Influence of bone definition and finite element parameters in bone and dental implants stress: A literature review

This article belongs to the Special Issue New Trends in Bioengineering in Osseointegration and Dental Implants.Bone plays an important role in dental implant treatment success. The goal of this literature review is to analyze the influence of bone definition and finite element parameters on stress in dental implants and bone in numerical studies. A search was conducted of Pubmed, Science Direct and LILACS, and two independent reviewers performed the data extraction. The quality of the selected studies was assessed using the Cochrane Handbook tool for clinical trials. Seventeen studies were included. Titanium was the most commonly-used material in dental implants. The magnitude of the applied loads varied from 15 to 300 N with a mean of 182 N. Complete osseointegration was the most common boundary condition. Evidence from this review suggests that bone is commonly defined as an isotropic material, despite being an anisotropic tissue, and that it is analyzed as a ductile material, instead of as a fragile material. In addition, and in view of the data analyzed in this review, it can be concluded that there is no standardization for conducting finite element studies in the field of dentistry. Convergence criteria are only detailed in two of the studies included in this review, although they are a key factor in obtaining accurate results in numerical studies. It is therefore necessary to implement a methodology that indicates which parameters a numerical simulation must include, as well as how the results should be analyzed

Mechanical tests for evaluation of the integrity of the implant abutment connection

Nos últimos trinta anos, a reabilitação oral por sistemas de implantes tornou-se uma das técnicas mais bem-sucedidas. Um sistema de implante tem habitualmente 2 corpos, um endosteal e um dispositivo de suporte para a prótese conectados por um parafuso. Ao longo desta interface, as microgaps podem se desenvolver. Estes espaços constituem um abrigo para bactérias, o que pode aumentar o risco de periimplantites, associadas a uma maior infiltração de células inflamatórias e perda de osso. Para reduzir esse risco e, portanto, o tamanho e número de microgaps, são realizados testes mecânicos para adquirir um maior conhecimentos sobre o desempenho de cada sistema de implantes. O comportamento dos dispositivos fora testados recorrendo a : análise microbiológica, extração de DNA, análise por estereomicroscópio, microscópio eletrônico de varredura, modelagem de elementos finitos, análise radiográfica e análise espectrofotométrica. Materiais e métodos : A pesquisa foi realizada entre novembro de 2016 e abril de 2017. Estudos experimentais, artigos de revisão e livros escritos em inglês com texto de versão de acesso completo, data de edição da publicação entre 2005 e 2017, e condições do teste mais realistas, como as condições na cavidade oral são critérios de inclusão. Os resultados foram posteriormente analisados, com o objetivo de avaliar a integridade da conexão de implante-pilar.Over the last thirty years, the oral rehabilitation by implants systems has become one of the most successful techniques. An implant system has two main parts, an endosteal fixture and a prosthesis-supporting abutment connected to fixture with a screw. Along this interface, microgaps can develop; they are defined as a microscopic space. This localisation play a role of safe house for bacteria, which can increase the risk of peri-implantitis, they are associated with a higher inflammatory cell infiltration and bone loss. To reduce this risk and therefore the size and number of microgaps, mechanical tests are carried out in order to develop knowledge about the capacities of each implant system. As tests, it was found: microbiological analysis, DNA extraction, analysis by stereomicroscope, scanning electron microscope, finite element modeling, radiographic analysis and spectrophotometric analysis. Material and methods: the research was done between November 2016 and April 2017. Experimental studies, review articles and books written in the English with a full access version text, the edition date of the publication between 2005 and 2017, and conditions of the test more realistic, like the conditions in oral cavity are inclusions criteria. Their results are subsequently analysed, for the aim of an evaluation of the integrity of the implant-abutment connection

Mechanical tests for evaluation of the integrity of the implant abutment connection

