Biocompatible ceramics

In addition to dense monolithic ceramics, porous silicon nitrides are gaining more importance in technological applications [24], Some porous silicon nitrides with high specific surface area have already been applied as catalysis supports, hot gas filters and biomaterials [25], There is an emerging tendency to facilitate silicon nitride as biomaterial, because of specific mechanical properties that are important for medical applications [25], Moreover, in a recent study it was shown that silicon nitride is a non-toxic, biocompatible ceramic which has the ability to propagate human bone cells in vitro [25], Bioglass and silicon nitride composites have already been realized to combine... 

The biocompatible CBPC development has occurred only in the last few years, and the recent trend has been to evaluate them as biocompatible ceramics. After all, biological systems form bone and dentine at room temperature, and it is natural to expect that biocompatible ceramics should also be formed at ambient temperature, preferably in a biological environment when placed in a body as a paste. CBPCs allow such placement. We have discussed such calcium phosphate-based cements in Chapter 13. Calcium-based CBPCs, especially those constituting hydroxyapatite (HAP), are a natural choice. HAP is a primary mineral in bone [3], and hence calcium phosphate cements can mimic natural bone. Some of these ceramics with tailored composition and microstructure are already in use, yet there is ample room for improvement. This Chapter focuses on the most recent biocompatible CBPCs and their testing in a biological environment. To understand biocompatible material and its biological environment, it is first necessary to understand the structure of bone and how it is formed. 

A biocompatible ceramic that mimics bone growth when implanted. 

C. Sella, J.C. Martin, J. Lecoeur, J.P. Bellier, M.F. Harmand, A. Nadji, J.P. Davidas, and A. Le Chanu, Corrosion protection of metal implants by hard biocompatible ceramic coatings deposited by radio-frequency sputtering. Clinical Materials, 5, 297-307 (1990). 

The material must allow a surface treatment that ensures a good adhesion of biocompatible ceramic coatings or living tissues. 

Vitahium FHS ahoy is a cobalt—chromium—molybdenum ahoy having a high modulus of elasticity. This ahoy is also a preferred material. When combiaed with a properly designed stem, the properties of this ahoy provide protection for the cement mantle by decreasing proximal cement stress. This ahoy also exhibits high yields and tensile strength, is corrosion resistant, and biocompatible. Composites used ia orthopedics include carbon—carbon, carbon—epoxy, hydroxyapatite, ceramics, etc. 

Nanocarbon structures such as fullerenes, carbon nanotubes and graphene, are characterized by their weak interphase interaction with host matrices (polymer, ceramic, metals) when fabricating composites [99,100]. In addition to their characteristic high surface area and high chemical inertness, this fact turns these carbon nanostructures into materials that are very difficult to disperse in a given matrix. However, uniform dispersion and improved nanotube/matrix interactions are necessary to increase the mechanical, physical and chemical properties as well as biocompatibility of the composites [101,102]. 

Biocompatibility and castability of modified fluorcanasite (Ca5Na4K2Sii203oF4) glass-ceramics have been investigated and Bandyopadhyay-Ghosh et at. showed that incorporation of an excess of CaO or P2O5 in stoichiometric fluorcanasite glass composition along with controlled heat treatment improved osteoblast-like cell activity in vitro [99],... 

The selection of a scaffold material is both a critical and difficult choice. There are many biocompatible materials available metals, ceramics, and polymers. 

The results of Figure 8.18 show that most commercially available dental restorative materials have wear rates that are lower (better) than human enamel. All of the materials listed in Table 8.15 have nominal colors equivalent to that of human teeth and are of acceptable biocompatibility. In particular, glass ionomer ceramics have become increasingly popular due to their favorable adhesion to dental tissues, fluoride release, and biocompatibility. 

Phosphates. Many phosphates claim unique material advantages over silicates that make them worth the higher material costs for certain applications. Glass-ceramics containing the calcium orthophosphate apatite, for example, have demonstrated good biocompatibility and, in some cases even bioactivity (the ability to bond with bone) (25). Recent combinations of fluorapatite with phlogopite mica provide bioactivity as well as machinability and show promise as surgical implants (26). 

Nanostructured ceramics provide alternatives not yet fully explored for orthopedic and dental implant applications the improved mechanical properties of these novel ceramic formulations, in addition to their established exceptional biocompatibility, constitute characteristics that promise improved orthopedic and dental efficacy. Requirements applicable for the design of nanophase ceramics for orthopedic and dental applications include the following ... 

Many polymers are biocompatible and may be used as coatings for metallic or ceramic particles, or can serve as hosts by either capturing... 

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