1. CLASSIFICATION OF BIOMATERIALS
Metals
Semiconductor Materials
Ceramics
Polymers
Synthetic BIOMATERIALS
Orthopedic screws/fixation
Dental Implants
Bone replacements
Biosensors
Implantable Microelectrodes
Skin/cartilage
Drug Delivery Devices
Ocular implants

2. METALIC BIOMATERIALS
Crystal structures and strong metallic bonds - orthopedic applications
- the face and jaw surgery
- cardio-vascular surgery
material joint prosthesis and bone renewal
Dental implant
Artificial heart parts, heart valve

3. Metals used as Biomaterials
Steel
Cobalt-containing alloys
Titanium and titanium containing alloys
Dental amalgam (XHg)
Gold
Nickel- titanium alloys

4. Corrosion;
The undesired chemical reaction of metals with their surruondings that forms oxygen, hydroxide and other compounds then degradation
Corroding Metal X Biocompatible

5. 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 ceramics
To introduce the use of ceramics as biomaterials
To explore concepts and mechanisms of bioactivity

6. Ceramics (keramikos- pottery in Greek)
Ceramics are refractory polycrystalline compounds
Usually inorganic
Highly inert
Hard and brittle
High compressive strength
Generally good electric and thermal insulators
Good aesthetic appearance
Applications:
orthopaedic implants
dental applications
compromise of non-load bearing for bioactivity

7. BIOCERAMICS Bioceramics;
Repair the parts of body that injured or lost their function, restructuring or special ceramics are designed to replace ;
- polycrystalline structure ceramic (alumina),
- bioactive glass,
- bioactive glass-ceramics,
- bioactive composites…

8. Using Areas of Bioceramics
Glasses,
Diagnostic devices,
Thermometers,
Tissue culture vessels.
Filling materials,
Gold-porcelain coating,
Prosthetic parts
Health Sector
Dental

9. Structure A: metal, +ve X: nonmetal, -ve Ceramic Structure: AmXn ZnS
CsCl
NaCl
X: nonmetal,
-ve

10. Nature’s Ceramic Composites
Natural hard tissues are “ceramic”-polymer composites:
Bones, Teeth, Shells
Tissue = organic polymer fibers + mineral + living cells
Mineral component (Ceramic)
Bone: hydroxyapatite (HA) – Ca5(PO4)3OH
Mineralization under biological conditions:
Many elemental substitutions
Protein directed crystallization
Unique characteristics – crystal morphology and solubility
Synthetic calcium phosphates are used as biomaterials – “bioactive”
Synthetic HA
Bone HA

11. Types of Ceramics
nearly bioinert
nearly bioinert

12. Bioactivity vs. Biocompatibility
Objective is to minimize inflammatory responses and toxic effects
Bioactivity - Evolving concept:
The characteristic that allows the material to form a bond with living tissue (Hench, 1971)
The ability of a material to stimulate healing and trick the tissue system into responding as if it were a natural tissue (Hench 2002).
Advantages: Bone tissue – implant interface, enhanced healing response, extends implant life
Biodegradability:
Breakdown of implant due to chemical or cellular actions
If timed to rate of tissue healing transforms implant to scaffold for tissue regeneration
Negates issues of stress shielding, implant loosening, long term stability

13. Classification based on tissue attachment

14. Mechanical Properties
B. Amsden
CHEE 340

15. BIOCERAMICS
Bioactive ceramic, that allows the chemical bond formation between tissue and implant
Bioinert ceramic, that doesn’t allow the chemical bond formation between tissue and implant
BIOINERT BIOACTIVE

16. MATERIAL
TISSUE
TOXIC
DEAD
Bioinert
NON-TOXIC
Bioactive
Soluble
Various thicknesses of fibrous tissue
binding of tissue-implant interface,
Tissue replaces
İmplant place

17. Classification of Bioceramics According to Tissue Responses
Implant Type
Tissue response
Example
Nonporous, dense and inert ceramics
The formation of very fine fibrous tissue
Alumina, Zirconia
Porous inert ceramics
The tissue growth in pores
Hydroxyapatite
Resorbable ceramics
Absorption
Tricalcium phosphate
Bioactive glasses
Ceramic implants are non-toxic

