Dental amalgam or resin composite fillings?

Thanks to technological advances, dentists and patients today have several choices when it comes to selecting materials to fill cavities. Among the choices are natural tooth-colored materials such as resin-based composite fillings and more traditional dental fillings such as those made of metal amalgam. The advent of new materials for fillings has been beneficial, especially in terms of aesthetics, but does not eliminate the appropriateness of traditional dental materials that are stronger, more durable and less expensive. These materials are best in situations where restored teeth must withstand extreme forces that result from chewing, such as in the back of the mouth.

What is dental amalgam?

Most people recognize dental amalgams as silver fillings. Dental amalgam is a mixture of mercury, silver, tin and copper. Mercury, which makes up about 50 percent of the compound, is necessary to bind the metals together to provide a strong, hard, durable filling. After years of research, mercury continues to be the only element that will bind these metals together in such a way that it can be easily manipulated to fill a cavity.

Dentists often prefer dental amalgam because it is easier to work with than other alternatives. Many dentists consider amalgam stronger than the resin-based composite, and therefore use amalgam for back teeth fillings. Many patients prefer dental amalgam for the same reasons, plus its cost-effectiveness and ability to fill cavities quickly. It is estimated that more than 1 billion amalgam fillings are placed annually.

What are resin composite fillings?

Resin composite fillings are made of ceramic and plastic compounds. Because resins mimic the appearance of natural teeth, these fillings have been used in front teeth for years. When they first appeared, however, resin compounds weren't strong enough to be used in back teeth, where high-pressure grinding and chewing require greater durability.

In the past 10 years, technology has improved enough to allow the use of resin material in posterior or back teeth. Still, many dental plans including Delta Dental don't cover resin fillings in teeth that aren't visible in a smile, and many dentists choose not to use resins for one or more of these reasons:

• With more durable resin material available for only a decade, resins haven't stood the test of time in teeth where grinding and chewing result in heavy wear; by contrast, the durability of amalgam fillings is well documented — the average life span of amalgams is 8 to 10 years, but many last 20 years or more.
• Amalgam is one of the best filling materials when dentists need to place fillings in areas of the mouth that are difficult to keep dry, such as molars (back teeth) or cavities below the gumline. Resin fillings need a specific environment in which to be placed; for example, the prepared tooth must be completely dry when the resin material is being applied and cured. Clinical experience has consistently shown that amalgam is, for a great many situations, still the most reliable filling material for long-term, low-maintenance function.
• Resin costs more than amalgam, which can make the cost of the service higher than for a comparable amalgam filling.

For these reasons, the majority of dental health carriers pay for coverage of resin fillings in teeth that are visible in a patient's smile. For example, virtually all of Delta Dental's plans cover resin fillings on the teeth where their cosmetic benefit is critical: the six front teeth (incisors and cuspids) and on the facial (cheek side) surfaces of the next two teeth (bicuspids).

ADA and FDA recommendations for fillings

Dental amalgam has a 150-year proven track record of as one of the safest, most durable and least expensive materials used to a fill a cavity. Ongoing scientific studies conducted over the past 100 years continue to show that amalgam is not harmful.

Much of the concern over the safety of amalgams arises from the use of mercury as a bonding agent. But when mercury is combined with other materials in dental amalgam, its chemical nature changes, rendering it harmless. The amount of mercury released in the mouth under the pressure of chewing and grinding is extremely small and no cause for alarm. In fact, it is less than what patients are exposed to in food, air and water, and less than what gets released in patients who opt to have an existing amalgam filling removed.

The American Dental Association (ADA) maintains that dental amalgam remains a safe, affordable and durable cavity filling choice for dental patients. In addition, the U.S. Food and Drug Administration (FDA) does not recommend the removal of amalgam fillings from patients who have them because this could cause more harm to the tooth structure and pose other health risks to the patient.

Deciding which type of filling to use is best made by the patient and dentist, taking into account the size and location of the cavity, patient history, cosmetic concerns and cost. Ask your dentist to discuss all of the choices available for dental fillings and help you decide which alternative is right for you.

The oral health information on this website is intended for educational purposes only. You should always consult a licensed dentist or other qualified health care professional for any questions concerning your oral health.