2. Amalgam Finishing and Polishing Flashcards
How is finishing a restoration performed?
by primarily evaluating the restoration for any flaw and make necessary modifications if needed
When should finishing be done
the day the restoration is placed
(T/F) Finishing is commonly performed with hand and rotary instruments
t
Define polishing a restoration
smoothing the surface to a point of high glosser luster
Does polishing an amalgam restoration pose a clinical advantage with a high copper amalgam except for having a smoother surface that is more comfortable to the patient
no- clinical outcome is the same
(t/f) A finished restoration should be smooth and have no overhanging margins
t
What are the 3 purposes of finishing
Ensure that
- There is no uneven area between the amalgam and restoration margin and the cavity prep wall
- Contour and occlusion are correct
- Smooth restoration
What is the purpose of polishing
to achieve high smoothness for the comfort of the patient
Why is it that polishing will not enhance the clinical outcome of a high copper amalgam if it is finished well
Because the high copper amalgams are less susceptible to corrosion (elimination of the gamma II phase)
Polishing should be done how long after finishing the restoration
24 hrs
Why wait 24 hrs to polish a restoration
this is how long it takes for amalgam to fully set
What two techniques may serve as substitutes to polishing
pre-carve burnishing and post-carve burnishing
Should the restoration be smooth after finishing before polishing?
Yes
Why is condensation of amalgam so important
because you don’t want gaps/voids in the restoration. Condensing will allow the amalgam to adapt to the prep walls and the matrix (when used) to be free of voids
Voids/gaps in the restoration can lead to…
marginal leakage
Proper condensation of amalgam offers what benefits (4)
- prevents marginal leakage
- reduces excess mercury content (thus leading to a reduction in corrosion, increase in strength, and increase in marginal integrity)
The little condenser is used (when) and a large condenser is used (when)
- Little= when finishing the restoration
- Large= when overpacking the restoration
(T/F): You don’t need to condense each increment of amalgam separately
f
Describe the pattern of condensing strokes you should take
-Each stroke should overlap the previous to make sure the amalgam is well adapted
By how much should the restoration be overpacked by
1 mm
Why do you overpack a restoration
to ensure the cave-surface margins are completely covered with well condensed amalgam (don’t want an under contoured restoration as well)
How long should condensing take
2.5-3.5 minutes
What should you do if you want to use more amalgam be it has already began to set in the well
-Quickly mix a new amalgam because it will not react well with the amalgam that has already been condensed because it has began crystalizing
Condensing should be done with (heavy/light) pressure
heavy
Knowing the amount of pressure that needs to be used to condense the amalgam is determined by two factors which are…
- diameter of the condenser
- type of amalgam
Spherical amalgam requires a (large/small) condenser… why?
large because using a small condenser will penetrate a mass of spherical amalgam and that will cause less effective force to adapt the amalgam to the walls
Admix amalgams require (large/small) condensers and why
small because the material is more resistant to condensation pressure
The smaller the condenser the (more/less) force needs to be applied…. if you double the diameter of the condenser the amount of force needed to attain the same amount of pressure is _ times as (great/less)
less…4x great
What should you do to ensure the amalgam is well condensed before carving
Pre-carve burnishing: burnish immediately with a large burnisher with heavy strokes both MD and BL
The purpose of pre-carve burnishing is…
ensure denser amalgam at the margin and bring out excess mercury and increase the marginal adaptation of the restoration
To maximize the efficacy of pre-carve burnishing what should you do
make sure the head of the burnisher is large enough so that the head touches the cusp slopes but not the margin for the final strokes.
What are the names of the hand instruments that are used to carve amalgam
- cleoid/discoid
- Walls no. 3 carver
- Hollenback
- Interproximal carver (IPC)
- No. 14L sickle-shaped carver
During carving the edge of the blade must be _ to the margin of the prep
perpendicular
Why is it important to keep part of the edge of the blade of the instrument on the unprepared tooth when carving
prevents overcharging and continues continuity of restoration
The carver should be pulled in what direction when carving
parallel to the margin of the prep (stroke should be from enamel to amalgam)
(T/F) you want to the tooth and amalgam surfaces to be even (no step down)
t
Why is having flash bad?
because it is a thin piece of amalgam that will chip away and damage the margin making it more prone to marginal leakage
What should the margin of the prep mimic
the cavosurface margin
what is post-carving burnishing
the light rubbing of the surface of a carved amalgam restoration with a burnisher (PKT3 burnisher)
Post carve burnishing should be done with a (large/small) burnisher
small
(T/F) Post carving burnishing produces a smoother and shinier restoration surface
f- smoother but NOT shinier
When should the dentist perform the finishing step of the restoration
the same day of the restoration
What does the finishing step consist of
checking occlusion and evaluating margins with an explorer
A heavy contact with occlusion paper looks like
A dark circle with a shiny center
(T/F) new amalgam shouldn’t have any heavy contact points
T- they should have light contacts
Carbide burs, white alumina stone and green carborundum stone are for (finishing/polishing)
finishing
Which is more abrasive the green carborundum or the white alumina
green carborundum
The long axis of the stone should be _ to the margin of the restoration when finishing
perpendicular
Why are the ends of finishing burs/stones rounded
prevent the destruction of occlusal anatomy that was created when carving
Since the surface must be smooth before it is polished, if the restoration has many irregularities, what can you do
use wet pumice and prophy cups as a pre-polishing step followed by tin-oxide and water or alcohol for high luster
What are the disadvantages of using the pumice for pre-polishing
splatter
What are the names of the two “burs” in our kits that can be used for both finishing and polishing
- brownie
- mini greenie
What are the names of the carbide burs we have for finishing
- Bullet
- Neumeyer
- Egg
- Long pear
The son-lex discs are good for finishing/polishing _ surfaces
convex
The abrasive impregnated polishing cups and tips can be used for polishing what kinds of surfaces
convex surfaces such as cusp tips (cups) and occlusal surfaces (tips)
(T/F) there shouldn’t be any stretches on the amalgam when you get to the rubber cups/tips
t
Rubber points and cups need to be used at (low/high) speed with coolant
low
Why is it important that the rubber points don’t overheat the amalgam restoration
- Rubber points disintegrate at high speeds
- Overheating the restoration can lead to plural damage
- Generation of heat brings liquid mercury to the surface causing excessive volatilization of mercury and weaker amalgam surface and increasing the likelihood of corrosion.