18. Bioceramics According to Structural Functions
Oxide ceramics, inert structure, polycrystalline ceramics consisting of metal ions in the plane formed by the dissolution of oxygen ions
Alumina (Al2O3) orthopedic applications
Zirconia (ZrO2) femoral prosthese

19. Inert Ceramics: Alumina
History:
since early seventies more than 2.5 million femoral heads implanted worldwide.
alumina-on-alumina implants have been FDA monitored
over 3000 implants have been successfully implemented since 1987
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

20. Inert Ceramics: Aluminum Oxides (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

21. Alumina Bioinertness Results in biocompatibility – low immune response
Disadvantage:
Minimal bone ingrowth
Non-adherent fibrous membrane
Interfacial failure and loss of implant can occur

22. Inert Ceramics: Zirconia, ZrO2
zirconium; named from the Arabic, zargun = gold color
Fabrication:
Obtained from the mineral zircon
Addition of MgO, CaO, CeO, or Y2O3 stabilize tetragonal crystal structure (e.g. 97 mol%ZrO2 and 3 mol%Y2O3)
Usually hot-pressed or hot isostatically pressed
Applications:
orthopaedics: femoral head, artificial knee, bone screws and plates, favored over UHMWPE due to superior wear resistance
dental: crowns and bridges

23. Glass and glass-ceramics:
Silica(SiO2) –based ceramics (Includes Lithium-Aluminum or Magnesium-Aluminum crystals )
Bioglass:
Instead of some silica groups, calcium, phosphorus or sodium is present (SiO2, Na2O, CaO, P2O5)

24. Bioactive Ceramics: Glass Ceramics
an inorganic melt cooled to solid form without crystallization
an amorphous solid
Possesses short range atomic order  Brittle!
Glass-ceramic is a polycrystalline solid prepared by controlled crystallization of glass
Glass ceramics were the first biomaterials to display bioactivity (bone system):
Capable of direct chemical bonding with the host tissue
Stimulatory effects on bone-building cells

25. Bioactive Ceramics: Glass Ceramics
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

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

27. Bioactive Ceramics: Glass Ceramics
Bioactive: capable of direct chemical bonding with the host biological tissue
Glass:
an inorganic melt cooled to solid form without crystallization
an amorphous solid
possesses short range atomic order  BRITTLE!
Glass-ceramic is a polycrystalline solid prepared by controlled crystallization of glass  LESS BRITTLE

28. Hydroxyapatite Ca5(PO4)3OH, Tricalcium phosphate, Ca3(PO4)2
Calcium-phosphate ceramics ; their structure is the form of multiple oxides of calcium and phosphate atoms
Hydroxyapatite Ca5(PO4)3OH,
Tricalcium phosphate, Ca3(PO4)2
Oktacalcium phosphate CaH(PO4)3.2OH
In medicine and dentistry

29. Biodegradable Ceramics: Calcium (Ortho) Phosphate
Structure resembles bone mineral; thus used for bone replacement
Coating of metal implants to promote bone ingrowth
Different forms exist depending on Ca/P ratio, presence of water, impurities and temperature
7 different forms of PO4 based calcium phosphates exist - depend on Ca/P ratio, presence of water, pH, impurities and temperature

30. Calcium Phosphate Powders Scaffolds
Coatings for implants – metals, heart valves to inhibit clotting
Self-Setting bone cement

31. Calcium Phosphates Uses
repair material for bone damaged trauma or disease
void filling after resection of bone tumors
repair and fusion of vertebrae
repair of herniated disks
repair of maxillofacial and dental defects
ocular implants
drug-delivery
coatings for metal implants, heart valves to inhibit clotting

32. Advantage of Bioceramics
The resistance to
Microorganisms,
Temparature,
Solvents
pH changes
High pressures is the advantage in health and dental aplications

33. The elderly, the bones are very brittle
Bioceramics are used repair or renewal of a hard connective tissue in the skeleton
The elderly, the bones are very brittle
slow-moving cracks,
uncertainties to durability
in different strokes and pressures
The most important reasons for limiting the use of bioceramics,

34. Interaction of bioceramics with tissues
All materials placed on live tissue, takes response from tissue
TISSUE - IMPLANT

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