Base de dados : LILACS
Pesquisa : G01.374.835 [Categoria DeCS]
Referências encontradas : 323 [refinar]
Mostrando: 1 .. 10   no formato [Detalhado]

página 1 de 33 ir para página                         

  1 / 323 LILACS  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo
Texto completo
Id: biblio-1052901
Autor: Kato, Kathia Terumi; Melo, Silvana Regina de; Dada, Maria Eduarda Gomes; Barbosa, Carmem Patrícia.
Título: Efeitos do estresse físico e psicológico juvenil sobre a glândula suprarrenal em ratos adultos / Effects of juvenile physical and psychological stress on the suprarenal gland in adult rats
Fonte: Saude e pesqui. (Impr.);13(1):53-61, jan/mar 2020. ilus.
Idioma: pt.
Resumo: Estresse é a resposta aos diferentes estímulos que o organismo sofre em busca de adaptação à homeostasia. Devido à sua alta incidência, diversos modelos experimentais estão sendo desenvolvidos para a melhor compreensão de sua inter-relação com outros órgãos. Neste contexto, o objetivo deste estudo foi avaliar os efeitos em longo prazo do estresse físico e psicológico juvenil agudo sobre as glândulas suprarrenais de ratos, no que se refere aos aspectos morfológicos, pois tais glândulas apresentam relação direta com situações de estresse. Para tanto, as glândulas suprarrenais destes animais foram processadas e análises morfológicas da medula e do córtex foram realizadas por meio de morfometria e quantificação por planimetria. Os resultados obtidos demonstraram que o estresse tanto físico quanto psicológico não provocaram alterações significativas em relação à área de superfície e espessura das suprarrenais, indicando adaptação dos animais aos fatores estressantes aqui estudados.

Stress is a response to different stimuli experienced by the organism for its adaption to homeostasis. Due to its high occurrence, several experimental models are being developed to understand better the interrelationships between these organs. Current paper evaluates long-term effects of juvenile physical and psychological stress on the suprarenal glands of rats with regard to morphological aspects. In fact, these glands have a direct relationship with stress conditions. Rats´ suprarenal glands were processed and their medulla and cortex were morphologically investigated through planimetry. Results show that physical and psychological stress failed to cause significant changes on the surface area and thickness of the glands. This fact showed adaptation of animals to the type of stress under analysis.
Descritores: Estresse Mecânico
Estresse Psicológico
Glândulas Suprarrenais
-Forma do Núcleo Celular
Limites: Animais
Camundongos
Responsável: BR313.1 - Biblioteca Ana Bove


  2 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Brasil
Texto completo
Id: biblio-975578
Autor: Pender, Daniel J.
Título: Suspensory Tethers and Critical Point Membrane Displacement in Endolymphatic Hydrops
Fonte: Int. arch. otorhinolaryngol. (Impr.);22(3):214-219, July-Sept. 2018. graf.
Idioma: en.
Resumo: Abstract Introduction Grossly displaced membranes are characteristic of endolymphatic hydrops. The process whereby physiological membrane displacement becomes pathological may be mediated by stress, but the membrane biomechanics underlying this transition are unclear. Objective This study seeks to determine the role of suspensory tethers during pressure-induced membrane displacement in the generation of the membranous lesions seen in this disease entity using a biomechanical model approach. Methods The location of membrane suspensory tethers was identified histologically. The influence of tethers on model membrane configuration during displacement was assessed graphically. The relationship of membrane configuration during displacement to curvature radius was quantified trigonometrically. The relationship of curvature radius to stress susceptibility was determined mathematically. The net effect of suspensory tethers on membrane stress levels for various degrees of membrane distention and displacement was then calculated numerically. Results In the inferior labyrinth, suspensory tethers are found to occur on the membranes' boundaries. Such tethering is found to impose a biphasic effect on membrane curvature with increasing degrees of displacement. As a consequence, tensile stress susceptibility is found to decline with initial membrane displacement to a critical point nadir beyond which stress then increases monotonically. No such effect was found for the superior labyrinth. Conclusion Boundary tethers in the inferior labyrinth are associated with significant tensile stress reductions until a critical point of membrane displacement is reached. Displacements short of the critical pointmay be physiological and even reversible,whereas such displacements beyond the critical point are apt to be overtly hydropic and irreversible.
Descritores: Perfuração da Membrana Timpânica/fisiopatologia
Hidropisia Endolinfática/fisiopatologia
-Estresse Mecânico
Fenômenos Biomecânicos
Cóclea/fisiopatologia
Resistência à Flexão/fisiologia
Orelha Interna/fisiopatologia
Limites: Humanos
Responsável: BR66.1 - Divisão de Biblioteca e Documentação


