Biomaterials Exam - Cements, Liners, Bases, and Waxes

Question 1

What is the function of cements?

Answer 1

used to bind restorations or appliances to tooth structure

Question 2

What are the requirements for cements?

Answer 2

low viscosity (needs to fill voids) but good mechanical properties

Question 3

If you wanted a cement to become more viscous, how would you modify it?

Answer 3

add more filler (powder)

Question 4

If you wanted a cement to become less modulus, how would you modify it?

Answer 4

add less filler (powder)

Question 5

Would a low powder:liquid ratio increase or decrease the working and setting time?

Answer 5

increase

Question 6

What are resin-based cements generally used for?

Answer 6

orthodontics, ceramic crowns and bridges, veneers, inlays/onlays

Question 7

What can be added to promote binding in resin adhesives?

Answer 7

4-meta modifier

Question 8

What are liners?

Answer 8

a relatively thin layer of material used to protect the dentin from residual reactants that diffuse out of the restoration or oral fluids that may penetrate leaky restoration interface

Question 9

Do liners have a low or high viscosity?

Answer 9

low

Question 10

When is a calcium hydroxide liner used?

Answer 10

when there is exposure or near exposure of the pulp during a caries restoration

Question 11

What is an indirect pulp cap?

Answer 11

the decay close to the pulp is left during restoration and secondary dentin is formed and after awhile, decay can be removed without damaging the pulp

Question 12

What is a direct pulp cap?

Answer 12

expose the pulp to medicament to stimulate secondary dentin formation

Question 13

How does a calcium hydroxide liner work?

Answer 13

liner releases hydroxide ions (pH>11); when ionized in low concentration, it stimulates odontoblast formation

Question 14

What is ZOE (zinc oxide eugenol) used for?

Answer 14

pain reduction

Question 15

Why can ZOE not be used with composite restorations?

Answer 15

because it inhibits polymerization

Question 16

Does calcium hydroxide lines inhibit polymerization?

Answer 16

no

Question 17

Why are liners and bases used?

Answer 17

to protect the pulp and minimize post-op sensitivity

• acts as a thermal and chemical barrier
• controls inflammation of the pulp
• controls fluid movement

Question 18

What is the function of bases?

Answer 18

used to provide thermal protection for the pulp and to supplement mechanical support for the restoration by distributing local stresses from the restoration across the underlying dentin surface during amalgam condensation (or cementation of indirect restorations)

Question 19

Do bases or liners require greater mechanical properties?

Answer 19

bases because they are providing physical protection

Question 20

What is the most common base?

Answer 20

glass-ionomer

Question 21

What do glass-ionomers release?

Answer 21

fluoride

Question 22

What are the requirements of waxes?

Answer 22

• temporary materials
• should melt at lower temperature
• be carveable
• burn off
• dimensionally stable

Question 23

True or false: higher molecular weight materials are in between polymers and organic liquids

Answer 23

FALSE. Lower molecular weight materials (waxes) are in between polymers and organic liquids.