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Paper Title Page
Abstract: Laser treatment is a promising technique for dental applications such as caries prevention,
dental hypersensitivity reduction and improvement of bond strength of restoration materials. In this
study the morphological, structural and chemical changes of enamel surface due to treatment with
KrF excimer laser radiation were evaluated using scanning electron microscopy, X-ray diffraction,
and X-ray photoelectron spectroscopy. For radiation fluences near 1 J/cm², laser processing
originates a relatively porous surface due to preferential removal of material in the enamel prism
sheaths. Increasing the fluence leads to a relatively flat surface with clear evidence of surface
melting. The X-ray diffractograms of both treated and untreated enamel are similar and correspond
to hydroxyapatite. The only modification due to the laser treatment is a slight shift of the peaks,
probably, due to a loss of the structural water of hydroxyapatite. X-ray photoelectron spectroscopy
confirmed that organic matter is removed from the irradiated surface but no significant changes in
the mineral phase occur.
42
Abstract: An elastin-like polymer (ELP) was designed by genetic engineering techniques to mimic
the extracellular matrix (ECM). The precise control of the polymer sequence offered many
advantages that allowed the definition of distinct and specific domains. The cell attachment domain
present in the sequence enhances the cell adhesion. Hexamethylene diisocyanate, a lysine-targeted
crosslinker, was used to crosslink the purified polymer. The produced matrices presented an
adequate mechanical performance and the morphological analysis by scanning electron microscopy
show a homogeneous porous structure, ranging from nanometers to few micrometres. The biological
tests will be assessed in future work. These results show the big potential of the ELPs in biomedical
applications, especially in the development of systems for tissue engineering and drug release.
47
Abstract: This paper reports a preliminary study on the development and characterization of a
porous calcium phosphate glass-ceramic for tissue engineering application. To obtain porous glass
scaffolds, a mixture of 3CaO.P2O5-SiO2-MgO glass (grain size below 20 'm) and NaCl with 200-
300 'm of particle size was taken in the volume proportion 1:1. The mixture was shaped into
cylindrical samples (10 mm diameter x 10 mm thick) by using unidirectional pressing. The sintering
thermal cycle was selected by means of thermal analyses (DTA/TG and dilatometry) in order to
attain a high enough cohesion among the glass particles. After thermal consolidation, the salt was
dissolved in water, resulting in highly porous materials. The effect of the sintering thermal cycle on
the structure and microstructure characteristics of the scaffolds was investigated in this paper.
52
Abstract: Permanent magnets based on intermetallic compounds are employed in dentistry to fix
dental prosthesis. However, these materials are very sensitive to corrosion. In this study the
corrosion behavior of a sintered commercial Nd-Fe-B magnet has been investigated at neutral pH in
a phosphate buffered solution (PBS). With this aim demagnetized specimens were immersed in the
test solution and their corrosion behavior were monitored at increasing test times by means of
electrochemical impedance spectroscopy ( EIS ), potentiodynamic polarization curves and surface
observation by scanning electron microscopy ( SEM ). Experimental results indicated that the
corrosion resistance is seriously affected in this solution. Moreover, no decrease in the intensity of
the corrosive attack was verified during test periods of up 4 hours. Impedance results have indicated
the occurrence of diffusion controlled phenomenon, likely linked to the presence of pores in the
magnet microstructure.
57
Abstract: Bioactive glasses are materials that have been used for the repair and reconstruction of
diseased bone tissues, as they exhibit direct bonding with human bone tissues. However, bioactive
glasses have low mechanical properties compared to cortical and cancellous bone. On the other
hand, composite materials of biodegradable polymers with inorganic bioactive glasses are of
particular interest to engineered scaffolds because they often show an excellent balance between
strength and toughness and usually improved characteristics compared to their individual
components. Composite bioactive glass-polyvinyl alcohol foams for use as scaffolds in tissue
engineering were previously developed using the sol-gel route. The goal of this work was the
synthesis of composite foams modified with higher amounts of PVA. Samples were characterized
by morphological and chemical analysis. The mechanical behavior of the obtained materials was
also investigated. The degree of hydrolysis of PVA, concentration of PVA solution and different
PVA-bioactive glass composition ratios affect the synthesis procedure. Foams with up to 80 wt%
polymer content were obtained. The hybrid scaffolds obtained exhibited macroporous structure with
pore size varying from 50 to 600 µm and improved mechanical properties.
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Abstract: Biomorphic silicon carbide ceramics is very promising as a natural base material for
biomedical applications due to their excellent mechanical-biochemical properties and biocompatible
behaviour. This innovative material is produced by molten-Si infiltration of carbon templates
obtained by controlled pyrolysis of biological precursors. The final product is a light, tough and
high-strength material with predictable microstructure.