  3 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
Id: biblio-1095303
Autor: Velho, Helder Callegaro; Baldissara, Paolo; Skupien, Jovito adiel; Wandscher, Vinícius Felipe.
Título: Fracture load and shear stress of prefabricated glass fiber posts
Fonte: Braz. j. oral sci;18:e191561, jan.-dez. 2019. ilus.
Idioma: en.
Resumo: Aim: This study evaluated the fracture load and pattern failure of different prefabricated glass fiber posts (GFPs) of the same diameter. Methods: Seventy-eight (n=13 for six groups) GFPs of 1.6 mm coronal diameter of different brands were evaluated­ Exacto (Angelus), Power Post (BM4), White Post DC (FGM), HiRem (Overfibers), MAQ (Maquira), and SD (Supordont). The posts were subjected to fracture load testing (45° of inclination and 1 mm/min until fracture). Each factor (load (N) and shear stress (MPa)) was analyzed separately using one-way ANOVA followed by the Tukey test (α=0.05). Results: The type of failure was evaluated on a stereomicroscope (×10). The Power Post samples presented higher values of fracture load (p<0.001) followed by Maquira fiber post, White Post , HiRem, Superpost, and the Exacto posts. The failure pattern observed was intralaminar mode II in-plane shear, such as a failure occur parallel to fibers. Conclusion: Despite the same diameter of GFPs, the fracture load and shear resistance were brand-dependent
Descritores: Estresse Mecânico
Teste de Materiais
Resistência ao Cisalhamento
Vidro
Responsável: BR218.1 - Biblioteca Carlos Henrique Robertson Liberalli


  4 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
Id: biblio-1095165
Autor: Sabino, Tatiana de Andrade; Silva-Concílio, Laís Regiane da; Neves, Ana Christina Elias Claro; Claro, Ana Paula Rosifini Alves; Amaral, Marina; Vitti, Rafael Pino; Claro, Cristiane Aparecida de Assis.
Título: Stress distribution in the peri-implant area of pure titanium and titanium-zirconium small implants
Fonte: Braz. j. oral sci;18:e191505, jan.-dez. 2019. ilus.
Idioma: en.
Resumo: Aim: In dental implant treatment, there is a demand for mechanically stronger implants. Despite the existence of several studies showing the clinical success of narrow diameter implants, most of them are based on pure titanium (cpTi) alloys. There is a few clinical evidences of the success rate of titanium-zirconium (TiZr) narrow diameter implants. The aim of this study was to evaluate the stress distribution in the peri-implant area of narrow diameter cpTi and TiZr implants under axial and oblique loads. Methods: Photoelastic models were produced using epoxy resin (PL2, Vishay Precision Group) from a master model. The implants (cpTi and TiZr; Straumann AG) had 3.3 mm in diameter and 12 mm in height. Loads of 100 N and 200 N were applied to the abutment at angles of 0° (axial), 10°, 20°, and 30° (oblique). A circular polariscope (Eikonal) was used under dark field white-light configuration. The isochromatic fringes were analyzed in the peri-implant region in 5 areas, using ASTM table with isochromatic fringes; cervical-mesial, cervical-distal, mid-mesial, mid-distal and apical. Results: In general, under axial and oblique loads, the stress in the TiZr implant was lower than in the cpTi implant. The load of 200 N produced the highest stress values in cpTi and TiZr implants. In both implants and loads, the fringes were located more in apical area at all angles evaluated. Conclusion: It can be concluded that for small implants, the load inclination and intensity change the pattern of stress distribution and the cpTi implant exhibited the highest peri-implant stress
Descritores: Estresse Mecânico
Titânio
Implantes Dentários
Análise do Estresse Dentário
Responsável: BR218.1 - Biblioteca Carlos Henrique Robertson Liberalli


