MATERIALS SCIENCE and

ENGINEERING
“ BIOMATERIALS”
Topics:
 Definition of Biomaterials

 Characteristics of Biomaterials

 History

 Uses of Biomaterials

 Synthetic Biomaterials

 Biomaterials Generation

 Examples of Biomaterials Applications

 Biomaterials: An Example

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Definition
A biomaterial is any material, natural or man-made, that comprises
whole or part of a living structure or biomedical device which performs,
augments, or replaces a natural function. Biomaterials can be metals
and alloys, polymers (synthetic or natural), ceramics and composites.
Often single materials cannot fulfill all the requirements imposed by a
specific application.

Characteristics of Biomaterials
Physical requirements

Hard material

Flexible material

Chemical requirements

Must not react with any tissue in the body

Must be non-toxic to the body

History
A decade into the twenty-first century, biomaterials are widely
used throughout medicine, dentistry. The word “biomaterial” was not
used. There were no medical device manufacturers (except for external
prosthetics such as limbs, fracture fixation devices, glass eyes, and
dental fillings and devices), no formalized regulatory approval
processes, no understanding of biocompatibility, and certainly no
academic courses on biomaterials.

More than 2000 years ago, Romans, Chinese, and Aztec’s used gold in
dentistry.

1958, Rob suggests Dacron Fabrics can be used to fabricate an arterial

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Late 1960 – early 1970’s biomaterial field solidified

1975 society for biomaterials formed

Uses of Biomaterials
Replacement of diseased or damaged part

Aid to treatment

Aid to diagnosis

Correct cosmetic problem

Assist in healing

Improve function

Correct functional abnormality

Synthetic Biomaterials
Metals

Dental implants

Orthopaedic screws/fixation

Polymers

Drug delivery devices

Skin/cartilage

Ocular implants

Ceramics

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Bone replacements

Heart valves

Dental implants

Semiconductor materials

Implantable microelectrodes

Biosensors]

Biomaterials generations
First generation of biomaterials When synthetic materials were first used
in biomedical applications, the using requirements were a suitable
physical properties to

match those of the replaced tissue with a minimal toxic response of the
host, so

biologically inert or nearly inert materials were used in order to reduce

and the releasing ions and particles after implantation to minimise the
immune

response and foreign body reaction. Mechanical properties and toxicity

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leading role in the selection of materials for implant manufacture. When
inert

biomaterials placed inside the body, it would elicit a foreign fibrous

the material which isolates it from the surrounding tissue.

Examples for the first generation biomaterials:

Metals (stainless steel and cobalt–chrome-based alloys, Ti and Ti

Ceramics (Alumina Al2O3 and Zirconia ZrO2).

Polymers (silicone rubber, acrylic resins).

The second generation of biomaterials used bioactive materials ‘ability

with the biological environment to enhance the biological response and

tissue/surface bonding’, and resorbable biomaterials that have ability to

while new tissue regenerates and heals.

Examples for the second generation biomaterials:

Metals (None of the biometallic materials are bioactive; However, two

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can be considered to obtain bioactive metals. The first one consists of
coating the

surface of the metal with a bioactive ceramic. The second one is to

the surface of the metal so as to induce proteins and cell adhesion and
other

tissue/material interactions.

Ceramics (Bioactive glass, glass–ceramics and calcium

Polymers (Biodegradable polymers of synthetic and natural origin

polyglycolide (PGA), polylactide (PLA).

The third-generation biomaterials used bioactive and bioresorbable

temporary three-dimensional porous structures which are able to

stimulate regeneration of living tissue. For these biomaterials, the

biodegradability concepts are combined, so the combination of

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biodegradability is the most characteristics of the third-generation
biomaterials.

Metals have been used in the development of porous structures that

titanium and titanium alloys.

Examples of Biomaterial Applications

Fabricated from carbons, metals, elastomers, fabrics, and natural valves

Must not react with chemicals in body

Attached by polyester mesh

Almost as soon as valve implanted cardiac function is restored to near

Bileaflet tilting disk heart valve used most widely

More than 45,000 replacement valves implanted every year in the united
states.

Problems with heart valve’s

Degeneration of tissues

Mechanical failure

Postoperative infection

Induction of blood clots

Dental implants

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Small titanium fixture that serves as replacement for the root portion of
missing tooth.

Implant is placed in the bone of the upper or the lower jaw and allowed
to bond with the bone.

Most dental implants are: pure titanium screw-shaped cylinders that act
as roots for crowns and bridges, or as supports for dentures.

Intraocular lenses

Made of PMM, silicone elastomer, and other materials.

By age 75 more thank 50% suffer from cataracts.

1.4 million implantations in the united states yearly.

Good vision is generally restored almost immediately after lens is

Implantation often performed on outpatient basis.

Vascular grafts

Must be flexible.

Designed with open porous structure.

Achieve and maintain homeostasis

Good structure retention.

Adequate burst strength

High fatigue resistance.

Good handling properties.

Biostable.

Hip- replacements
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Most common medical practice using biomaterials.

Corrosion resistant high strength metal alloys.

Very high molecular weight polymers.

Thermostat plastics.

Biomaterials: An Example
Biomechanics of artificial joints
Normal versus arctic hip

Sir john charnel: 1960’s, fundamental principles of the artidicial hip

Frank Gunston: 1969, developed one of the artificial knee joints.

Hip replacements done in the world per year: between 250,000 and
500,000

Of all the factors leading to total hip replacement, osteoarthritis is the

Biocompatibility

The ability of a material to elicit an appropriate biological response in a

Strongly determined by primary chemical structure.

What are some of the challenges?

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To more closely replicate complex tissue architecture and arrangement
in vitro.

To better understand extracellular and intracellular modulators of cell

To develop novel materials and processing techniques that are

To find better strategies for immune acceptance.

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