2/1: Amalgam Flashcards
What are the benefits to amalgam?
Easy to manipulate
Can be placed in its plastic state and carved before it hardens
Excellent physical properties
Cost effective
What are the excellent physical properties of amalgam?
Strong and predictable
Self-sealing
- due to corrosion over time
What is an effective barrier against recurrent caries with amalgam?
Its self-sealing properties
What is the composition of amalgam?
From most to least
Ag, 70%, strength
Sn, 16%, expansion
Cu, 13%, strength
Zn, 1%, deoxidizer
What is amalgam an alloy of?
Silver, copper, tin, and zinc
What is amalgam mixed with?
Mercury to form an alloy that can be packed into a dental prep
What is conventional amalgam known as?
“low copper”
What does high copper amalgam contain?
9-30% copper
The presence of copper in high copper amalgam eleminates:
Gamma-2 phase, resulting in stronger restoration
What kind of amalgam do we use at the school?
High copper amalgam
What are the three phases of amalgam setting?
Gamma
Gamma-1
Gamma-2
What is gamma amalgam setting?
Tin and silver react with mercury, forms silver mercury (gamma-1) and tin mercury (gamma-2)
What kind of amalgam is strong, corrosion resistant?
Gamma
What is gamma-1 amalgam?
Silver-mercury
What amalgam is weaker, susceptible to corrosion?
Gamma-1
What is gamma-2 amalgam made of?
Tin-mercury
What amalgam is weakest, most susceptible to corrosion?
Gamma-2
What happens when you add copper to amalgam?
Creates a copper-tin phase (eta), eliminates tin-mercury gamma-2 phase
What is the equation for low copper amalgam?
gamma + mercury -> gamma + gamma-1 + gamma-2
What is the equation for high copper amalgam?
gamma + copper + mercury -> gamma + gamma-1 + CuSn
What is lathe shape?
Outdated - particles were formed by cutting a block of alloy with a lathe
What does lathe shape for amalgam result in?
Large, irregular particles
What are admixed particles?
Lathe type particles mixed with small spheres
What force do admixed particles require?
More condensation force
What type of particle is most commonly used type of amalgam?
Admixed
What kind of strength do admixed particles have?
Low early strength (1-hour)
What are examples of admixed particles?
Kerr Contour and Ivoclar valiant
What are the strength of spherical particles?
Higher early strength (1-hour) and higher 24-hour strength than admixed
What is a con of spherical particles?
May be more difficult to achieve interproximal contact
What particles require less condensation force?
Spherical
All the shapes of particles have similar _______, but different ________
Success; handling properties
What is the mercury to alloy ratio?
- less mercury in final resrtoration is superior (better strength and corrosion resistance)
- proper condensation and finishing results in less mercury in final restoration
- admixed alloys ~50% mercury, spherical alloys slightly less
What is trituration of amalgam?
- mixing the amalgam
- longer and faster trituration = sets faster
- follow manufacturer’s guidelines
What is the most critical variable of amalgam?
Condensation
What is the most common error made my dentists?
Undercondensation
What is recommended with high copper alloys?
Pre-carve and post-carve burnish
What evidence supports the safety of amalgam?
- mercury vapor is realesed in chewing
- no side effects at such low doses
- dental professionals are exposed to more mercury than non dental professional
Most of the “data” that suffests amalgam is unsafe is _______
anecdotal
Amalgam has/has not been found to play a role in neurodegenerative diseases?
Has not
Amalgam has ______ compressive strength and ______ tensile strength
High; low
What does it mean that amalgam is brittle in small bulk?
- requires minimal thickness of material to avoid breaking
- 1.2-2mm pulpal depth
- isthmus can be 1 mm (chewing forces not directed at isthmus width)
What is amalgam sensitive to?
Moisture contamination during placement
- Water reacts with the zinc in the amalgam and causes an eventual expansion of
the alloy out of the preparation
- Amalgam is still a good choice in situations where moisture control is difficult.
You can scrape off the top, contaminated layer and keep packing amalgam
Does amalgam corrode?
Yes - Modern alloys have a high copper content which minimizes corrosion, but
doesn’t prevent it entirely
What does amalgam create and regenerate between itself and the tooth?
Seal
Oxides are formed which expand and fill tiny voids, preventing microleakage
No other dental restorative material does this.
What are disadvantages of amalgam?
- Poor esthetics.
- Need for good mercury hygiene.
- Remove more tooth structure for adequate bulk of material.
- Doesn’t bond to tooth structure.
- Thermal conductor, necessitating use of a liner or base to prevent postop sensitivity on deeper restorations.
- Eventually may “ditch” at the margins, collecting plaque in that area.
What are advantages of amalgam?
- More forgiving in areas where moisture is hard to control.
- High wear resistance and compressive strength.
- Can be placed in less time than other options (lower cost.)
- Relatively long-lasting.
- Regenerates its seal.
- Is less prone to recurrent decay than bonded composite resin restorations.
What are indications for amalgam?
- Moderate to large Class I and Class II restorations.
