Impression Material-Dr. G

Question 1

How are impression materials classified?

Answer 1

• Flexable
• Rigid

Question 2

What are elastomeric impression materials

Answer 2

• Flexible cross-linked polymers when set
• dominate the market due to
  
  • greater accuracy
  • dimensional stability w/time
  • ability to record details

Question 3

when additional silicone impression materails are mixed in equal quantities, what type of chemical reaction takes place?

Answer 3

• Addition reaction
  
  • occurs b/w the vinyl and hydrogen groups
  • no biproduct formed

Question 4

What volatile biproducts is formed in addition to silicone impression materials?

Answer 4

• No volatile biproduct is formed

Question 5

What are the consequencess of the hydroxyl groups w/silicones?

Answer 5

• Side reaction
  
  • results in formation of hydrogen

Question 6

What is the benefit of adding palladium to additional impression materials?

Answer 6

• Hydrogen absorber
  
  • allows immediate pouring of casts

Question 7

What ingredient make all addition silicone materils hydrophilic?

Answer 7

• Surfactants

Question 8

What are the different types of consistencies for additional silicone materials?

Answer 8

• Low viscosity
• medium viscosity
• high viscosity
• very high viscosity

Question 9

What type of automatic mixing systemss are available for additional silicone impression materials?

Answer 9

• Dual cartridge/auto mix
  
  • base in one tube
  • catalyst in the other
  • exit tip mixed together
• Mechanical mixers
  
  • bulk pastes in containers
  • mix with dynamic tip
  • activated by switch

Question 10

What is a monophase additionn silicone impression material?

Answer 10

• single-consistency material
• used as low and high viscosity materials
• Formulated so under:
  
  • high shear forces: low visocity
    
    • e.g. extruded from syringe
  • Low shear forces: High viscosity
    
    • placed in tray with spatula

Question 11

At the time of removal of additional silicone impression material from the mouth, what is its elastic recovery percentage?

Answer 11

• 99.8%

Question 12

What is the tissue culture test response for addition silicone impression material?

Answer 12

• Negative on base and catalysts
  
  • causes less tissue reaction than other materials

Question 13

What type of gloves should be used to manipulate putty additional silicone impression materials?

Answer 13

• vinyl gloves or bare hand
  
  • avoid latex

Question 14

What contributes to dimensional change in polyether impression materials?

Answer 14

• Polyether absorbs water and changes dimensions if stored in water until equilibrium is reached

Question 15

How long should a polyether impression material be immersed in disinfecting solution?

Answer 15

10 minutes

Question 16

What factors limit the accuracy of wax when used for bitte registration?

Answer 16

• Distortion on removal
• release of internal stress on storage
• high flow properties
• Large dimensiona change from mouth to room temperature

Question 17

What is the working time for elastomeric bite registration materials?

Answer 17

• short working time: 1.5-3 minutes

Question 18

Why are elastomeric bite registration material unsuitable for making regular impressions?

Answer 18

• have less elastic recovery