The document summarizes research on the structural properties and biocompatibility of alumina/zirconia bioceramics. X-ray diffraction and Fourier transform infrared spectroscopy showed that titanium dioxide addition modified the structure of alumina/zirconia composites while retaining the tetragonal phase of zirconia. Animal studies found that both 90% alumina-10% zirconia and 90% alumina-10% zirconia with 5% titanium dioxide composites integrated well with bone over 6 weeks without inflammatory responses. Calcium/phosphorus ratios from scanning electron microscopy indicated improved osseointegration with titanium dioxide addition.

1. Correlation between structural
properties and in vivo
biocompatibility of
alumina/zirconia bioceramics
Simona Cavalu
Professor
Preclinical Sciences Department
Faculty of Medicine and Pharmaceutics
University of Oradea
ROMANIA

2. Motivation
 There is a continuous input from bioengineering for
reaching a high level of comfort, improving reliability,
finding new applications.
 This development is also a response to the growing
number of patients afflicted with traumatic or non-
traumatic conditions: the number of implants is
continuously growing, due to the increase in persons
suffering of arthritis and joint problems.
 As the average age of population grows, the need for
medical devices to replace damaged or worn tissues
increases.
 As patients have become more and more demanding
regarding esthetic and biocompatibility aspects of
their dental restorations

3. Motivation
Al2O3 ZrO2
 Excellent hardness and  Was introduced to overcome
wear properties. the limitations of alumina.
 Fracture toughness values  When properly manufactured,
are lower than those of zirconia has a higher strength,
the metals used in but only 50% of alumina’s
orthopedic surgery. hardness.
 Chemical and  Unstable material. The
hydrothermal stability. tetragonal phase tends to
 It is a brittle material, transform into the monoclinic
phase. The addition of
with low resistance to the stabilizing materials
propagation of cracks. (Y2O3)during manufacture, can
control the phase
transformation of zirconia.
Al2O3, ZrO2, TiO2 have been considered as bioinert ceramics
since they cannot induce apatite formation in SBF. They do
however support bone cell attachment, proliferation and
differentiation.

4. The ideal ceramic is a high performance biocomposite that combines
the excellent material properties of alumina in terms of chemical
stability and low wear and of zirconia with its superior mechanical
strength and fracture toughness.
 Alumina/zirconia ceramics were successfully used in total
hip/knee arthroplasty in the last decades.
 For dental application: root canal posts, orthodontic
brackets, implant abutments and all- ceramic
restaurations.

5. Goal
 An evaluation of the structural and
biocompatibility properties of a new
zirconia toughened alumina ceramics.
 The composition of proposed materials
for this study:
90%Al2O3-10%ZrO2 and
90%Al2O3-10%ZrO2+5%TiO2
 prepared by using modern processing
technologies – spark plasma sintering.

6. Methods
 Investigation of the structural changes induced by TiO2
addition to Al2O3/ ZrO2 are made by FTIR spectroscopy and X-
ray diffraction (XRD) analysis .
 Scanning Electron Microscopy (SEM) and EDX are used for
microstructure and morphology investigation of the samples.
 In order to perform in vivo tests, the rat model has been applied
for biocompatibility evaluation. The rat model has been accepted
as a model for the effects of systemic disease on osseointegration.
 SEM micrographs are recorded on the rats femur along with the
elemental composition of the sheared implant surfaces at
different time intervals after the surgery.
 Histological examination of the connective tissue is performed
to detect any immunological or inflammatory responses.

7. Results: XRD Spectroscopy
XRD patterns of (a) 90Al2O3∙10ZrO2 and
(b) 90Al2O3∙10ZrO2 + 5%TiO2 samples.
1200
Z
A
 The TiO2 addition slightly
A Z modifies the relative intensities
1000 of XRD peaks. Both samples
A A show similar peak positions,
800 A Z
A
A
the slight change of relative
Z
A A intensities of XRD peaks could
be attributed
T
to weak
Intensity (a.u.)
Z A
600
Z A A Z
(a) differences in size and shape of
the crystals in these samples
400
A A
A
A
A
 This result suggest that
200 Z A zirconia present in the
T
Z
A
composite is, therefore,
0
A
(b) retained in the tetragonal form
as alumina particles prevent
0 10 20 30 40 50 60 70 80 90 100
the tetragonal to monoclinic
2 theta (degrees)
transformation by matrix
constraint.

