Calcium phosphate (CaP) bioceramics are widely used in the field of bone regeneration, both in orthopedics and in dentistry, due to their good biocompatibility, osseointegration and osteoconduction. The aim of this article is to review the history, structure, properties and clinical applications of these materials, whether they are in the form of bone cements, paste, scaffolds, or coatings. Major analytical techniques for characterization of CaPs, in vitro and in vivo tests, and the requirements of the US Food and Drug Administration (FDA) and international standards from CaP coatings on orthopedic and dental endosseous implants, are also summarized, along with the possible effect of sterilization on these materials. CaP coating technologies are summarized, with a focus on electrochemical processes. Theories on the formation of transient precursor phases in biomineralization, the dissolution and reprecipitation as bone of CaPs are discussed. A wide variety of CaPs are presented, from the individual phases to nano-CaP, biphasic and triphasic CaP formulations, composite CaP coatings and cements, functionally graded materials (FGMs), and antibacterial CaPs. We conclude by foreseeing the future of CaPs.

Calcium Phosphate Bioceramics: A Review of Their History, Structure, Properties, Coating Technologies and Biomedical Applications.

https://www.tandfonline.com/doi/pdf/10.1080/21870764.2019.1669861

Bioactive coating as a surface modification technique for biocompatible metallic implants: a review

With the increasing demand for bone implant therapy, titanium alloy has been widely used in the biomedical field. However, various potential applications of titanium alloy implants are easily hampered by their biological inertia. In fact, the interaction of the implant with tissue is critical to the success of the implant. Thus, the implant surface is modified before implantation frequently, which can not only improve the mechanical properties of the implant, but also polish up bioactivity and osseoconductivity on a cellular level. This paper aims at reviewing titanium surface modification techniques for biomedical applications. Additionally, several other significant aspects are described in detail in this article, for example, micromorphology, microstructure evolution that determines mechanical properties, as well as a number of issues concerning about practical application of biomedical implants.

Surface Modification of Biomedical Titanium Alloy: Micromorphology, Microstructure Evolution and Biomedical Applications

Powder mixed-EDM is a newly emerging proposed manufacturing process which can simultaneously shape and coat the surface of conductive materials. Transformation of machined surface is occurred throu...

Bio-ceramic coatings adhesion and roughness of biomaterials through PM-EDM: a comprehensive review

A new kind of functionally graded material (FGM) that mimics the inner porous structure and outer dense layer of human bone was produced using powder metallurgy. The inner part of the FGM material (16 mm in diameter) has porosity of approximately 60%, and its mechanical properties are compatible with cortical bone; however, the shell (1.8 mm in thickness) is composed of a layer of Ti-10% wt. hydroxyapatite (HA) and shows hydrophilic behavior and improved biofunction. Elastic moduli of the core and shell layer were calculated as 18.99 and 42.98 GPa, respectively, and those values are compatible with that of cortical bone. Addition of HA to the shell had a significant effect on the wettability (81.6% decrease) and cell viability (46% increase). Furthermore, the porosity of the shell layer (28.88%) is similar to that of human cortical bone. It is concluded that the developed Ti-HA FGM has promising properties for implant applications.

Production and Characterization of a Bone-Like Porous Ti/Ti-Hydroxyapatite Functionally Graded Material

Hydroxyapatite–titanium dioxide (HAp-TiO2) nanohybrid composite was coated on Ti–6Al–4V and Ti–13Nb–13Zr substrates by electrophoretic deposition. Coating surface characteristics and biocompatibility were analysed using X-ray photoelectron spectroscopy, water contact measurement, scanning electron microscopy and fluorescence microscopy. The results indicated high degree of crystallinity and densely packed crack free morphology of the coating. The coated substrates displayed lower contact angle (Ti–13Nb–13Zr, 17·4°; Ti–6Al–4V, 22·2°) than the controls (Ti–13Nb–13Zr, 80·8°; Ti–6Al–4V, 72·6°). The cytocompatibility of the coated substrates was determined by staining the human dermal fibroblast cells with 4′,6-diamidino-2-phenylindole and imaging under fluorescent microscope. Both SEM and florescence microscope images showed comparatively enhanced cell adhesion on coated Ti–13Nb–13Zr and Ti–6Al–4V than the uncoated substrates. This difference could be attributed because of the higher wettability of Ti–13Nb–13...

