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Comparing Amalgam and Composite

Today, dentists have many options to choose from when restoring teeth damaged by decay or injury. These choices include white fillings that can be used for front and back teeth. A question that patients often ask is: “If white filling materials that can match my teeth are available, why do dentists still use silver–colored fillings for my back teeth?”

The silver–colored fillings used in dentistry are made of silver amalgam. This durable, long–lasting dental material has been used successfully by dentists for over 150 years. It is made up of a combination of metals including silver, mercury, tin, and copper. Silver amalgam resists recurrent decay and is strong enough to withstand biting forces on the back teeth.

Most white fillings are made from a type of material known as a composite resin (usually just called a “composite”). Composites consist of a clear plastic material that sets when exposed to certain wavelengths of light. The plastic is strengthened by the addition of very small particles of ceramic or glass that increase resistance to wear. These fillers also improve handling properties and make the composite white. Composites are often more expensive because the cost of the filling material is greater and they are more difficult to place. At one time, composites were only placed in front teeth because they were not strong enough to withstand biting pressure. The composites that dentists use today are more durable than in the past and can be used to fill back teeth, especially when patients are concerned about esthetics.

For many patients, however, composites may not last as long as silver amalgams. This is especially true for larger fillings. A recent study published in The Journal of Evidence–Based Dentistry compared 1,748 restorations that were followed for up to seven years. The study found that amalgam restorations performed better than did composite restorations, especially when more than three tooth surfaces were involved. This study supports the results of earlier research comparing composites and amalgams. For this reason, many companies that purchase dental insurance often pay only for the cost of silver amalgams in back teeth and allow the patient the option of paying the additional cost for tooth–colored fillings. This helps employers make affordable health benefits available for all employees.

Some patients are also concerned about the presence of mercury in silver amalgam. Although mercury and mercury containing compounds can be hazardous, the mercury contained in amalgams is chemically bound to the other metals. As a result, the amount of mercury released is very small. The US Food and Drug Administration recognizes silver amalgam as safe and effective. Comprehensive reviews of scientific studies on silver amalgam have not identified any credible evidence of harm caused by the use of silver amalgam except in a very small number of patients who are allergic to mercury. Silver amalgam, therefore, remains a long–lasting and cost–effective option for restoring back teeth.

When properly placed, both silver amalgam and composite resin are acceptable filling materials for restoring back teeth and can provide excellent service for patients. The dentist must make the decision to use either material based on his or her best clinical judgment while taking into consideration the desires and concerns of the patient. As with all medical and dental procedures, patients should discuss the potential risks and benefits of the use of amalgam and composite before making an informed choice.

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