ICMCTF2018 Session DP: Symposium D Poster Session

Abstract In orthopedic surgery related to trauma or disease, it often requires the use of artificial bone plate to hold the fractured bones to effectively heal the fracture of a long bone. During surgery and postoperative healing period, the antibiotic management is critical to patients with infection control. A wound healing is also promoted by osteointegration and bone regeneration. A proper system needs to be effective to treat the wound, to reduce pain, and to restore function of a healthy life. High performance polyetheretherketone (PEEK) biomedical composites have been investigated for bone plate applications. By appropriate design, the biomedical composite materials can match the different parts of human body bones, quite helpful for long-term functional rehabilitation after surgery. They also remain x-ray transparency, making it easier for clinicians to assess the healing process. We have been developing PEEK composites with biodegradable polylactic-co-glycolic acid (PLGA) double layer structure bone plates and hydroxylapatite (HA) to promote bone regeneration and to derive antibiotic applications. In this report, the analysis of the material characteristics, in-vitro tests, and comparison with literature data will be presented and further discussed. A good understanding in the structure-property relationship would provide better guidelines for implant designs.

Recent investigations have been focused on β type titanium alloys as they present biocompatibility, non-toxicity, improved mechanical properties and also exhibit corrosion resistance. These novel alloys are bioinert, consequently surface modifications are required to improve its bioactivity. Plasma Electrolytic Oxidation (PEO) can be employed to produce a porous film which contains oxides of elements that compound the titanium alloys, that is known to exhibit good bioactivity and biocompatibility. With the continuous interest in titanium alloys, the purpose of this study was to modify two different titanium-niobium surfaces via PEO and understand the structure of these films while also analyzing the improvement in bioactivity via cellular viability. Ti-10Nb and Ti-20Nb alloys were treated by PEO under 250 V in 1mol.l^-1 H₃PO₄ electrolyte during 60 s. For the samples characterization we perform metallographic analysis, X-ray diffraction, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Nanoindentation technique, and cellular viability tests with MC3T3 cells with further analysis on SEM to understand the cellular behavior with the titanium implants. Metallographic analysis and X-ray patterns showed that Ti-10Nb and Ti-20Nb are composed by ( α+ β) which were due to the process performed above the β transus temperature to a ( α+ β) region, and the slow rate of cooling during the manufacturing process. Nanoindentation testes revealed that Ti-20Nb alloys exhibited the highest value to hardness,(3.0 ± 0.2) GPa, and the lowest elastic modulus, 98 ± 2 GPa. Using the 3D view of SEM technique, Ti-Nb coatings presented important values of roughness with round porous and random diameters. In addition, these images presented values of tickness from ~1.7 µm for Ti-10Nb and 1.0 µm for Ti-20Nb. Due to the electrolyte used, the presence of phosphorous compound which was incorporated into the coating during the PEO process was detected by the EDS spectra. X-ray patterns exhibited a highly crystalline film on Ti-10 Nb alloy which was also observed in great intensity with Raman spectroscopy with anatase phase. Conversely, Ti-20Nb presented a highly amorphous film with a decrease amount of bands of anatase phase observed by Raman spectroscopy. Cellular viability with MC3T3 cells showed no signs of cytotoxicity of these alloys with values higher than the control sample (>70%) but no significant differences were observed between these alloys; although TiNb10% presented mean higher values. These cells attached, differentiated and proliferated well in these alloys due to the porosity, roughness and the elements presented in the film.

Stainless steel (AISI) materials have an important role in the manufacture of many devices subjected to the corrosive environment including implants. It occurs due to their higher mechanical strength, hardness, and resistance to wear. Regards to the AISI 316L, it is one of the most used implanted material due to its mechanical properties and low cost. However, many papers have been reporting its tribocorrosion and the needing of replacement before ten years. The deposition of Silicon Carbide (SiC) coatings is a cheap strategy to improve its lifetime in corrosive environments due to its properties such as high hardness, biocompatibility, and resistance to corrosion. Additionally, TiO₂ nanoparticles can be incorporated into the SiC films to improve its corrosion resistance.

This paper show was investigated the effect TiO₂ nanoparticles of SiC film on chemical structure, the film morphology, and tribocorrosion behavior in Ringer's solution. The AISI 316L substrates were covered with SiC films with and without TiO₂ nanoparticles using Laser Cladding technique. The laser cladding provides a fast and cheap way to modify the material surface. The mechanical and structural properties of the SiC films were evaluated according to the power and speed parameters of the laser. The tribocorrosion were performed using open circuit potential (OCP) performed in three steps: Static, reciprocating, and static modes with an exposed area of 1.5 cm² with 5N force and 5 mm/s sliding speed using an alumina ball as the counter body. The corrosion rate was lower for both films when compared with bare AISI 316L. The best tribocorrosion resistance result was achieved for SiC film+TiO₂ mixture.