Final Exam: Prof's Review Flashcards
- Know what you can and cant use an RMGI with when cementing in place
a. Can’t use with non reinforced all ceramic restorations
b. Can use with luting cements, restorative and liners/sealants?
- Describe fluoride release of glass ionomer - Know it can be a reservoir for more fluoride
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
- Self- etching bonding agents.
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
- Know 6th generation self etching process.
After the self etching mix add bonding agent over top of it or mix it yourself with the primer and etching (6th generation)
- Know 7th generation self etching process.
7th they are all mixed together already – primer, etching and bonding agent
- How does most of the bonding occur?
Micromechanical linking into undercuts of enamel, in dentin you are trying to grab around collagen fibers – micromechanical retention
- List 3 most common oligomer used in composites
Bis-GMA, U-DMA and TEG-DMA
- Understand how amount of filler and organic resin affect properties of composites, If you increase filler what does it do to properties of material
a. More filler (microfiller) = higher CTE, more shrinkage, more water shrinkage, lower strenth
b. Most bad things are from polymer matrix
- Most common photo initiator
Camphorquinone
- Biggest problem in polymer shrinkage when you put composite
– it wants to pull away from tooth and you get microgaps, want bonding agent to hold against tooth when it starts to cure
- What happens to the film thickness of cement, consistency of cement when change powder liquid ratio.
Heavy consistency = >
Heavier consistency = greater film thickness = less complete seating of the restoration
- Advantages of adding copper
Ties up tin = reduces gamma 2 formation, increases strength, reduces tarnish and corrosion and reduces creep and marginal deterioration
- Know setting reaction for amalgam (basic) gamma, silver, tin particles
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.
- When we mix with mercury some silver and tin come out, what do silver and tin react with?
Ag and Sn dissolve in Hg
- Eta phase:
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.
- Spherical:
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,
- Gamma 2 phase is bad guy – How do we eliminate it?
eliminate with high copper
- What makes amalgam a brittle material?
Compression strength higher than tensile strength
- Know what creep is
correlates with marginal breakdown
- What in amalgam affects creep
copper affects creep, higher copper amalgams have creep resistance
- What happens to amalgam when over and under triturated
a. Over-trituration: hot mix (sticks to capsule), decreases working/setting time, slight increase in setting contraction
b. Under-trituration: grainy, crumbly mix
- Process of forcing amalgam into cavity prep
– 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
- 4-5 Q’s on amalgam safety
Refer to amalgam safety lecture
- Properties of glass ionomers -
- 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
- Know how the two types of reactions that set the resin modified glass ionomer
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
- 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)
Ability to release fluoride is the reverse
Most fluoride release: is glass ionomer
Least Fluoridation release: is composite.
- Know what high concentration of copper do for use in amalgams
Ties up tin = reduces gamma 2 formation, increases strength, reduces tarnish and corrosion and reduces creep and marginal deterioration
- Know why zinc is added to amalgam materials
Used in manufacturing, oxidizes first so it decreases the oxidation of other elements (sacrificial anode)
- Gamma 2 phase bad guy –
Copper helps eliminate it
- Know about corrosion of amalgam:
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
- Know dimensional changes of amalgam –
– 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
- What property in amalgam correlates most to our marginal breakdown?
Creep - causes it to flow out and causes marginal breakdown. Gamma 2 dramatically affects creep rate, copper resists this.
- Know why amalgam is good restorative material
Inexpensive, ease of use, proved track record (>100 years), familiarity, resin free = less allergies to it
- What’s one advantage a microfilled composite has over micro hybrid?
Esthetics
- Know what factors affect curing of material (curing lights):
time and irradiance, distance, color, cone, collimation (poor you need more curing time)
- Know aqueous from non-aqueous when given list
a. Aqueous – Agar and alginate
b. Non-aqueous elastomers – polysulfide, silicones (condensation and addition) and polyether
- Syneresis and Imbibition
a. Syneresis: fibril cross linking continues – contracts with time and exudes water
b. Imbibition: water absorption - swells
- Know whether or not we can pour an impression more than one time
a. Reversible Hydrocolloid is single cast (disadvantage)
b. Addition Silicones are multiple casts (advantage)
- Know which one can give us the most problem taking out of mouth (which one sets up more rigid)
Polyether: Rigid. Difficult to remove from undercuts
