Today, many people suffer from the defect of bone due to an accident, congenital diseases, age increasing, etc. Therefore, it is necessary to find a suitable alternative for treatment. Despite the advantages that natural alternative has, they also have some disadvantages that limit their use. Therefore, the use of artificial replacements has found a special attention. For the biomaterial being used for bone implant, osseointegration and bone connection of artificial implant to their surrounding tissue is very important. On the other hand, it has been shown that desirable cell adhesion and spreading on the surface of implant is needed at cellular level, to achieve this goal(1). Therefore, modifying surface parameters such as roughness and wettability (2) become important.
Recently Polyether ether ketone (PEEK) is taken into consideration due to its interesting properties such as physical properties(radiolucency), and mechanical properties (elastic modulus close to bone modules, high strength wear resistance), forming process (Ability to prepare a three-dimensional implants customized to fit the exact size of the lesion y laser sintering method), and less local inflammation and stress shielding problem compare to metal implant as biomaterial specially in the field of bone implant and orthopedic application (3, 4). Unlike the desirable characteristics of this polymer, its ability to bond with the surrounding bone tissue is low due to its low bioactivity and poor interfacial biocompatibility. On the other hand, it is known that the surface of biomaterials is a major factor in successful connection with surrounding tissue in the body. It is believed that surface properties such as topography and surface chemistry (including surface composition, charge, functional group and density of functional groups) are two important factors for cell adhesion to the surface of biomaterials and causing the bone-implant interactions to be successful (5-7).
To achieve this goal several methods have been used such as acid etching, chemical modification, plasma modification, composite structure and laser treatment (8). Laser treatment is an appropriate choice for enhancing surface bioactivity because of its advantages such as high operation speed, low cost, easy operation, good repeatability(9) flexibility and the ability to modify small areas without affecting other areas(10, 11).
One of the ways to improve surface properties of materials is surface engineering by the laser. The input of radiation from laser to solid surface, including electron stimulation and return to non-intrusive mode, is very short on time. In other word the total energy input to the surface is not enough to change the material’s bulk temperature. This makes it possible to modify surface layer in the acute conditions, without changing of the properties of bulk, which is, of course, one of the other advantages of using the laser in surface modification(11). Laser surface engineering has many uses for increasing surface properties such as hardness, wettability, fracture, fatigue, wear resistance, corrosion, and so on. Therefore, phenomena caused by laser interaction with surface such as melting, evaporation and slipping depth are an integral relation to the optical parameters of the laser (pulse energy, pulse width, pulse number, irradiation time), and chemical, physical and optical properties of the metal. What is certain is that the modification by laser depends on energy density of the laser and its optical-kinetic conditions which effect on their wettability and ultimately their biocompatibility(10, 12).
Scientists try to enhance the bioactivity of PEEK through physical, chemical and biological methods to achieve successes in the field of implant applications. But despite a lot of valuable research that has already been done, an appropriate implant has not been obtained yet and more research is needed. Therefore, the aim of this study is to modify the surface of PEEK to improve its interaction with tissue environment and bone interaction in the next step. For this purpose, a micro-nano structured surface (with specified parameters) will be created by laser treatment. We hope to enhance the surface wettability and roughness to improve its bioactivity by applying different parameter of laser to choose the optimum condition.