217, May-Jun/2014. tab, graf.
Idioma: en.
Resumo: Knowing how stresses are dissipated on the fixed implant-supported complex allows adequate treatment planning and better choice of the materials used for prosthesis fabrication. Objectives: The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods: Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results: The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion: The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant. .
Descritores: Resinas Acrílicas/química
Planejamento de Prótese Dentária
Prótese Dentária Fixada por Implante
Facetas Dentárias
Ligas Dentárias/química
Porcelana Dentária/química
-Análise de Variância
Força Compressiva
Técnica de Fundição Odontológica
Análise do Estresse Dentário
Teste de Materiais
Paládio/química
Valores de Referência
Reprodutibilidade dos Testes
Propriedades de Superfície
Prata/química
Resistência à Tração
Fatores de Tempo
Tipo de Publ: Estudo de Avaliação
Responsável: BR1.1 - BIREME


  7 / 23 LILACS  
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Loguercio, Alessandro Dourado
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Id: lil-622933
Autor: Bauer, José Roberto de Oliveira; Grande, Rosa Helena Miranda; Rodrigues-Filho, Leonardo Eloy; Pinto, Marcelo Mendes; Loguercio, Alessandro Dourado.
Título: Does the casting mode influence microstructure, fracture and properties of different metal ceramic alloys?
Fonte: Braz. oral res;26(3):190-196, May-June 2012. ilus, tab.
Idioma: en.
Projeto: CNPq; . FAPEMA.
Resumo: The aim of the present study was to evaluate the tensile strength, elongation, microhardness, microstructure and fracture pattern of various metal ceramic alloys cast under different casting conditions. Two Ni-Cr alloys, Co-Cr and Pd-Ag were used. The casting conditions were as follows: electromagnetic induction under argon atmosphere, vacuum, using blowtorch without atmosphere control. For each condition, 16 specimens, each measuring 25 mm long and 2.5 mm in diameter, were obtained. Ultimate tensile strength (UTS) and elongation (EL) tests were performed using a Kratos machine. Vickers Microhardness (VM), fracture mode and microstructure were analyzed by SEM. UTS, EL and VM data were statistically analyzed using ANOVA. For UTS, alloy composition had a direct influence on casting condition of alloys (Wiron 99 and Remanium CD), with higher values shown when cast with Flame/Air (p < 0.05). The factors 'alloy" and 'casting condition" influenced the EL and VM results, generally presenting opposite results, i.e., alloy with high elongation value had lower hardness (Wiron 99), and casting condition with the lowest EL values had the highest VM values (blowtorch). Both factors had significant influence on the properties evaluated, and prosthetic laboratories should select the appropriate casting method for each alloy composition to obtain the desired property.
Descritores: Ligas de Cromo/química
Técnica de Fundição Odontológica
Ligas Metalo-Cerâmicas/química
-Análise de Variância
Testes de Dureza
Teste de Materiais
Microscopia Eletrônica de Varredura
Paládio/química
Estresse Mecânico
Propriedades de Superfície
Prata/química
Resistência à Tração
Tipo de Publ: Estudo de Avaliação
Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME


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Id: lil-531399
Autor: Tuna, Suleyman Hakan; Pekmez, Nuran Ozcicek; Keyf, Filiz; Canli, Fulya.
Título: The electrochemical properties of four dental casting suprastructure alloys coupled with titanium implants
Fonte: J. appl. oral sci;17(5):467-475, Sept.-Oct. 2009. ilus, graf, tab.
Idioma: en.
Resumo: OBJECTIVES: As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions. MATERIAL AND METHODS: The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests. RESULTS: The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples. CONCLUSIONS: Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.
Descritores: Implantes Dentários
Ligas Dentárias/química
Revestimento para Fundição Odontológica/química
Materiais Dentários/química
Titânio/química
-Fenômenos Químicos
Corrosão
Ligas de Cromo/química
Técnicas Eletroquímicas
Ligas de Ouro/química
Espectrometria de Massas
Teste de Materiais
Microscopia Eletrônica de Varredura
Oxirredução
Polarografia
Potenciometria
Paládio/química
Solubilidade
Propriedades de Superfície
Saliva Artificial/química
Limites: Humanos
Tipo de Publ: Estudo Comparativo
Responsável: BR1.1 - BIREME


