L4: Metal Ceramic Restorations

Question 1

What are the components of metal based ceramics?

Answer 1

1. metal coping
2. opaquing porcelain
3. body porcelain
4. high fusing shoulder porcelain

Question 2

For a PFM the metal coping should be ____ thick when using a noble metal and ____ thick when using a base metal

Answer 2

0.3-0.5 mm

0.2 mm

Question 3

Where porcelain is not overlayed to the metal coping, the metal should be ___ thick

Answer 3

0.8-1.0 mm

Question 4

Opaquing porcelain is usually ____ thick

Answer 4

0.2-0.3 mm

Question 5

Body porcelain is done in ____ and should be _____ thick

Answer 5

layers; 0.8-2.0 mm

Question 6

List the layers of the body porcelain:

Answer 6

1. dentin
2. enamel
3. translucent
4. modifiers

Question 7

What results when you go beyond the 2.0 mm of body porcelain?

Answer 7

The porcelain becomes unsupported and risks fracture

Question 8

The purpose of this component of a PFM is to keep the porcelain from shrinking back, creating a gap and leading to fracture risk:

Answer 8

high fusing shoulder porcelain

Question 9

Label the following PFM:

Answer 9

Incisal porcelain: 1.5-2.0 mm
Incisal portion:
Middle/body portion: 0.8-0.9mm
Opaque porcelain: 0.1-0.2 mm

(inside)

Cervical metal: 0.3-0.4 mm
Incisal metal: 0.2-0.3

Question 10

-Designed with thickness to support the porcelain
-Designed to support occlusal & proximal contacts
-Designed with extensions to support porcelain
-Margin design to adapt perfectly to margins & support the porcelain if placed on margins

Answer 10

metal coping

Question 11

Describe the design of a metal coping in a PFM:

Answer 11

1. convex, rounded angles
2. ledge of metal to support a 90 degree metal-ceramic finish

Question 12

Metal ceramic bridge designs needs adequate thickness in both the ____ & ____ for rigidity to prevent porcelain fracture, while also trying to optimize esthetics

Answer 12

pontic & connectors

Question 13

Starting with a ____ to create the ideal contour & esthetic, a metal coping is then designed based on the desired porcelain thickness. This metal is then ____ at ____ or ____

Answer 13

wax up; cast at 2300-2600 degrees or milled

Question 14

Once the metal coping is made, the porcelain:

Answer 14

“stacked” onto coping in layers

Question 15

Masks the metal & establishes the metal-ceramic bond:

Answer 15

opaque porcelain

Question 16

Colors include, dentin, enamel, translucent and shoulder porcelains:

Answer 16

body porcelain

Question 17

The final color match/modification once the crown is complete; lower fusing temp than body porcelains:

Answer 17

stains/glazes

Question 18

What does the Identalloy system sticker provide?

Answer 18

Percent & type of metals in the metal substructure crown

Question 19

Au-PT-Pd:

Answer 19

gold-platinum-palladium

Question 20

Au-Pd-Ag:

Answer 20

gold-palladium-silver

Question 21

Ni-Cr-Be:

Answer 21

nickel-chromium-beryllium

Question 22

What are the classifications of the metals used in the metal substructure of a PFM:

Answer 22

1. high noble
2. noble
3. base metal

Question 23

Desirable characteristics of metal ceramic alloys:

Answer 23

1. biocompatibility
2. accuracy of fit
3. HIGH modulus of elasticity
4. HIGH yield strength
5. HIGH resistance to deformation
6. EASILY soldered

Question 24

Noble metal content greater than or equal to 60% with at least 40% of the content being gold:

Answer 24

High noble metals

Question 25

gold-platinum-palladium gold-palladium-silver gold-palladium These are all considered:

Answer 25

high noble metals

Question 26

What happens if the metal substructure contains too much gold?

Answer 26

sag

Question 27

In gold-palladium-silver, what issue did we run into with the silver?

Answer 27

The silver used to discolor some porcelains in a process called greening. This problem is mostly gone & overcome with news formulations

Question 28

When silver discolors porcelain:

Answer 28

greening

Question 29

Benefits of gold-palladium: What component is at a higher percentage?

Answer 29

1. resistant to sag 2. excellent working properties Gold (45-55%)

Question 30

What formulation is what we use in our PFMs at UMKC?

