Barbieri Thesis - BioMedical Materials program (BMM)

Chapter 7 – Polymer mole ecular weight annd
instructive co omposites
the same period lengthh.
These fac cts indicate thhat
in vivo th he materials may have
degraded ssimilarly
to the
trend indica ated by the inn
vitro degradation
experim ment. Since
the apatitee
layers after three–month hs in vitro deggradation
dec creased (due to apatite
dissolution),
this indicaates
that no apatite partiicles
were fu urther expose ed by the
degradation
of the mateerial
(Table 3) ). This last faact
strengthen ns the results on in vivo
mineralizattion
mentioneed
earlier. Con ncluding, the different incre ease in thickn ness of the
apatite layeers
on the twoo
composites is i not due to a possible incr rease in apatit te particles
exposure ccaused
by the
degradation n process, buut
to precipita ation of apatite e from the
surroundings.
Figure 8. BSSEM
images of (aa,
c) ML and (b, , d) MH explantss.
Image (c) has been taken in th he same spot
shown in the
box in Figuree
7b. Bone for rmed in ML sammple
(white sta ars), while layers s of surface
mineralisationn
are clearly visibble
(white triangle es) in both materrials.
These layer rs are thicker than
the starting
granules, meeaning
calcium pphosphates
prec cipitated from boody
fluids and nucleated n onto the t materials
surfaces. Impportantly,
bone iss
tight to the mineralized
layers aaround
ML surfac ce (c). It is interesting
that the
bulk of the twwo
materials apppear
degraded. The T white boxes in (a) and (b) indicate
the spots shown in (c)
and (d) respeectively.
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