Tooth-colored vs silver fillings: which is better, and should old ones be replaced?

Which is better: a tooth-colored filling or a silver filling?

Neither is better for every tooth. Each material has strengths. The ADA’s MouthHealthy site says your dentist considers materials on an individual basis, based on the size and location of the cavity. Looks, how long the filling could last, insurance coverage and out-of-pocket cost can matter too.

Here is how the main materials compare, using the FDA, the ADA, NIDCR and Cleveland Clinic.

The right answer for you depends on the cavity. The guide to crowns, fillings and onlays explains what happens when the damage is too large for any filling.

What is a silver filling made of?

A silver filling is dental amalgam. It is a mix of liquid mercury and a powdered metal alloy of silver, tin and copper. The FDA says about half of an amalgam filling is mercury by weight. The mercury binds the metal particles into a solid, strong filling.

Many people call it a “silver” filling because of the color. The FDA does not recommend the term “silver filling,” because it does not correctly explain the materials in amalgam. Dentists have used amalgam for more than 150 years.

What are tooth-colored fillings made of?

Tooth-colored fillings are plastic and glass. The most common type is composite resin. The FDA says composite resin fillings are the most common alternative to dental amalgam. They are made of a plastic resin with powdered glass filler, and the shade can be matched to the surrounding tooth. The layers are often hardened with a blue light.

Glass ionomer is another tooth-colored option. The FDA says it releases fluoride over time and suits very small fillings. It is not made for large ones.

Composite takes more time to place than amalgam. The ADA says the tooth must be kept clean and dry while the cavity is filled. For that reason, a composite filling can take longer than a metal one.

How long do the different fillings last?

Amalgam tends to last longer than tooth-colored fillings in the research. NIDCR says both types of tooth-colored fillings are less durable than amalgam, making them more susceptible to breakage and new decay in the tooth. Cleveland Clinic gives a wide range of 10 to 20 years for fillings, depending on the material.

NIDCR points to one large study. Among more than 700,000 tooth-colored fillings in the U.S., 16 percent failed within five years of being placed. The most common causes were new cavities and broken teeth.

Please keep this in mind. A study average does not predict your filling. The ADA says no dental filling lasts forever. Size, location, bite force, grinding and daily cleaning all count. Regular checkups help your dentist see wear early.

The practical takeaway is simple. Amalgam has the stronger record for durability, and tooth-colored fillings have the better look. Many people accept a shorter expected life for a filling that blends in. Others pick the stronger material for a back tooth that takes heavy chewing. Both are reasonable choices, and the decision is yours with your dentist.

Are silver fillings safe?

The FDA says the available evidence does not show that mercury from amalgam leads to adverse health effects in the general population. NIDCR says studies show dental amalgam fillings are safe for most people. The FDA also says mercury may pose a greater risk to certain groups.

The FDA lists these groups:

• Pregnant women and their developing fetuses.
• Women who plan to become pregnant.
• Nursing women and their newborns and infants.
• Children, especially those younger than six.
• People with a neurological disease.
• People with impaired kidney function.
• People with a known sensitivity or allergy to mercury or other amalgam metals.

NIDCR says mercury-free materials, such as glass ionomers or composite resins, are recommended for pregnant women and children. If you are in one of these groups, tell your dentist before treatment.

Should I replace my old silver fillings?

Usually not, if they are in good shape. The FDA does not recommend removing amalgam fillings that are in good condition with no decay beneath them. Removal takes away healthy tooth and briefly raises the amount of mercury vapor released.

A filling does need attention when:

• It is cracked, chipped or worn through.
• Decay has formed under or beside it.
• It has pulled away from the tooth, leaving a gap.
• Part of the tooth around it has broken.

The ADA’s MouthHealthy site adds that older fillings may weaken, fracture and leak around the edges, which lets bacteria collect. Your dentist can check old fillings with an exam and X-rays. If you are worried about the mercury, ask about the FDA’s advice and your own health history before you decide.

