Bone-implant bonding

Figure 6.2 Schematic of pull off detaching test for determining bone-implant bonding (based upon T. Yamamuro, ref. 4).

NBE-PEO macromonomers providing two distinct properties. Gentamicin (GS)-terminated macromonomer 18b aimed to provide antibiotic properties in an acidic medium, while carboxylic acid-terminated macromonomer 18c enabled the grafting of the nanoparticles onto biomaterial surface. After the transfer of the particles in water, the controlled release of GS at acidic pEl was demonstrated by breakage of the imine bond as well as by the efficient antibacterial activity using S. epidermidis as the bacterial strain. Scheme 2.7. These double-functionalized nanoparticles were grafted onto a titanium-based alloy, which is a preferred biomaterial for bone implants because of its biocompatibility, mechanical strength, and corrosion resistance [32]. The particles were covalently linked... 

Bone implants are commonly made of metal coated in a similar material to bone, i.e. synthetic hydro5Q apatite, to improve the biocompatility and to aid bonding between the natural bone and the implant. Raman studies of bone implants utilize the spectral difference between bone and that of synthetic hydro5Q apatite. The synthetic material lacks many of the characteristic Raman vibrations of bone and those of phosphate have significantly reduced band-widths. Thus, it is possible to study the interface between the implant and the recipient s bone. Biomineralization of implants coated with materials other than hydrojQ apatite can be followed by monitoring the intensity of the phosphate vibration related to those produced by the coating material. 

Bioactive materials when in contact with physiological fluids are coated with carbonate hydroxyapatite that favors the colonization of osteoblasts, followed by proliferation and differentiation of cells to form new bone that bonds the implant surface and living tissues [111]. 

Titanium is the ninth most abundant element, constituting 0.6% of Earth s solid crust. The metal is greatly valued for its low density, high structural strength, and corrosion resistance. The first two properties account for its extensive use in the aircraft industry and the third for its uses in the chemical industry in pipes, component parts of pumps, and reaction vessels. Titanium is also used in dental and other bone implants. The metal provides a strong support and bone bonds directly to a titanium implant, making it a part of the body. 

Phospha.tes. Many phosphates cl aim unique material advantages over siUcates that make them worth the higher material costs for certain apphcations. Glass-ceramics containing the calcium orthophosphate apatite, for example, have demonstrated good biocompatibiUty and, in some cases even bioactivity (the abiUty 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). 

Bioglasses are surface-active ceramics that can induce a direct chemical bond between an implant and the surrounding tissue. One example is 45S5 bioglass, which consists of 45% Si02, 6% 4.5% CaO, and 24.5% Na20. The various calcium phosphates have exceUent compatibUity with bone and... 

However, more recent work about using the PEG/PBT as a bone substimte in critical size defects in the iliac bone of goats and humans did not show the expected good bone-bonding and calcification behaviors. Reasons for the discrepancy with the earlier results in small animals may be caused by the differences in regenerative capacity between the species, the size of the defect, and the type of bone into which the substitute was implanted. 

Radder AM, Leenders H, and van Blitterswijk CA. Bone-bonding behaviour of PEO/PBT copolymer coatings and bulk implants A comparative study. Biomaterials, 1994, 21, 532-537. 

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