  5 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
Id: biblio-1051332
Autor: Lemos, Cleidiel Aparecido Araujo.
Título: Análise biomecânica de próteses implantossuportadas variando a conexão, o sistema de retenção, material restaurador, tipo e o nível do tecido ósseo: estudo pelo método dos elementos finitos tridimensionais / Biomechanical analysis of implant-supported prostheses varying the connection, retention system, restorative material, type and level of bone tissue: study by the methods of finite three-dimensional elements.
Fonte: Araçatuba; s.n; 2019. 160 p. ilus, tab, graf.
Idioma: pt.
Tese: Apresentada a Universidade Estadual Paulista "Julio de Mesquita Filho". Faculdade de Odontologia de Araçatuba para obtenção do grau de Doutor.
Resumo: Este projeto teve como objetivo analisar as tensões geradas em próteses implantossuportadas fixa unitária variando o sistema de conexão implante/prótese, o sistema de retenção, material restaurador, tipo ósseo, e o nível de tecido ósseo ao redor do implante através do método dos elementos finitos tridimensionais, e realizar uma revisão sistemática com meta-análise sobre o tema osteoporose em relação a taxa de sobrevivência e perda óssea marginal ao redor dos implantes dentários. Em relação à metodologia experimental, foram simulados 24 modelos tridimensionais com ajuda dos programas de desenho assistido Rhinoceros 3D 4.0 (NURBS Modeling for Windows, USA) e SolidWorks 2011 (SolidWorks Corp, USA), e para confecção da porção óssea será utilizado o programa InVesalius (CTI, São Paulo, Brasil). Cada modelo representou uma secção de osso da região posterior maxilar, na forma de um bloco ósseo tipo IV (normal e osteoporótico), variando o nível de reabsorção do tecido ósseo (a nível do pescoço do implante; perda de 1,5 mm; perda de 3,0 mm; e perda de 4,5 mm) com a presença de um implante de 4,0 mm de diâmetro e 10 mm de comprimento com diferentes tipos de conexão (hexágono externo e cone morse), restaurado com coroas (metalocerâmicas e/ou metal free) com diferentes sistemas de retenção (cimentada e/ou parafusada). Os desenhos tridimensionais foram exportados ao programa de pré e pós processamento FEMAP v.11.2 (Siemens Product Lifecycle Management Software Inc. USA) para geração da malha e aplicação de uma carga de 200N axial e 100N oblíqua (45°) simulando um carregamento nas vertentes internas de cada cúspide da coroa. A análise foi realizada no programa de elementos finitos NEiNastran 11 (Noran Engineering, Inc., EUA) e os resultados serão visualizados através de mapas de tensão von Mises e deslocamento para avaliação das tensões sobre os implantes/componentes e tensão máxima principal, microdeformação e deslocamento para avaliação das tensões no tecido ósseo no tecido ósseo em cada modelo proposto no programa FEMAP v.11.2. Os resultados do capítulo 1, verificaram que a perda do tecido ósseo progressiva apresentou influência na distribuição das tensões na região do tecido ósseo, implantes e componentes. A qualidade do osso afetou apenas os valores de microdeformação, principalmente, no tecido ósseo trabeculado. Os implantes cone Morse apresentaram menores concentrações de tensões na região de tecido ósseo comparado aos implantes de hexágono externo, somente para os modelos sem perda óssea. Os implantes de hexágono externo apresentaram pior comportamento biomecânico nos implantes e parafuso de fixação, principalmente no carregamento oblíquo. Em relação ao capítulo 2 foi possível verificar que os implantes do tipo cone Morse apresentam melhor comportamento biomecânico na região de tecido ósseo cortical e parafuso de fixação em relação aos implantes de hexágono externo em relação as próteses fixas implantossuportadas parafusadas. As próteses cimentadas apresentam uma ligeira redução no tecido ósseo cortical, porém, com maior sobrecarga no parafuso de fixação dos implantes de hexágono externo. Os diferentes materiais restauradores não influenciam no comportamento biomecânico das estruturas. No capítulo 3 após a condução sistematizada das buscas, um total de cinco estudos foram incluídos para tabulação dos resultados. Após a realização da meta-análise foi observado que os implantes dentários devem ser considerados uma alternativa de tratamento viável para a reabilitação de pacientes com osteoporose, porém, cuidados clínicos são necessários aos profissionais para garantir a manutenção da estabilidade óssea periimplantar(AU)

