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Flashcards in dental materials Deck (34):
1

what is the medical devices directive changes?

-statement of manufacture offered to all patients recieving dental appliance
-GDC often invite patients to ask for this certificate

2

what is an alloy?

-a mixture of two or more metals

3

what is a grain boundary?

-where the crystals meet
-a source of tension

4

how are grain boundaries visualised?

-light reflecting microscope

5

what are the 3 different types of solid solution?

1. ordered solid solution
2. random solid solution
3. interstitual solid solution

6

what are the two compositions of amalgam?

1.conventional
2.copper enriched ( high copper)

7

what is to composition of conventional amalgam?

65% Ag, 29% Sn, 6% Cu, 2% Zn, 3% Hg

8

what is the composition of high copper amalgam?

40% Ag, 32% Sn, 30% Cu, 2% Zn, 3% Hg

9

what is the ISO limits of expansion/contraction??

+/- 0.1%

10

what does Zn act as in amalgam?

-Zn acts as a scavenger for Oxygen

11

when is amalgam fully set?

24hrs after placement

12

what is creep?

-protrusions at restoration margins
-gamma 2 phase is largerly, not exclusively responsible

13

what does corrosion provide?

-corrosion provides marginal seal

14

Mercury compounds in amalgam are known to be toxic to what?

-CNS

15

what are silicates?

-earliest tooth coloured restorative material
-releases flouride
-prone to eriosion
-brittle

16

what are the 4 stages of free radical polymerisation of methyl methacrolate?

1.activation
2.initiation
3.propogation
4.termination

17

what is a resin composite?

-a combination of two chemically different materials with a distinct interface seperating the components and having properties which could not be achieved by any of the components alone

18

what are the 3 kinds of resin composites?

1.microfilled
2.hybrid
3.macrofilled

19

for a product to be on the market, what must they confirm with?

-ISO 4049

20

what is an ormocer?

-monomer free nano-hybrid composite

21

can you place an amalgam in a pt that is pregnant?

-No. Department of health banned amalgam placing in pts that are pregnant

22

what are the two classifications of impression material?

-elastic
-non-elastic

23

what are the two types of hydrocolloid?

-reversible and irreversible

24

give an example of a reversible hydrocolloid?

-agar

25

give an example of irreversible hydrocolloid?

-alginate

26

what features do reversible and irreversible hydrocolloids both have in common?

-both colloidal suspensions of polysaccharides in water

27

what is agar?

-complex polysaccharide derived from seaweed

28

give examples of mucostatic materials?

-plaster
-alginate

29

what are some alternatives to impressions?

-CAD CAM
-Intra oral scanner

30

what are 4 types of elastomeric impression material?

1.polysulphides
2.silicon rubbers(condensation curing)
3.silicon rubbers(addition curing)
4.polyether

31

what is the byproduct of silicon rubbers (condensation curing)?

-alcohol (ethyl)

32

what is the by product of silicone rubber (addition curing)?

-there is no by product

33

what are the 3 products of gypsum?

1.dental plaster
2.dental stone
3.densite

34

what does borax act as in gypsum?

-borax acts as the retarder and slows down the reaction