  9 / 23 LILACS  
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Valle, Accácio Lins do
Bonfante, Gerson
Texto completo
Id: lil-471448
Autor: Scolaro, Juliano Milczewsky; Pereira, Jefferson Ricardo; Valle, Accácio Lins do; Bonfante, Gerson; Pegoraro, Luiz Fernando.
Título: Comparative study of ceramic-to-metal bonding
Fonte: Braz. dent. j;18(3):240-243, 2007. ilus.
Idioma: en.
Projeto: FAPESP.
Resumo: Dentists and technicians have used dental ceramics associated with different types of alloys without taking into account the characteristics of compatibility of these materials. Knowing the properties of the alloy and ceramic used in metal/ceramic restorations is a key factor for treatment success. The purpose of this study was to evaluate the bond strength of a palladium-silver alloy (Pors-on 4) to 3 ceramics (Ceramco, Noritake and Vita VMK-68) using shear forces at the metal-ceramic interface. A stainless steel cylindrical matrix was used for preparation of the metal dies, application of ceramic and shear strength testing. Thirty palladium-silver alloy cylinders received two layers of opaque and two layers of body porcelain, and shear tests were performed in a universal testing machine at a cross-head speed of 0.5 mm/min. Shear bond strength means (in MPa) were: 28.21(Ceramco), 28.96 (Noritake) and 24.11 (Vita VMK-68). One-way ANOVA did not show statistically significant differences (p>0.05) among the materials. The results of this study indicate that the three evaluated ceramic systems are suitable to be used in combination with the tested palladium-silver alloy.

Muitos profissionais utilizam restaurações metalocerâmicas sem atentarem para as características de compatibilidade entre metal e cerâmica, fator muito importante para o sucesso deste tipo de restauração. Este estudo avaliou a resistência de união entre uma liga de paládio-prata (Pors-on 4) e 3 cerâmicas (Ceramco, Noritake e Vita VMK-68) aplicando-se forças de cisalhamento na interface metal/porcelana. Uma matriz especialmente desenvolvida serviu para a confecção dos corpos-de-prova e realização dos testes de cisalhamento. Trinta corpos-de-prova foram confeccionados, com duas camadas de cerâmica opaca e de corpo, e os testes realizados em máquina universal de ensaios (0,5 mm/min). As médias de resistência de união (em MPa) foram: 28,21 (Ceramco), 28,96 (Noritake) e 24,11 (Vita VMK-68). A análise de variância a um critério não demonstrou diferença estatisticamente significante entre os materiais (p>0,05). Os resultados demonstraram que todas as cerâmicas foram compatíveis com a liga avaliada.
Descritores: Colagem Dentária
Análise do Estresse Dentário
Ligas Dentárias/química
Porcelana Dentária/química
-Análise de Variância
Paládio
Resistência ao Cisalhamento
Prata
Estresse Mecânico
Tipo de Publ: Estudo Comparativo
Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME


  10 / 23 LILACS  
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Id: lil-402704
Autor: Giraldo R., Olga Lucía.
Título: Metales y aleaciones en odontología / Metals and alloys in dentistry
Fonte: Rev. Fac. Odontol. Univ. Antioq;15(2):53-63, ene.-jun. 2004.
Idioma: es.
Resumo: El conocimiento de los materiales dentales que se utilizan para los trabajos protésicos es una necesidad para los profesionales de odontología. Los metales son tutinariamente usados en odontología en gran variedad de aplicaciones, incluyendo la fabricación de prótesis, coronas temporales y permanentes, bandas de ortodoncia y en restauraciones directas de los dientes. Los metales más usados son: oro, níquel, cobalto, cromo, estaño, aluminio, titanio, hierro, paladio, platino, cobre, plata, vanadio y mercurio. Los tipos de aleaciones para restauraciones protésicas se han incrementado notablemente en los últimos 25 años, haciendo que su elección sea muy difícil para una situación clínica dada. Un número de propìedades -incluyendo resistencia, dureza, módulo elástico, fases microestructurales, tamaño del grano, corrosión, coeficiente de expansión térmica, óxido y color- son relevantes en la selección apropiada de una aleación. El factor más importante es la bioseguridad del paciente. La decisión de la selección de una aleación tiene profundas consecuencias financieras, legales, técnicas, de satisfacción para el práctico y para la salud del paciente
Descritores: Ligas Dentárias
Prostodontia
-Alumínio
Ligas de Cromo
Corrosão
Ligas de Ouro
Níquel
Paládio
Prata
Propriedades de Superfície
Estanho
Titânio
Tipo de Publ: Revisão
Responsável: AR29.1 - Biblioteca



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