8. FTIR Spectroscopy: (a) 90Al2O3∙10ZrO2 and
(b) 90Al2O3∙10ZrO2 + 5%TiO2 samples.
 The large bands around 1088
cm-1 are assigned to stretching
vibration of Al–O–Al bonds.
 The Al-O stretching vibrations of
465
0.6
1088
tetrahedral AlO4 groups are
614
660
related with the bands in the
780
1168
region 900 – 750 cm-1 and
564
518
797
0.5
bands in 650 – 460 cm-1 region
Intensity (a.u.)
(a)
are associated with stretching
modes of AlO6 octahedra.
0.4
 The absorption bands at 518 to
564 cm-1 correspond to Zr-O
vibrations in tetragonal ZrO2
0.3
phase.
(b)  Upon TiO2 addition to alumina-
zirconia matrix, the relative
0.2 intensity of 660/614 cm-1 band
1200 1000 800
Wavenumber (cm )
-1
600 400
is considerably modified, as a
superposition of the
characteristics absorption bands
occurs in this region.

9. SEM: Irregular shape of 90%Al2O3-10%ZrO2(a)
and 90%Al2O3-10%ZrO2+5%TiO2 (b) granules and
their corresponding microstructure (c, d)
a) c)
b) d)

10. Biocompatibility evaluation: Animal model
(Wistar rats)
 Surgical procedure

11. Surgical procedure: filling the critical size
defect created in the femur
Collagen film

12. Monitoring the osseointegration process at
different time intervals (3, 6 weeks).
Radiographic images
90Al2O3∙10ZrO2
90Al2O3∙10ZrO2 + 5%TiO2

13. SEM images of the sheared implant surfaces:
3 weeks
90Al2O3∙10ZrO2
90Al2O3∙10ZrO2 + 5%TiO2

14. SEM images of the sheared implant surfaces:
6 weeks
90Al2O3∙10ZrO2
90Al2O3∙10ZrO2 + 5%TiO2

15. Haversian canal details

16. SEM Analysis reveals:
 Fibrinous and collagenous matrix extensively interdigitated
with the three-dimensional interconnected porous structure
after first 3 weeks.
 Distinct gaps between the implant and the bone were
observed in a few locations.
 After 6 weeks, the matrix around the surface implanted
area appeared more densely, well covered and extensively
integrated into a mixture of mineralized tissue, osteoid and
dense matrix.
 As revealed from the EDAX spectra, calcium/phosphate
ratio is an indicative of the surface implant coverage for a
successful osseointegration, varying from 1.5 (after 3
weeks) to 1.9 (after 6 weeks).
 The results suggest that TiO2 presence in the samples favor
the osseointegration process.

17. XRD spectrum of the femoral bone
900
800 Z AlZr Biocomposite
700 A
A Z Z A
A A A A
A
T Z
600
500 Z Bone/AlZr
I (a.u.)
B Z Z
A A A
400 A B A AZ
300 *
200
* Bone
100
0
0 20 40 60 80 100
2Θ (deg)

18. Histological images: The connective tissue
was also examined to detect any
immunological or inflammatory responses
osteoblasts
A network of woven bony trabecular architecture with cellular infiltration
was observed

19. Conclusions
 Structural investigations of the proposed composites
using XRD and FTIR spectroscopy confirms the
stability of the microstructure upon TiO 2 addition to
alumina/zirconia matrix.
 In vivo: both implanted materials in critical size
defect of the femur were well integrated in the
original bone defects and covered with a layer of soft
tissue at 6 weeks after implantation, as demonstrated
by SEM images.
 As revealed from the EDAX spectra, Ca/P ratio is an
indicative of the surface implant coverage for a
successful osseointegration, varying from 1.5 (after 3
weeks) to 1.9 (after 6 weeks).
 No signs of inflammatory reactions, such as necrosis
or reddening suggesting implant rejection, were found
upon histological examination.

20. The team:
 Prof. dr. Gultekin Goller and dr. Ipek Akin, Istanbul
Technical University, Materials Science Department.
 Prof. dr. Viorica Simon and dr. Oana Ponta Babes-Bolyai
University, Faculty of Physics & Institute of Interdisciplinary
Research in Bio-Nano-Sciences, Cluj-Napoca, Romania.
 Assoc. prof. Cristian Ratiu and dr. Ioan Oswald
University of Oradea, Faculty of Medicine and Pharmaceutics,
Oradea, Romania.
 Romania-Turkey Bilateral Cooperation project 385/2010.

21. Jerry and Jimmy
Linda
Thank you