Entwicklung und Charakterisierung von Zahnimplantaten mit definierter Porosität und biokompatiblen Beschichtungen

Schiefer, Herwig

Dissertation / PhD Thesis/Book

Entwicklung und Charakterisierung von Zahnimplantaten mit definierter Porosität und biokompatiblen Beschichtungen

Schiefer, H. (Corresponding author)FZJ*

2008
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 4268, IX, 148 p (2008) = Bochum, Univ., Diss., 2007

Please use a persistent id in citations: http://hdl.handle.net/2128/13950

Report No.: Juel-4268

Abstract: Implants are increasingly gaining importance in modern medicine. For loaded implants, such as dental and hip implants, metallic materials are predominantly employed. Their excellent biocompatibility together with their advantageous mechanical and physical properties mean that titanium and its alloys have a high potential for use as long-term implants. To improve the quality of the connection between tissue and implant, the surface of metallic implants can be specifically modified. Surface keying and open porous coatings have proven beneficial. Additionally, the coating of the implant with bioactive materials, such as calcium phosphates, can accelerate the healing process and can also improve the primary stability of the implant in the bone. In this dissertation, different techniques are developed that systematically modify the surface of dental implants. An essential feature is the application of a porous coating to the area of the dental implant that is in contact with the bone. For this purpose, the powder-metallurgical space holder method, developed at IEF-1, was advanced. The evaluation of the ideal process parameters was based on the characterization of mechanical properties, especially the compression strength and the fatigue strength, for model geometries. Evidence of the principal functionality of the implants was supplied by a modified fatigue test according to ISO 14801. This test showed that the developed implants with an openporous coating can withstand up to 2 million cycles without damage. For the two most promising implant geometries, different loading conditions were simulated using the finite element method (FEM). First, the load distribution within the implants during the fatigue test was calculated. Then, the loading in the jaw-bone was modelled, taking into account different rates at which bone grew into the porous structure. FEM calculations demonstrated that the loading of the individual implant components decreases with increasing bone content in the porous structure. The simulation of extreme loading conditions identified the main loaded components of the dental implants. In order to improve the biocompatibility of dental implants, two coating techniques were examinated. To accelerate the growth of bone tissue into the porous structure, a bioactive calcium phosphate layer was applied to the porous titanium structure by an electrochemical process. A crystalline layer formed at the edge of the sample only and only infiltrated the first 1…2 pore layers of the porous structure. The formation of an intermediate layer was detected by EDX. This layer can be attributed to the incipient conversion of the brushite phase to hydroxyapatite. The angular form of the crystals is probably the reason behind the disadvantageous properties observed during cell culture experiments. A second coating technique consisted of applying a zirconia layer to dense titanium by electron beam evaporation. The aim was to improve the quality of the contact between the gingiva and the implant. The coating morphology of the zirconia layers showed a strong dependence on the substrate temperature during the coating process. Cell culture experiments revealed that fibroblasts adhere better to zirconia than to titanium.

Note: Record converted from VDB: 12.11.2012
Note: Bochum, Univ., Diss., 2007

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