Chemistry Reference
In-Depth Information
layer. The high thermal and kinetic energy of the plasma lead to
melting and acceleration of the particles created from the powders.
The interactions between the molten materials and plasma beam
and surrounding atmosphere influence the way the particles in the
plasma beam melt and transform physically and chemically [2,8].
Plasma-sprayed HA coatings have the advantages of promoting
faster and stronger fixation and bone growth both in vivo and have
shown promising short-term and medium-term clinical results in
femoral stems, knee prostheses, pins/screws, and dental implants.
The HA coatings favored direct bonding with surrounding living
tissues compared to a loosely adherent layer of fibrous tissue at
the implant interface in other cementless fixation [49]. Figure 6.21
schematically illustrates the interaction between plasma sprayed
coatings on titanium and surrounding bone tissues at the interface.
Figure 6.21
Schematic diagram of the establishment of bone-implant
bonding: (a) Partial dissolution of HA coating causing an
increase of Ca
2+
and PO
3-
4
ion concentrations in the local area
around the coating. (b) Precipitation of crystals on HA coating
and ion change with surrounding tissues. (c) Formation of a
carbonated calcium phosphate layer with the incorporation of
a collageneous matrix and bone growth toward the implant. (d)
Bone remodeling-osteoclasts resorb normal bone, creating a
local pH of
4.8, leading to faster resorption of both carbonated
HA in bone and the HA coating. (e) Bidirectional growth and
formation of a bonding layer between bone and HA coating
through further bone remodeling. Reprinted with permission
from Ref. [49], Copyright © 2001 John Wiley & Sons, Inc.
∼
Search WWH ::
Custom Search