What are fillings?

Fillings are special materials that your dentist places on your teeth to repair tooth decay (cavities) or defects on the tooth surface. Fillings (also called restorations) restore the tooth to form and function. Advances in dental materials and methods provide new, effective ways to restore teeth.

There are several different types of restorations, including direct and indirect restorations.

Direct restorations

These need a single visit to place a filling directly into a prepared cavity. Materials used for these fillings include:

• Dental amalgam, also called silver fillings. Amalgam fillings have been used for decades. They have been tested for safety and resistance to wear. Dentists have found them safe, reliable, and effective.

• Glass ionomer fillings. These are tooth-colored materials made from fine glass powders and acrylic acids. They are used in small fillings that don't have to withstand heavy pressure from chewing. They chemically bond to the mineral in the tooth.

• Resin ionomer fillings. These are made from glass with acrylic acids and acrylic resin. Like the glass ionomers above, they chemically bond to the mineral in the tooth.

• Composite (resin) fillings. These are the best-looking of the tooth-colored direct fillings. They are made from acrylic resin filled with tiny glass or quartz particles. They are not quite as strong or wear resistant as amalgam. But they are stronger and more durable than glass ionomers and can be used on biting surfaces. They are bonded to the tooth.

Indirect restorations

These often need 2 or more dental visits and include:

• Inlays

• Onlays

• Porcelain

• Veneers

• Crowns

• Bridges

These are made with gold, base metal alloys, ceramics, porcelain fused to metal, or specially formulated composites. At the first visit, a dentist will prepare the tooth and make an impression of the area to be restored. At the second visit, the dentist will cement the new restoration into the prepared area. Some offices use newer technology called CAD/CAM (computer-aided design/computer-aided manufacturing). This lets them to make the indirect restoration in the office and use it at the same appointment. So it's all done in one visit.

For an indirect restoration, a dentist may use an all-porcelain or ceramic material. This material looks like natural tooth enamel in color and translucency. Another type of indirect restoration may use porcelain that is fused to metal, which provides added strength. Gold alloys are used often for crowns, foundations for porcelain fused to metal crowns, or inlays and onlays. Inlays and onlays can also be made from ceramic or composite resin materials. Less expensive metal alloys may be used as different options to gold for all-metal and porcelain fused to metal crowns. Indirect composites are like those used for fillings and are tooth colored. But they are not as strong or wear resistant as ceramic or metal restorations.