Fall Lecture 2: Amalgam Finishing and Polishing Flashcards
When do we finish the amalgam restoration?
same day it’s placed
instruments to finish amalgam:
discoid, cleoid, rotatory
Polishing:
smooth amalgam to high gloss/ luster
TF? The clinical outcome will be compromised if the amalgam is not polished.
F. Prognosis the same.
Purpose of finishing
no uneven areas bw amalgam and cavity prep wall, ensure contour and occlusion are correct, resto is smooth
Is it more important to finish high copper or low copper amalgam?
low copper, high copper less susceptible to tarnish and corrosion (no g2 phase)
When to polish amalgam:
at least 24h after placement
What can sometimes serve as a viable substitue for conventional polishing?
pre-carve burnishing in conjunction w post-carve burnishing
TF? If the amalgam restoration is not smooth after 24h and you are ready to polish, you should smooth, but you must wait another 24h’s.
F. Refinish, then polish
This will occur if there is a gap between the amalgam and the cavity prep:
marginal leakage
Effects of proper condensation:
red marginal leakage, Hg content in resto, and corrosion, inc strength and marginal integrity
Condensors for finishing, condensor for overpacking
smaller, larger
Explain the condensing strokes:
each condensing stroke should overlap the previous
How much to overpack amalgam:
1mm+
Overpacking prevents:
undercontouring of resto
General condesation time:
2.5 - 3.5m
Type of condensor for spherical amalgam:
large condensor (plastic, buttery consistency)
Type of condensor initially used for admixed amalgam:
small condensor, more resistant to pressure
condensor with 2X the diameter requires how much more pressure?
4X
Pre-carve burnishing:
to ensure marginal amalgam is well condensed before polishing, burnishing immediately after over packing (M-D and F-L)
benefits of pre-carve burnishing:
denser amalgam at margin, excess Hg release (?), inc marginal adaptation
Size of ball burnisher to choose for pre-carve burnishing:
head contacts cusp slope but not margin
When to carve amalgam:
immediately after pre-carve burnishing
Best instrument for carving:
cleiod/ discoid carver, larger end at beginning
Which has a sharper end, discoid or cleoid?
cleioid
Instrument to use to carve CG and pit and fissure areas::
cleioid
Position of discoid blade for carving:
edge perp to resto margin, resting on unprepped tooth, prevents overcarving amalgam, creates continuity of surface contour
Carver should be pulled in a direction parallel to:
the margin of the prep
Major issue with leaving flash:
chip away, damage margin, marginal leakage
Post-carve burnishing:
light rubbing of surface of carved amalgam resto w burnisher (PKT3 burnisher, small burnisher) smooth, but not shiny appearance, don’t create grooves
How to check finishing:
check occlusion (before and after procedure), explorer around margins (don’t scratch restoration)
Type of contact amalgam should have (CG of molar)
light occlusal contact
Appearance of heavy contact on amalgam:
dark area with shiny center
How to adjust occlusion on amalgam or make a continuity of surface contour across the margin:
finish with different shapes of carbide burs, fine-grit white alumina stone or green carborundum stone
Which is more aggressive, fine-grit white alumina stone or green carborundum stone
green
How to blunt the tip of finishing stone:
diamond wheel, helps prevents alteration of the anatomical features
Amalgam restoration is surfaced with:
a round finishing bur
Position to hold the finishing stone:
long axis of stone or the bur’s long axis at a R angle to the margin
Instrument to use after finishing stone or bur:
large, round finishing bur
Pre-polishing step if the resto is not smooth enough yet and is already set, can’t smooth anymore:
rubber prophy cup w wet pumice, tin oxide in water or alcohol carrier for high luster, faster, creates luster
Shapes of carbide finishing burs we have:
bullet, neumeyer, egg, long pear
use brownie and greenie for:
finishing and polishing
To polish convex surfaces:
Sof-Lex discs (composite or amalgam), high luster and finishing polishing, abrasive impregnated polishing cups
To polish concave surfaces:
abrasive impregnated polishing tips
Should polishing begin with the coarse rubber abrasive disc/ cup/ point on high or low speed?
low speed, just above “stall out” speed
How long should amalgam w smooth surface take to shine w first, coarse disc/ cup/ point?
few sec, if not, refinish with finishing bur and repolish, point should get rid of all scratches (same thing w each successive, finer grit)
3 reasons to polish at low speed, just above “stall out” speed with the presence of air-water coolant:
- point disintegrates at high speeds. 2. over-heating of resto –> pulpal damage. 3. Heat brings liquid Hg to surface, causing excessive volatilization of Hg and weaker amalgam surface.
Appearance of amalgam when over heated:
cloudy, even though it may have a high polish (Hg has been brought ot surface, corrosion, loss of strength
Purpose of wedge in Topplemeyer placement:
recreate embrasure
Fxn of inner knob of Topplemeyer:
changes diameter of matrix band
Ends of matrix band fit into:
vice
The matrix band can go to the R or the L through the:
guide slots
guide slots always face toward:
gingiva
Which knob to turn to tighted the matrix band:
inner
Insert wedge from buccal/lingual aspect:
lingual, only needed on side of missing wall
How to take off Topplemeyer:
unscrew outer knob, releases the band ends
Why remove Topplemeyer while leaving the band, initially?
prevent material from crumbling interproximally