What is the difference between direct and indirect fillings?

A direct filling is shaped and placed in the tooth in one visit. Amalgam, composite and glass ionomer are all direct fillings. Cleveland Clinic says direct fillings do not need a dental laboratory or a temporary restoration.

An indirect filling is made outside the mouth, usually in a lab. Inlays and onlays are indirect fillings, made of gold or porcelain. They take two visits in most cases. Cleveland Clinic says dentists use them when a tooth has too much damage for a direct filling but not enough for a crown. If your cavity is large, your dentist may talk with you about an indirect option. See the crown, filling or onlay guide for more.

How does each material stay in the tooth?

Composite is bonded to the tooth. Amalgam is packed into the shaped cavity and forms a tight seal. NIDCR says other filling materials do not bond well to the tooth in the presence of saliva, while amalgam does not have that problem. That is one reason dentists find amalgam easier to place, and why composite needs a clean, dry tooth.

The FDA lists a plus for composite. It allows minimal removal of healthy tooth structure. The FDA also warns that composite can blend in with tooth structure, which can make later removal hard without taking some healthy tooth.

What about the environment and other concerns?

Mercury is also an environmental concern. NIDCR says dentists must use an amalgam separator to keep excess amalgam out of the wastewater, and that many countries, including the U.S., are working to reduce amalgam use. Some countries, including Norway and Sweden, have stopped using it.

Composite has its own question. NIDCR notes that composite resins can contain bisphenol A (BPA), a chemical that can negatively affect children’s health, and that scientists are developing new resins without it. If you have concerns about either material, bring them up. Your dentist can explain what is in the product being used.

What are signs that a filling needs a look?

Many fillings give no warning. A dentist often finds a problem during a regular exam or on an X-ray. Cleveland Clinic lists these signs that call for a visit:

• A throbbing toothache. Decay may have reached the pulp.
• Pain when you bite down. The filling may be too high and need reshaping.
• Pain to heat or cold that lingers after the trigger is gone.
• A filling that breaks, or a swollen face or jaw.

Mild sensitivity right after a new filling is normal. Pain that gets worse, or pain that lasts past two weeks, is a reason to call.

How is each filling placed?

The steps are alike. Cleveland Clinic describes them:

1. The dentist numbs the tooth with local anesthetic.
2. The dentist removes the damaged tissue.
3. The dentist fills the space with the chosen material.
4. For composite, a curing light hardens the material.
5. The dentist smooths the filling and checks your bite.

Afterward, Cleveland Clinic says you can return to routine activities if you did not have sedation. It adds that waiting until the numbness wears off keeps you from biting your cheek. Minor sensitivity and gum soreness are normal and should fade in a week or two. Call your dentist if the filling breaks, or if you have severe pain that does not go away.

Does the choice change cost and insurance?

Yes, it can. The ADA says composites cost more than amalgam and occasionally are not covered by some insurance plans. NIDCR says amalgam is cost-effective. Town Center Dental does not publish prices. The office gives each patient their own estimate, and the insurance and financing page explains how the office works with plans.

Ask for the estimate for each material your dentist offers. Ask what your plan pays for each one. Some plans may pay only part of the cost for certain materials, so ask your plan.

What should I ask my dentist?

These questions help you decide:

1. Which materials suit this tooth, and why?
2. How long do you expect each one to last in my mouth?
3. Will you need to remove more tooth for one than the other?
4. What is the estimate for each option, and how does my plan treat it?
5. Do any of my health conditions affect the choice?
6. Are any of my old fillings worth watching, or worth replacing?
7. Is this spot early enough that fluoride and better cleaning might be an option instead of a filling?

If a cavity is very small, early care may protect the tooth before any filling is needed. The cavities guide explains how decay starts and how a dentist finds it.

Next step

If you have an old filling that worries you or a new cavity to repair, ask for an exam and talk through the options. Read about dental fillings at Town Center Dental, then call (636) 273-5866 or request an appointment.