Lee Seung-Hwan
(Department of Prosthodontics, School of Dentistry, Kyungpook National University)
,
Jo Kwang-Hun
(Department of Prosthodontics, School of Dentistry, Kyungpook National University)
A modelling scheme for the stress analysis taking into account load transfer characteristics of the osseointegrated interfaces between dental implant and surrounding alveolar bone was investigated. Main aim was to develop a more realistic simulation methodology for the load transfer at the interface...
A modelling scheme for the stress analysis taking into account load transfer characteristics of the osseointegrated interfaces between dental implant and surrounding alveolar bone was investigated. Main aim was to develop a more realistic simulation methodology for the load transfer at the interfaces than the prefect bonding assumption at the interfaces which might end up the reduced level in the stress result. In the present study, characteristics of osseointegrated bone/implant interfaces was modelled with material nonlinearity assumption. Bones at the interface were given different stiffness properties as functions of stresses. Six different models, i.e. tens0, tens20, tens40, tens60, tens80, and tens100 of which the tensile moduli of the bones forming the bone/implant interfaces were specified from 0, 20, 40, 60, 80, and 100 percents, respectively, of the compressive modulus were analysed. Comparisons between each model were made to study the effect of the tensile load carrying abilities, i.e. the effectivity of load transfer, of interfacial bones on the stress distribution. Results of the present study showed significant differences in the bone stresses across the interfaces. The peak stresses, however, were virtually the same regardless of the difference in the effectivity of load transfer, indicating the conventional linear modelling scheme which assumes perfect bonding at the bone/implant interface can be used without causing significant errors in the stress levels.
A modelling scheme for the stress analysis taking into account load transfer characteristics of the osseointegrated interfaces between dental implant and surrounding alveolar bone was investigated. Main aim was to develop a more realistic simulation methodology for the load transfer at the interfaces than the prefect bonding assumption at the interfaces which might end up the reduced level in the stress result. In the present study, characteristics of osseointegrated bone/implant interfaces was modelled with material nonlinearity assumption. Bones at the interface were given different stiffness properties as functions of stresses. Six different models, i.e. tens0, tens20, tens40, tens60, tens80, and tens100 of which the tensile moduli of the bones forming the bone/implant interfaces were specified from 0, 20, 40, 60, 80, and 100 percents, respectively, of the compressive modulus were analysed. Comparisons between each model were made to study the effect of the tensile load carrying abilities, i.e. the effectivity of load transfer, of interfacial bones on the stress distribution. Results of the present study showed significant differences in the bone stresses across the interfaces. The peak stresses, however, were virtually the same regardless of the difference in the effectivity of load transfer, indicating the conventional linear modelling scheme which assumes perfect bonding at the bone/implant interface can be used without causing significant errors in the stress levels.
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제안 방법
Each model represented 0, 20, 40, 60z 80z and 100 percents, respectively, of the compressive modulus. Comparisons between each model were made to study the effect of the tensile load carrying abilities, i.e. the effectivity of load transfer, of interfacial bones on the stress distribution. Results of the present study showed rather significant differences in the bone stresses across the interfaces among different mod이s.
The numbers following the word 'tens' stands for the tensile modulus in percent of compressive modulus, which in turn represent the effectivities of tensile stress transfer. Comparisons between each model were made to study the effectivity of tensile load transfer of interfacial bones on the stress distribution. Within the scope of the present study, the f이lowing conclusions were drawn.
In order to simulate the different load transfer characteristics at the implant/bone interface, L텬e came up with a rather new idea for interface modelling, Lee analysed three different models to investigate effects of osseointegration at the interface between dental implants and surrounding bones on the stress distribution, Bone/implant interfaces on the screws of the implant were divided into three characteristic surfaces, i.e. compression dominant, tension dominant, and shear dominant ones. In the Bond model, a condition of perfect bonding was assumed at the whole interface.
The fraction factors were given from 0 to 100% at the step of 20%. Total six types of interface modelling, i.e. tensOz tens20z tens40z tens60, tens80z and tenslOO were analysed to simulate the possible variation in the mechanical properties of the osseointegration at the interface. The numbers following the word 'tens' stands for the tensile modulus in percent of compressive modulus, which in turn represent the effectivities of tensile stress transfer.
The tensile moduli were specified as some fractions of the compressive modulus for the bones at the vicinity of the implants, to simulate the different stress transmit behaviour between tensile and compressive stresses at the interfaces. Using the fraction factors from 0 to 100% at the step of 20%, a total of six types of interface modelling, i.e. tensO, tens20z tens40z tens60z tens80z and tens 100 were analysed to simulate the possible variation in the mechanical properties of the osseointegration at the interface.
대상 데이터
The threads were simplified into the serrations and the spiral groove at the self tapping area was mod- 이led with smooth surface. In the whole mesh, the CAX 8 solid elements of ABAQUS (8 node quadrilateral element) were used. Aspect ratio of all the elements was controlled not to exceed 5.
Meanwhile coarse meshes in the other areas were used to reduce computing time. The model consisted of 3967 elements and 10928 nodes in total. Only the bones surrounding the implants of model.
이론/모형
Different tensile and compressive stiffness were specified for the bones near the implant/bone interface to simulate the presumed differences in the stress transfer pattern between tensile and compressive loads. The characteristics of osseointegrated bone/implant interfaces was modelled with material nonlinearity assumption. The tensile moduli of the bones forming the bone/implant interfaces were divided into six different models, i.
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