Tissue-implant interface surfaces

Interactions at surfaces and interfaces also play an essential role in the design and function of clinical implants and biomedical devices. With a few recent exceptions, implants do not attach well to tissue, and the resulting mobility of the tissue-implant interface encourages chroitic inflammation. The result can be a gathering of platelets at the site, leading to a blood clot or to the formation of a fibrous capsule, or scar, around the implant (Figure 3.3). 

Polymer/tissue interfacial properties the implant interface is a unique site where different chemicals coexist and interact. If the surface of an implant has an affinity towards specific chemicals, an abnormal boundary layer will develop. The subsequent intra-layer rearrangement or reactions with other species then trigger tissue reactions. The defence reactions of the host tissue often lead to encapsulation of an... 

The foreign body reaction occurring around soft tissue implants and thrombosis on surfaces in contact with blood are the major reactions encountered with implants. Both reactions involve the interaction of cells with the implant, especially in the later stages, and much previous study has therefore emphasized cellular events in the biocompatibility process. However, cells encounter foreign polymer implants under conditions that ensure the prior adsorption of a layer of protein to the polymer interface. The properties of the adsorbed layer are therefore important in mediating cellular response to the material. 

The aim of this paper is to present the use of a microwave digestor to prepare nanopowders via hydrothermal route. In the field of biomaterials the researchers (due to some problems with the traditional materials) are looking for the design of biomaterials with surface properties similar to physiological bone (grain sizes in the nanometric range [5]). This would aid in the formation of new bone at the tissue/biomaterial interface and therefore improve implant efficacy. With the advent of nanostructured materials (materials with grains sizes less than 100 nm in at least... 

It is clear that future efforts to improve the host tissue responses to implant materials will focus, in large part, on controfling cell and tissue responses at implant interfaces. This goal will require continued acquisition of fundamental knowledge of cell behavior and cell response to specific materials characteristics. It is likely that a better understanding of the cellular-derived extracellular matrix-implant interface wiU offer a mechanism by which biologic response modifiers such as growth and attachment factors or hormones may be incorporated. Advancements of this type will likely shift the focus of future research from implant surfaces which as osseoconductive (permissive) to those which are osseoinductive (bioactive). 

The bone tissue response w as characterized by active bone remodeling at the surface of the degrading implant, the lack of fibrous capsule formation, and an unusually low number of inflammatory cells at the bone-implant interface. Poly (DTH carbonate) exhibited very close bone apposition throughout the 26 week... 

Figure 16.2. Schematic representation of the events at the bone-implant interface (a) Protein adsorption from blood and tissue fluids, (b) Inflammatory and connective tissue cells approach the implant, (c) Formation of an afibrillar mineralized layer and adhesion of osteogenic cells, (d)Bone deposition on both the bone and the implant surfaces, (e) Remodeling of newly formed bone. ...

The slow degradation rate of polycarbonates has led to its investigation in orthopaedic tissue engineering applications. Additionally, P(DTR carbonate) elicits a response for bone ingrowth at the bone-polymer implant interface, supporting the use of P(DTR carbonate) as a bone scaffold [84]. Recent studies have shown that osteoblast cells do attach to the surface of P(DTR carbonate). Results indicate that these osteoblasts maintained their phenotype and rounded cell morphology [85]. 

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