Kimyasal mekanik cilalama prosesinin titanyum bazlı medikal implantlarda uygulanması

Biomaterials are commonly used as implant materials in the body for dental prostheses, orthopedic applications, heart valves and catheters. Based on the research studies conducted up to date, titanium and its alloys are known to be the most biocompatible materials due to their surface properties as well as extraordinary mechanical properties. Processing methods for the implant materials also affect the surface properties and may lead to contamination that can lessen the biocompatibility and after implantation may cause infection on patients which can be up to 4% in numbers. Changing the surface roughness and forming a surface oxide film have been implemented through various methods in the literature to increase of the biocompatibility and to ensure bio-inertness to the implant material. Sand blasting and chemical etching methods are commonly used for patterning the titanium surfaces to alter the surface roughness which can cause surface contamination. However, the other alternative methods such as high temperature plasma coating and laser patterning are costly. In this dissertation, Chemical Mechanical Polishing (CMP) process is established as an alternative technique to the existing methods in the literature in order to change the implant material surface properties. CMP process is one of the methods used in the semiconductor industry to ensure surface planarization through simultaneous mechanical and chemical actions. The abrasive particles in the polishing slurries provide the mechanical effect during the process enabling nanometer level erosion and cleaning the implant from any potential contamination during its machining. The chemical components of the slurry including the stabilizers, pH adjusters and oxidizers, on the other hand, help form a passive oxide film coating the surface. Generally, CMP is used to form very smooth surfaces but it has been demonstrated that by changing the slurry particle size and the pad material properties, it is possible to generated controlled roughness on the polished surface as well. The protective nature of the generated oxide film enables planarization in semiconductor applications. In implant applications of CMP, it is believed to help reduce the contamination on the surface of the bio-implants in the body environment and reducing the infection risk by stopping the chemical reactions in-vivo. It has been shown in the literature that the application of CMP on Ti films has been successful in terms of creating a smooth surface and a TiO2 oxide film. However, its native oxide film after CMP has not been characterized fully for its protective nature other than the passivating properties of the Ti/TiN films in semiconductor CMP applications. Titanium oxide film is known to promote the biocompatibility, cell adhesion, formation of hydroxyapatite layers. Yet, the oxide films obtained by artificial oxidation methods result in thick films and have porous structures. Therefore, in this study, CMP process has been applied to the Ti plates synergistically to remove the potentially contaminated surface layers and induce controlled roughness on the implant surfaces. In addition, the treated surface oxide layers have been characterized for the nature of the metal oxide layers in terms of their self-protective properties. Furthermore, biocompatibility of the CMP implemented surfaces have been evaluated through cell growth and infection resistance capabilities through biofilm analyses and optimal surface parameters were determined according to the desirability of the surface responses which help promote the cell behavior.In terms of carrying the results of this dissertation to the future studies, development of a 3 dimensional CMP process considering the 3-D nature of the implants is the most important necessity. The application of the 3-D CMP process on the implant surfaces is believed to be both an economical and more effective method on structuring the surface of the titanium based bio-implants. It is aimed to further develop a CMP driven surface nano-structuring methodology to create engineered surfaces on the Ti based bio-implants with self-protective surfaces to minimize chemical and bacterial reactivity, while promoting their biocompatibility through simultaneous surface patterning.