This paper reviews current physicochemical and biochemical coating techniques that are investigated to enhance bone regeneration at the interface of titanium implant materials. By applying coatings onto titanium surfaces that mimic the organic and inorganic components of living bone tissue, a physiological transition between the non-physiological titanium surface and surrounding bone tissue can be established. In this way, the coated titanium implants stimulate bone formation from the implant surface, thereby enhancing early and strong fixation of bone-substituting implants. As such, a continuous transition from bone tissue to implant surface is induced. This review presents an overview of various techniques that can be used to this end, and that are inspired by either inorganic (calcium phosphate) or organic (extracellular matrix components, growth factors, enzymes, etc.) components of natural bone tissue. The combination, however, of both organic and inorganic constituents is expected to result into truly bone-resembling coatings, and as such to a new generation of surface-modified titanium implants with improved functionality and biological efficacy.

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Organic–Inorganic Surface Modifications for Titanium Implant Surfaces

Additive manufacturing (AM) technology from engineering has helped to achieve several advances in the medical field, particularly as far as fabrication of implants is concerned. The use of AM has made it possible to carry out surgical planning and simulation using a three-dimensional physical model which accurately represents the patient's anatomy. AM technology enables the production of models and implants directly from a 3D virtual model, facilitating surgical procedures and reducing risks. Furthermore, AM has been used to produce implants designed for individual patients in areas of medicine such as craniomaxillofacial surgery, with optimal size, shape and mechanical properties. This work presents AM technologies which were applied to design and fabricate a biomodel and customized implant for the surgical reconstruction of a large cranial defect. A series of computed tomography data was obtained and software was used to extract the cranial geometry. The protocol presented was used to create an anatomic biomodel of the bone defect for surgical planning and, finally, the design and manufacture of the patient-specific implant.

Cranial reconstruction: 3D biomodel and custom-built implant created using additive manufacturing

Zirconium alloys for biomedical applications are receiving increasing attention due to their two unique properties: 1) the formation of an intrinsic bone-like apatite layer on their surfaces in body environments, and 2) better compatibility with magnetic resonance imaging (MRI) diagnostics due to their low magnetic susceptibility, as well as their overall excellent biocompatibility, mechanical properties, and bio-corrosion resistance. In particular, since both of the MRI quality and speed depend on magnetic field strength, there is a compelling drive for use of high magnetic field strength (>3 Tesla) MRI systems. This paper provides a comprehensive review of the characteristics of commercially pure (CP) Zr and Zr-based alloys as orthopaedic and dental implant materials. These include their 1) phase transformations; 2) unique properties including corrosion resistance, biocompatibility, magnetic susceptibility, shape memory effect, and super-elasticity; 3) mechanical properties; 4) current orthopaedic and dental applications; and 5) the d-electron theory for Zr alloy design and novel Zr-alloys. The mechanical properties of Zr-based bulk metallic glasses (BMGs) and their application as implant materials are also assessed. Future directions for extending the use of Zr-alloys as orthopaedic and dental implants are discussed.

Zirconium Alloys for Orthopaedic and Dental Applications

https://hal.archives-ouvertes.fr/hal-00857502/document

Progress on the preparation of nanocrystalline apatites and surface characterization: Overview of fundamental and applied aspects

Considering that the densification level and the attendant quality of selective laser melted Ti6Al4V parts depend strongly on the operating temperature of the melting system, which is mainly controlled by the processing parameters. The processing parameters of selective laser melting were thus investigated in this study to fabricate denser Ti6Al4V parts without post-processes. Temperature distribution calculation was firstly carried out based on a three-dimensional model. It was found that there exists a great temperature gradient from the surface of powder bed to the experimental platform, and the maximum depth of molten powder layer is about 45 μm, very close to the total thickness of powder bed (50 μm) under the condition of laser power of 110 W and scan rate of 0.2 m/s. The Ti6Al4V parts with lower porosity and higher density were then well fabricated by experimental method under the condition of laser power of 110 W and scan rate of 0.2 m/s. The experimental results also indicate that the microstructures exhibit more and more pores and the layer structures are more and more obvious with the increase in the scan rate. Moreover, the microhardness measurement yields different values with increasing scan rate, owing to the increase of α phase and porosity.

/pdf/process-parameter-selection-for-selective-laser-melting-of-18ib8swxre.pdf

Process parameter selection for selective laser melting of Ti6Al4V based on temperature distribution simulation and experimental sintering

Titanium may be considered a relatively new engineering material. It was discovered much later than the other commonly used metals, its commercial application starting in the late 1940s. Its usage as an implant material began in the 1960s, despite the fact that titanium exhibits superior corrosion resistance and tissue acceptance when compared with stainless steels and Cr-Co-based alloys. This paper reviews the use of titanium and titanium alloys for use in biomedical applications.

Januz Kopac

Papers

Review: titanium and titanium alloy applications in medicine