Tissue-implant interface

Several effects of fluoride ions have been claimed (Table 1) concerning the stability of the biomaterials, the implant-tissue interface, or the tissue itself. The incorporation of fluoride ions in apatitic materials is generally aimed at increasing their stability and decreasing their solubility. 

Von Recum AF, Optiz H, Wu E. Collagen types I and III at the implant/tissue interface. Journal of Biomedical Materials Research 1993, 27, 757-761. 

Coatings may double as dmg delivery vehicles for the delivery of therapeutic agents to the implant-tissue interface... 

If a nearly inert material is implanted into the body it initiates a protective response that leads to encapsulation by a nonadherent fibrous coating about 1 i.m thick. Over time this leads to complete isolation of the implant. A similar response occurs when metals and polymers are implanted. In the case of bioactive ceramics a bond forms across the implant-tissue interface that mimics the bodies natural repair process. Bioactive ceramics such as HA can be used in bulk form or as part of a composite or as a coating. Resorbable bioceramics, such as tricalcium phosphate (TCP), actually dissolve in the body and are replaced by the surrounding tissue. It is an important requirement, of course, that the... 

In an in vivo pilot study (Ertel, 1995), poly(DTH carbonate) pins were febricated and compared to commercially available Orthosorb pins made of polydioxanone. The pins were implanted transcortically in the distal femur and proximal tibia of New Zealand Wliite rabbits for up to 26 weeks. In addition to routine histological evaluation of the implant sites, bone activity at die implant/tissue interface was visualized by LTV illumination of sections labeled with fluorescent markers and the degree of calcification around the implants was ascertained by backscattered electron microscopy. 

Placing a biomaterial within living tissue will always render a tissue response at the implant/tissue interface. In particular, the following four responses may result from implantation, which govern the degree of medical complications and ultimate lifetime of an implant ... 

Fig. 15 Central nervous system reaction at the implant/tissue interface four weeks after implantation of a silicon microelectrode. The microelectrode was placed at the left drawn to scale) and the foreign body response is indicated by activated microglia (ED-1 stain), astrocytes (GFAP), local neuron loss (NeuN), and reduced neurofilament (NF) density [109]...

In the context of implantable thin-film microelectrodes for long-term use, the term biocompatibility includes both the bulk material as well as the surface characteristics. Finite element modeling (FEM) of the implant/tissue interface has shown that flexible polymeric materials such as polyimide, which has a Young s modulus of approximately 3 GPa, can reduce strain at the implant/tissue interface when... 

---