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Flashcards in DMS Tutorial Deck (12)
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1
Q

What is hardness?

A

resistance to permanent surface indentation

1
Q

knoops vs vickers hardness

A

vickers hardness = measure of hard metals/alloys
knoops hardness = measure of composite

2
Q

What is compressive strength?

A

maximum compressive force the material can withstand before permanent deformation

3
Q

What is wear resistance?

A

the ability of a material to resist the progressive loss of volume from along its surface through mechanical actions such as repeated rubbing, sliding, or scraping.

4
Q

What should always be known before using a light cure material?

A

depth of cure

5
Q

What is bond strength?

A

strength of micromechanical retention of the bonding agent into the etched surfaces of enamel and primed dentin.

6
Q

What is the bond strength of composite usually?

A

typically between 20-40MPa
usually 10% of compressive strength

7
Q

What is the compressive strength of composite usually?

A

300-400MPa

8
Q

What does shrinkage cause?

A

leads to gaps > fractures > ingress of fluid > microleakage > secondary caries

9
Q

What is young’s modulus/elastic modulus?

A

Resistance to elastic deformation of a material by force that is calculated as the ratio of elastic stress to elastic strain.

10
Q

What happens if the stress is higher than the elastic limit?

A

permanent deformation

11
Q

What is young’s modulus for composite, enamel, and dentine?

A

composite = 15 GP
enamel = 60 GP
dentine = 20 GP