Metallic, Ceramic and Polymeric Biomaterials

Question 1

physical properties of metals

Answer 1

shininess - luster
higher density
conducts heat and electricity
ductile
malleable
high melting point

Question 2

chemical properties of metals

Answer 2

easily lose electrons, electro-positive elements
metals like to react/have reactive surfaces
loss of mass (some corrode easily)

Question 3

metal alloys

Answer 3

a metal made from mixing two or more metallic elements to optimize materials properties

Question 4

biocompatibility of metals

Answer 4

involves the acceptance of an artificial implant by the surrounding tissues and by the body as a whole

Question 5

why are metals a great choice for implanting into the body

Answer 5

do not irritate surrounding structures
no excessive inflammatory response
do not stimulate immuno-reactions
do not cause cancer

adequate mechanical properties: strength, stiffness, fatigue properties and density

Question 6

stainless steel biomaterials

Answer 6

favorable combination of mechanical properties, corrosion resistance, cost effective and ease for manufacturing
strong
ductile
biocompatible

Question 7

cobalt-chrome alloys

Answer 7

high specific strength, high corrosion resistance and good wear resistance
metal framework for dental partials

Question 8

titanium alloys

Answer 8

most attractive metallic materials for biomedical applications
used for implant devices replacing failed hard tissue

should be free of vanadium and aluminum

Question 9

amalgam pros

Answer 9

low cost, easy to use, high strength and durable
Zn acts as an oxygen scavenger
long service life
posterior load-bearing locations
resistance to fracture
low margin to leakage over time

Question 10

amalgam cons

Answer 10

color does not match tooth
somewhat brittle
subject to corrosion and galvanic action
does not help retain weakened tooth structure
concern about waste disposal

Question 11

mercury in amalgam

Answer 11

unique properties to make it an important component of dental amalgam contributing to its durability

Question 12

characteristics of gold

Answer 12

weak, soft, flexible, malleable, ductile
resists corrosion and tarnish
has high density
has high melting temperature
has low thermal coefficient of thermal expansion

Question 13

ceramic biomaterials

Answer 13

an inorganic, non-metallic, crystalline oxide, nitride or carbide material fired at high temperature
used for: metal crowns, partial dentures, all ceramic crowns, inlays/veneers, ceramic denture teeth

form hard, brittle materials due to strong intramolecular bonds

Question 14

porcelain ceramic biomaterials

Answer 14

family of ceramics composed of kaolin, quartz, and feldspar
porcelain jacket crowns, low-strength and generally limited to anterior teeth

Question 15

feldspar

Answer 15

main ingredient of dental porcelain
crystalline and opaque
has a colour between grey/pink
has fusion temp ~1150C, depending on purity
impurities impart colour, undesirable

Question 16

manufacturing of dental porcelains

Answer 16

mixture decomposes to form a glass amorphous phase and crystalline consisting of leucite
mixture is cooled in water to cause mass to shatter - produces frit glass
metal oxides are added to modify colour

Question 17

glass materials

Answer 17

formed by heating of dry mixtures into a viscous state
then rapidly cooled to prevent crystallinity

Question 18

glass properties

Answer 18

strong
hard - resists scratched and abrasions
elastic
chemical corrosion-resistant
thermal shock-resistant - withstands intense heat or cold
heat-absorbent - retains heat
optical properties - light
electrical insulting - resists electric current

Question 19

polymeric biomaterials

Answer 19

a large molecule composed of many smaller repeating units
used for: complete or partial dentures, impression trays, temporary crowns, maxillofacial prostheses

Question 20

natural polymer

Answer 20

derived from nature
rubber, starch

Question 21

synthetic polymer

Answer 21

manufactured in a lab, generally with petroleum-based materials
MMA, polystyrene

Question 22

addition polymers

Answer 22

consecutively adding monomers
polysaccharides

Question 23

condensing polymers

Answer 23

joining two monomers with elimination of water/acid/alcohol

Question 24

rearrangement polymers

Answer 24

undergoes rearrangement during polymerization

Question 25

biodegradeable

Answer 25

from sources like: cellulose, chitin/chitosan

Question 26

agar

Answer 26

linear polymer
made of two polysaccharides - agarose and agaropectin
linear repeating unit of agarobiose
reversible hydrocolloid
used as dental impression materials

Question 27

converting monomers to polymers

Answer 27

polymerized chains have molecular weights thousands of times greater than their monomer constituents so the chemical and physical properties of polymers are distinct

Question 28

cross-linking of polymers

Answer 28

can have very different stability if polymer network is linked together which has two (or more) double bonds that can participate in free radical polymerization

Question 29

cross-linking of polymers results in

Answer 29

increased rigidity
increased temperature resistance
improved wear
reduced susceptibility to organic solvents

Question 30

homopolymers

Answer 30

only contain one type of starting monomer

Question 31

copolymers

Answer 31

when using two monomers for free-radical polymerization

Question 32

composites

Answer 32

a material with two or more distinct substances
polymers + ceramics

organic resin is a matrix (continuous phase), and hard, ceramic filler particles (discontinuous phase)

Question 33

synthetic resins are used as restorative materials due to the following properties

Answer 33

insoluble in the oral environment
tooth-like appearance/color
insensitive to dehydration
easily manipulated
relative low cost