Dental Materials Alloys

Front 1

What gives ceramic bonding alloys the chemical and mechanical retention?

Back 1

An oxide layer

Front 2

What is the amount of expansion or contraction called?

Back 2

Coefficient of thermal expansion

Front 3

What is the melting range of ceramic bonding alloys?

Back 3

850-1350 deg C

Front 4

In ceramic bonding alloys, what elements are added to high-noble & noble alloys to form the oxide layer?

Back 4

Gallium, indium, or tin

Front 5

What are solders used for?

Back 5

a. join an orthodontic wire to a band
b. join a clasp wire to a RPD
c. join two units of a FPD
d. Add proximal contact
e. Repair an occlusal defect in a casting

Front 6

What is the melting point of solder?

Back 6

425 deg C

Front 7

A material that cleans the alloy to be soldered and dissolves any surface oxide on the metal is called what?

Back 7

Flux

Front 8

What is the advantage of a laser solder

Back 8

Very precise and solders in seconds

Front 9

What is the relationship between the melting point of the solder and that of the metal you are soldering to?

Back 9

MP (melting pt) of solder has to be lower than the MP of the metal you are soldering

Front 10

What are some common uses for wrought alloys?

Back 10

a. orthodontic wires
b. endodontic files
c. RPD clasps

Front 11

What are wrought alloys?

Back 11

Alloys that are shaped into another form by mechanical force

Front 12

What is significant about the grain structure of wrought alloys?

Back 12

Wrought alloys have a grain structure often described as fibrous

Front 13

When might you be suspicious of a metal allergy?

Back 13

Inflammation around the margin- if the crown is placed correctly, etc suspect that it might be an allergy

Front 14

What is the most common allergy to metal?

Back 14

Nickel

Front 15

What is the biocompatibility of alloys related to?

Back 15

Corrosion

Front 16

Why is corrosion bad?

Back 16

Corrosion releases more of its elements into the mouth increasing the risk for unwanted reactions

Front 17

What symptoms might a patient experience from corrosion of an alloy?

Back 17

a. unpleasant tastes
b. irritation
c. allergy

Front 18

What do base-metal alloys primarily contain?

Back 18

Nickel, cobalt, or titanium

Front 19

What alloy is considered the most difficult to manipulate in the laboratory?

Back 19

Base-metal alloys

Front 20

What are the best features of base-metal alloys?

Back 20

a. Extremely high yield strength & hardness
b. Very low cost

Front 21

What are the negative features of base metal alloys?

Back 21

High corrosion and questionable biocompatibility in the mouth

Front 22

What are the main uses for base-metal alloys?

Back 22

Crowns, FPD, RPD, implants, & wrought forms

Front 23

What % of noble metal content do noble alloys contain?

Back 23

At least 25% of noble metal content

Front 24

What are the primary bases that compose noble alloys?

Back 24

a. gold-based
b. palladium-based
c. silver-based

Front 25

What alloy has a higher yield strength and hardness, high-noble alloys or noble alloys?

Back 25

Noble alloys

Front 26

What are the biggest draw-backs to noble alloys?

Back 26

They are expensive

Front 27

What is the corrosion like in noble alloys?

Back 27

Low

Front 28

What are the main uses for noble alloys?

Back 28

FPD and crowns

Front 29

What % of gold, palladium, or platinum must an alloy be to be considered a high-noble alloy?

Back 29

60%

Front 30

What alloy is easy to manipulate in the lab?

Back 30

High-noble alloys

Front 31

What is corrosion like for high-noble alloys?

Back 31

Very low corrosion

Front 32

What are the grains between crystals referred to as?

Back 32

Grain boundaries

Front 33

What are grain refiners?

Back 33

Small size of the grains give better properties to the alloy

Front 34

What are the grains between crystal called?

Back 34

Grain boundaries

Front 35

What is the benefit of nickel added to an alloy?

Back 35

Improves mechanical properties of base metal alloys

Front 36

What are some base metals?

Back 36

a. Nickel
b. Silver
c. Zinc
d. Copper
e. Titanium

Front 37

What is the benefit of copper added to an alloy?

Back 37

It increases strength and hardness

Front 38

What is the benefit of zinc added to an alloy?

Back 38

a. Acts as a scavenger (deoxidizing agent)
b. Improves the castability and fluidity of the alloy

Front 39

What is the benefit of silver added to an alloy?

Back 39

Improves mechanical properties of gold alloys

Front 40

What properties are base metals required in alloys for?

Back 40

a. strength
b. flexibility
c. wear

Front 41

What is a negative feature of base metals?

Back 41

Corrosion

Front 42

What does a higher melting temperature indicate?

Back 42

Harder to cast

Front 43

What system is used to describe gold-based dental solders?

Back 43

Fineness

Front 44

How is fineness obtained?

Back 44

F = %gold x 10

Front 45

What is the melting temperature of platinum?

Back 45

1755 deg C

Front 46

What is the melting temperature of palladium?

Back 46

1555 deg C

Front 47

Which noble metal has a higher melting temperature, platinum or palladium?

Back 47

Platinum (1755 deg C)

Front 48

How are carats calculated?

Back 48

K = 24 x %gold/100

Front 49

How may gold content be expressed in terms of?

Back 49

a. percentages
b. carat
c. fineness
d. color

Front 50

What is the melting temp of gold?

Back 50

1063 deg C

Front 51

What are the noble metals?

Back 51

Au Pt & Pd

Front 52

What are the good properties of gold?

Back 52

Soft, malleable, ductile metal w/high nobility that resists tarnish & corrosion

Front 53

What is an alloy?

Back 53

Mixture of different metals

Front 54

What is a casting?

Back 54

The melting process of the metal forming the alloy

Front 55

How are solders heated?

Back 55

a. blow torch
b. traditional oven
c. laser

Front 56

_______ & ________ are combined to create an alloy

Back 56

Metals & nonmetals

Front 57

What is the yield strength of a soft alloy, restorations subjected to low stress: some inlays?

Back 57

type I alloy <140

Front 58

What is the yield strength of a medium alloy, restorations subjected to moderate stress: inlays & onlays

Back 58

Type II alloy 140-200

Front 59

What is the yield strength of a hard alloy, restorations subjected to high stress: crowns, thick veneer crowns, long-span FPD, RPD

Back 59

Type III alloy 201-340

Front 60

What is the yield strength of a extra hard alloy, restorations subjected to very high stress: thin veneer crowns, long span FPD, RPD

Back 60

Type IV alloy >340

Front 61

What are some problems associated with Ceramic Bonding alloys?

Back 61

The color of the oxide
Greening
Debonding of the ceramic

Front 62

What is greening in ceramic bonding alloys?

Back 62

Vaporization of metal alloys that will discolor the ceramic matrix, making it look greenish, due to high amounts of silver and copper.