Comportamento mecânico de implantes modificados na região de ápice: análise pelo método de elementos finitos, fotoelasticidade, torque de inserção e frequência de ressonância
Data
2017-09-29
Autores
Sciasci, Plínio [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A proposta deste estudo foi analisar o comportamento mecânico e a distribuição de forças de diferentes geometrias de ápice em implantes cilíndricos por meio de método de elementos finitos (MEF), fotoelasticidade, torque de inserção e frequência de ressonância. Foram usinados quatro tipos de implantes: sem corte apical (A), com corte apical bi-partido (B), corte apical tri-partido (C), corte apical quadri-partido (D) e um quinto (grupo controle) implante Titamax Ti Ex (Neodent, Curitiba, Paraná, Brasil) (E), todos com dimensões (4,1 X 11,0 mm) de plataforma hexagonal externa. Para o ensaio fotoelástico, blocos de acrílico (30X30X10mm) com um implante foram copiados com Borracha Silicone. Dentro de cada molde de silicone foi vertido resina fotoelástica semi-fexível. Para o ensaio fotoelástico duas situações foram simuladas: aplicação de carga axial de 1 kgf e em outro momento aplicação do torque de 10 N.cm. As fotografias realizadas no polariscópio circular foram transferidas para um computador para leitura dos parâmetros fotoelásticos no software powerpoint (Office 2010). Para o estudo de elementos finitos, o desenho dos implantes foram reproduzidos em CAD (computer Aided design) através do software Autodesk Inventor® (versão 2015, São Paulo, Brasil) e o bloco ósseo tipo IV de dimensões (2X2X2cm) foram posteriormente processados pelo software Rhinoceros v5.0 SR8 (McNeel North America, Seattle, WA, USA). As simulações foram executadas pelo software (Ansys Workbench 10.0, Swanson Analysis Inc., Houston, PA, USA); no Centro de Tecnologia da Informação Renato Archer (CTI, Campinas, São Paulo- Brasil). As propriedades mecânicas do implante (titânio grau II), e do osso normal tipo IV foram obtidos na literatura. Os modelos foram configurados com propriedades elástica-linear, isotrópica e homogênea. Foi simulado torque de 10 N.cm em todos os modelos que foram comparados com o ensaio fotoelástico de torque. Para os ensaios de torque e por frequência de ressonância. Trinta e cinco implantes cilíndricos de conexão hexágono externo foram usinados em sua região de ápice e divididos em cinco grupos, conforme os cortes citados acima: (A) (n=9), (B) (n=9), (C) (n=9), (D) (n=8) e (grupo controle) implante Titamax Ti Ex (n=7), todos com dimensões (4,1 X 11,0 mm). Blocos ósseos de poliuretano de dimensões (2,0 X 2,0 X 1,5 mm) análogo ao osso trabecular humano tipo III sem cortical óssea foram utilizados para inserção dos implantes. Os valores do torque de inserção foram obtidos por meio de um torquímetro digital em N.cm e a estabilidade primária foi mensurada com o Osstell Mentor (ISQ). Para ensaio de torque de inserção, os implantes do grupo D e Titamax Ti Ex apresentaram as maiores médias e foram significativamente diferentes dos demais implantes, com exceção entre os implantes do grupo C e D (p<0,05). Os implantes do (controle) e (A) obtiveram a maior média para a estabilidade primária quando comparada aos demais grupos (p<0,05). No entanto, não houve diferença estatisticamente significantes para as médias de estabilidade obtidas entre os implantes D e (controle). Pela análise de elementos finitos e fotoelasticidade constatou-se que todos os implantes apresentaram distribuição de tensões que decresceram de modo constante até a região de ápice, sendo que a região de maior concentração de forças foi localizada na plataforma e no ápice dos implantes. Os implantes do grupo A, B, C e D com os ápices modificados obtiveram padrões similares de forças nessas regiões enquanto que o implante (controle) apresentou maior concentração de tensões nessa região. Concluiu-se que as modificações realizadas na região de ápice dos implantes podem contribuir para o aumento da estabilidade secundária do implante e na diminuição de concentração de tensões na região de plataforma quando submetidos à força torque. As alterações realizadas na região de ápice dos implantes apresentam boa distribuição de tensões. Alterações geométricas em implantes na região de ápice influenciam significativamente sua estabilidade primária. As modificações propostas para a região de ápice dos implantes B, C e D podem sugerir vantagens futuras para aplicação clínica, já que o crescimento ósseo por entre os espaços criados no ápice pode travar o implante e resistir melhor as forças de torção.
