Ceramics

Question 1

Which material is responsible for ceramic’s translucency?

Answer 1

Feldspar

Question 2

The main constituent in feldspathic porcelain:

Answer 2

Feldspar

Question 3

How much does feldspar account for in the composition of feldspathic porcelain (in %)

Answer 3

60-80%

Question 4

Leucite is combination of which two materials?

Answer 4

Feldspar and potassium

Question 5

In feldspathic porcelain, Kaolin is responsible for:

Answer 5

Opacity

Question 6

Which of the porcelain constituents provide strength and hardness?

Answer 6

Silica

Question 7

Which porcelain constituents remains unchanged during firing?

Answer 7

Silica

Question 8

Which feldspathic porcelain constituent gives an addition of strength and opacity while also being an additional glass former?

Answer 8

Aluminum

Question 9

Color pigments are usually made up of:

Answer 9

Metal oxides

Question 10

The elastic modulus of ceramics is considered:

Answer 10

High

Question 11

Ceramic’s fracture toughness is:

Answer 11

Low

Question 12

What is the main limitation of ceramics?

Answer 12

Low fracture toughness

Question 13

Which ceramics has the highest fracture toughness?

Answer 13

Oxide-ceramics (Zirconia)

Question 14

Since ceramics are hard, this will ultimately affect opposing dentition by causing?

Answer 14

Teeth wear

Question 15

What are the weakest ceramics (in terms of ceramic composition)?

Answer 15

Predominantly glass

Question 16

Strongest ceramic (in terms of composition)

Answer 16

Polycrystalline

Question 17

What are the three broad categories of dental ceramics?

Answer 17

Glass-matrix, polycrystalline, resin-matrix

Question 18

Two important constituents of polycrystalline ceramics are:

Answer 18

Alumina and Zirconia

Question 19

Which category of ceramics is used in bruxing patients due to its high resiliency?

Answer 19

Resin-matrix

Question 20

Which category does lithium disilicate (E-max) belong to?

Answer 20

Glass-based ceramics

Question 21

The zirconia-reinforced lithium silicate ceramic belongs to which category?

Answer 21

Polycrystalline

Question 22

Glass-infiltrated ceramics are mostly used as:

Answer 22

Framework/Core

Question 23

In veneering ceramics, which should be the most translucent

Answer 23

Incisal

Question 24

Methods for strengthening dental ceramics:

Answer 24

• Changing microstructures by physical or chemical means
• Minimizing stress concentration of prostheses by reducing inherent surface flaws and redesigning components

Question 25

Interruption of crack propagation is done by:

Answer 25

Dispersion of crystalline phase

Question 26

Development of residual compressive stresses is achieved by:

Answer 26

Ion exchange (chemical tempering)

Question 27

In interruption of cracks methods, the initial phase is ______ then it transforms to __________ phase.

Answer 27

Tetragonal
Monocline

Question 28

To overcome ceramic’s low tensile and shear strength:

Answer 28

Use PFM

Question 29

Disadvantages of MC restorations:

Answer 29

• More tooth reduction
• Less esthetics
• Discoloration (especially during gingival recession)

Question 30

In PFM restorations, the alloying metal should have a firing temperature:

Answer 30

100º-150º higher than the porcelain

Question 31

In PFM restorations, opaque porcelain should be applied in a thickness of:

Answer 31

0.3 mm

Question 32

In the case of noble metal alloys, what forms the chemical bond?

Answer 32

Tin and indium oxide

Question 33

In base-metal alloys, the chemical bonds forms due to:

Answer 33

Chromium oxides or titanium oxides