The aim of this thesis was to perform the analysis on the stress distribution for implant-supported fixed prostheses varying the implant-abutment connection system, the fixation system, restorative material, bone type, and the level of bone tissue around the dental implant using the finite element method. Furthermore, the aim was to perform a systematic review and meta-analysis about the effect of osteoporosis in terms of implants survival rate and marginal bone loss. In relation to the experimental methodology, 24 three-dimensional models were simulated with the aid of the Rhinoceros 3D 4.0 (NURBS Modeling for Windows, USA), SolidWorks 2011, and InVesalius (CTI, São Paulo, Brazil) softwares. Each model represented a bone section of the maxillary posterior area (bone type IV) (normal and osteoporotic), varying the level of bone resorption (at the level of the implant, loss of bone tissue in 1.5 mm, loss of bone tissue in 3.0 mm and loss of bone tissue in 4.5 mm). All models containing the presence of a dental implant with 4.0 mm in diameter and 10 mm in length with two different abutment-implant connection (external hexagon and Morse taper), restored with crowns (metaloceramic and/or monolithic) with different fixation system (cemented and/or screwed). The designs were exported to FEMAP v.11.2 pre-and post-processing software (Siemens Product Lifecycle Management Software Inc. USA) for mesh generation and loading application of 200N axial and 100N oblique (45° in the long axis of implant, suppressing lingual cusps) in the slopes each cusp of the crown. The analysis was performed in the NEiNastran 11 (Noran Engineering, Inc., USA) and the results will be imported to FEMAP 11.2 through von Mises stress maps (implants and components) and maximum principal stress and microdeformation (bone tissue). The results of chapter 1 showed that the progressive loss of the bone tissue showed an influence on the stress distribution in the bone tissue, implants and components. The quality of the bone tissue (osteoporosis) affected only the microdeformation, mainly in the trabecular bone tissue. Morse taper implants showed lower stress concentrations in the bone tissue compared to external hexagon implants, only for models without bone loss. The external hexagon implants presented worse biomechanical behavior in the implants and screw fixation, especially in oblique loading. Regarding to chapter 2, it was possible to verify that Morse taper implants showed better biomechanical behavior area of cortical bone tissue and screw fixation compared to external hexagon implants for screwed prostheses. The cemented prostheses showed a slight reduction of stress in the cortical bone tissue; however, with greater stress in the fixation screw for the external hexagon implants. The type of restorative materials (metalceramic and/or monolithic) did not affect the biomechanical behavior of the structures. In chapter 3 after systematic review, a total of five studies were included for tabulation of the data. After performing the meta-analysis it was observed that dental implants should be considered as a viable treatment alternative for the rehabilitation of patients with osteoporosis; however, clinical care is necessary to guarantee the maintenance of peri-implant bone stability, due to high marginal bone loss was observed for patients with osteoporosis(AU)
Descritores: Estresse Mecânico
Prótese Dentária Fixada por Implante
-Fenômenos Biomecânicos
Implantes Dentários
Prótese Dentária
Análise de Elementos Finitos
Responsável: BR186.1 - Biblioteca Honório Monteiro
BR186.1


  6 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Chile
Texto completo
Id: biblio-1003635
Autor: Espinoza, Cristián; Díaz, Magda C; González, Magdalena; Olmedo, Ivonne; Pedrozo, Zully.
Título: Policistina-1 protege a los cardiomiocitos de la necrosis inducida por estrés mecánico / Policystin-1 protects cardiomyocytes from mechanical stress induced necrosis
Fonte: Rev. chil. cardiol;38(1):29-36, abr. 2019. graf.
Idioma: es.
Projeto: Fondo Nacional de Investigación Científica y Tecnológica, FONDECYT; . FONDAP; . CEMC.
Resumo: Resumen: Antecedentes: La muerte de los cardiomiocitos es determinante en el desarrollo de patologías cardiacas posteriores al infarto del miocardio y la insuficiencia cardiaca. Las variaciones en la expresión de la familia de proteínas BCL-2 regulan vías, tanto de muerte, como de sobrevida celular. Así, BCL-2 es una proteína anti- apoptótica y NIX una proteína que induce la necrosis y/o la apoptosis celular. La Policistina-1 (PC1) es un mecanosensor vital para la función contráctil cardiaca; sin embargo, se desconoce su papel en la sobrevida de los cardiomiocitos durante el estrés mecánico. Objetivo: Determinar si PC-1 previene la muerte de los cardiomiocitos inducida por estrés mecánico y las proteínas BCL-2 y NIX. Métodos: Se utilizó cultivo de cardiomiocitos de ratas neonatas controles o deficientes en la expresión de PC1, estimulados con solución hiposmótica (HS), como modelo de estrés mecánico. Se midió la muerte por necrosis y apoptosis y los niveles de BCL-2 y NIX. Resultados: La deficiencia de la PC1 en los cardiomiocitos induce un aumento de la necrosis y los niveles proteicos de NIX en las células estimuladas con HS. El estrés mecánico induce la apoptosis basal relacionada a una disminución de BCL- 2, independiente de la expresión de la PC1. Conclusiones: La PC1 protege a los cardiomiocitos de la necrosis por estrés mecánico, lo que podría deberse en parte a su papel en la regulación de los niveles de las proteínas NIX.

