Dental Fillings

What is a filling?

Dental fillings are metallic or ceramic based substances used to fill in cavities in your tooth. Cavities are holes in the enamel of your tooth that usually expose underlying dentin. Very large cavities or cracks in your tooth that have eroded past the dentin down to the nerve root may require other interventions, such as a root canal, instead of fillings.

What types of filling are there?

Dental fillings are of two main types:

1. Silver (Amalgam) fillings
   Dental amalgam is a mixture of mercury, and an alloy of silver, tin and copper. Mercury makes up about 40-50 percent of the compound. Mercury is used to bind the metals together and to provide a strong, hard durable filling. After years of research, mercury has been found to be the only element that will bind these metals together in such a way that can be easily manipulated into a tooth cavity.
   
   
2. Composite (White) fillings
   A composite resin is a tooth colored plastic mixture filled with glass (silicon dioxide). Following preparation, the dentist places the composite in layers, using a light specialized to harden each layer. When the process is finished, the dentist will shape the composite to fit the tooth. The dentist then polishes the composite to prevent staining and early wear.

(see "Composite fillings" for more in-depth information)

Why do I need to have my cavities filled?

Cavities are caused by breakdown of tooth enamel which exposes underlying structures that are much less resistant to infection and decay. Left untreated cavities can result in both the destruction of involved teeth as well as infection of the surrounding gums and bones. Filling cavities stops this process.

Which type of filling is best?

There is no single correct answer to this. Factors to consider (in conjunction with a dentist) include cost, cavity location, cavity size, cosmetic results and possible health considerations.

Amalgam fillings
In use for over 150 years, with over 1 billion amalgam restorations (fillings) placed each year.

Today, dental amalgam is used in the following situations:

• in individuals of all ages,
  
  
• in stress-bearing areas and in small-to moderate-sized cavities in the posterior teeth,
  
  
• when there is severe destruction of tooth structure and cost is an overriding consideration,
  
  
• as a foundation for cast-metal, metal-ceramic, and ceramic restorations,
  
  
• when patient commitment to personal oral hygiene is poor,
• when moisture control is a problem,
  
  
• when cost is an overriding patient concern.

  It is not used when:

• esthetics are important, such as in the anterior teeth and in lingual endodontic-access (root canal) restorations of the anterior teeth,
  
  
• patients have a hisotry of allergy to mercury or other amalgam components,
  
  
• a large restoration is needed and the cost of other restorative materials, such as crowns, is not an important factor in the treatment decision.

Composite (White) fillings
In use since the mid 1960's, the quality of composite resin fillings has continued to improve.

Advantages

Esthetics are the main advantage, since dentists can blend shades to create a color nearly identical to that of the actual tooth.

Disadvantages

Along with the higher cost and the extra placement time, the patient can experience postoperative sensitivity. Also, the shade of the composite can change slightly if the patient drinks tea, coffee or other staining foods. Composites tend to wear out sooner than silver fillings in larger cavities, although they hold up as well in small cavities.

Are silver (amalgam) fillings safe?

Although amalgam fillings have been used for over 150 years and no verifiable adverse health effects have been documented aside form a rare allergic reaction no large scale studies have been done demonstrating either the presence or absence of adverse health effects.

Consensus among major dental organizations, based on years of use and lack of verifiable toxic effects of dental amalgam, is that amalgam fillings are certainly safe. Indeed, a vast majority of persons with amalgam fillings probably have little to worry about from their fillings.

However, all forms of mercury are toxic to humans and very small amounts of mercury vapors are released from amalgam fillings. The minimum amount of mercury exposure required to cause symptoms in the most sensitive individuals is not known.

Currently, all dental, public health and major scientific organizations agree that amalgam based fillings should not be replaced for prevention of "potential mercury toxicity". Replacement of perfectly good fillings adds great expense as well as increasing mercury exposure. Dentists touting such preventative removal services while claiming amalgam fillings cause a wide spectrum of human disease are viewed as opportunistic and possibly unethical.

See:

Current Controversies in Dentistry-Are Amalgams Safe?

for more in-depth coverage of this topic

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