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Treatment for Cavities

Once the decay has penetrated the surface of the enamel and a cavity has formed, the emphasis shifts from prevention to restoration. The tooth cannot repair itself; instead, your dentist must correct the damage. If the damage extends into the dentin (but has not yet reached the pulp) and the tooth is stable, repair usually means cleaning out the area and filling the cavity.

How Your Dentist Fills a Cavity

After numbing the area, your dentist will clean away the decayed enamel using a high-speed rotary drill, an air-abrasive device, or a laser system. He or she may also use a slower drill or manual scooping tool to remove damaged dentin. Once the decayed portion is removed, your dentist will cut the hole into a shape that enables the filling to adhere securely and gives the rest of the tooth the most support.

The next steps depend on the size of the hole to be filled and the material to be used. In some cases, the dentist will coat the inside of the hole with a lining material that prevents tooth sensitivity, seals against leakage, and helps the filling material adhere. This step is often taken for large or deep cavities. When tooth-colored fillings (composites) are used, the dentist must etch the interior of the prepared cavity with acid to ensure that the filling material adheres to the enamel.

Silver amalgam restorations are generally completed in one visit with no other preparatory steps. Other types may take more than one visit to complete. Inlays (which fit into the tooth) and onlays (which fill the tooth and cover part of the biting surface) must be specially made to match the size and shape of the area being filled. These restorations, which are usually reserved for larger cavities, may take two or three visits to complete.

Materials Used for Fillings

You and your dentist should consider several factors when choosing a filling material. These include the size and location of the filling, the health of the surrounding teeth, the chewing force the affected tooth must endure, the number of visits necessary to make the repair, the cost of the procedure, and the appearance of the completed restoration. The table below describes the materials commonly used to repair damaged teeth and summarizes their benefits and drawbacks.

Choosing a Material to Fill Your Cavity

Type of material

What is it?

How is it used?



Silver amalgam

Mixture of silver, mercury, and traces of other metals; silver-gray color when new, but may tarnish and turn black with age; the most common filling material used

For small to large fillings in load-bearing teeth (molars)

Strong and easy to use

Repair often can be completed in one visit

Inexpensive compared with other forms of repair

Limited duration; lasts an average of 10 years

Composite resin

Finely ground glass or silica mixed with an acrylic resin; various tooth colors

For small to moderate-sized fillings and for the repair of front teeth

Matches natural tooth color

Preparation requires less removal of existing tooth

Bonds tightly to tooth

Difficult to use for large repairs

Area must be moisture-free when filling is placed

Longevity of filling depends on placement technique

Technique demands high level of skill by dentist

Can cost two or three times more than amalgam for back teeth, depending on the size of the filling

Can require more than one visit

Glass ionomer

Mixture of glass powder and an acrylic acid; white in color

For small cavities, especially around roots; as a cavity liner; as cement for crowns and bridges

Material contains fluoride, which is released to the tooth

Natural tooth color

Preparation preserves more of existing tooth

Demands high level of skill by dentist

Moderately expensive

Can require more than one visit

Color may not be a good enough match for highly visible areas

Gold alloys

Gold mixed with other metals and poured into a mold made from an impression of the tooth

For inlays, onlays, and crowns in back teeth; for fixed bridges

Highly durable; can last a lifetime

Restorations wear at the same rate as natural teeth, so opposing teeth do not suffer

Demands high level of skill by dentist

Tooth needs to be shaped significantly to accommodate restoration


Process requires multiple visits

Base metal alloys

Palladium mixed with nickel or copper

For crowns, fixed bridges, and partial dentures


Resistant to wear and corrosion

Metal (nickel) causes allergic reaction in some people

More expensive than glass ionomers or silver amalgam (less expensive than gold)

Process requires multiple visits


Porcelain, ceramic, or glasslike material

For inlays and onlays, crowns, veneers, and bridges

Color and translucency closely match natural teeth

Durable but subject to fracture on impact

Can wear down opposing teeth


Process requires multiple visits

Ceramic bridges still considered experimental

Porcelain fused to metal

Thin layer of porcelain bonded to a metal frame made of gold alloy or base metal alloy

For crowns and bridges

Stronger than porcelain alone

Method of choice for bridges

Can wear down opposing teeth

Gold-free alloys (such as nickel) may cause an allergic reaction in some people


Process requires multiple visits

Is Silver Amalgam Safe?

Silver amalgam, the most common filling material, has been used for more than 150 years, but it continues to be controversial. The source of the concern is fear that mercury, a component of amalgam, may promote conditions such as Alzheimer’s disease, multiple sclerosis, and autism. Amalgam fillings release mercury vapor not only when they are placed in and removed from the teeth, but also during chewing.

Over the years, a variety of health organizations such as the FDA, ADA, World Health Organization, National Institutes of Health, CDC, and U.S. Public Health Service at one point or another have stated that amalgam is safe for all but the few individuals who are allergic to the material and that banning it would eliminate an important filling option for many people.

However, the FDA made headlines a few years back with a change in its position on the subject. After reviewing studies on amalgam from 1997 to 2006, the agency initially drafted a report that reiterated the position that amalgam is safe for nearly all people. But in September 2006, the advisory panel that reviewed this report said there were too many uncertainties to make that claim. In 2008, the FDA took steps to reopen the discussion by soliciting new scientific evidence on the topic. The agency is considering whether restrictions on this type of filling may be prudent, especially for groups such as pregnant women, children, and people who are sensitive to mercury. The ADA has stood firmly behind the safety of amalgam, issuing the following statement: “The overwhelming weight of scientific evidence supports the safety and efficacy of dental amalgam, and it should continue to be made available to dentists and their patients.”

Meanwhile, the debate about amalgam has prompted some dental professionals to substitute more expensive restorations for intact silver fillings for all patients. But there is no evidence that removing your amalgam fillings will benefit your health. Most amalgam fillings wear out in 10 years or less and need to be replaced. At that time, you and your dentist should discuss which restoration material is best for your dental needs.

Dental Health for Adults: A Guide to Protecting Your Teeth and Gums. Copyright © by Harvard University. All rights reserved.

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