Bioactive Materialsby Wanpeng Cao & Larry L. Hench

Sept 20th 2012

Literature Review

By : Leon ValentinoAdvisor : Prof. Shao-Ju Shih

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Main Objective• To Study about what is:

Tissue attachment General Theory of Biomaterials Bioactivity Bioactive Ceramics Mechanism of Bioactive Bonding Bioactive Coating and Composites

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Tissue attachment of Biomaterials

ImplantHost Tissue Response1. Nearly Inert2. Porous3. Bioactive4. Resorbable

1. Morphological fixation2. Biological fixation3. Bioactive fixation4. Replacement with tissue

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Tissue response to near inert implantHost Tissue Nearly Inert implant

Response

Non-adherent fibrous capsule (mechanical lock)

More reactive

Thicker Non-adherent fibrous

capsule layer

Micromotion

Degradation of implan/tissue

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Tissue response to porous biomaterial implant

Host Tissue Porous biomaterial implantResponse

Ingrowth of tissue into pores (biological fixation)

Good Biological fixation Pore >100-

150

Capable of withstanding more

complex stress

Provide blood supply

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Tissue response to Bioactive MaterialHost Tissue Bioactive MaterialResponse

Series of biophysical and biochemical reaction occur at interface

Mechanically strong chemical interfacial

bond

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Tissue response to Resorbable MaterialHost Tissue Resorbable

MaterialResponse

Resorbable material degrade gradually and replace by natural tissue

Must metabolically accepted

Rate of degradation must equivalent to regeneration rate

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General Theory of Biomaterial by Hench and Ethridge

a) Ideal implant material perform as if it equivalent to host tissue

b) Axiom 1. The tissue at interface should be equivalent to normal host tissue

c) Axiom 2. Response of the material to physical stimuli should be like that tissue it replaces.

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Bioactivity

Bioactive material

Elicit biological response at interface that form bond

Create osteogenesis environment

BioactivityTime for more than 50% of interface

bonded

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Class in bioactive materialsBioactive Material

Class A (Osteoproductive)

Class B (Osteoconductive)

Elicit intracellular response

Elicit extracellular response

Elicit extracellular response

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Bioactive ceramics• Base component in most bioactive glass and

ceramics (traditional) are SiO2, Na2O,CaO and P2O5.

• By comparing composition of SiO2-Na2O-CaO with P2O5 constant, a diagram of bioactivity are like this:

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Bioactive Bonding

Stage 1-5Do not depend on

the presence of tissues.

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Interaction implant-tissue• Extracellular interaction => determined by

surface features (important for protein and collagen adsorption)

• Intracellular interaction => caused by soluble silicon release from glass surface. Soluble silicon => potent mitogen => enhanced alkaline phospatase activity and osteocalcin (product of resorption of bone) release

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Calcium Phosphate Ceramics

Calcium Phosphate

Precipitation

Hydrolysis

Hydrothermal reaction

Sol-Gel

Solid state reaction

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Biological apatite and Synthetic HABiological Apatite (HCA) Synthetic HA

Contains carbonate (3.2-5.8 wt%) Much more Isotropic than biological apatite

Contains minor element (Mg,Na,K) and trace element (Sr,Pb,Ba) and acid phosphate.

Much larger in grain size

Contains organic material which exist in grain boundaries and has large influence to physical-chemical and biological properties

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Bioactive Composite and CoatingBioactive Composites

and Coating

Have much better biomechanical properties than bioactive ceramics

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Bioactive CompositeBioactive Composites

Matrix : Bioactive glasses/glass-ceramicsReinforce : metal fibers or tough

ceramic part

Matrix : biocompatible PolymerReinforce : Bioactive

glass/ceramic particle or fibers

Elastic moduli > bone

Stress shielding

Mechanical properties close to bone

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Bioactive Composite

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Bioactive coating

Bioactive Coating

Solve mechanical limitation for load-bearing application

Use Metals and alumina (medical grade) as susbtrate coated by HA,TCP,Bioglass

Calcium Phospate deposit using HIP, plasma/flame spraying,ion beam sputtering,

sol-gel deposition and RF sputtering

Good for short term stabilization but cannot be used for long term due to deficiencies

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Conclusion• There are many factors influence bioactivity

such as Morphology (surface morphology,pores), composition, mechanical properties,etc.

• To achieve biochemically and biophysically strong interface between host tissues-implant is very important

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Future Work• Produce MBG using Sol-Gel methode for temp

400 C and 600C

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