Classes of Materials Used in Medicine

Question 1

Classification of materials: conventional, novel

Answer 1

• ceramics
• metals
• polymers (synthetic and natural)
• composites
• Nanomaterial
• Smart material (able to respond to environment such as chemicals, environmental sensitive polymers)

Question 2

Ceramics

Answer 2

inorganic compounds contain metallic and non-metallic elements, for which interatomic bonding is ionic or covalent, and which are generally formed at high temperatures
most ceramics occur as minerals, mostly silicon and aluminum

Question 3

Ceramics advantages

Answer 3

• inert or bioactive in body
• high wear resistance (orthopedic and dental applications)
• high modulus and compressive strength
• esthetic properties

Question 4

Ceramic disadvantages

Answer 4

• brittle
• low tensile strength
• poor fatigue

Question 5

Ceramic applications

Answer 5

• femoral heads and cup inserts for ceramic on polyethylene
• ceramic on ceramic hip replacement bearings
• knee prostheses
• spinal fusion devices
• orthopedic instrumentation - dental-crowns
• bridges, implants and caps
• inner ear implants (cochlear implants)
• drug delivery devices

Question 6

Nearly bioinert ceramtics

Answer 6

Alumina (Al2O3) and Zirconia (ZnO2) ceramics

Question 7

hydroxyapatite (bioactive)

Answer 7

low strength but useful as coating for metallic implants, aids in tissue fixation of the implant by providing a porous surface and its surrounding tissue

Question 8

Metals

Answer 8

closely packed crystal structure, valuable as load-bearing implants as well as internal fixation devices

Question 9

Metal characteristics

Answer 9

high tensile strength, fatigue, and yield strength, low reactivity

Question 10

Metal complication

Answer 10

Stress shielding
in hip implantation: the high strength of the metal in the impact induces it to assume more than its share of responsibility for the load in that region decreasing the load born by the surrounding tissue and therefore shielding it from experiencing stress causing bone density to decrease as bone tissue resorbs, cause complications in the implant/tissue

Question 11

Metal applications

Answer 11

medical tubing, stents, catheters

Question 12

Polymers

Answer 12

consist of small repeating units strung together in long chain, largest class of biomaterials, flexible structure enables it to be useful in applications from plastic garbage bags to rubber tires, adjusting the length of the chain and produce different properties with different applications

Question 13

Polymer characteristics

Answer 13

• Hydrophilic
• Hydrophobic
• Biostable
• Biodegradable
• Natural
• Synthetic
• Highly processable

Question 14

Composites vs other materals

Answer 14

• provide improved properties that typical metals, polymers, and ceramics alone cannot provide
• combine strength and flexibility by reinforcing a relatively flexible material with a harder, stronger one
• properties can be tailored by changing the composition ratio
• desirable for applications ranging from orthopedics, dentistry, and drug delivery to frontiers such as cancer theranostics

Question 15

Composites

Answer 15

formed by combining multiple components of materials, such as metals, polymers, and ceramics; incorporates the desired characteristics of different materials to meet the stringent demands of living tissue

Question 16

Bioactive materials vs biointertness

Answer 16

play a more aggressive role in the body. While a biocompatible material should affect the equilibrium of the body as little as possible, a bioactive material recruits specific interactions between the material and surrounding tissue.

Question 17

Bioactive Materials

Answer 17

• encourage tissue integration to aid in the fixation of an implant in the body.
• a porous coating of Hydroxyapatite (HA), a normal component of bone, to help permanently stabilize the stem of the implant in the bone. The coating encourages ingrowth from the surrounding tissue that interlocks within the pores much like the pieces of a puzzle lock together.

Question 18

Which ceramic material, known for its composition similar to bone mineral, is primarily used to promote bone growth in grafting procedures?
A) Zirconia B) Alumina C) Silicon carbide D) Hydroxyapatite

Answer 18

D) hydrozxyapatite

Question 19

Considering factors like strength and resistance to body fluids, which metal alloy would be the optimal choice for constructing long-term orthopedic implants? A) Stainless steel B) Aluminum alloy C) Copper alloy D) Zinc alloy

Answer 19

A) stainless steel

Question 20

Given its properties of biodegradability and compatibility, which polymer would be most suitable for developing temporary surgical sutures? A) Polyethylene (PE) B) Poly(lactic acid) (PLA) C) Polyvinyl chloride (PVC) D) Polymethyl methacrylate (PMMA)

Answer 20

B) Poly(lactic acid) (PLA)

Question 21

Composite materials are used in dental applications. What is the primary function of the matrix component in a dental composite? A) To provide hardness B) To bond the filler particles together C) To act as a filler D) To enhance thermal conductivity

Answer 21

B) to bond the filler particles together (picture on slide with composites)
polymer processing for dental application
after implantation, interacts with living tissue, particles diffuse out of composite into living tissue to stimulate bone growth, the surrounding tissue will interact with the composite and may be able to interact

Question 22

Requirements of biomaterials

Answer 22

• inert or specifically interactive
• biocompatible with the physiological context
• mechanically and chemically stable or
• biodegradable
• processable (for manufacturability)
• nonthrombogenic (if blood-contacting)
• sterilizable