In this study the possibility to produce biomorphic silicon carbide ceramics using marine precursors
is demonstrated. Due to the great biodiversity offered by the marine medium, a previous selection
of algae (Laminaria ochroleuca Bachelot de la Pylaie, Undaria pinnatifida (Harvey) Suringar,
Saccorhiza polyschides (Lightfoot) Batters and Cystoseira baccata (Gmelin) Silva) and marine
plants (Zostera marina L. and Juncus maritimus L.) was carried out, taking into account its
microstructure, porosity and interconnectivity of each species.
The bioceramization process was evaluated in three phases: original material analysis, pyrolysis
process and reactive melt Si-infiltration. For each marine precursor, a detailed study by Scanning
Electron Microscopy (SEM) of the natural material, the carbon preform and the final SiC
biomorphic product is described. The viability to obtain biomorphic SiC ceramic material for all the
selected marine precursors is discussed.
67
Abstract: Bone marrow cells are a potential source to induce different lineage cells which can be
used to rebuild or replace damaged tissues using a Tissue Engineering (TE) approach. However, TE
strategies usually require the use of a material to support the development of a biological tissue.
Beta-polyvinylidene fluoride (β-PVDF) is a biocompatible, thermoplastic with piezo-electrical
properties that has been shown to provide a good cellular attachment and therefore might present
advantageous properties as a scaffold material for cell seeding/culturing. The present study
describes the characterization of β-PVDF membranes as a support material for growth and
differentiation of goat marrow cells (GMCs) into osteoblasts, leading to the formation of substitutes
for tissue regeneration.
The obtained results suggest that β-PVDF piezoelectric properties influence cellular behavior. β-
PVDF membranes not only enhance GMCs adherence and proliferation but also improve
differentiation towards the osteogenic phenotype both in static and dynamic culture conditions.
Furthermore, β-PVDF membranes exhibit very promising properties, suggesting that this material
provides adequate support for the seeding and the development of undifferentiated cells towards a
desired phenotype.
72
Abstract: Chitosan membranes were subjected to a pre-treatment in a double diffusion system, with
a calcium solution in one chamber and a phosphate solution in the other chamber. Both chambers
were separated by the chitosan membrane and subject to three mineralization periods (5, 10 and 15
minutes). After this pre-treatment the bioactivity of the different calcium phosphate coatings formed
was tested for different periods of immersion time, 7, 14 and 21 days at room temperature and 37°C,
in acellular simulated body fluid (1.0x). The results obtained demonstrated that the calcium
phosphate coatings formed during the pre-treatment process are bioactive. It was found that the
calcification is effective just in the side of the membrane exposed to the calcium solution chamber.
This enabled to develop membranes with asymmetric osteoinductive properties that can be useful in
different orthopedic applications.
77
Abstract: There have been many clinical trials to collect bone debris utilizing special equipment
and to apply in the bone graft procedure simultaneously. Collected bone debris (CBD) may be
contaminated by bacteria. This may lead to iatrogenic contamination of recipient sites by grafted
bone debris. The purpose of this study was to evaluate the effect of strict suction protocol on the
levels of bacterial contamination. Total 41 patients (21 male and 20 female patients) with a mean
age of 48.97 were selected in this study. They were randomly divided into two groups in this study.
One group consisted of a single-suctioning group, while the other was dual-suctioning group. A
bone collecting device was used to collect bone specimens during drilling. Samples were obtained
and cultures of CBD were performed. Among the 41 samples of cultured bone debris, only 16
samples yielded viable microorganisms. Microorganisms were detected in the 54.5% (12/22) of
single-suctioning group, and in 21.1% (4/19) of dual-suctioning group (p=0.03). The majority of
microorganisms were Gram positive cocci. It was shown that erythromycin and clindamycin were
more effective than penicillin in the antibiotics sensitivity test.
It was concluded that the use of strict suction protocol could reduce the bacterial contamination.
82
Abstract: In this research, bioactive glass powders were electrophoretically deposited on
biomorphic SiC ceramic substrates. A post-deposition thermal treatment was carried out to improve
the properties of the coatings. Particle size, surface morphology, composition and thickness of the
coatings have been studied by Scanning Electron Microscopy (SEM), Energy Dispersive
Spectroscopy (EDS) and interferometric profilometry respectively. The analysis demonstrated that
the electrophoresis parameters, such as the voltage, the distance between the electrodes and the
deposition time, play an important role on the thickness of the coatings. The post-deposition thermal
treatment produces glass particles cohesion and leads to obtaining a homogeneous microstructure.
The excellent coverage of the porous SiC surface morphology is also demonstrated. Finally, in
order to assess the bioactive character of the glass coatings, in vitro test by immersion in simulated
body fluid (SBF) was carried out.
86