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1

Comparative 3D FEM analysis of three different dental implant shapes

Kut S.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2014

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z. 86 [290], nr 4

549--559

EN

This paper presents the results of numerical modeling using the finite element method of three implants. Geometric models of individual parts of the analyzed system (implant, abutment and screw) and the standard models of the bone and the crown were built in the Ideas NX environment. On the basis of real geometric models the fully three-dimensional numerical models were built. The calculations for different implant systems were carried out using MARC/Mentat commercial software. The numerical models of each system consist of five deformable bodies being connected to each others. Modeling was carried out in two stages. The first stage includes the modeling of the stresses in the bone-implant-abutment-screw assembly. The preload of models was set so that the axial stress in the screw core is equal to 75% of yield stress of material from which the screw was made. In the second stage the model with assembly stresses was being loaded with oblique force on the crown with values in the range from 0 to 250 N. An analysis and comparison of stress distributions and values of stresses in analysed implant systems were carried out. This investigation shows the meaningful influence of the shape of implant of an abutment on distribution and values of stress, load capacity of individual implant systems, and furthermore, stress in osseous tissue.

PL

W pracy przedstawiono wyniki modelowania numerycznego MES trzech systemów implantologicznych. Modele geometryczne poszczególnych części badanych układów (implant, łącznik, śruba) oraz standardowe modele kości i korony zostały utworzone w programie Ideas NX. Na podstawie modeli geometrycznych zbudowano trójwymiarowe modele numeryczne badanych systemów. Symulacje numeryczne poszczególnych systemów implantologicznych przeprowadzono za pomocą komercyjnego oprogramowania MARC/Mentat. Model numeryczny każdego systemu składał się z pięciu ciał odkształcalnych połączonych ze sobą. Analizę numeryczną dla poszczególnych systemów implantów przeprowadzono w dwóch etapach. Pierwszy obejmował modelowanie naprężeń montażowych. Obciążenie montażowe było zadawane w taki sposób, aby naprężenia osiowe w rdzeniu śruby wynosiły 75% granicy plastyczności materiału, z którego jest ona wykonana. W drugim etapie model ze wstępnymi naprężeniami montażowymi był obciążany na koronie ukośnie siłą w zakresie wartości od 0 do 250 N. Dokonano analizy oraz porównania rozkładów i wartości naprężeń występujących w badanych systemach implantologicznych. Badania wykazały znaczący wpływ kształtu implantu oraz łącznika na rozkład i poziom naprężeń oraz nowości poszczególnych systemów implantologicznych, a tak że na naprężenia w tkance kostnej.

2

Stresses present in bone surrounding dental implants in FEM model experiments

Żmudzki J., Walke W., Chladek W.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 1

71-74

EN

Purpose: Appropriate selection of material and geometric characteristics of intraosseus pillar implant part creates a possibility to control the bone tissue loading. Design/methodology/approach: A basic tool that is commonly used the evaluation of bone loading state is the linear FEM analysis. It requires setting of appropriate experiment conditions. Hence, an analysis has been carried out in order to determine the influence of dividing method of finite elements (tetragonal type 187 in Ansys system v.11) on stresses in pillar and surrounding bone tissue. Findings: Seeking of loading values cortical bone tissue is highly affected by the increase of mesh density on the edge of implant insertion into the cortex bone. Loading stresses values have significantly increased along with increased mesh density, whereas the differences have even reach 47 MPa. Research limitations/implications: Research has been carried out only for the Ansys system in the linear range assuming standard shape and mechanical characteristics of implant and bone, as well as regarding the after the osseointegration phase because if the presumed complete adherence of the pillar to the bone. Practical implications: Excessive increase of mesh density leads to overestimation of loading stresses values and further to an unjustified increase of pillars' diameter. At the other hand, too large elements might lead, through an underestimation of loading stress level, to overloading atrophy of bone tissue. Originality/value: This paper points out the necessity of more determined activities aimed on defining appropriate and uniform FEM experiment conditions that would enable achievement of more real results of model researches and their comparability.

