Biomedical Engineering Reference
In-Depth Information
widely used because the mineral composition of these implants materials does fully
biocompatible (Rey C. 1990, LeGeros. 2002). The porous structure of the ceramics is claimed
to enhance bone deposition and implant stabilization in the recipient bone. The optimal pore
size is still debated to be ranging from 50 and 565 μm (Gauthier et al., 1998, Chang et al.,
2000). However, porosity of the material is inversely proportional to the mechanical stability
of these calcium phosphate based ceramics (Le Huec et al., 1995). This loss of stability is
often cited as a limitation in the use of calcium phosphate-based ceramics in clinical practice.
A convenient compromise to overcome this problem is to use a biphasic ceramic, which
maintains its mechanical resistance until the resorption is achieved (Gauthier et al., 1998).
Various types of xenografts are used in medicine, dentistry, and also in periodontology.
One of the xenografts is Unilab Surgibone, which is currently being used succesfully in
medicine and implantology. Moreover, osteoconductive properties are also known (Zhao et
al., 1999). Unilab Surgibone is obtained from freshly sacrificed calves which is partially
deproteinized and processed by the manufacturers. It is available in varius shapes like
tapered pins, blocks, cubes, granules, circular discs and pegs (Balakrishnan et al., 2000).
Xenograft materials, bovine bones have been the most preferred ones, basically because they
are easily obtainable and there are no great ethical considerations. Additionally they have
the great advantage of practically unlimited availability of source/raw material. Partially
deproteinized and defatted preparations (e.g.Unilab Surgibone) was indicated reduce
antigenity and mild immune response (William et al., 2008).
Generally, xenografts are one of the alternative graft materials used in different fields for
filling osseous defects Slotte and Lundgren, 1999, Salama 1983). Nonetheless, an interesting
alternative to xenografts is Biocoral® (natural coral), which has been shown to exhibit
osteoconductive and biocompatible properties whereby gradual replacement with newly
formed bone occurred after its resorption (Guillemin et al.,1989, Doherty et al., 1994, Yılmaz
and Kuru, 1996, Yukna Ra and Yukna CN, 1998).
Another xenogeneic, bone-derived implant material is Bio-Oss, which is similar to the
xenograft investigated in our studies (Develioglu et al.2009, 2010). Bio-Oss has been
proposed as a biocompatible graft material for bony defects for it has shown
osteoconductive properties — that is, it was replaced with newly formed bone after grafting
(Yıldırım et al, 2001, Sculean et al., 2002, Carmagnola et al., 2002). However, regarding the
resorption of Bio-Oss, contradicting reports have emerged. On one hand, a previous study
revealed that the bovine bone mineral underwent resorption (Pinholt et al., 1991). On the
other hand, numerous researchers claimed that the resorption process of Bio- Oss® was very
slow (Skoglund et al., 1997, Jensen et al 1996, Klinge et al., 1992).
In our previous studies with Ceraform (calcium phosphate ceramics) and xenograft (Unilab
Surgibone), multinuclear giant cells (MNGC) were observed in the implantation region on
1
st
, 3
rd
, 6
th
ve 18
th
months.
The observed MNGCs are featured morphologic characteristics of foreign body giant cell
(FBGC). These cells are osteoclast-like cells. Both cell types develop from a common
precursor (Anderson, 2000) Since foreign body giant cell (FBGC) are the fusion products
of monocytic precursors, which are also the precursors of macrophages, (Brodbeck at al.,
2002, Matheson et al., 2004) the presence of such leukocytes in the wound healing
compartment may be of central importance in driving the tissue reaction to the material.
No necrosis, tumorigenesis, or infection was observed at the implant site up to 18 months
(Figure 18-20).
