A goal of current implantology research is to design devices that induce controlled,
guided, and rapid healing. In addition to acceleration of normal wound healing phenomena,
endosseous implants should result in formation of a characteristic interfacial layer
and bone matrix with adequate biomechanical properties. To achieve these goals, however,
a better understanding of events at the interface and of the effects biomaterials
have on bone and bone cells is needed. Such knowledge is essential for developing
strategies to optimally control osseointegration. This paper reviews current knowledge
of the bone-biomaterial interface and methods being investigated for controlling it.
Morphological studies have revealed the heterogeneity of the bone-implant interface.
One feature often reported, regardless of implant material, is an afibrillar interfacial
zone, comparable to cement lines and laminae limitantes at natural bone interfaces.
These electron-dense interfacial layers are rich in noncollagenous proteins, such
as osteopontin and bone sialoprotein. Several approaches, involving alteration of
surface physicochemical, morphological, and/or biochemical properties, are being investigated
in an effort to obtain a desirable bone-implant interface. Of particular interest
are biochemical methods of surface modification, which immobilize molecules on biomaterials
for the purpose of inducing specific cell and tissue responses or, in other words,
to control the tissue-implant interface with biomolecules delivered directly to the
interface. Although still in its infancy, early studies indicate the value of this
methodology for controlling cell and matrix events at the bone-implant interface.