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Amalgam Fillings vs Composite


Patients who have been told they need a dental filling will need to weigh the benefits of amalgam fillings vs composite. Both have been proven to be safe and effective materials. Even so, knowing about basic differences between the two can help patients make an informed decision. Composite, or tooth-colored fillings, are often chosen for a more natural-looking appearance. Additionally, this option is often preferred by patients who choose not have metal placed in their bodies. However, amalgam is more durable and may be best for patients who grind their teeth. Metal fillings are also more affordable.

Illustration of amalgam vs composite filling

Tooth-colored fillings are often chosen over amalgam by patients who prefer a natural-looking restoration.

Amalgam Fillings

Amalgam has been used extensively in restorative dental care for more than 150 years. The material contains liquid mercury which is mixed with a metal alloy powder predominantly made up of silver, tin, and copper. Amalgam has a claylike consistency when it is mixed. It starts to harden almost immediately after placement, and within an hour or two, it becomes extremely hard and resistant to chewing forces.

A Strong, Durable Material

Amalgam is strong, durable, and easy to work with. It also has another important advantage: amalgam possesses the unique characteristic of corroding at the margins where it contacts the tooth. This corrosion is beneficial because it seals the edges, lessening the chances of recurrent, or new, decay developing around the filling.

Drawbacks Regarding Preparation and Appearance

In contrast to composite, the amalgam material does not bond directly with the tooth. Instead, the restoration must be retained by undercuts and grooves made to the tooth during its preparation. This means that more of the tooth's healthy structure must be removed to attain retentive strength.

Another disadvantage of amalgam is the dark, noticeable color. There is also a tendency for silver fillings to stain the adjacent enamel so that it takes on a dark gray color. Even if the restoration itself is placed in a location where it cannot be seen, the stain it causes may be visible.

Both amalgam and composite are safe and effective materials for dental fillings. Weighing aesthetics, longevity, and cost can help you choose which type is best for your needs.

Concerns Over Safety

A final concern regarding amalgam relates to its safety. The liquid mercury it contains is a toxic substance. Because the fumes can be breathed in and absorbed by the body, mercury must be handled and disposed of carefully. When the amalgam is mixed, the liquid mercury binds firmly with the alloy powder, but the amalgam restoration continues to emit tiny amounts of the metal.

Despite the presence of mercury in amalgam filling material, studies show it is not a significant health concern. The U.S. Food & Drug Administration (FDA) has performed an exhaustive review of related scientific literature and found insufficient evidence supporting the fact that amalgam fillings containing mercury have adverse health effects. There were, however, some exceptions. Women who are pregnant, children under the age of six, and patients who are routinely exposed to mercury or who have a diet that consists largely of seafood (which can contain high levels of mercury) should avoid amalgam filling material. Other agencies and organizations, including the American Dental Association (ADA) and the Centers for Disease Control and Prevention (CDC), have released similar statements.

Composite Resin Restorations

Tooth-colored plastic materials have been widely used in dentistry since the 1990s. Like amalgam, the dentist mixes this material chairside and places the filling while it is in a soft, putty-like state. Within minutes, the material hardens to nearly its maximum strength.

Natural-Looking and Conservative

Composite resins have the obvious advantage of being tooth-colored. The material is available in various shades so it can be precisely matched to the patient's natural tooth.

Another advantage of composites is that they can be bonded in place with an acid-etching process. This means that they can essentially be glued to the tooth structure and do not require large, undercut tooth preparations for retention. As a result, these fillings can be very small and the preparations conservative.

Require More Frequent Replacement

The downside of composite fillings is that they are not as hard and resistant to abrasion as amalgam restorations. This means they often require more frequent replacement. In addition, they are more technically difficult to place than amalgam. A dry, uncontaminated treatment area must be strictly maintained during placement for effective bonding to occur. The filling is more likely to fail if this is not accomplished. Composite materials also have the disadvantage of slightly shrinking during the setting process. This creates a microscopic gap at the margin between the filling and the tooth, which increases the chances of leakage and places the tooth at a higher risk for decay.

Making an Informed Decision

In summary, amalgam is strong, easy to use, inexpensive, and resistant to recurrent decay. However, it is less aesthetically pleasing, and it can stain the adjoining tooth enamel. Amalgam also contains the toxic element mercury, but its use as a restorative material has not been shown to cause any adverse health issues in most patients.

Composite resin is more lifelike than amalgam and can be bonded directly to the tooth. However, this material is more technically difficult to use than amalgam. It is not as strong and these restorations are more susceptible to new decay forming at their margins. For these reasons, composite resin may be more beneficial in visible areas near the front of the mouth. Anterior teeth are subjected to less pressure than molars and the patient has better access to properly brush and floss.

Preserve Your Oral Health

Dental amalgam and composite resin filling materials each have advantages and disadvantages, but after decades of use, both have proven to be extremely effective. Left untreated, decay can spread and eventually reach the inner portion of the tooth. Timely placement of both types of fillings can help patients avoid extraction and costly restorative treatment. With accurate and adequate information, patients can work closely with their dentist to make an informed decision about which type of restoration is right for them.

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