bioceramic

1. Ceramic Biomaterials (Bioceramics)
The class of ceramics used for repair and replacement of diseased
and damaged parts of the musculoskeletal system are referred to
as bioceramics.
OBJECTIVES
 To examine chemical/physical properties of bioceramics
 To introduce the use of ceramics as biomaterials
 To mention the current and future status in bioceramics

2. Bioceramics
Advantages
High Compression Strength
Disadvantages
High Modulus
Wear & Corrosion Resistance Low Strength In Tension
Bioactive/inert
Low Fracture Toughness
Can Be Highly Polished
Difficult To Fabricate

3. Types of Bioceramics

4. Mechanical Properties

5. Biocompatibility & Bioinertness
Biocompatibility:
Objective is to minimize inflammatory responses and toxic effects
Bioinertness:
Results in biocompatibility – low immune response
Advantage: Making material more biocompatible
Disadvantages: Minimal bone ingrowth, Non-adherent
fibrous membrane, Interfacial failure and loss of implant
can occur

6. Bioactivity & Biodegradability
Bioactivity:
Having a capacity to interact with a living tissue or system.
Advantages: Bone tissue – implant interface, enhanced healing
response, extends implant life
Biodegradability:
The capacity of a natural environment to chemically break down an
object.

7. Inert Ceramics: Aluminum Oxide (Alumina – Al2O3)
History:
 Since 1975, alumina ceramic has proven its bioinertness
 Since early seventies more than 2.5 million femoral heads implanted

worldwide
Over 3000 implants have been successfully implemented since
1987

8. Inert Ceramics: Aluminum Oxide (Alumina – Al2O3)
Smaller the grain size and porosity, higher the strength
– E = 380 GPa (stress shielding may be a problem)
High hardness:



Low friction
Low wear
Corrosion resistance
Friction: surface finish of <0.02 um
Wear: no wear particles generated – biocompatible

9. Inert Ceramics: Aluminum Oxide (Alumina – Al2O3)
Applications
 orthopaedics:
»femoral head
»bone screws and plates
»porous coatings for femoral stems
»porous spacers (specifically in revision
surgery)
»knee prosthesis
 dental: crowns and bridges

10. Inert Ceramics: Zirconium Dioxide (Zirconia - ZrO2)

Obtained from mineral zircon

Usually hot-pressed

Bright future because of its high mechanical strength
and fracture toughness

11. Inert Ceramics: Zirconium Dioxide (Zirconia - ZrO2)
Applications
-
Orthopaedics:
femoral head
bone screws and plates
Artificial knee
-
Dental:
crowns and bridges

12. Bioactive Ceramics: Glass Ceramics
Glass:
 an inorganic melt cooled to solid form without crystallization
 an amorphous solid
 Possesses short range atomic order  Brittle!

13. Bioactive Ceramics: Bioglass
 Composition includes SiO2, CaO and Na2O
 Bioactivity depends on the relative amounts of SiO2, CaO
and Na2O
 Cannot be used for load bearing applications
 Ideal as bone cement filler and coating due to its biological
activity

14. Bioactive Ceramics: Bioglass
SiO2
B
C
A
D
CaO
A: Bonding within 30 days
Na2O
B: Nonbonding, reactivity too low
C: Nonbonding, reactivity too high
D: Bonding

15. Bioactive Ceramics: Hydroxyapatite (HA)
Formula: Ca10(PO4)6(OH)2

Similar composition to bone

High biocompability
Good osteoconductive
properties


16. Bioactive Ceramics: Hydroxyapatite (HA)
Applications
-
Femoral knee
-
Femoral hip
-
Tibial components
-
Acetabular cup

17. Biodegradable Ceramic: Calcium (Ortho) Phosphate
 Structure resembles bone mineral; thus used for bone replacement
 7 different forms of PO4 - depend on Ca/P ratio, presence of water,
pH, impurities and temperature

18. Biodegradable Ceramic: Calcium (Ortho) Phosphate
Usage Areas:






repair material for bone damaged trauma or disease
void filling after resection of bone tumors
repair of herniated disks
repair of maxillofacial and dental defects
ocular implants
coatings for metal implants

19. Why Use Bioceramics?
General
Options
Toxic/
Imunogenic/
Disease
transmission?
Mechanical
Properties?
Bioactive?
Degradable?
Autograft
Allograft
Metals
Ceramics
Excellent
Moderate
Low
Polymers
Composites
Advantages to Bioceramics:
Disadvantage of Bioceramics:
• Biological compatibility and activity
• Brittleness – not for load bearing
applications
• Less stress shielding
• No disease transmission
• Unlimited material supply

20. Current Status And Trends
√ Calcium phosphates for bone grafting and tissue
engineering
√ Calcium phosphates as fillers in composites
√ Chemically and physically modified
hydroxyapatite

21. Current Status And Trends
Animal testing, clinical trials, a new material takes
around 15 to 20 years to hit the market

Trend is towards resorbable materials
which eliminate the need for a
secondary procedure and
mouldable materials


22. Bioceramics in Future
Other trends include engineering the materials for
specific tasks.
Ongoing research involves the chemistry, composition,
micro and nanostructures of the materials to improve
their biocompatibility.

23. Bioceramics in Future

Improvement of the mechanical
performance of existing
bioactive ceramics.
•
Enhanced bioactivity in terms of
gene activation.
•
Development of improved
biomimetic composites.
•
Treatment works of cancer.