Comparison of Restorative Materials Flashcards Preview

BDS 2: Dental Materials > Comparison of Restorative Materials > Flashcards

Flashcards in Comparison of Restorative Materials Deck (43)
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1
Q

Resin composites can be chemically cured, what does this mean for the dispensary method?

A

Two paste system

2
Q

What are some of the disadvantages of two paste resin composites? (5)

What do these disadvantages ultimately effect?

A
  • Mixing is difficult
  • Incorporation of air bubbles
  • Discolouration with time
  • Homogeneous mix is not easy to get
  • Degree and time of polymerisation varies throughout the mass
  • Effect modulus and strength
3
Q

What are some advantages of using light cured resins over two pastes? (4)

A
  • Minimal porosity
  • Less discolouration
  • Virtually command set
  • Rapid polymerisation
4
Q

What are some disadvantages of light cured resins? (5)

A
  • Light sensitive during application
  • Thin inhibited layer
  • Limited depth of cure
  • Cure in increments
  • Retina damage from curing light
5
Q

Why do we use amalgamators instead of manual mixing for amalgams? (2)

A
  • Better mix using amalgamators

- Mercury vapour exposure when manually mixing

6
Q

Name some advantages of phenolate bonded acid-base cements (3)

A
  • Easy to mix
  • Long working time
  • Quick set in the mouth
7
Q

Name the 2 phenolate bonded acid base cements

A
  • Zinc oxide eugenol (ZOE)

- Calcium hydroxide

8
Q

Name the 2 polycarboxylate bonded acid base cements

A
  • Zinc polycarboxylate cements

- Glass ionomer cements

9
Q

How would you mix zinc phosphate cements? (3)

A
  • Cooled slab
  • Small increments
  • Over large area
10
Q

With a zinc phosphate cement how would decreased powder:liquid affect;

  • Compressive strength
  • Solubility
  • Initial acidity
  • Setting time
A
  • Decrease
  • Increase
  • Increase
  • Increase
11
Q

With a zinc phosphate cement how would increased rate of powder incorporation affect;

  • Compressive strength
  • Solubility
  • Initial acidity
  • Setting time
A
  • Decrease
  • Increase
  • Increase
  • Decrease
12
Q

With a zinc phosphate cement how would increased mixing time affect;

  • Compressive strength
  • Solubility
  • Initial acidity
  • Setting time
A
  • Decrease
  • Increase
  • Increase
  • Decrease
13
Q

With a zinc phosphate cement how would water contamination affect;

  • Compressive strength
  • Solubility
  • Initial acidity
  • Setting time
A
  • Decrease
  • Increase
  • Increase
  • Decrease or Increase
14
Q

List the pH values for the following cements;

  • Phosphoric acid solution
  • Poly(acrylic acid) solution
  • Zinc phosphate cement
  • Glass ionomer cement
  • Zinc polycarboxylate cement
  • ZOE cement
  • Calcium hydroxide cement
A
  • 1.5
  • 2.5
  • 3.0
  • 3.5
  • 4.0
  • 5.0
  • 9.0
15
Q

What happens to the pH of acid-base cements over time? Why?

A

Increases over time as acid becomes neutralised

16
Q

Which cement causes severe pulpal irritation?

A

Zinc phosphate

17
Q

Which cements cause the least amount of pulpal irritation? (2)

Why do these cements not cause pulpal irritation?

A
  • ZOE cement
  • Calcium hydroxide cement
  • As not acidic
18
Q

Which restorative material is the least soluble?

A

Composites

19
Q

Which restorative material is the most soluble?

A

Calcium hydroxide cement

20
Q

Which restorative material has conductivity properties similar to that of dentine?

A

ZOE cement

21
Q

Which restorative material has diffusivity properties similar to that of dentine?

A

GIC

22
Q

Which restorative material has the best conductivity and diffusivity properties?

A

Amalgam

23
Q

Which restorative material has expansion properties similar to that of a tooth?

A

GIC

24
Q

What is the compressive strength of;

Enamel?
Dentine?

A
  • Enamel = 350 MPa

- Dentine = 270 MPa

25
Q

Which restorative material has the highest compressive strength?

A

Amalgam

400-500 MPa

26
Q

Which restorative material has the lowest compressive strength?

A

Calcium hydroxide cement

10-25 MPa

27
Q

What is the average lifespan of amalgam fillings?

A

12 Years

28
Q

What is the average lifespan of composite fillings?

A

5-7 Years

29
Q

Comment on the biocompatibility of amalgams?

A

Amalgams contain mercury which is potentially toxic

Rare cases of allergy

30
Q

Comment on the biocompatibility of composites?

A

Composites can leach components that are potential carcinogens

31
Q

Compare the level of wear between composites and amalgams

A

Composites wear more than amalgam

32
Q

Compare the level of shrinkage between composites and amalgams

A

Amalgam shrink less as composites undergo polymerisation shrinkage

33
Q

Compare the incidence of secondary caries between composites and amalgams

A

Composites show a higher incidence of secondary caries

34
Q

Compare the amount of required tooth removal between composites and amalgams

A

Composites require removal of less tooth structure

35
Q

Comment on how composites are placed in the oral cavity

A

Composites need to be placed in layers as depth of cure is 2mm

36
Q

Comment on how amalgams are placed in the oral cavity

A

Amalgams need to be incrementally condensed with a condenser

37
Q

Compare the amount of time required to place the filling between composites and amalgams

A

Placement of a composites restoration is a longer procedure

Roughly 1½ times that of amalgam

38
Q

Comment on the working time of ZOE and Calcium hydroxide cements

A

Both long working time

39
Q

Comment the affect of water on ZOE and Calcium hydroxide cement setting

A

Water accelerates set of both cements

40
Q

Compare the strength between ZOE and Calcium hydroxide cements

A

ZOE is stronger

41
Q

Compare the solubility between ZOE and Calcium hydroxide cements

A

ZOE is less soluble than Calcium Hydroxide

42
Q

Comment on the affect ZOE has on inflamed tissue

A

ZOE has a calming effect on inflamed tissues

43
Q

Which of ZOE and calcium hydroxide cements stimulates secondary dentine formation?

A

Calcium hydroxide cements