Amalgam

Amalgam has been used as a dental filling material for more than 150 years.

Composition

An alloy of mainly silver, tin, copper and mercury

Properties

  • Hard and durable; high wear resistance
  • Easy to use
  • Safe

Amalgam safety

International dental health organization like the World Health Organization, Federation Dentaire International, and also the U.S. Food & Drug Administration have declared dental amalgam as safe and effective.

The followings are some queries about amalgam:

  • Mercury, which is poisonous, is used in dental amalgam. Is amalgam filling safe?
    Amalgam contains various metals such as silver, copper and tin, as well as mercury. When mercury is combined with these metals, it becomes an inactive stable substance. Only under unusually great pressure or abrasion will the amalgam release a minute amount of mercury vapour. As compared to the daily dosage of mercury being absorbed from the environment, such as food, water and air, the minuscule amount of mercury released from the amalgam fillings is insignificant.
  • Should people have the amalgam fillings in their mouths removed in order to prevent certain serious illnesses such as Alzheimer's disease?
    There is no scientific literature or evidence which shows that the removal of amalgam fillings helps patients recover from their illnesses, nor is there any evidence which suggests such a relationship. Unless there is an allergic reaction, it is not advisable to have amalgam fillings replaced because of the following reasons:
    • Replacement of filling materials will lead to further loss of tooth structure.
    • Amalgam is still the most preferred filling material owing to its safety and effectiveness. Tooth-coloured filling material such as composite is not as resistant to stress as amalgam and is not suitable for large cavities. Gold is an effective material, but it is expensive.
  • Are some people allergic to amalgam?
    Allergic reaction to amalgam is very rare. Within 150 years of usage, there were only 100 documented cases. This type of patients should use other filling materials.

Disadvantage

The greyish-silver colour of amalgam is not esthetically appealing.

Application

It is mainly used for restoring back teeth where stress load is high.

Procedures for amalgam filling

  • First remove decayed tooth substances.
  • Place amalgam filling into the tooth cavity.
  • Shape the filling, trim off excessive material, and polish the filling.
    Photograph of decayed tooth before a filling is placed.
    Before filling
    Photograph of decayed tooth after an amalgam is placed.
    After filling
     

    Animation showing the use of dental instruments to remove the decayed portion of a tooth and fill with amalgam.
Composite

Composition

A substance made up of acrylic resin filled with inorganic substances such as glass, quartz as additives to enhance the strength

Properties

Esthetic; colour is similar to that of natural teeth

Disadvantage

Not as hard as amalgam

Application

  • To restore decayed teeth
    Photograph of a decayed tooth before a filling is placed.
    Before filling
    Photograph of a decayed tooth after filling with composite.
    After filling

  • To restore the appearance of the teeth, such as to modify the shape, size and colour of the teeth
    Photograph showing a wide space between two upper incisors.
    Before filling
    Photograph showing the reduced space between the two upper incisors after treatment.
    After filling

Procedures for composite filling

  • Remove decayed or weakened portion of the tooth.
  • Etch the tooth cavity surface with diluted acid (for example, 30% phosphoric acid).
  • Apply dental adhesive material on the prepared tooth cavity.
  • Put composite onto the prepared tooth cavity and shape the filling.
  • Harden the filling by using a light curing equipment.
  • Trim off excessive material and polish the filling.
    Animation showing the use of dental instruments to remove the decayed portion between two upper incisors and  filling with composite.
Glass Ionomer Cement

Composition

A substance made up of aluminosilicate glass powder and a liquid polyacrylic acid

Properties

  • Esthetic; colour is similar to that of natural teeth, but lack of translucency
  • Bonds to the tooth
  • Fluoride releasing prevents recurrent tooth decay around the filling material

Disadvantage

Insufficient strength to bear chewing force in long term, relatively low wear resistance

Application

  • Use on tooth surfaces that are not exposed to heavy chewing force, e.g. outer surface, to restore the abraded part
    Photograph showing the abraded portion of a tooth around its neck.
    Before filling
    Photograph showing the abraded portion of the tooth being filled by glass ionomer cement.
    After filling

  • Use as filling material for deciduous teeth
    Photograph of a decayed deciduous tooth before  a filling is replaced.
    Before filling
    Photograph of a decayed deciduous tooth after filling with glass ionomer cement.
    After filling

Procedures for Glass Ionomer Cement filling

  • Remove the decayed tooth substances.
  • Place the glass ionomer cement onto the prepared tooth and shape the restoration.
  • Trim off excessive material and polish the restoration.
    Animation showing the use of dental instruments to remove the decayed portion of a tooth and fill with glass ionomer cement.

  • To increase the strength of Glass Ionomer Cement, acrylic resin is added. For this type of material, light curing is required to harden it.
Compomer

Composition

It is a mixture of composite and glass ionomer cement.

Properties

  • It possesses the properties of both composite and glass ionomer cement.
  • Better appearance and better wear resistance than glass ionomer cement but not as good as composite.
  • The manipulation is easier than composite.

Application

Used as filling material for deciduous dentition

Photograph showing the decayed portion of a deciduous tooth.
Before filling
Photograph showing the appearance of a deciduous tooth after the decayed portion is filled with glass ionomer cement.
After filling

Procedures for Compomer filling

  • Remove tooth decay.
  • Place dental adhesive on the prepared tooth cavity.
  • Put compomer onto the prepared tooth cavity and shape the restoration.
  • Use light curing instrument to harden the filling.
  • Trim the excessive material off and polish the restoration.
    Animation showing the use of dental instruments to remove the decayed portion of the tooth and fill with glass ionomer cement.
Stainless Steel Crown

Silver in colour, fixed sizes, and usually used for deciduous molars

Photograph showing a stainless steel crown

Procedures for stainless steel crown