Dental restorations are among the most common dental procedures and include fillings, inlays and onlays, veneers, implants, crowns, bridges, and dentures. They are used to restore damaged, decayed or missing teeth. They can also relieve associated dental pain. They can frequently save teeth that would otherwise need to be extracted. Direct restorations are made in the dental office directly in the patient's mouth. Indirect restorations are made in a dental laboratory using impressions made of the patient’s teeth. These usually require multiple visits to the dental office. Restorations can be performed on both permanent and primary teeth. Restoration on primary teeth is performed in the same manner as permanent teeth.

Restorations require removing portions of damaged teeth. For some types (e.g., crowns) the teeth will be filed down to accommodate the added material. There is usually little or no discomfort after a dental restoration has been placed, although some patients may experience sensitivity to hot and cold. Restorations can be damaged or dislodged by stresses from chewing on hard substances (e.g., nuts, ice), oral piercing, grinding teeth and biting fingernails.

Modern dental restorations can be made from different materials. The right material for a particular case is typically determined by a dentist in consultation with the patient. The decision is based on factors such as the patient’s dental and overall health, the type of restoration used, and the location of the restoration. Restorations may be cemented or sealed into place. Types of materials used in dental restorations include:

• Amalgam. A mixture of mercury, silver, tin, copper and other metals, this material is used in fillings that require strength (e.g., the molars). Amalgam is easier to place than other materials. It can tolerate some moisture during the placement procedure and is less expensive. It is very strong and highly resistant to wear. Amalgam requires removing a larger amount of tooth structure than composite resin or ionomers and may cause hot or cold sensitivity after it has been placed in some patients. There has been some debate on the safety of amalgam fillings due to their mercury content. However, according to the American Dental Association (ADA), U.S. Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH) and the U.S. Food and Drug Administration (FDA), there is no sound scientific evidence of a link between amalgam and these or any other health problems.
  
  
• Composite resin. A material made of glass or quartz fillers and an acrylic plastic material. It may be used to make fillings, inlays and onlays, veneers, and crowns. The color and translucency closely match natural teeth. Composite resin is resistant to wear and fracture. It is well-tolerated by patients and gentle to nearby teeth. However, it stains more readily than porcelain and is not as strong as porcelain or amalgam materials.
  
  
• Ionomers. Materials made of acid and glass powders that contain fluoride. They may also include acrylic resin for additional strength. Ionomers are used for small fillings in areas without much stress (e.g., between the teeth, tooth roots). They may also be used to line cavities and as cement for crowns and bridges. Ionomers release fluoride into the teeth and can help prevent tooth decay. The color closely matches natural teeth and they are well-tolerated by patients. However, ionomers are prone to fracture and can wear down quickly.
  
  
• Gold alloys. Composed of a combination of gold, copper and other metals, these are used to make inlays, onlays, crowns and bridges. The materials are tough and highly resistant to tarnishing, corrosion, fracture and wear. They do not usually require as much removal of the underlying tooth as other types. They are gentle to nearby teeth and are well-tolerated by patients. However, patients may not like the metallic gold color.
  
  
• Base-metal alloys. Materials made of a combination of base metals (e.g., nickel, chromium). They are used for crowns and bridges. These materials are strong and highly resistant to fracture, wear, tarnishing and corrosion. This type does not usually require as much removal of the underlying tooth. However, they have a metallic silver color that many patients do not like. They may also cause sensitivity or discomfort with hot and cold in some patients.
  
  
• Porcelain. Made of porcelain, ceramics or glasslike materials. All-porcelain inlays, onlays, veneers and crowns are available. These materials can closely match natural teeth and are resistant to wear. However, they may be prone to fracture and can wear down nearby teeth if the porcelain surface becomes rough. They require removing a larger amount of natural tooth for a strong crown. Porcelain tends to be more expensive than metal alloys.
  
  
• Porcelain fused to metal. Made of a porcelain surface bonded to a metal base. This material is often used in crowns. The combination of porcelain and metal is very strong, durable and highly resistant to wear. The color also closely matches natural teeth. This material can wear down nearby teeth if the porcelain surface becomes rough. It may also cause sensitivity or discomfort with hot and cold in some patients. In addition, this type requires removing a larger amount of natural tooth to support the material.

Researchers are investigating potential new materials for dental restorations that may be stronger, less brittle, more attractive and more like natural teeth than currently available materials.