Biomedical Engineering Reference
In-Depth Information
resorbable by osteoclastic cells like dentin materials thus avoiding draw-
backs of plasma-sprayed HA coatings [139-148].
The surface of titanium dental implants may be coated with bone-
stimulating agents such as growth factor members of the transforming
growth factor (TGF) family, in particular bone morphogenetic proteins
(BMPs), platelet-derived growth factor (PDGF) and insulin-like growth
factors (IGF-1 and 2) [149-154]. Other candidates are molecules controlling
the bone remodeling process such as antiresorptive drugs, e.g., biphos-
phonates [155-158]. Chemical treatment of titanium dental implants with
fl uoride is yet another approach to enhance osseointegration [159-161].
A more sophisticated approach mentioned above involves coating the
implant with RGD (arginine-glycine-aspartic acid). RGD is a cell adhesion
receptor molecule that interacts with membrane-bound talin and vinculin
proteins to promote the cellular surface adhesion process. In other words,
RGD's role is to accelerate the process of tissue binding to the implant
surface. This has been empirically demonstrated, with up to a two-fold
increase in cellular adhesion strength after 12 hours of cell culture time
[162, 163].
6.7
Angiogenesis, Vasculogenesis, and Inosculation
for Life-Sustained Regenerative Therapy;
The Platform for Biomimicry in Dental and
Craniofacial Tissue Engineering
One of the most particular features of any normally functioning tissue is
its ability to interact with the surrounding tissues to ensure homeostasis.
Active incorporation within the vascular network of the organism would
help this interaction take place effectively. Adequate vascularization of
any tissue, or tissue construct, is then a prerequisite for its sustainability
and integration or simply for its “biomimicry.” On the other hand, cre-
ating such a vascularized tissue, or tissue construct, will have to follow
some bio-inspired strategies mimicking the physiological healing and vas-
cularization processes.
6.7.1
Vascularization to Reach Biomimicry; A Prerequisite for
Life Sustained Regeneration
To engineer a three dimensional (3D) tissue construct suitable for trans-
plantation, a vascular supply to the developing tissue is necessary for
survival. Simple diffusion normally limits oxygen and nutrition supply
to cells to a maximum range of 200 μm into a given matrix [164], so sub-
optimal initial vascularization after grafting will defi nitely limit survival
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