Dental Fillings Health Article

Definition

Dental fillings are metal amalgams or composite resins used to fill a cavity.

Purpose

Dentists use dental fillings to restore teeth damaged by dental caries (tooth decay). Dental caries are caused by microorganisms that convert sugars in food to acids which erode the enamel of a tooth, creating a hole or cavity. The dentist cleans out the decayed part of the tooth and fills the opening with an artificial material (a filling) to protect the tooth's structure and restore the appearance and utility of the tooth.

Precautions

As in any dental procedure, the dentist and dental assistant will need to use sterile techniques. Gloves and masks are essential as well as the sterilization of equipment and tools. This not only helps prevent the spread of infectious diseases like AIDS and hepatitis, but also the common cold.

The patient's reaction to anesthesia is the other main concern of the dentist and dental assistant when performing dental fillings. Nitrous oxide should be avoided with pregnant patients, and local anesthetics should be used with caution, though they are considered safe. Local anesthetics like Novocain and lidocaine have been in practical use for decades with few side effects reported. Some patients, however, are allergic to these drugs.

Description

Though dentists are encountering fewer and smaller cavities in their patients, there is still a need for dentists to fill cavities. Old fillings suffer wear and need to be replaced. Patients are demanding more restorative work on their teeth, sometimes opting for full mouth restorations that involve installing crowns, bleaching teeth or applying veneers, and replacing dark metal fillings with tooth-colored ones that create a monochomatic view in a patient's mouth.

Once the decay is removed and the tooth is prepared (see Preparation), the dentist has a wide choice of dental filling materials to choose from.

Amalgam fillings

The most common and strongest filling material is amalgam. It is a silver filling that is usually placed on the rear molars, which endure more stress during chewing. Amalgam fillings—used for large, deep cavities—are strong and very resistant to wear. Amalgam has been in use since 1833.

Amalgam is a mixture (an amalgam) of several metals, including liquid mercury (35% silver, 15% tin or tin and copper, a trace of zinc, and 50% mercury). When it is prepared, it has a malleable consistency which can easily be shaped to fit the prepared tooth. It hardens to a durable metal.

Despite its durability, many dentists and patients avoid amalgam fillings. Dentists have found that amalgam has a tendency to expand with time. As a result, teeth become fractured from the inside, often splitting the tooth. Patients often avoid amalgam for strictly aesthetic reasons. Amalgam fillings darken over time and make teeth look as if they are decayed.

The biggest reason amalgam has lost favor is a health concern due to its 50% mercury content. Although the American Dental Association (ADA) has pronounced amalgam safe in the quantity and composition of amalgam, some patients and dentists are disturbed by various reports of illness in relation to the mercury in amalgam fillings. Mercury is a toxic material. Some states are required to dispose of mercury waste as if it were a hazardous product. There is also an added risk of inhaling mercury particles when old fillings are removed.

Gold fillings

Gold fillings or inlays are created outside of the mouth by a dental technician and then cemented into place. They are also used to fill the back molars. Gold fillings are very durable. Like amalgam, however, they are not as aesthetically pleasing as tooth-colored fillings.

Composite fillings

Composite fillings, often called white fillings, are made of a plastic resin and finely ground glass. They must be applied to the tooth surface in thin layers. Dentists try to match the color of composites with neighboring teeth for a more natural look, making the filling appear invisible. Composite resin fillings often are made smaller than amalgam fillings and require less tooth preparation, thereby saving more natural tooth surface.

Composite fillings are bonded to the tooth so that the tooth becomes stronger than it was before. They are also less sensitive to temperature changes in the mouth that can damage the tooth; therefore there is less chance that the tooth will shatter because of the filling.

These fillings may not be suitable for large cavities in molars. Though composite durability increased in the 1990s, a porcelain inlay or crown may be the best choice for a durable, natural-looking restoration of a molar.

The major drawback of composite resin fillings is cost. They average one-and-a-half to two times more than the price of amalgam fillings. They also can be stained from drinking coffee and tea. Large composite fillings tend to wear out sooner than amalgam fillings.

Composite fillings can last seven to ten years, which is similar to the lifespan of amalgam fillings.