Amalgam Flashcards
what is amalgam made up of?
An amalgam is a mixture of two metals, mercury and silver based alloy
reaction of liquid (Mercury) and powder (Silver, Tin, Copper (10 – 30%)and other metals such as Palladium & Indium).
what are the indications of use for amalgam?
Cavities in permanent teeth
For patients with inadequate oral hygiene
Extent of caries
poor moisture control
what are the advantages and disadvantages of amalgam fillings?
advantages- strong under occlusal load, long lasting, easy to use not moisture or technique sensitive , good abrasion resistance to TB, cheap.
Disadvantages- aestheticly unpleasing, mercury toxicity, may need to remove healthy tooth to retain amalgam, thermal conductor.
what are principles of amalgam cavity preparation?
outline form- gain access to caries using high speed and fissure bur.
remove peripheral caries and clear ADJ
Retention ( hold the substance)
resistance ( occlusal forces biting down)
correct cavity margins
what do you place amalgam in?
Mixed amalgam is transferred to the tooth by an amalgam gun or carrier.
what are 3 types of matrix bands?
Tofflemire
Siqveland – narrow/wide
Omni-Matrix
Kerr Hawe Adapt Super Cap Matrix
Automatrix
Sectional matrices
what are 5 functions of matrix bands?
Replaces missing walls
Helps retain material during placement
Prevents material entering subgingivally
Provides moisture control
Prevents joining teeth together with restoration
what are functions of wedges?
prevents overhangs
Prevents excess material at the cervical area of the cavity forming a ledge
Helps retain the matrix band
Absorbs Crevicular fluid
reasons for carving amalgam?
Removes excess mercury
Removes excess amalgam
Restores tooth morphology
Restores tooth function
Produces a smooth surface
ways for good mercury hygiene?
good ventilation in surgery
no carpets or tiles on surgery floor
mix and store away from heat
what are reasons for replacing older amalgams?
secondary caries
fracture of filling
pulpal involvement/ endo treatment