Nos últimos trinta anos, a reabilitação oral por sistemas de implantes tornou-se uma das técnicas mais bem-sucedidas. Um sistema de implante tem habitualmente 2 corpos, um endosteal e um dispositivo de suporte para a prótese conectados por um parafuso. Ao longo desta interface, as microgaps podem se desenvolver. Estes espaços constituem um abrigo para bactérias, o que pode aumentar o risco de periimplantites, associadas a uma maior infiltração de células inflamatórias e perda de osso. Para reduzir esse risco e, portanto, o tamanho e número de microgaps, são realizados testes mecânicos para adquirir um maior conhecimentos sobre o desempenho de cada sistema de implantes. O comportamento dos dispositivos fora testados recorrendo a : análise microbiológica, extração de DNA, análise por estereomicroscópio, microscópio eletrônico de varredura, modelagem de elementos finitos, análise radiográfica e análise espectrofotométrica. Materiais e métodos : A pesquisa foi realizada entre novembro de 2016 e abril de 2017. Estudos experimentais, artigos de revisão e livros escritos em inglês com texto de versão de acesso completo, data de edição da publicação entre 2005 e 2017, e condições do teste mais realistas, como as condições na cavidade oral são critérios de inclusão. Os resultados foram posteriormente analisados, com o objetivo de avaliar a integridade da conexão de implante-pilar.Over the last thirty years, the oral rehabilitation by implants systems has become one of the most successful techniques. An implant system has two main parts, an endosteal fixture and a prosthesis-supporting abutment connected to fixture with a screw. Along this interface, microgaps can develop; they are defined as a microscopic space. This localisation play a role of safe house for bacteria, which can increase the risk of peri-implantitis, they are associated with a higher inflammatory cell infiltration and bone loss. To reduce this risk and therefore the size and number of microgaps, mechanical tests are carried out in order to develop knowledge about the capacities of each implant system. As tests, it was found: microbiological analysis, DNA extraction, analysis by stereomicroscope, scanning electron microscope, finite element modeling, radiographic analysis and spectrophotometric analysis. Material and methods: the research was done between November 2016 and April 2017. Experimental studies, review articles and books written in the English with a full access version text, the edition date of the publication between 2005 and 2017, and conditions of the test more realistic, like the conditions in oral cavity are inclusions criteria. Their results are subsequently analysed, for the aim of an evaluation of the integrity of the implant-abutment connection

Mechanical analysis and design of dental restorations: fatigue, mcrogap and screw loosening

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Effect of macrogeometry in the biomechanical behavior of osseointegration dental implants in low-quality bone

Orientador: Bruno Salles Sotto MaiorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A macrogeometria do implante está relacionada ao desenho do colar, conexão protética, formato das roscas e do corpo do implante. Diferentes desenhos do implante podem criar diferentes concentrações de tensão/deformação no tecido ósseo peri-implantar de boa qualidade, entretanto existe limitada informação sobre a influência desses parâmetros no comportamento biomecânico do implante instalado em osso de baixa qualidade. Nesse sentido, dois estudos foram conduzidos, sendo que o primeiro avaliou a influência do desenho do colar e das roscas na concentração de tensão e deformação no implante e no osso de suporte e o segundo estudo avaliou diferentes tipos de conexão protética e formatos do corpo do implante no comportamento biomecânico do osso peri-implantar. No primeiro estudo, seis modelos de implantes cilíndricos (4 x 10mm) hexágono externo foram obtidos pela combinação de dois desenhos de colar (liso e com microroscas) e três formatos de rosca (quadrado, trapezoidal e triangular). Para o segundo estudo, quatro modelos de implantes foram construídos com dois tipos de conexão protética (Hexágono Externo e Cone Morse) e dois formatos de corpo (cilíndrico e cônico). Em ambos estudos, os implantes receberam uma coroa unitária na região de 1° molar superior, a qual foi realizado um carregamento axial de 200N. Em seguida, foram analisados pelo método tridimensional de elementos finitos. Os modelos foram criados a partir de um software de desenho assistido por computador e o modelo ósseo foi construído a partir de tomografia computadorizada do tipo cone-beam da região posterior da maxila. Os dados do primeiro estudo foram analisados quantitativamente por ANOVA one-way com nível de significância a 5%. No estudo 2, utilizou-se os critérios de tensão de cisalhamento (?max) e deformação (?max) no osso peri-implantar. O estudo 1 mostrou que o desenho do colar afetou todos os parâmetros no implante e no osso cortical (P < 0.05), contribuindo com 99,79% no total de tensão de von Mises (?vM) e mais de 90% no total de tensões/deformação. O colar com microroscas apresentou maior ?vM (54.91±1.06 MPa) no implante bem como maior ?max (11.98±0.07 MPa) e ?max (0.97±0.07 x 10-3 ?m) no osso cortical, embora tenha gerado um padrão de distribuição de tensões/deformação mais adequado no osso peri-implantar. O desenho das roscas influenciou biomecanicamente apenas o osso trabecular (P < 0.05), contribuindo com mais de 95% das tensões geradas. O desenho de rosca triangular foi responsável por produzir menor tensão de tração (3.83±0.34 MPa), tensão de cisalhamento (4.14±0.47 MPa) e deformação (0.90±0.04 x 10-3 ?m). O estudo 2 mostrou que o tipo de conexão protética e formato do corpo influenciaram ?max e ?max no osso peri-implantar, sendo os implantes do tipo Cone Morse e formato cilíndrico responsáveis em produzir os menores valores de ?max e ?max no osso cortical e trabecular, respectivamente. Concluiu-se que a presença das microroscas no colar do implante, conexão Cone Morse, formato de rosca triangular e corpo cilíndrico são os parâmetros da macrogeometria que positivamente influenciam o comportamento biomecânico de implante unitário ancorado em osso de baixa qualidadeAbstract: Implant macro design is related to its collar design, prosthetic connection, thread design and body shape. Different implant macro designs can create distinct stress/strain concentrations in the peri-implant sites of good-quality bone, however there is limited information about the influence of these implant macro design parameters on the biomechanical behavior of the implant installed in a low-quality bone. Accordingly, two studies were conducted, and the first evaluated the effect of the collar and threads designs on the stress and strain distribution in the implant and low-quality bone and the second study evaluated different types of prosthetic connection and implant body shapes on the biomechanical behavior of the peri-implant bone. In the first study, six cylindrical external hexagon implants models (4 x 10 mm) were obtained by the combination of two collar designs (smooth and microthread) and three thread shapes (square, trapezoidal and triangular). For the second study, four implant models were constructed with two types of prosthetic connection (External Hex and Morse Taper) and two implant body shapes (cylindrical and conical). In both studies, the implants supported single upper first molar crowns and the restorations received 200 N axial loading and were analyzed by three-dimensional finite element method. The models were created from a computer-aided design modeling software and the bone model was constructed based on a cone-beam computer tomography of the posterior region of maxilla. Data of the first study were quantitatively analyzed by one-way ANOVA at a significance level of 5%. In the study 2, the criteria of shear stress (?max) and strain (?max) were used to evaluate peri-implant bone. The first study showed that collar design affected all parameters of the implant and cortical bone (P < 0.05), contributing to 99.79% of total von Mises stress (?vM) in the implant and more than 90% of total stresses/strain generated in the cortical bone. The microthread collar showed the highest values to ?vM (54.91±1.06 MPa) in the implant, as well as to ?max (11.98±0.07 MPa) and ?max (0.97±0.07 x 10-3 ?m) in the cortical bone, despite it had produced the more favorable stresses/strain distribution pattern on the peri-implant bone. Threads design influenced biomechanically only the trabecular bone (P < 0.05), contributing more than 95% of total stresses generated. The triangular thread shape was responsible for producing the lowest values to ?max (3.83±0.34 MPa) and ?max (4.14±0.47 MPa) stresses and ?max (0.90±0.04 x 10-3 ?m). The second study showed that the two types of prosthetic connection and implant body shape influenced ?max and ?max on the peri-implant bone and Morse taper and cylindrical implants were responsible to produce the lowest ?max and ?max values in the cortical and trabecular bone, respectively. It was concluded that the presence of microthread collar on the implant neck, Morse Taper connection, triangular thread shape and cylindrical implant are the implant macro design parameters that positively influence the biomechanical behavior of single implant restoration in the low-quality boneDoutoradoProtese DentalDoutora em Clínica Odontológic