Abstracts: Background: Cardiomyocytes death is a determining factor in the development of cardiac dysfunction after myocardial infarction and heart failure. The change in BCL-2 family protein expression regulates both cell death and survival pathways, whereas BCL-2 is an anti-apoptotic protein and NIX induces necrosis and/or apoptosis. Polycystin-1 (PC1) is a crucial mechanosensor for cardiac contractile function. However, its role in cardiomyocyte survival during mechanical stress is unknown. Aim: To study the relationship of PC1 with mechanical stretch-death in cardiomyocytes and the BCL-2, and NIX proteins. Methods. Controls or deficient expression of PC1 neonatal rat ventricular myocytes were stimulated with hypoosmotic solution (HS) and used as a model of mechanical stress. Necrosis or apoptosis cell death, BCL-2 and NIX protein levels were measured. Results: Deficient expression of PC1 increases cardiomyocyte necrosis and NIX protein levels in cells stimulated with HS. Mechanical stress induces basal apoptosis related to a decrease in BCL-2, independent of PC1 expression. Conclusion: PC1 protects cardiomyocytes from mechanical stress necrosis, at least in part, by regulating NIX protein levels.
Descritores: Proteínas Proto-Oncogênicas c-bcl-2/metabolismo
Miócitos Cardíacos/metabolismo
Canais de Cátion TRPP/metabolismo
Necrose/prevenção & controle
-Estresse Mecânico
Western Blotting
Ratos Sprague-Dawley
Apoptose
Citometria de Fluxo
Proteínas de Membrana/metabolismo
Limites: Animais
Masculino
Ratos
Responsável: CL126.2 - Biblioteca Médica Dr. Profesor Hernán Alessandri R.


  7 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Brasil
Texto completo
Id: lil-797974
Autor: Lim, Kiatlin; Yap, Adrian U-Jin; Agarwalla, Shruti Vidhawan; Tan, Keson Beng-Choon; Rosa, Vinicius.
Título: Reliability, failure probability, and strength of resin-based materials for CAD/CAM restorations
Fonte: J. appl. oral sci;24(5):447-452, Sept.-Oct. 2016. tab, graf.
Idioma: en.
Projeto: National University of Singapore.
Resumo: ABSTRACT Objective: This study investigated the Weibull parameters and 5% fracture probability of direct, indirect composites, and CAD/CAM composites. Material and Methods: Discshaped (12 mm diameter x 1 mm thick) specimens were prepared for a direct composite [Z100 (ZO), 3M-ESPE], an indirect laboratory composite [Ceramage (CM), Shofu], and two CAD/CAM composites [Lava Ultimate (LU), 3M ESPE; Vita Enamic (VE), Vita Zahnfabrik] restorations (n=30 for each group). The specimens were polished, stored in distilled water for 24 hours at 37°C. Weibull parameters (m= modulus of Weibull, σ0= characteristic strength) and flexural strength for 5% fracture probability (σ5%) were determined using a piston-on-three-balls device at 1 MPa/s in distilled water. Statistical analysis for biaxial flexural strength analysis were performed either by both one-way ANOVA and Tukey's post hoc (α=0.05) or by Pearson's correlation test. Results: Ranking of m was: VE (19.5), LU (14.5), CM (11.7), and ZO (9.6). Ranking of σ0 (MPa) was: LU (218.1), ZO (210.4), CM (209.0), and VE (126.5). σ5% (MPa) was 177.9 for LU, 163.2 for CM, 154.7 for Z0, and 108.7 for VE. There was no significant difference in the m for ZO, CM, and LU. VE presented the highest m value and significantly higher than ZO. For σ0 and σ5%, ZO, CM, and LU were similar but higher than VE. Conclusion: The strength characteristics of CAD/ CAM composites vary according to their composition and microstructure. VE presented the lowest strength and highest Weibull modulus among the materials.
Descritores: Zircônio/química
Desenho Assistido por Computador
Silicatos/química
Dióxido de Silício/química
Resinas Compostas/química
Cimentos de Resina/química
Tocoferóis/química
Restauração Dentária Permanente/métodos
-Valores de Referência
Estresse Mecânico
Propriedades de Superfície
Resistência à Tração
Fatores de Tempo
Fraturas dos Dentes
Teste de Materiais
Microscopia Eletrônica de Varredura
Probabilidade
Reprodutibilidade dos Testes
Análise de Variância
Maleabilidade
Falha de Restauração Dentária
Tipo de Publ: Estudo de Avaliação
Responsável: BR1.1 - BIREME


