Comparison of Restorative Materials Flashcards
Resin composites can be chemically cured, what does this mean for the dispensary method?
Two paste system
What are some of the disadvantages of two paste resin composites? (5)
What do these disadvantages ultimately effect?
- 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
What are some advantages of using light cured resins over two pastes? (4)
- Minimal porosity
- Less discolouration
- Virtually command set
- Rapid polymerisation
What are some disadvantages of light cured resins? (5)
- Light sensitive during application
- Thin inhibited layer
- Limited depth of cure
- Cure in increments
- Retina damage from curing light
Why do we use amalgamators instead of manual mixing for amalgams? (2)
- Better mix using amalgamators
- Mercury vapour exposure when manually mixing
Name some advantages of phenolate bonded acid-base cements (3)
- Easy to mix
- Long working time
- Quick set in the mouth
Name the 2 phenolate bonded acid base cements
- Zinc oxide eugenol (ZOE)
- Calcium hydroxide
Name the 2 polycarboxylate bonded acid base cements
- Zinc polycarboxylate cements
- Glass ionomer cements
How would you mix zinc phosphate cements? (3)
- Cooled slab
- Small increments
- Over large area
With a zinc phosphate cement how would decreased powder:liquid affect;
- Compressive strength
- Solubility
- Initial acidity
- Setting time
- Decrease
- Increase
- Increase
- Increase
With a zinc phosphate cement how would increased rate of powder incorporation affect;
- Compressive strength
- Solubility
- Initial acidity
- Setting time
- Decrease
- Increase
- Increase
- Decrease
With a zinc phosphate cement how would increased mixing time affect;
- Compressive strength
- Solubility
- Initial acidity
- Setting time
- Decrease
- Increase
- Increase
- Decrease
With a zinc phosphate cement how would water contamination affect;
- Compressive strength
- Solubility
- Initial acidity
- Setting time
- Decrease
- Increase
- Increase
- Decrease or Increase
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
- 1.5
- 2.5
- 3.0
- 3.5
- 4.0
- 5.0
- 9.0
What happens to the pH of acid-base cements over time? Why?
Increases over time as acid becomes neutralised
Which cement causes severe pulpal irritation?
Zinc phosphate
Which cements cause the least amount of pulpal irritation? (2)
Why do these cements not cause pulpal irritation?
- ZOE cement
- Calcium hydroxide cement
- As not acidic
Which restorative material is the least soluble?
Composites
Which restorative material is the most soluble?
Calcium hydroxide cement
Which restorative material has conductivity properties similar to that of dentine?
ZOE cement
Which restorative material has diffusivity properties similar to that of dentine?
GIC
Which restorative material has the best conductivity and diffusivity properties?
Amalgam
Which restorative material has expansion properties similar to that of a tooth?
GIC
What is the compressive strength of;
Enamel?
Dentine?
- Enamel = 350 MPa
- Dentine = 270 MPa
Which restorative material has the highest compressive strength?
Amalgam
400-500 MPa
Which restorative material has the lowest compressive strength?
Calcium hydroxide cement
10-25 MPa
What is the average lifespan of amalgam fillings?
12 Years
What is the average lifespan of composite fillings?
5-7 Years
Comment on the biocompatibility of amalgams?
Amalgams contain mercury which is potentially toxic
Rare cases of allergy
Comment on the biocompatibility of composites?
Composites can leach components that are potential carcinogens
Compare the level of wear between composites and amalgams
Composites wear more than amalgam
Compare the level of shrinkage between composites and amalgams
Amalgam shrink less as composites undergo polymerisation shrinkage
Compare the incidence of secondary caries between composites and amalgams
Composites show a higher incidence of secondary caries
Compare the amount of required tooth removal between composites and amalgams
Composites require removal of less tooth structure
Comment on how composites are placed in the oral cavity
Composites need to be placed in layers as depth of cure is 2mm
Comment on how amalgams are placed in the oral cavity
Amalgams need to be incrementally condensed with a condenser
Compare the amount of time required to place the filling between composites and amalgams
Placement of a composites restoration is a longer procedure
Roughly 1½ times that of amalgam
Comment on the working time of ZOE and Calcium hydroxide cements
Both long working time
Comment the affect of water on ZOE and Calcium hydroxide cement setting
Water accelerates set of both cements
Compare the strength between ZOE and Calcium hydroxide cements
ZOE is stronger
Compare the solubility between ZOE and Calcium hydroxide cements
ZOE is less soluble than Calcium Hydroxide
Comment on the affect ZOE has on inflamed tissue
ZOE has a calming effect on inflamed tissues
Which of ZOE and calcium hydroxide cements stimulates secondary dentine formation?
Calcium hydroxide cements
