RESTORING CAVITIES WITH DENTAL AMALGAM

AMALGAM:an alloy with mercury and another metal

1895 GV BLACK: develops new formula of modern amalgam - 67% silver, 27%tin, 5% copper, 1%zinc

1960's - conventional low copper lathe cut alloys - smaller particles.

1970’s
first single composition spherical
ternary system (silver/tin/copper)
1980’s
alloys similar to those in 70’s
1990’s
mercury-free alloys (gallium)
Increased corrosion & excessive post setting expansion

WHY AMALGAM:
inexpensive, easy to use, durable (can last for 10yrs +), familiarity with material, less likely to have hypersensitivity than with comp

REMOVE CARIES: from EDJ first then base of cavity. Ensure any unsupported enamel is removed, ensure resistance/and retention features are in place

THERAPIST CONTROLLED VARIABLES: Trituration(mixing time) refer to manufacturer. Overtrituration-hot sticky mix, sets fast. Undertrituartion- grainy mix, longer to set

CONDENSATION RULES!
condenser must fit.. check before mixing!
Place amalgam in small increments and pack
Overpack and remove mercury rich layer

BURNISHING:
PRE CARVE - removes mercury and improves margins
POST CARVE - improves smoothness
COMBINED - less leakage

BONDED AMALGAM RESTORATION
used when there is not enough tooth substance ie missing cusp and for complete marginal seal to prevent ingress of bacteria and protects pulp

DISADVANTAGE:
Time consuming
costly
Lack of evidence on long term prognosis

AMALGAM TOXICITY:
Toxicity - mercury poisoning
Allergy - to amalgam may cause contact dermatitis or Lichen Planus
PREGNANT PT'S - theoretical rick to foetus as mercury can pass through placenta