bioceramics for load bearing applications: organic/ inorganic treatments to enhance their...

8/11/2019 Bioceramics for Load Bearing Applications: Organic/ Inorganic Treatments to Enhance their Bioactivity and Biocompatibility

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Prof. dr. Simona Cavalu

Faculty of Medicine and

Pharmacy

University of Oradea

ROMANIA



Motivation

As the average age of population grows, the need formedical devices to replace damaged or worn tissuesincreases.

As patients have become more and more demandingregarding esthetic and biocompatibility aspects oftheir dental restorations .



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/kneearthroplasty in the last decades.

For dental application: root canal posts, orthodontic brackets,implant abutments and all- ceramic restorations.



Bioceramicinteraction with

living tissue

BioinertBioactive

Surface modifications and post –synthesistreatments for better performances

Tough and strong ceramics like zirconia, alumina or alumina-zirconiacomposites are not capable of creating a biologically adherent interfacelayer with bone due to the chemically inert nature of these two stableoxides .



Surfacecovering

layers/coatings

Biological

response

Cells viability

Cellsattachment

Cellsproliferation

Surface modification: organic coating/

inorganic treatmentOrganic: proteins, DNA, sugars.Inorganic: surface blasting , acid etching ,fluoride



Goal In the present study we are focused on the possible

beneficial effect of organic coating (fibrinogen) andinorganic treatment (fluorination with SnF2 andNaBF4) with respect to new alumina/zirconia

bioceramics.

The main objective is to analyze the biocompatibility of alumina/zirconia ceramics upon treatment via invitro and in vivo tests.



Materials

Composition: 80%Al2O 3 –

20%YSZ with 5%TiO2 addition

Spark plasma sintering method at 1350-1400◦C.

Structural characterization by FTIR and XRD spectroscopy

Morphological details of the surface investigated by SEM

Mechanical properties:Fracture toughness 5.3 MPa m½ (under a load of 19.6 N) Vickers hardness 16.7 GPa (under a load of 9.8N).

O. Ormanci, S. Cavalu- Mater Sci Eng C 40 (2014)



FTIR spectroscopy

1200 1000 800 600 400

0

3

5

x

Al2O

3

80Al2O

3·20ZrO

2·xTiO

2

Inten

sity/a.u.

Wavenumbers (cm-1)

648

617

465

Modifications of stretching

vibration modes AlO6 octaedra



XRD patterns

Al2O3

80Al2O3-20YSZ

80Al2O3-20YSZ +5TiO2

No monoclinicphase ZrO2



SEM

80Al2O3-20YSZ 80Al2O3-20 YSZ with 5% TiO2

Al2O3



Texture of protein

(fibrinogen) coating on

alumina/zirconia ceramics-

electrodeposition



Native Fibr

Fibr/specimen 1

Fibr/specimen 2

Native Fibr Fibr /specimen 1 Fibr/specimen 2

F T I R s p e c t r o s c o p y a n d

d e c o n v o l u t i o n

α helix % β sheet% β turns % Random % Side chain%

19.9 9.2



Surface treatment with SnF2 and NaBF4

- ATR FTIR evidence

Fig. 1 ATR FTIR spectra of SnF2 and NaBF4 powders as received from the

supplier .

Fig. 2 ATR FTIR spectra recorded onspecimen surface before and aftertreatment using SnF2 and NaBF4.

Al-O Zr-O



Surface treatment- XPS evidence

1200 1000 800 600 400 200 0

F1s

Al2s

Zr3d

Al2p

C

1s

N

1s

O

1s

S

n4d

Zr4pF2s

Sn3p

1

Sn3d

Zr3d

N

1s

F1s

Al2pN

a1s

O

1s

C

1s

Intensity(a.u)

Binding Energy (eV)

Sn3p

3

Al2s

O

Auger

Zr4p

Specimen 2

SnF2

NaBF4



In vitro test: cells culture Human fibroblast (HLF) seeded in a concentration of 2x104/cm2 cells on the

surface of each sample (SnF2 respectively NaBF4 treated ) and cultured for 3h,7h and 24h.

Cell nuclei were stained with 5 mM Draq5 diluted 1:1000 in distilled water for 5min at room temperature.

A B

C D

Visual inspectiondemonstrating initial

adherence and proliferation offibroblasts.

3h 24 h

SnF2

NaBF4



Fibroblasts

adherence/proliferation

evidence by confocal

microscopy

SnF2

NaBF4

24 h7 h

SnF2

NaBF4

7 h 24 h3 h



SEM – initial stage of adherence 3h

SnF2

NaBF4



7h

NaBF4 SnF2



24 h

SnF2

NaBF4



MTT assay results showing viable fibroblasts cells

with respect to control and surface treated

alumina/zirconia specimens after 3, 7 and 24 hours of

culture.

The label * indicates p<0.001 versus control, **indicates p<0.01and *** indicates a p<0.001 with respect to specimen 1.

