Abstract: Apatite-mullite glass-ceramics have been developed as an alternative to hydroxyapatite
for use in vivo as a bioactive, osseoconductive biomedical alloy coating. In the cerammed state,
they present a number of advantages including control over dissolution rates and mechanical
properties by altering the composition of the parent glass or heat treatment regime. In the present
study, a simple sedimentation route was used to coat a biomedical titanium alloy, commonly used
for orthopaedic applications. The material was deposited as a glass and cerammed in situ to create a
well adheared coating that resisted delamination or cracking. To investigate the nature of the
coating-substrate reaction, a number of characterization techniques were used to examine the
crystallization behaviour of the glass, the glass-ceramic microstructure, and the interfacial reaction
region composition. The presence of products such as titanium silicides and unexpected pores are
explained by proposed reaction routes between the titanium and glass coating.
Abstract: Lithium disilicate glass and glass with addition of P2O5, CaO and CaF2 (in relative
ratios corresponding to 10 wt. % of „apparent fluoroapatite”) were prepared by quenching
their melts obtained at 1400 °C. Then, the parent glasses were thermally treated at 550°C and
750°C to obtain glass ceramics. The bioactivity test in vitro and the Wicker hardness in
relation to „apparent fluoroapatite“ presence and heat treatment were investigated. The
presence of fluoroapatite in samples promotes mineralization of new phase apatite-like on the
surface of glass and glass ceramics after 6-week immersion in SBF as proved by SEM and
EPMA. The bioactivity decreases with thermal treatment of parent glass. However, whole
surface of glass-ceramics was covered with apatite phase after long-term immersion in SBF.
The Vickers hardness of samples increases with increasing temperature treatment and with the
presence of fluoroapatite.
Abstract: Pulsed laser deposition was used to obtain functionally graded bioactive glass coatings on
titanium substrates. An UV KrF* (λ=248 nm, τ>7 ns) excimer laser was used for the multi-pulse
irradiation of the targets. The depositions were performed in oxygen while keeping substrate
temperature at 400°C. We used sintered glass targets in the system SiO2-Na2O-K2O-CaO-MgOP2O5
that differed in SiO2 content, which was either 57 wt.% (6P57) or 61 wt.% (6P61). A glass
6P61 was used as the first layer in direct contact with the metallic substrate, while the outer
bioactive layer was made of glass 6P57. Both the bioactive coatings and the bulk glasses were
analyzed by Fourier transform infrared spectrometry (FTIR), grazing incidence X-ray diffraction
(GIXRD), and scanning electron microscopy (SEM). The FTIR spectra of the glass powders and
glass coatings showed the main vibration modes of the Si-O-Si groups. GIXRD analysis confirmed
that the glass coatings had an amorphous structure. The SEM micrographs of the glass coatings
showed the films to consist of droplets with diameters ranging from 0.2 to 5 μm. SEM was used to
determine the rate of apatite formation on the coating when exposed to simulated body fluid (SBF)
solution for 7 days. We demonstrated that pulsed laser deposition leads to good glass-metal
adhesion on the substrate and well attached bioactive particles on the surface. We consider therefore
this method appropriate for forming implants that can develop an apatite layer after immersion in
Abstract: Sodium-doped CPP was synthesized using three dopant sources (sodium carbonate,
sodium hydroxide and sodium phosphate). These materials were analyzed by XRD to determine
phase composition and by differential thermal analysis to identify phase transition temperatures.
Sintering of resulting glass powders showed that both dopant source and dopant concentration
affects sinter neck formation and crystallinity. The open porosity of sodium phosphate and sodium
carbonate doped samples at 0.1 Na2O/CaO sintered at different temperatures changed significantly.
Crystallization of the construct during sintering was noted at temperatures lower than expected.
