Osseointegration calcium phosphates

In spite of these investigations, many reports in the literature demonstrate that these nanoapatite ceramics are not always osteoinductive and, furthermore, do not possess mechanical properties similar enough to bone for sustained osseointegration (Muller-Mai el al., 1995 Doremus, 1992 Du et al., 1999 Weng et al., 1997), criteria necessary for increased orthopedic and dental implant efficacy. Moreover, mechanisms of osteoinduction of calcium phosphate ceramics are not clear and seem to depend on specific nanoapatite material properties (such as surface properties and crystallinity) and the animal tested (i.e., dog versus rabbit). Undoubtedly, the incidental cases of calcium phosphate biomaterial-induced osteogenesis indicate promise in... 

The timeline of basic steps occurring at a bioconductive interface during osseointegration of an implant in the presence of an osseoconductive calcium phosphate coatings can be summarised as follows ... 

Addition of compounds with appropriate functionality to serve as nucleation sites for calcium phosphate growth to polymers can potentially improve the biocompatibility of the latter and thus the long-term stability of implant devices (Drelich and Field, 2007). Zinc stearate was added to poly(ethylene) to form poly(ethylene)-stearate blends with increased surface porosity potentially able to improve mechanical stability of the implant through enhanced osseointegration, improved rates and quality of bone-implant fusion and enhanced soft tissue wound healing via stimulation of angiogenesis. While immersion of these blends in supersaturated calcium phosphate solutions triggered deposition of a porous layer, the deposition rate was very slow, around 100 nm/day. 

Chitosan coatings are capable of supporting and enhancing osseointegration similarly to calcium-phosphate-coated and uncoated implants... 

Frayssinet P, et al. Osseointegration of macroporous calcium-phosphate ceramics having a different chemical-composition. Biomaterials 1993 14(6) 423—9. 

In the past few decades, many methods such as physical machining and controlled oxidation have been used to improve the in vivo osseointegration of titanium-based implants. Calcium phosphate—based thin films such as HA have been used frequently on orthopaedic implants. As a new concept in tissue engineering, it has been suggested that HA has distinct luminescence properties allowing rapid identification of phase distribution of biomimetic apatite thin films. In a research smdy, Sepahvandi et al. reported that the photoluminescence property can be used in the characterization and early detection of biomimetic bonelike apatite formation on the surface of alkaline-treated titanium implants (in SBF solution). 

S. Meyer, T. Floerkemeier and H. Windhagen, Histological osseointegration of a calcium phosphate bone substitute material in patients. Biomed. Mater. Eng. 17 347-356,2007. 

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