- Heavy occlusal wear.
- High caries rate.
- Difficult isolation.
- Gingival margins on root.
- Class V restorations in non-esthetic zones.
- Temporary restorations on teeth with questionable
prognosis. - Buildups under crowns for extensively damaged teeth
- Usually with supplemental retention (pins, posts, grooves)
What are the materials that are used for an occlusal restoration in clinic?
- Calcium hydroxide (ex: dycal)
-2 paste system, dispenses from separate tubes, mix
-Stimulates reparative dentin formation - glass ionomer (Ex: vitrebond)
-2 paste system, dispenses from “clicker,” mix
-Light cure
-Releases fluoride over time
What are types of desensitizers?
- Copal resin (Ex.: Copalite)
- Bonding Agents
- Gluteraldehyde & (2-hydroxyethyl)methylacrylate [HEMA] desensitizer
(Ex.: Gluma)
What are the advantages and disadvantages to copal resin (ex: copalite)?
a. Advantage: inexpensive , quick to use
b. Disadvantage: leaves a film thickness (could wash out, causing microleakage)
What are the advantages and disadvantages to unfilled dentin bond agent (ex: PQ-1, Peak)?
a. Advantage: intermediate in cost
b. Disadvantage: some require more than one step; involves some
form of etching with an acid, which researchers suggest may leave
teeth more vulnerable to recurrent caries; leave a film thickness.
What are advantages/disadvantages to gluma?
a. Advantages: no film thickness, one step to apply
b. Disadvantages: EXPENSIVE, somewhat caustic to
soft tissues & possibly to the pulp in deep preparations
What is the application of gluma?
-apply to walls for 30 seconds , dry, rinse, dry again.
-material is caustic; minimize contact with gingivae
and protect pulp with liner/base in deep preparations
prior to applying.
Does UMKC teach the standard use of dentin desensiziters under amalgam?
NO
- Studies suggest they make negligible difference in tooth sensitivity on routine cases.
- The smear layer will seal most dentinal tubules, and, after a few weeks, the amalgam will seal itself with an oxide layer.
- Occasionally, after consultation with faculty, one might use Gluma on an especially sensitive tooth, but place a liner or base first in deep preparations.
What are the 5 steps of an amalgam restoration?
- Place amalgam
- Condense amalgam
- Pre-carve burnish
- Carve anatomy
- Refine restoration
When filling a prep, should you overfill it?
Yes, ~1.0mm beyond the margins
When checking and refining the occlusion of an amalgam restoration, what should you preserve?
Cusp seats in the bottoms of fossae (long axis forces on the teeth)
What should the finish of amalgam be?
Matte finish
Research suggests that a well condensed, well carved amalgam DOES/DOES NOT gain longevity from the finishing process
Does not
If you do need to finish/polish an amalgam restoration, you
must wait _____ hours after placement for amalgam to be
completely set up.
24
What are finishing burs?
*Green stone (coarse)
*White stone (medium)
*12 bladed polishing bur
(medium-fine)
What are polishing burs?
- Brown (pre-polish)
- Green (polish)
- Green with yellow collar
(superpolish)
What are the bladed flute finishing burs for amalgam?
Needle Point
Flame 7902
Round 7006
Bullet 7404
Small round 7002
Bullet pointed 7104
What is the most important area of an amalgam restoration?
Cavosurface margin
* All flash and overhangs should be eliminated
* The tip of an explorer should pass from the tooth surface to the restoration
surface and vice versa without jumping or catching
What is the instrument sequence of polishing amalgam?
- Brown point on slow speed
- Green point on slow speed
- green point with stripe slow speed
What are the differences between amalgam and composite resin restoration?
AMALGAM
1. Triturate amalgam
2. Place amalgam
3. Condense amalgam
4. Pre-carve burnish
5. Carve anatomy
6. Assess occlusion, refine
restoration
COMPOSITE
1. Etch 20 sec, rinse
2. Place bond, gently air dry, light cure
3. Place composite increment, condense,
light cure, repeat until prep is filled
4. Create anatomy, finish occlusal
surface, light cure
5. Assess occlusion, refine restoration
6. Polish
When placing a composite resin filling what are the differences we do prior to placing restorative material?
IN CLINIC: 1. Acid etch prepared tooth structure
Rinse
IN CLINIC AND LAB:
2. Place bond agent into enamel and dentin
Gently air dry
Light cure
What instrument should you use to create anatomy on a composite restoration?
Hollenback
Optrasculpt to create grooves without the “pullback”
What are advantages of composite?
◦ Preparation can be more forgiving
◦ Esthetic
◦ Operator control of set up time
◦ Preserve tooth structure
◦ Don’t need to remove as much for retention (because it bonds to tooth) or
bulk of restorative material
What are disadvantages of composite?
◦ Restoration more technique sensitive
◦ Additional steps
◦ May not last as long
◦ Not as strong
◦ No moisture tolerance
_______ restoration will be more traumatic to gingiva than _______ restoration
Overcontoured; under contoured
