Material Science of Metal-Ceramics

Question 1

What are four mechanical properties of metal ceramics

Answer 1

mechanical
physical
chemical
biologic

Question 2

What 5 things are involved with mechanical properties

Answer 2

ultimate strength
yield strength
modulus of elasticity
elongation
hardness

Question 3

This component of dentin is higher than enamel

Answer 3

tensile strength

Question 4

What 5 things are involved with physical properties

Answer 4

mass properties
thermal properties
electrical properties
optical properties
surface properties

Question 5

What are the preparation specifications for an MCC

Answer 5

1.5mm axial reduction where you need esthetic looking porcelain

Question 6

Why are alloys used for cast metal and metal-ceramic restorations

Answer 6

because metals in pure form are soft

Question 7

What two mechanisms can be used to improve alloy mechanical properties

Answer 7

solid solution hardening

grain refining

Question 8

Strengthening noble metals can be done what two ways

Answer 8

must be made to resist deformation

modified to impede dislocations

Question 9

This of noble metals resists deformation; block dislocation movements

Answer 9

grain boundaries

Question 10

Fine or Coarse structure resists deformation

Answer 10

fine

Question 11

These two things are greatly improved with small grains

Answer 11

tensile strength and elongation

Question 12

What two things affect the classification of casting alloys

Answer 12

noble metal content

hardness

Question 13

What is the casting alloy classification scale, according to noble metal

Answer 13

very high (>80% gold)
high (60->40% gold)
noble metal (25%) no Au requirement
predominately base metal (25%, no Au require.)

Question 14

This is used at OSU for CVCs; type III (hard) yellow appearance; noble metal alloy

Answer 14

Midas

Question 15

What two things do alloys allow that pure metals do not

Answer 15

improve mechanical and physical properties

improve metal-ceramic bonding

Question 16

This is used at OSU for MCCs, type IV (very hard) white appearance, noble metal alloy (no gold)

Answer 16

Super-Star

Question 17

What three things compose dental procelain

Answer 17

potash feldspar (70-80)
quartz (10-30)
kaolin; clay (0-3)

Question 18

These types of bonds are associated with ceramics and stronger than metallic

Answer 18

ionic or covalent

Question 19

This bond is the electron donor and electron acceptor

Answer 19

ionic bonds

Question 20

This bond involved equally shared electron

Answer 20

covalent bonds

Question 21

Which bond is stronger, covalent or ionic

Answer 21

covalent > ionic

Question 22

This is the building block of dental porcelain; its primarily a glass with some crystalline residuals

Answer 22

SiO4 tetrahedron

Question 23

Ceramics have good what properties

Answer 23

optical

Question 24

Why do ceramics fail

Answer 24

brittle fracture
initiated from internal
cyclic fatigue
stress corrosion

Question 25

What are three properties of ceramics

Answer 25

electrical and thermal insulator
high compressive strength
atoms have no ability to deform brittle fracture

Question 26

What three things are required for porcelain to bond

Answer 26

lower melt temperature than that of metal
must have similar expansion coefficient
must wet the surface of metal

Question 27

This is formed upon heating for a requirement for bonding porcelain to metal

Answer 27

metal oxide

Question 28

This portion of the porcelain is used to mask the color of metal; bond to metal

Answer 28

opaque porcelain

Question 29

This portion of the porcelain provides a majority of the color mimics the dentin color and translucency

Answer 29

body porcelain (dentin)

Question 30

This portion of the porcelain is typically more translucent mimics enamel translucency

Answer 30

incisal porcelain (enamel)