Abstract: Hierarchically 3D porous bioactive glasses (BGs) with various combination of both
pore sizes and pore structures have been produced by multi-polymer templating, such as
amphiphilic block copolymers, poly urethane (PU) forms, poly styrene (PS) beads, or methyl
cellulose (MC), sol-gel method, evaporation-induced self-assembly process, and rapid prototyping
technique. The amphiphilic block copolymers used for producing the meso pores into the BGs,
which induces large specific surface area and subsequently carries with good bone-forming
bioactivity of BGs. Each poly urethane form, poly styrene bead, and methyl cellulose adapted for
the fabrication of macro pores. The rapid prototyping (RP) techniques introduced to produce 3D
BGs scaffolds with giant pores.
Abstract: Porous scaffolds have been developed in many forms and materials, but few have
reached the combination of adequate physical, biological and mechanical properties. In previous
works hybrid foams bioactive glass polyvinyl alcohol (PVA) were prepared by the sol-gel process
for application as scaffold for bone tissue engineering. We observed that synthesis parameters such
as PVA hydrolysis grade, PVA solution concentration, and PVA content in the hybrids affected
both synthesis results and structural characteristics of the obtained foams. A marked change in
foaming behavior occurs for PVA contents around 60%. In this work we analyze the effect of
different compositions and synthesis parameters on the mechanical behavior of PVA-bioative glass
foams. The compression tests showed that an increase of PVA fraction changes the mechanical
behavior due to different mechanisms leading to cell collapse. For hybrids with lower PVA contents
(20 to 30%) the cell collapse is due to brittle crushing. For intermediate polymer content (40-60%)
the contribution of plastic yielding in the plateau region increases and it becomes the predominant
mechanism of cell collapse for samples with higher polymer content (70-80%).
Abstract: The effect of composition on the reactivity of a calcium phosphate cement (CPC) made
of tricalcium phosphate (TCP) – water mixtures was investigated by isothermal calorimetry at 37°C.
The parameters of interest were the mean particle size of the powder, the use of small amounts of
nanosized hydroxyapatite powder, and the phosphate concentration and the pH of the aqueous
solution. The results could be well explained by theoretical considerations. The main parameter
controlling CPC reactivity was TCP particle size.
Abstract: The first generation of synthetic bone substitute materials (BSM) was initially
investigated in the mid 1970s using hydroxyapatite (HA) as a biomaterial for remodeling of bone
defects. The concepts established by CPC pioneers in the early 1980s were used as a platform to
initiate a second generation of BSM for commercialization. Since then, advances have been made in
composition, performance and manufacturing.
A self-setting and injectable calcium phosphate cement (CPC) based on amorphous calcium
phosphate (ACP) with calcium to phosphate (Ca/P) atomic ratio less than 1.5, combined with
dicalcium phosphate dihydrate (DCPD or brushite, seeded with apatite), is proposed.
Amorphization of raw material was observed following high energy mechano-chemical processing.
Upon hydration, the cement hardened in less than 3 minutes at 37°C and reached a maximum
compressive strength of about 50 MPa.
The final product was a low crystalline calcium deficient carbonated apatite similar to the
composition and structure of bone mineral.
In vivo performance of this cement in mediating bone healing was compared to α-BSM® in a rabbit
femoral defect model.
Performance characteristics of some commercially available CPC products are compared. The
concerns of CPC designers and the needs of product users (surgeons) are discussed.
Abstract: The effect of mechanical mixing on compressive strength, relative porosity and reliability
of strength data of a brushite forming cement at different powder to liquid ratios (PLRs) was
investigated. Mean compressive strengths were measured, associated reliability (Weibull moduli)
and survival probability distributions of the data sets were analysed. Relative porosities were
determined using helium pycnometry. For low PLR (2.2g/ml), no significant differences in
compressive strength were observed for either mechanical or hand mixed samples, although
reliability of the former was significantly increased. At high PLR (3.4g/ml), mechanically mixed
cements exhibited approximately twice the mean compressive strength compared with hand mixing,
although Weibull moduli remained statistically similar. At medium PLR (2.8g/ml) strength and
reliability of cements were similar and independent of mixing regime. For all PLRs, a significant
decrease in porosity of mechanical- compared with hand-mixed cements was observed. Mechanical
mixing of a brushite cement can provide lower porosity, increased reliability and higher strength.