  8 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Brasil
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


  9 / 323 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Chile
Texto completo
Id: biblio-1002270
Autor: Wei, Xinsen; Dong, Yiyi; Zhang, Zihui.
Título: Finite element analysis of the femur of Japanese quail ( Coturnix coturnix japonica ) / Análisis por elementos finitos del fémur de codorniz japonesa ( Coturnix coturnix japonica )
Fonte: Int. j. morphol;37(2):641-646, June 2019. graf.
Idioma: en.
Projeto: National Natural Science Foundation of China.
Resumo: The biomechanical performance of limb bones is useful to reflect an animal's adaptation to external loads and behaviors. In this study, we used the finite element method to simulate the load acting on the intact femur of the Japanese quails (Coturnix coturnix japonica) in the context of terrestrial locomotion and take-off for flight, in order to explore the functional significance of the femoral form and limb postures. It is shown that the distribution of stress was similar in all cases, furthermore, the lower 2/3 of the dorsal and ventral region of the femur suffered higher stress, and the junction between the distal diaphysis and the medial condyle was the most vulnerable area. The stress reaches its highest value under the condition of about 90-100 degrees of loading angle; when this angle is larger than 110 degrees, the femur will be relatively safe. These findings suggested that quail femur is more suitable to terrestrial locomotion than take-off. This kind of work will contribute to revealing the locomotor behavior of fossil taxa.

El rendimiento biomecánico de los huesos de los miembros es útil para reflejar la adaptación de un animal a las cargas y comportamientos externos. En este estudio, utilizamos el método de elementos finitos para simular la carga que actúa sobre el fémur intacto de las codornices japonesas (Coturnix coturnix japonica) en el contexto de la locomoción terrestre y el despegue para el vuelo, con el objetivo de explorar la importancia funcional de la forma femoral y posición de los miembros. En el estudio, la distribución del estrés fue similar en todos los casos; además, los 2/3 inferiores de la región dorsal y ventral del fémur sufrieron un mayor estrés, y la unión entre la diáfisis distal y el cóndilo medial fue el área más vulnerable. La tensión alcanza su mayor valor bajo la condición de, aproximadamente, 90-100 grados de ángulo de carga; cuando este ángulo es mayor a 110 grados, el fémur esta relativamente seguro. Estos hallazgos sugieren que el fémur de codorniz es más adecuado para la locomoción terrestre que para el despegue. Este tipo de trabajo contribuirá a revelar el comportamiento locomotor de los taxones fósiles.
Descritores: Coturnix
Fêmur/fisiologia
-Estresse Mecânico
Fenômenos Biomecânicos
Análise de Elementos Finitos
Fêmur/anatomia & histologia
Locomoção
Limites: Animais
Responsável: CL1.1 - Biblioteca Central


