Denal materials

Question 1

name the 6 different categories in materials

Answer 1

cermet, metallic, organo-metallic, polymers, composite, ceramics

Question 2

what 2 mixed make composites?

Answer 2

ceramics and polymers

Question 3

describe metals

Answer 3

high conductivity, luster, malleable, forms Cations when disolved

Question 4

describe polymers

Answer 4

large molecule formed by many small ones

Question 5

describe ceramics

Answer 5

inorganic & non-metallic, usually oxides but also sulfides ( glass is a type of ceramic)

Question 6

describe composites

Answer 6

combination of ceramic powder and polymers

Question 7

describe cermet

Answer 7

metal and ceramic powders combined

Question 8

describe organometallic

Answer 8

dispersion of metal powders in a polymer, not common in dentistry

Question 9

name the properties that are commonly tested for in dentistry

Answer 9

compression, tension, torsion, shear.

Question 10

strength testing devices test what 2 things?

Answer 10

strain( change in dimension), stress( force/ area)

Question 11

tensile tests test what

Answer 11

force/area, force pulling up and area being pulled

Question 12

name some tests for bending

Answer 12

3 point, 4 point flexure test

Question 13

shear testing is often used for what?

Answer 13

bonding

Question 14

name the 3 adhesion mechanisms

Answer 14

mechanical, chemical, wetting/contact angle

Question 15

torsion is important in what

Answer 15

tooth extraction, implant placement

Question 16

describe fracture toughness

Answer 16

resistance to fracture when crack is present

Question 17

describe elastic modulus

Answer 17

even slope= elastic, above is rigid, below is ductle

Question 18

what is brittle?

Answer 18

no visible deformation before breaking

Question 19

what is duclte?

Answer 19

visible deformation before breaking

Question 20

what is cyclic fatigue?

Answer 20

how many cycles its used until failure

Question 21

what is thermal cycling?

Answer 21

hot and cold baths alternating for fixed number of cycles. Then test bond strength, compare to strengths without cycling

Question 22

DPH

Answer 22

Diamond pyramid hardness. Tests the hardness of a material

Question 23

other ways to test hardness

Answer 23

Rockwell- conical

brinell- spherical

Question 24

wear resistance

Answer 24

abrasion- mechanical or scratching
chemical- erosion
3 body wear- includes material between 2 surfaces ( food)

Question 25

what is rheology

Answer 25

flow, viscous( honey,syrup) or non-viscous (water)

Question 26

rheology testing tells you if the material is...

Answer 26

Newtonian pseudoplastic- flow increases with shear rate dilatant- flow decreases with shear rate( silly putty)

Question 27

what is corrosion/tarnish?

Answer 27

electrochemical reaction of 2 metals, oxidation. It can affect all materials

Question 28

what is radiopacity?

Answer 28

absorption of x-rays ( white). It correlates with atomic weights of components

Question 29

heavy elements that are good include...

Answer 29

gold, silver, palladium, platiunum, tungsten, barium sulfate, bismuth oxide

Question 30

heavy but toxic include...

Answer 30

arsenic, mercury, tellurium, lead, antimony

Question 31

what is color metamerism?

Answer 31

2 material match under one light but don't under another

Question 32

biocompatibility of materials depends on....

Answer 32

cytoxicity, allergenicity, irritation, implantation, mutagenicity

Question 33

results of cytotoxicity depend on what

Answer 33

cell line, direct contact, roughness of material, materials composition, reaction with medium,

Question 34

balance of cytotoxicity

Answer 34

mammalian cells- tolerate high PH | Bacteria- Anticeptic

Question 35

what is glass?

Answer 35

inorganic, non-crystalline, can be radiopaque, usually silica based

Question 36

is silica the same as silicone?

Answer 36

no, silicone is organic

Question 37

thermoplastic vs thermosetting

Answer 37

thermoplastic can be reformed

Question 38

common ceramic #1

Answer 38

zinc oxide, has antimicrobial properties. Also is a filler and reacts with salts to make restoratives

Question 39

common ceramic #2

Answer 39

calcium hydroxide, soluble in high ph. Also has High PH which is a antimicrobial property as well. It reacts with CO2 to form calcium carbonate ( which is seashells, snail shells, egg shells, coral, marble)

Question 40

organics

Answer 40

silicone- polymers of rotating Silicone and oxygen molecules with organic side groups

Question 41

terminology for metals | alloy, amalgam, stainless steel

Answer 41

alloy-combination of 2 metals, amalgam- alloy of mercury used for dental fillings. stainless steel- iron alloy with more that 10.5% Cr

Question 42

what is Ni-Ti used for?

Answer 42

nickel titatnium- used for endodontics and orthodontics since it is flexible

Question 43

what is straight titanium used for?

Answer 43

its very stiff and used for implants

Question 44

what is a micron?

Answer 44

1 millionth of a meter

Question 45

what is a nanometer?

Answer 45

1 billionth of a meter

Question 46

what is a nanoparticle?

Answer 46

have much higher surface to volume rations

Question 47

basic principle to remember

Answer 47

body temperature accelerates reactions, radiopacity relys on high atomic weights, acid plus base =salt