3

Warstwy nanokrystalicznego diamentu na implanty dentystyczne : [streszczenie]

Olborska A., Karczemska A.

Engineering of Biomaterials

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2007

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Vol. 10, no. 65-66

7-7

PL

Różne rodzaje warstw węglowych otrzymanych różnymi sposobami, między innymi warstwy diamentopodobne (DLC) oraz warstwy nanokrystalicznego diamentu (NCD) otrzymane w procesie rozkładu metanu w polu wysokiej częstotliwości RFPACVD, są w wysokim stopniu biokompatybilne. W zależności od parametrów nanoszenia, różnią się one bio-fizycznymi oraz mechanicznymi właściwościami, DLC są amorficzne i zawierają około 60% diamentu oraz 40% grafitu, NCD składają się niemalże całkowicie z czystego diamentu. Zastosowanie warstw węglowych w medycynie jest znane od wielu lat. Prace nad implantami stomatologicznymi rozpoczęły się ponad dziesięć lat temu.

EN

Different kinds of carbon coatings, obtained by different methods are highly biocompatible, among them both diamond-like carbon (DLC) and nanocrystailine diamond (NCD) coatings obtained with the radio frequency plasma activated chemical vapour deposition (RFPACVD) process. They have different bio-physical and mechanical properties, in dependence of the parameters of deposition; DLC are amorphous coatings consisting of about 60% diamond and 40% graphite, NCD contains almost pure diamond. The application of carbon coatings in medicine is investigated for many years. Research on dental implants has begun more that decade ago. Otborska and all has explained the good mechanical properties of amorphous carbon coatings - DLC. Amorphous carbon (a-C) coatings, obtained by RFPACVD method, were deposited on implants used in maxillofacial surgery and on the dental prostheses. In all cases the substrate was the medical steel AISI 316L. After that the coating was investigated by Auger electron spectroscopy (AES). AES results show that the surface layer consists of carbon and the interface layer consisting of the substrate carbides (i.e. Cr, Ni, Mo, Fe) makes the coating more adhesive and improves its quality. However, the next generation coatings-NCD, improved in many ways the mechanical properties of the first carbon coatings. Nanocrystailine diamond coatings (NCD), posses the unique bio-medical and mechanical properties and so have found many applications in medicine. NCD is about 1mim thin coating with a very high adhesion to substrate thanks to the interface layer containing substrate carbides. It consists almost pure diamond, the crystals are of the sizes of nanometers. The small amount of graphite, on the grain baundries, even improves the mechanical quality of the coating, it is less brittle. NCD can be coated on different materials, such as titanium and its alloys or medical steel AISI316L, especially interesting are its applications as the coatings for medical implants. Investigations, lasting for many years, show the high biocompatibility of NCD and its good mechanical and physico-chemical properties, it is also resistant to bacterial colonization. Nanocrystailine diamond is also used as the coating for artificial heart valve because of its heamocompatibility and for dental implants. Dental implants have been coated with nanocrystailine diamond by RFPACVD method. Then their surface was analyzed by Raman Spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. The good quality, uniform NCD coating, obtained on the dental implants surface, is a promising material in this area of research.

4

Fatigue algorithm for dental implant

Wierszycki M., Kąkol W., Łodygowski T.

Foundations of Civil and Environmental Engineering

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2006

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No. 7

363-380

EN

Restorations with the application of implants are effective and commonly used in dental treatment. The computer simulation of implant fatigue life employing FEA is considered in the paper. For the simulation of implant structure behavior a 3D model including a spiral thread is applied, which allows for the full simulation of the kinematics of the implant, describing the multiaxial state of stress and, in consequence, the possibility of screw loosening. The cyclic scheme of the physiological occlusal loading and fatigue changes of dental material, bone loss phenomenon and changeability of boundary conditions are investigated. The valuable results for fatigue life which may be applied in modern prosthodontics are presented.

5

Przyczyny niepowodzeń w leczeniu implantologicznym

Frączak B., Tutak M., Kijak E., Frączak P.

Inżynieria Biomateriałów

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2004

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R. 7, nr 37

27-29