# The Modification of Titanium Surface by Decomposition of Tannic Acid Coating
## 1 Introduction
Such surfaces can result in poor osseointegration, which will subsequently lead to a retarded integration of bone cells with the implant material and the generation of reactive oxygen species at the implant-bone interface. Titanium, although characterized by high biocompatibility, can cause various defensive reactions, including the rejection of the implant, because the body's sensitivity to elements is not the same for all individuals. The occurrence of an allergic reaction may be associated with the material used, the surgical technique or often with the condition surrounding the tissue implant. In order to circumvent these inherent bioinert surface-related limitations associated with biometallic surfaces and to improve the performance of Ti implants for successful clinical applications, there are many different processes and technologies for the surface treatment of titanium [10]. The surface modification of titanium and its alloys consist of modifying or altering the top layer of the metal in order to change the morphology, topography and chemistry of the surface [11]. The surface modification of titanium and its alloys consists of modifying the interface between the biomaterial surface and physiological surroundings to regulate biological responses, to improve wear-corrosion resistance (tribocorrosion behavior) and to provide excellent surface mechanical properties (increased surface hardness, compressive residual stress, scratch resistance, etc.). These surface modification techniques can be broadly classified into two categories--physical (plasma spray technology, plasma immersion ion implantation, physical vapor deposition, etc.) and chemical (chemical vapor deposition, sol gel, micro-arc oxidation, etc.). The physical type of surface modification focuses toward engineering the metallic surfaces by exposing the surfaces towards highly energetic charges, whereas chemical techniques encompass methods which chemically modify the surfaces through exposure to chemically active solutions. It is difficult to strictly separate these techniques in this manner, as most of these methods can often result in changes in the morphology, topography and chemistry of the generated surface. There are many known techniques for modifying surfaces by applying coatings to the metal, including those outlined in [12]. Moreover, the blood compatibility of obtained materials has been studied. Techniques include:  
* Glow techniques--these belong to the processes of thermo-chemical treatment in a gas atmosphere using the glow discharge phenomenon;
* Vacuum deposition techniques with chemical vapor deposition chemical methods--in these methods, as a result of chemical reactions of two or more gaseous substrates, reactions occur through the use of various forms of energy (light, plasma, heat, etc.) on the surface of the substrate or in its vicinity and are created on the surface of the substrates, creating utility products, such as coatings;
* The techniques of vacuum deposition with PVD physical methods--these methods are some of the techniques that increase the operational properties of usable elements by producing an anti-wear coating on their surface. The above techniques require specialized equipment or special conditions. The simplest method for the deposition of substances on the substrate surface is the vacuum deposition process. The variety of processes and techniques for refining the surface of titanium is large. The method of modifying the surface of titanium plates proposed in this paper is cheap and fast. Therefore, it could be an alternative to the methods currently known. In addition, the varied shapes of the implants are not a problem for the method proposed in this paper, while for others, they represent a limitation. In addition, as titanium naturally does not have antibacterial, antiviral or antioxidant properties, it can be given such properties through the method of applying coatings to its surface by modifying it with appropriate substances. Such substances may be polyphenic acids, as proposed in this paper.