Amalgam and matrix systems for restorative dentistry

Thermal change

Contraction and expansion

Amalgam

Powder mixed with mercury to create pliable mixture

Matrix system

Creates temp. Wall for placement/ Incorporated into restorative procedures

Smaller circumference

Gingival edge / towards gingiva

Larger circumference

Occlusal edge. Towards occlusal

Where is the wedge inserted? What does it hold?

In lingual embrasure. Holds matrix band firmly against gingival margin

Class I

Occlusal

Class I I

Mesial or distal walls down

When are direct esthetic and restorative materials placed on tooth

When material is pliable and can be carved and finished

Composition of dental amalgam

Mercury 43-54% / amalgam alloy powder 57-46%

High copper alloys

Spherical- round/ irregular- rough / admixed- both

Amalgam alloy power is made of?

Silver, tin, copper, zinc

AAP- silver

Strength

AAP- tin

Workability + strength

AAP- Copper

Strength + corrosion resistance

AAP- zinc

Suppresses oxidation

Mercury to alloy ratio

1:1 by weight / earnes technique

Galloy

Liquifies at 86 degrees / sensitive to moisture (corrosion) / gallium, indium, tin

Mercury controversies

Toxicity levels, potential harm

Results of Increased exposure to mercury

Tremors, kidney disfunction, depression, central nervous system disorders CNSD

Process of trituration

Amalgamation, alloy + mercury mixed, pistol added as activator