Biomechanical analysis of two types of osseointegrated transfemoral prosthesis

In the last two decades, osseointegrated prostheses have been shown to be a good alternative for lower limb amputees experiencing complications in using a traditional socket-type prosthesis; however, restraining biomechanical issues, such as peri-prosthetic bone fractures or loosening, are present. To better understand and overcome these limiting issues, and thus reduce the number of implant failures, many studies have investigated the stress distribution on bone and implant during normal daily activities. The aim of this study was a biomechanical analysis of two different osseointegrated implants, a screw-type (OPRA) and a press fit system (OPL, Osseointegrated Prosthetic Limb), to evaluate the stresses generated in bone and prosthesis during a fall. In particular, four scenarios have been experimentally reproduced to determine the loads on the limb during different kinds of fall. For this purpose, a motion capture system and a force plate have been used. Numerical FEM (Finite Element Method) simulations have been performed to compare the behaviour of the OPRA and OPL systems in different fall scenarios. The obtained results showed that a fall backwards due to balance loss is the most stressful scenario among the ones analysed. As regards the comparison between OPRA and OPL devices, it emerged they have similar behaviours in terms of peak values of the stress, but the OPL implant generates larger high-stress areas in the distal femur as compared with the OPRA system

Biomechanics of Contemporary Implants and Prosthesis: Modeling, Experiments, and Clinical Application

Modern medicine is now more oriented towards patient-based treatments. Taking into account individual biological features allows for increasing the quality of the healing process. Opportunities for modern hardware and software allow not only the complex behavior of implants and prostheses to be simulated, but also take into account any peculiarities of the patient. Moreover, the development of additive manufacturing expands the opportunities for materials. Technical limits for composite materials, biomaterials, and metamaterials are decreasing. On the other hand, there is a need for more detailed analyses of biomechanics research. A deeper understanding of the technological processes of implants, and the mechanobiological interactions of implants and organisms will potentially allow us to raise the level of medical treatment. Modern trends of the biomechanics of contemporary implants and prostheses, including experimental and mathematical modeling and clinical application, are discussed in this book