Final Exam: Prof's Review

Question 1

1. Know what you can and cant use an RMGI with when cementing in place

Answer 1

a. Can’t use with non reinforced all ceramic restorations

b. Can use with luting cements, restorative and liners/sealants?

Question 2

2. Describe fluoride release of glass ionomer - Know it can be a reservoir for more fluoride

Answer 2

a. Rapid early release from matrix then slow long term release from particle. Doesn’t result in loss of properties. Can be fluoride reservoir – uptake and re-release

Question 3

3. Self- etching bonding agents.

Answer 3

Conditioner + Primer
- Self etching bonding agents (know what you mix – conditioner and primer and maybe bonding agent depending on generation) Priming and etching are mixed together to hope that primer goes as far as the etch, when you etch separate it doesn’t go as far

Question 4

4. Know 6th generation self etching process.

Answer 4

After the self etching mix add bonding agent over top of it or mix it yourself with the primer and etching (6th generation)

Question 5

5. Know 7th generation self etching process.

Answer 5

7th they are all mixed together already – primer, etching and bonding agent

Question 6

6. How does most of the bonding occur?

Answer 6

Micromechanical linking into undercuts of enamel, in dentin you are trying to grab around collagen fibers – micromechanical retention

Question 7

7. List 3 most common oligomer used in composites

Answer 7

Bis-GMA, U-DMA and TEG-DMA

Question 8

8. Understand how amount of filler and organic resin affect properties of composites, If you increase filler what does it do to properties of material

Answer 8

a. More filler (microfiller) = higher CTE, more shrinkage, more water shrinkage, lower strenth
b. Most bad things are from polymer matrix

Question 9

9. Most common photo initiator

Answer 9

Camphorquinone

Question 10

10. Biggest problem in polymer shrinkage when you put composite

Answer 10

– it wants to pull away from tooth and you get microgaps, want bonding agent to hold against tooth when it starts to cure

Question 11

11. What happens to the film thickness of cement, consistency of cement when change powder liquid ratio.
    Heavy consistency = >

Answer 11

Heavier consistency = greater film thickness = less complete seating of the restoration

Question 12

12. Advantages of adding copper

Answer 12

Ties up tin = reduces gamma 2 formation, increases strength, reduces tarnish and corrosion and reduces creep and marginal deterioration

Question 13

13. Know setting reaction for amalgam (basic) gamma, silver, tin particles

Answer 13

Ag3Sn (γ) + Cu3Sn (ε) + Hg ->
Ag3Sn (γ) + Cu3Sn (ε) + Ag2Hg3 (γ1) + Cu6Sn5 (ŋ)

Note: As Ag and Sn dissolve out of the alloys and into the mercury solution, both (γ1) and (ŋ) are formed. This is what prevents creep. Notice also that gamma-2 (Sn8Hg) is not being made because it is being tied up in the formation of (ŋ) Cu6Sn5.

Question 14

14. When we mix with mercury some silver and tin come out, what do silver and tin react with?

Answer 14

Ag and Sn dissolve in Hg

Question 15

15. Eta phase:

Answer 15

held tightly around silver copper eutectic material– surrounds Ag-Cu alloys
(Admixed high Copper alloy)
Sn diffuses to surface of Ag-Cu particles and reacts with Cu to form eta.

Question 16

16. Spherical:

Answer 16

copper is added as an epsilon coating around gamma particles, when we mix with mercury the silver and tin come out, tin is attracted to surface where copper is, some forms rebars of silver mercury matrix,

Question 17

17. Gamma 2 phase is bad guy – How do we eliminate it?

Answer 17

eliminate with high copper

Question 18

18. What makes amalgam a brittle material?

Answer 18

Compression strength higher than tensile strength

Question 19

19. Know what creep is

Answer 19

correlates with marginal breakdown

Question 20

20. What in amalgam affects creep

Answer 20

copper affects creep, higher copper amalgams have creep resistance

Question 21

21. What happens to amalgam when over and under triturated

Answer 21

a. Over-trituration: hot mix (sticks to capsule), decreases working/setting time, slight increase in setting contraction
b. Under-trituration: grainy, crumbly mix

Question 22

22. Process of forcing amalgam into cavity prep

Answer 22

– condensing, what are we trying to accomplish are no voids, we want it well adapted to walls and floors of cavity prep, get rid of excess mercury

Question 23

23. 4-5 Q’s on amalgam safety

Answer 23

Refer to amalgam safety lecture

Question 24

24. Properties of glass ionomers -

Answer 24

• Good things about them = fluoride release, don’t have to etch – will chemically bond to tooth by itself, can use on wet settings (biocompatible), CTE is about same as tooth

Question 25

25. Know how the two types of reactions that set the resin modified glass ionomer

Answer 25

a. Traditional glass-ionomer acid base reaction – proceeds more slowly b. Free Radical Polymerization – similar to composites, light initiated and chemical c. Cross-linked resin-reinforced matrix

Question 26

26. Be able to rate the glass ionomer and composites and ? (one more) - from most fluoride release to least, best polish ability, strain from most to least (chart)

Answer 26

Polishing and strength is: Glass ionomer (worst/weakest) -> RMGI -> compomer -> composite (best/strongest) ------------ Ability to release fluoride is the reverse Most fluoride release: is glass ionomer Least Fluoridation release: is composite.

Question 27

27. Know what high concentration of copper do for use in amalgams

Answer 27

Ties up tin = reduces gamma 2 formation, increases strength, reduces tarnish and corrosion and reduces creep and marginal deterioration

Question 28

28. Know why zinc is added to amalgam materials

Answer 28

Used in manufacturing, oxidizes first so it decreases the oxidation of other elements (sacrificial anode)

Question 29

29. Gamma 2 phase bad guy –

Answer 29

Copper helps eliminate it

Question 30

30. Know about corrosion of amalgam:

Answer 30

we want it to corrode to seal off the margins, high copper makes it take longer to corrode (6-24 months). It also reduces strength

Question 31

31. Know dimensional changes of amalgam –

Answer 31

– it tends to contract a little bit, which contract the most? High copper contracts more, spherical contracts more b/c less mercury, greater condensation you get higher contraction and over-trituration causes more contraction

Question 32

32. What property in amalgam correlates most to our marginal breakdown?

Answer 32

Creep - causes it to flow out and causes marginal breakdown. Gamma 2 dramatically affects creep rate, copper resists this.

Question 33

33. Know why amalgam is good restorative material

Answer 33

Inexpensive, ease of use, proved track record (>100 years), familiarity, resin free = less allergies to it

Question 34

34. What’s one advantage a microfilled composite has over micro hybrid?

Answer 34

Esthetics

Question 35

35. Know what factors affect curing of material (curing lights):

Answer 35

time and irradiance, distance, color, cone, collimation (poor you need more curing time)

Question 36

36. Know aqueous from non-aqueous when given list

Answer 36

a. Aqueous – Agar and alginate | b. Non-aqueous elastomers – polysulfide, silicones (condensation and addition) and polyether

Question 37

37. Syneresis and Imbibition

Answer 37

a. Syneresis: fibril cross linking continues – contracts with time and exudes water b. Imbibition: water absorption - swells

Question 38

38. Know whether or not we can pour an impression more than one time

Answer 38

a. Reversible Hydrocolloid is single cast (disadvantage) | b. Addition Silicones are multiple casts (advantage)

Question 39

39. Know which one can give us the most problem taking out of mouth (which one sets up more rigid)

Answer 39

Polyether: Rigid. Difficult to remove from undercuts