SnF2NaBF4



In vivo tests: animal model (rabbit)Implant 1- SnF2 treatment

Implant 2-NaBF4 treatment

Implant 3- Fibrinogen



50µm

Implantsite

Haversiancanal

New boneproliferation

Interface bone-implant

Haversiancanal

New boneproliferation

Interface bone-implant50µm

Implantsite

Histology; implant 1 = SnF2 treatmentimplant 2 = NaBF4 treatment

1

2



Ca/P= 1.62- 1.80

Haversian canal

Bone morphology after 4 and8 weeks post -surgery

4 weeks

8 weeks

EDAX



XRD spectrum of the femoral bone

0 20 40 60 80 100

0

100

200

300

400

500

600

700

800

900

*

*

AZA

Z

A

ZA

BA

Z

A

AA

Z

A

Z

A

ZA

A

A

I(a.u.)

2 (deg)

AlZr Biocomposite

Bone/AlZr

Bone

A

T

Z

B



Histology: implant 3- bone

marrow cells interaction

Implant 3- fibrinogen coating

Goldner’s Trichrome stain



Histology: implant 3-

host bone interaction

Goldner’s Trichrome stain

Implant 3- fibrinogen coating



SEM/EDX bone-implant interface

Ca/P= 1.62

Ca/P= 1.77

4 weeks

8 weeks



Summary Ceramic specimens with the composition

80%Al2O3 - 20%3YSZ + 5% TiO2 processed by SPS were surface treated with SnF2/NaBF4 respectively fibrinogen by electrodeposition.

The surface modifications/texture were revealed by ATR-FTIR, XPS and SEM; it was demonstrated that the SnF2 treatment is more effective than NaBF4.Protein characteristics are preserved upon deposition procedure.

Fibroblasts cells culture in the presence of fluorine-treated specimens allowedto assay cell adhesion, cell proliferation and colony capability by fluorescenceevaluation. Both inorganic treatments shows similar results, but cellcolonization capability seems to be promoted by the SnF2 treatment (cellsculture for fibrinogen coated is not shown, work in progress…..)

Morphological details of the fibroblasts attached on the surface of fluorine

treated samples were emphasized by SEM showing the formation of a shell-likecoating after 24 hours incubation.

Histological images demonstrated the biocompatibility of the treated implantsas no gaps, fibrous tissue, multinucleated cells or inflamation were found at thebone implant interface. A better bone to implant contact was noticed in thecase of SnF2 treatment.



Animal model- The presence of young, compact lamellar bone andosteocytes near the implant surface indicated good biocompatibility, andcertainly the presence of the implant did not disturb the processes of boneformation at the interface, for both organic/inorganic treatment.

Microstructure details (including Haversian canals) of bone andbone marrow tissue and elemental composition at the interfaceindicated Ca/P =1.62 - 1.77

Summary

Conclusions: Organic (proteic) film or f luoride as surface

conditioning might be an alternative approach to induce thebioactivity and improve the biocompatibility of dense bioceramicsdesigned to load bearing bone replacement (hip joint, dentalabutments) and to optimize the biological response for specificapplications of biomedical implants.



Related papers:

O. Ormanci, I. Akin, F. Sahin, O. Yucel, V. Simon, Simona Cavalu, G. Goller, Spark Plasmasintered A2O3-YSZ-TiO2 composites: Processing, characterization and in vivo evaluation,

Materials Science and Engineering C, 40 (2014) 16-23.

Simona Cavalu, C. Ratiu, O. Ponta, V. Simon, D. Rugina, V. Miclaus, I. Akin, G. Goller,Improving osseointegration of alumina/zirconia ceramic implants by fluoride surface

treatment, Digest Journal of Nanomaterials and Biostructures Vol. 9, No. 2 (2014) 797–

808.

Simona Cavalu, V. Simon, F. Banica, I. Akin, G. Goller, Surface modification ofalumina/zirconia bioceramics upon different fluoride-based treatments, Int. J. Appl. Ceram.Technol., 11 [2] 402–411 (2014 ).

Simona Cavalu, V. Simon, I. Akin, G. Goller, Adherence properties of acrylic bone cementto alumina ceramics designed for clinical application, Acta Physica Polonica A, nr.2,vol.125(2014) 603-605

S. Cavalu, V . Simon, C. Ratiu, I. Oswald, R. Gabor, O. Ponta, I. Akin, G. Goller, Correlationbetween structural properties and in vivo biocompatibility of alumina/zirconia bioceramics,Key Engineering Materials vols. 493-494, 1-6(2012)



Acknowledgments:

UEFISCDI project PNII-ID-PCE 2011-3-0441 contract nr. 237/2011 andBilateral Cooperation RO-TR.

•Prof. dr. Viorica Simon Babes-BolyaiUniversity, Faculty of Physics & Institute ofInterdisciplinary Research in Bio-Nano-

Sciences, Cluj-Napoca, Romania.

• Dr. Cristian Ratiu, Ioan Oswald andSilviu Vlad, University of Oradea, Facultyof Medicine and Pharmaceutics, Oradea,Romania.

• Dr. Dumitrita Rugina, USAMV Cluj-Napoca.

•Prof. dr. Gultekin Goller and assist. prof.Ipek Akin, Istanbul Technical University,Materials Science Department.

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