  10 / 323 LILACS  
              first record previous record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Chile
Texto completo
Id: biblio-975713
Autor: Long, Hui-Qing; Xuan, Jing; Kyung, Hee-Moon; Bing, Li; Wu, Xiu-Ping.
Título: Biomechanical analysis of micro-implants lingual straight wire appliance during retracting maxillary anterior teeth / Análisis biomecánico de microimplantes con dispositivo de alambre recto lingual durante la retracción de dientes maxilares anteriores
Fonte: Int. j. morphol;36(4):1386-1393, Dec. 2018. tab, graf.
Idioma: en.
Projeto: National Natural Science Fund of China; . International Cooperation Project of Science and Technology Department of Shanxi Province (China - Korea).
Resumo: This study aimed to establish three-dimensional finite element models of micro-implants-lingual straight wire appliance and to investigate the effects of different wire patterns on the initial displacement of the maxillary anterior teeth and the stress of the periodontal ligament and tooth root during retracting maxillary anterior teeth in lingual orthodontics. A three-dimensional geometric models of maxilla with maxillary dentition was established using Cone-beam CT scan .Three types of maxilla models including microimplants and Duet-Slot Lingual Bracket appliance with three different arch wires ( model A: 0.016 inch × 0.022 inch stainless steel square wire; modelB: 0.016 inch stainless steel round wire; model C: double wire of 0.016 inch × 0.022 inch stainless steel square wire + anterior teeth 0.016 inch stainless steel round wire) were assembled by Unigraphics NX 8.5 software. The labial intrusion force and lingual retraction force were simulatively loaded to obtain initial displacement of the anterior teeth and the stresses of each tooth root and periodontal ligament, using three-dimensional finite element calculation software Ansys Workbench 15. The initial displacement of the lateral incisors was close to the bodily movement; and central incisors and lateral incisors slightly extruded. Compared with group A and group C, canine teeth appeared obviously horizontal "arched effect" by crown labial tipping in group B. The stress distribution of the tooth root and periodontal ligament was minimal and uniform in the group C. The 0.016 × 0.022- in stainless steel rectangular wire combined with 0.016- in stainless steel round wire used in the anterior teeth can better control the torque of the maxillary anterior teeth for space close in lingual orthodontics. Moreover, the stress distribution of tooth root and periodontal ligament is even, which is difficult to damage the periodontal ligament or result in external resorption of tooth root.

Este estudio tuvo como objetivo establecer modelos tridimensionales de elementos finitos de microimplantes linguales de alambre recto e investigar los efectos de diferentes patrones de alambre en el desplazamiento inicial de los dientes maxilares anteriores y el estrés del ligamento periodontal y la raíz del diente durante la retracción lingual sobre los dientes anteriores del hueso maxilar en ortodoncia. Se establecieron modelos geométricos tridimensionales del hueso maxilar con dentición utilizando una exploración por tomografía computarizada de haz cónico. Tres tipos de modelos maxilares, incluidos los microimplantes y el dispositivo Duet-Slot Lingual Bracket con tres arcos diferentes (modelo A: 0.016 pulgada × 0.022 pulgada alambre cuadrado de acero inoxidable; modelo B: alambre redondo de acero inoxidable de 0.016 pulgadas; alambre cuadrado de acero inoxidable de 0.016 pulgada × 0.022 pulgada y alambre redondo de acero inoxidable de 0.016 pulgada) ensamblados por el software Unigraphics NX 8.5. La fuerza de intrusión labial y la fuerza de retracción lingual se cargó simultáneamente, para obtener el desplazamiento inicial de los dientes anteriores y las tensiones de cada raíz dental y ligamento periodontal, usando el software tridimensional de cálculo de elementos finitos Ansys Workbench 15. El desplazamiento inicial de los incisivos laterales se relacionaba al movimiento corporal; mientra que los incisivos centrales e incisivos laterales se mostraron ligeramente extruidos. Comparado con el grupo A y el grupo C, los dientes caninos presentaron un "efecto arqueado" horizontal por la inclinación labial de la corona en el grupo B. La distribución del estrés de la raíz del diente y el ligamento periodontal fue mínima y uniforme en el grupo C. El alambre rectangular de acero inoxidable combinado con el alambre redondo de acero inoxidable de 0.016 usado en los dientes anteriores puede controlar mejor el torque de los dientes maxilares anteriores para cerrar el espacio en ortodoncia lingual. Además, la distribución del estrés de la raíz del diente y del ligamento periodontal es pareja, lo que dificulta dañar el ligamento periodontal o provocar una resorción externa de la raíz del diente.
Descritores: Fios Ortodônticos
Próteses e Implantes
Técnicas de Movimentação Dentária
Braquetes Ortodônticos
Análise de Elementos Finitos
-Aço Inoxidável
Estresse Mecânico
Língua
Fenômenos Biomecânicos
Teste de Materiais
Maxila
Limites: Humanos
Responsável: CL1.1 - Biblioteca Central



página 1 de 33 ir para página                         
   


Refinar a pesquisa
  Base de dados : Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde