Exam II-Impression,amalgam,g.i.,etc Flashcards
Lets get it shorty: What are the 4 advantages to GLASS IONOMERS?
1.Chemical adhesion to tooth 2.Flouride Release 3. CTE similar to tooth 4.Biocompatable
What is an RMGI and what are the two ways it is cured?
Resin-modified glass ionomer…1.acid/base reaction 2.light/chemical cure
What are the three phases in the CONVENTIONAL setting reaction for a Glass Ionomer?
1.Ion-Leaching Phase 2.Hydrogel 3.Polysalt-Gel Phase
What is the MOST important part of the Ion-leaching phase in conventional G.I. setting? What are two nuggets of info about this step?
Formation of NaF!…1.Its not native to the Matrix 2.Its physical properties are not affected by depletion
What are the two steps to the setting reaction of RMGI?
1.Acid-base rxn: proceeds slowly 2.Free radical polymerization (light/chemical initiated)
What is the method of Fluoride release in Glass Ionomers? How long for the first stage?
1.Rapid early release from matrix: 1-2 days 2.Slow long term release from particle
Fluoride release does not result in loss of _________ from the glass ionomer because it does not take part in the ______ formation.
physical properties…matrix
Which one releases more fluoride: conventional or RMGI?
HAHA gotcha! they are similar…
G.I. can act as a fluoride _______ by the uptake and _______ of topical fluorides.
reservoir…re-release
What are the 2 contraindications for LUTING cements (RMGI’s for CRWN&BRDGE!)?
1.Non-reinforced (can expand) 2.can CRACK all ceramic crowns
What are the two types of Elastic impression material?
1.Aqueous Hydrocolloids and 2.Non-Aqueous Elastomers
What are the two types of Aqueous Hydrocolloids? Are they reversible??
1.Agar (reversible) 2.Alginate (irreversible)
What is the “squeezing” or exuding of H20 from fibril cross linking as it contracts with time?
SYNERESIS
What are the three types of non-aqueous impression materials?
1.polysulfide 2.Silicones 3.Polyether
What type of impression material is VPS? (4 categories of the tree)
1.Elastic 2.Non-aqueous 3.Silicone 4.Addition
Which impression material was noted for only having a single pour? Which impression material was noted for having multiple pours?
Single Pour-Irreversible Hydrocolloid (alginate) Multiple-Addition Silicones (VPS)
What is the most RIDGID of all impression materials? It is therefore difficult to remove from areas of _________.
Polyether….UNDERCUTS!
Imbibition of an impression material is swelling due to ________.
water absorption
What impression material has the longest working time? Shortest?
Agar=longest….Alginate=shortest
What is the LEAST rigid of all the impression materials?
polysulfide=hydrocolloids
Why do we use AMALGAM?? 1.cost: is is _______ 2.Ease of _____ 3.Proven track record of more then ____ years. 4.Familiarity 5.It is _____-free therefore is has less allergies then composite.
1.inexpensive….2.easy to USE 3.100 years 5.RESIN
Which two materials have the best Fluoride recharge? Which material has the worst?
G.I. & RMGI have the best…Compomers have the worst
FUNCTION of COPPER in our alloy: it ties up _____, which reduces _______ formation, it reduces ______ which therefore reduces _______ deterioration.
TIN…Gamma-2 formation…reduces CREEP….marginal
ZINC in amalgam: it’s used in the _________ process, it decreases _______ of other elements by being the sacrificial _______.
manufacturing….OXIDATION…ANODE
The basic composition of amalgam: it is a ______-______ MATIRX containing FILLER particles of ______-______.
Silver-Mercury matrix…..Silver-Tin filler
In our brick wall analogy: the filler is the _______ (what two metals again!?) and the matrix is the ______(what two metals again?!)
filler-bricks (silver-tin)…..matrix-cement (silver-mercury)
What is the formula for the silver-tin filler and what is another NAME for it?? What are the three possible SHAPES for the filler??
Ag3Sn…. GAMMA…numero 1.irregular (LATHE-cut) 2.Spherical 3.Combo
What is the formula and another name for our silver-mercury matrix cement?
Ag2Hg3…GAMMA 1
What is the formula and name for the VOIDS in our silver-mercury matrix cement?
Sn8Hg….GAMMA 2
What is the composition of Single Composition High-Copper Alloys? What two elements then dissolve in mercury?
A Gamma sphere (Ag3Sn) with Epsilon coating (Cu3Sn)…Ag and Sn dissolve in mercury
What are the 4 methods of adding Copper to amalgam?
1.(SCS) Single Composition Spherical 2.(ALE)-Admixture: Lathe-cut + spherical Eutectic 3.(ALSCS) Admixture: Lathe-cut + Single Composition Spherical 4.(SCL)-Single Composition Lathe-cut
In Single Composition Spherical (SCS)-you use _____ condensation force and a ______ condenser.
LESS force….LARGER condenser
Amalgam Material-Related Variables–Dimensional Change: Most high-copper amalgams under go a net _______ which leaves a marginal ____ so there is initial _____ and post-op _______. How is this reduced over time?
CONTRACTION…GAP..leakage…sensativity…reduced with CORROSION over time
Amalgam-Dimensional change: What are the 3 factors leading to Net contraction?
1.Type of alloy 2. Condensation technique 3.Trituration Time
Amalgam-dimensional change: What type of alloy has more contraction? is this due to more or less mercury?
Sperical Alloys have more contraction..less mercury
In amalgam grater condensation technique= _______ contaction.
HIGHER contraction
In amalgam overtrituration causes ______ contraction.
HIGHER contraction
Amalgam has higher ______ strength VS _____ strength.
Higher compressive strength vs tensile strength
Corrosion of amalgam: ______ strength, but _____ margins. Which type of amalgam will corrode faster: low copper or high copper?
reduces strength, but SEALS margins..low copper amalgam corrodes faster
______: is slow deformation of amalgam placed under constant load.
CREEP
Creep correlates with marginal ________.
breakdown
_____ copper amalgams have creep resistance and to PREVENT this Gamma 2 phase you need more than ____% Copper.
HIGH…more than 12% copper
What is Trituration?
Mixing of liquid mercury with and alloy powder
Overtrituration: will make a “___” mix that _____ to the capsule. It also _____ working/setting time and there is a slight ______ in setting contraction.
“hot” mix that sticks to the capsule…decreases…..increase
Undertrituration will cause a _____, _____ mix.
Grainy, crumbly
What adapts amalgam to the cavity walls?
Condensation
Condensation of amalgam reduces the residual ______ in the restoration.
Mercury
After this man, ______, dentists started to “specialize” in removing amalgam to treat purported _______ toxicity.
Hal Huggins…mercury
What are the three diseases that removing amalgam purportedly cures?
Leukemia, Hodgkin’s Lymphoma, and Multiple Sclerosis
Lay population unfamiliar with peer-reviewed dental literature rely on ______ stories and ______.
media stories and the internet
About how many amalgam restorations are done per year? Leading to about how many TONS of mercury?
1/2 BBAAABAAABAAABillion….75 tons of Hg
What are the two everyday activities that can lead to Mercury vapor being release?
Brushing and Chewing
A study showed that it is difficult to determine mercury ______ levels accurately.
vapor
What is the average daily dose of mercury of a patient with 8-10 amalgam surfaces? How does this compare to threshold levels?
1-2 micrograms/day avg….1% of the threshold 50 micrograms
What are the three forms of mercury? Rank them from least toxic to most…
1.Elemental 2.Inorganic 3.Organic(methyl)
What is the only way Mercury can be absorbed in the body?
LUNGS! only 0.1% from G.I. and Skin
What accounts for most occupational and home mercury exposures?
Mercury VAPOR
What is the MOST TOXIC form of Mercury and is responsible for several mass poisonings???
Organic: Alkyl–> METHYL mercury
How do you check for CHRONIC mercury exposure? How do you check for acute exposure?
Chronic: 300+ micrograms/L in URINE…Acute: 6+ micrograms/L in BLOOD
How does testing mercury levels in hair compare in accuracy?
Hair is NOT a reliable method for determining mercury exposure
Studies found no relationship between amalgam restorations and _________.
Multiple Sclerosis
Controlled human studies fail to find link between amalgam or mercury levels and ________.
Alzheimer’s
Studies showing no _______ dysfunction due to amalgam restorations
renal
Properties of Cements: ____ thickness of a cement has a profound effect on the adaptation of the restoration to the tooth AS WELL AS changing the ___:___ ratio!
Film… POWDER:LIQUID ratio!
Ultimate film thickness depends on: _________ of the powder in the liquid…._______ of the liquid…..________ of the cement……Amount of ______ applied at cementation

Concentration….Viscosity….Consistency….force
What are the 2 factors that influence the ease with which cement is expressed from under the restoration?
1.Consistency of the cement and 2. the type of restoration
