Dental amalgam

Dental amalgam
• Dental amalgam is a mixture of metals,
consisting of liquid (elemental) mercury and a powdered alloy
composed of silver, tin, and copper

Composition :
Silver : 63-70 %
• Whiten alloy
• Decrease creep
• Increase strength
• Increase resistance to tarnish

• Tin : 26-28 %
• Reduce tarnish and corrosion
• Reduce strength and hardeness

• Copper : 2-5 %
• Increase hardeness
• Increase setting expantion

• Zinc : 0-2 %
• Deoxidizer and scavenger
• Delay expansion in amalgam

• Other metal
• Palidium , gold,…

Indication :
• Class I , II cavities moderate and large restoratons
• As core build up material
• Resoration that cant be well isolated.

contraindication
• Anterior teeth where ethetic is a prime concern
• Small cavities

Advantages
• Ease of use
• Ease to manipulate
• Inexpensive
• Excellent wear resistant
• Good compressive strength
• Sealing ability improved by formation corrosion products at tooth
amalgam interface

Disadvantages
• Non esthetic
• Tarnish
• Metalic tast ,galvanic shock
• Discoloration of tooth structure
• Lack of chemical adhesion to tooth structure
• Mercure toxicity
• Delayed expantion
• Thermal expansion 3 time more than dentin

Classification :
• Based on copper content
• Low copper alloy 6% ( conventional)
• High copper 12-30 % copper (non gamma II phase)
• Based on zinc content :
• Zic contained alloy
• Zinc free alloy

• Based on shapeor alloy particles
• Lathe cut alloy (harder)
• Sphircal alloy
• Admixed