The purpose of this study was to analyze the mechanical behavior and force distribution of five different implant designs using finite element method (FEM), photoelasticity, insertion torque and resonance frequency of different geometric modifications proposed for the apex region Of cylindrical implants. Four types of implants were machined: without apical cut (A), with a two-part apical cut (B), apical tri-split cut (C), apical cut quadri-split (D) and fifth group was composed by Titamax Ti Ex Neodent all with dimensions (4.1 X 11.0 mm). For the photoelastic test, acrylic blocks (30X30X10mm) with implant installed were copied with Blue ASB-10 Silicone Rubber (Polipox). Inside each silicone mold was poured semi-flexible photoelastic resin (Polipox). A titanium UCLA prosthetic intermediate was screwed onto the implant and a dental crown on (Ni-Cr) was fixed on the set. For the photoelastic test two situations were simulated: application of axial load of 1 kgf and torque of 10 N.cm. The photograph and the reading of the photoelastic parameters were performed in a circular polariscope. For the finite element study, the computerAided design (CAD) implants and a Type IV human bone block of dimensions (2X2X2cm) were processed by the software Rhinoceros v5.0 SR8 (McNeel North America, Seattle, WA, USA) At the Renato Archer Information Technology Center (CTI, Campinas, São Paulo - Brazil). The mechanical properties of the implant (titanium grade II) and normal bone type IV were obtained in the literature. The mechanical models were configured with elastic-linear, isotropic and homogeneous properties. Torque of 10 N.cm was applied in all the models that were compared with the photoelastic torque test. For the torque and resonance frequency tests, thirty-five cylindrical implants with external hexagon connection of dimensions (4.1 X 11.0 mm) were machined in their apex region and divided into five groups: without apical cut (A), (B), apical cut tri-split (C), apical cut quadri-split (D) and fifth group was composed by the implant Titamax Ti Ex Neodent all with dimensions (4.1 X 11.0 mm ). Artificial bone blocks of polyurethane dimensions (2.0 X 2.0 X 2.0 mm) analogous to normal bone type III (National Ossos - Jaú - SP) were used for insertion of the implants. The insertion torque and removal torque values were obtained by means of a digital torque wrench and the primary stability was measured with the Osstell Mentor (Diagnostics Integration AB, Göteborgsvägen, Sweden). For insertion torque, the D and E implants had the highest mean values and were significantly different from the other implants, except for implants of group C and D that presented the same mean (p <0.05). Group A implants had the highest mean for primary stability when compared to the other groups (p <0.05). By the analysis of finite elements and photoelasticity it was verified that all the implants presented a distribution of tensions that decreased steadily, being that the region of greatest concentration of forces was located in the platform and at the apex of the implants. Implants A, B, C and D with modified apexes obtained similar forces patterns in these regions whereas implant E presented a higher concentration of stresses in this region. It was concluded that the modifications performed in the apex region of the implants may contribute to the increase of the stability of the implant and the reduction of stress concentration in the platform region when submitted to the torque force. The changes made in the apex region of the implants present good stress distribution. Geometric changes in implants in the apex region significantly influence their primary stability. The proposed modifications for the apex region of implants B, C and D may suggest advantages for clinical application.
The purpose of this study was to analyze the mechanical behavior and force distribution of five different implant designs using finite element method (FEM), photoelasticity, insertion torque and resonance frequency of different geometric modifications proposed for the apex region Of cylindrical implants. Four types of implants were machined: without apical cut (A), with a two-part apical cut (B), apical tri-split cut (C), apical cut quadri-split (D) and fifth group was composed by Titamax Ti Ex Neodent all with dimensions (4.1 X 11.0 mm). For the photoelastic test, acrylic blocks (30X30X10mm) with implant installed were copied with Blue ASB-10 Silicone Rubber (Polipox). Inside each silicone mold was poured semi-flexible photoelastic resin (Polipox). A titanium UCLA prosthetic intermediate was screwed onto the implant and a dental crown on (Ni-Cr) was fixed on the set. For the photoelastic test two situations were simulated: application of axial load of 1 kgf and torque of 10 N.cm. The photograph and the reading of the photoelastic parameters were performed in a circular polariscope. For the finite element study, the computerAided design (CAD) implants and a Type IV human bone block of dimensions (2X2X2cm) were processed by the software Rhinoceros v5.0 SR8 (McNeel North America, Seattle, WA, USA) At the Renato Archer Information Technology Center (CTI, Campinas, São Paulo - Brazil). The mechanical properties of the implant (titanium grade II) and normal bone type IV were obtained in the literature. The mechanical models were configured with elastic-linear, isotropic and homogeneous properties. Torque of 10 N.cm was applied in all the models that were compared with the photoelastic torque test. For the torque and resonance frequency tests, thirty-five cylindrical implants with external hexagon connection of dimensions (4.1 X 11.0 mm) were machined in their apex region and divided into five groups: without apical cut (A), (B), apical cut tri-split (C), apical cut quadri-split (D) and fifth group was composed by the implant Titamax Ti Ex Neodent all with dimensions (4.1 X 11.0 mm ). Artificial bone blocks of polyurethane dimensions (2.0 X 2.0 X 2.0 mm) analogous to normal bone type III (National Ossos - Jaú - SP) were used for insertion of the implants. The insertion torque and removal torque values were obtained by means of a digital torque wrench and the primary stability was measured with the Osstell Mentor (Diagnostics Integration AB, Göteborgsvägen, Sweden). For insertion torque, the D and E implants had the highest mean values and were significantly different from the other implants, except for implants of group C and D that presented the same mean (p <0.05). Group A implants had the highest mean for primary stability when compared to the other groups (p <0.05). By the analysis of finite elements and photoelasticity it was verified that all the implants presented a distribution of tensions that decreased steadily, being that the region of greatest concentration of forces was located in the platform and at the apex of the implants. Implants A, B, C and D with modified apexes obtained similar forces patterns in these regions whereas implant E presented a higher concentration of stresses in this region. It was concluded that the modifications performed in the apex region of the implants may contribute to the increase of the stability of the implant and the reduction of stress concentration in the platform region when submitted to the torque force. The changes made in the apex region of the implants present good stress distribution. Geometric changes in implants in the apex region significantly influence their primary stability. The proposed modifications for the apex region of implants B, C and D may suggest advantages for clinical application.
Descrição
Palavras-chave
Implantes dentários, Análise de elementos finitos, Fenômenos mecânicos, Torque, Dental implants, Finite Element Analysis, Mechanical phenomena, Torque