Answer 30

Gold-palladium

Question 31

Resistance to deformation at high temperatures with good yield strength and a high modulus of elasticity:

Answer 31

Sag

Question 32

At least 25% noble metals, but doesn't have to be gold:

Answer 32

noble metals

Question 33

List the formulations of noble metals:

Answer 33

Palladium-silver Palladium-copper Palladium-cobalt Palladium-gallium

Question 34

Noble metals are a compromise between the high noble metals and the base metals in terms of:

Answer 34

1. cost 2. density

Question 35

What aspect of noble metals tends to contribute to having higher strength & greater resistance to deformation?

Answer 35

Less gold

Question 36

List the formatulations of base metals:

Answer 36

1. nickel-chromium 2. nickel-chromium-beryllium 3. cobalt-chromium

Question 37

-stiffer metal -harder metal -greater sag resistance -lowest density -often lowest cost -high likelihood of reaction/sensitiity

Answer 37

Base meta;

Question 38

This property of base metal makes it more difficult to cast & therefore more difficult to finish in preparation for the porcelain & not able to create strong solder joints:

Answer 38

lowest density

Question 39

The lowest density property of base metal can also lead to high oxide formation and therefore problems with:

Answer 39

bonding

Question 40

With base metals, the lab tech handling the ____ is at risk due to carcinogenicity

Answer 40

Beryllium

Question 41

PFM crowns are layered with:

Answer 41

Feldspathic porcelain

Question 42

Feldspathic porcelain is brittle, meaning the _____ strength is better than the ____ strength

Answer 42

compressive; tensile

Question 43

With feldspathic porcelain on a PFM, there is stress dependent chemical reaction between ____ & ____ that cause growth & further fracture even with comparatively low occlusal loading over long periods

Answer 43

water vapor & crack tips

Question 44

-Predominately glass -etchable -most translucent -weakest strength -most esthetic

Answer 44

Feldspathic porcelain

Question 45

-particle-filled glass ceramic -etchable -increased strength -less translucent than feldspathic (but not the least)

Answer 45

Lithium discilicate (e.Max & Empress)

Question 46

-polycrystalline ceramic -not etchable -highest strength -lowest translucency

Answer 46

Zirconia

Question 47

Feldspathic porcelain has several components including:

Answer 47

1. Feldspar (75-85%) 2. Quartz (silica_ 3. Alumina 3. Glass modifiers 5. Leucite

Question 48

Component of feldspathic porcelain responsible for forming the glass matrix:

Answer 48

Feldspar

Question 49

Component of feldspathic porcelain creating the framework around which other components flow:

Answer 49

Quartz

Question 50

Component of feldspathic porcelain which is a hard, strong oxide that increases strength as well as increase the viscosity of the metal when firing:

Answer 50

Alumina

Question 51

Components of porcelains: -alkali fluxes (mostly potassium & sodium oxides) -increases coefficient of CTE -includes opacifiers & colorants

Answer 51

Glass modifiers

Question 52

Component of feldspathic porcelain that is the KEY INGREDIENT to increase CTE to bring ceramic closer to the CTE of metal:

Answer 52

Leucite (10-20%)

Question 53

Porcelain has a low CTE meaning:

Answer 53

It doesn't expand/contract in response to temperature changes

Question 54

Porcelains low CTE puts it at risk for:

Answer 54

fratcure

Question 55

____ increases the CTE of porcelain, making it more fracture resistant

Answer 55

leucite

Question 56

We want metal CTE to be ____ compared to the porcelain CTE

Answer 56

lower (because if the metal expands too much under the porcelain it will cause fracture to the porcelain)

Question 57

Where does the strength of the PFM come from?

Answer 57

1. bond between the ceramic and the metal substructure 2. compatibility of the metal & porcelain 3. design & rigidity of the metal coping or framework

Question 58

The metal-porcelain bond in a PFM is accomplished through:

Answer 58

1. mechanical interlocking of materials 2. Vander Waal's forces 3. chemical bonding (at molecular level) 4. compressive forces

Question 59

The microabrasions from metal finishing or air abrasion:

Answer 59

1. clean the surface 2. create surface that allows for interlocking of porcelain & metal 3. increase surface area of metal 4. increase wearability

Question 60

Allows the porcelain to flow over the metal material better and therefore flow into the abraded surface:

Answer 60

wetability

Question 61

Which of the porcelain layers bonds to the metal coping?

Answer 61

Opaque layer (the silica oxide from the porcelain with the oxide layer of the metal + VDWF)