Surface modification of Ti–13Nb–13Zr and Ti–6Al–4V using electrophoretic deposition (EPD) for enhanced cellular interaction

Hydroxyapatite (HAP) has tremendous applications in orthopaedics and dentistry fields due to its enhanced biocompatibility and bioactivity. In the present investigation, ethanol-based HAP nanoparticles (NPs) are prepared by sol–gel method using calcium nitrate tetrahydrate and triethyl phosphite, without using any additives or chelating agents. The sol–gel-derived HAP NPs were characterised using FT-IR, XRD, TGA-DTA, SEM-EDAX, ICP-OES and TEM analyses. In vitro cytocompatibility assessment of different concentrations of HAP NPs (200–1000 μg/ml) was performed using cultured NIH-3T3 fibroblast cell for 24–48 h. The results indicated that HAP NPs did not have any cytotoxic effects on NIH-3T3 cells. Further to this study, sol–gel-derived HAP sol was coated as triple layers on the Ti-6Al-4V by spin coating technique and the developed coatings were characterised by SEM-EDAX to determine the surface uniformity, chemical composition and thickness. The surface wettability of the coatings was observed by co...

Preparation and characterisation of sol–gel-derived hydroxyapatite nanoparticles and its coatings on medical grade Ti-6Al-4V alloy for biomedical applications

Biomaterials play a crucial role in regenerative medicine, which aims to restore and reinstate lost/failed tissues or organs in the human body. Biomaterials are three dimensional temporary substrates which help in the development of new tissue and organization. Mimicking the characteristics of natural bone is challenging and those biomaterials which posses that property serves beneficial and also helps in the speedy recovery of the patient. These characteristics are of nanoscale regime and helps in wounding healing and tissue regeneration in the most effective way. In this chapter the development of nanostructured biomaterials, nanosurface modifications and nanoscaffolds has been discussed in detail. The different application of these bulk and surface modified nanomaterials has been convened. In conclusion, the nanostructured biomaterials is an emerging area of research and the application of these materials can improve the performance and longevity of the implants and at the same time pave way for the development of new technologies in the future.

Use of nanostructured materials in implants

The electrochemical behaviour of CP-Ti (commercially pure-Ti) and Ti–6Al–4V, commonly used implant materials, particularly for orthopedic and osteosynthesis applications, were investigated together with that of other Ti based alloys viz. Ti–13Nb–13Zr, Ti–15V–3Cr–3Al–3Sn, Ti–13Nb–20Zr, Ti–20Nb–20Zr and gum metal. The corrosion properties were evaluated through the analysis of the corrosion potential variation with time, potentiodynamic polarisation curves, and electrochemical impedance spectroscopy (EIS) test results. Very low current densities were obtained (order of nA cm−2) from the polarisation curves, indicating a typical passive behaviour for all investigated alloys in artificial physiological solution. The corrosion rates obtained were in the order CP-Ti>Ti–6Al–4V>Ti–15V–3Cr–3Al–3Sn>Ti–20Nb–20Zr>Gum metal>Ti–13Nb–13Zr. The EIS results clearly revealed the capacitive behaviour (high corrosion resistance) with phase angles close to −60° and high impedance values (order of 104 Ω cm2) at low and medium ...

M. Geetha

Papers

Surface modification of Ti–13Nb–13Zr and Ti–6Al–4V using electrophoretic deposition (EPD) for enhanced cellular interaction

Preparation and characterisation of sol–gel-derived hydroxyapatite nanoparticles and its coatings on medical grade Ti-6Al-4V alloy for biomedical applications

Use of nanostructured materials in implants

Comparative study of electrochemical behaviour of CP-titanium and Ti–6Al–4V with other titanium based alloys for biomedical applications