If you have a cavity, your dentist will remove the decayed part of the tooth and fill the space so the tooth can work normally again. What goes into that space is a real choice, and it is one you are entitled to make with your dentist. The ADA’s MouthHealthy site puts it plainly: you have the right to decide, after talking with your dentist, what treatments and materials are used for your care (MouthHealthy: Dental amalgam). This guide compares the common filling materials, their trade-offs, and the questions worth asking before your appointment.
Why the material matters
Every filling material balances strength, appearance, how the tooth must be prepared, how easy it is to place in a given spot, and cost. A filling on the biting surface of a back molar faces very different demands than one on a front tooth that shows when you smile. A small cavity near the gumline in a mouth that is hard to keep dry is different again. There is no single “best” filling for everyone; there is a best fit for a particular tooth, cavity and patient.
If you are not sure how cavities form in the first place, our guide to tooth decay and cavities explains the process and how early decay can sometimes be managed before a filling is needed.
The main options
Dental amalgam (“silver” fillings)
Amalgam is a mixture of metals. According to the U.S. Food and Drug Administration, it consists of liquid (elemental) mercury and a powdered alloy of silver, tin and copper, and roughly half of dental amalgam is elemental mercury by weight (FDA: Dental amalgam fillings). The mercury binds the alloy particles into a hard, durable filling.
Strengths. The FDA lists amalgam’s benefits as being strong and long-lasting, useful for patients at high risk of decay and for large preparations, and useful where moisture makes it hard for resin materials to bond. It is also the least expensive filling material. MouthHealthy adds that amalgam hardens quickly and takes less time to place, which can help with children or patients who have trouble staying still.
Drawbacks. It is silver-colored and does not look natural, and the dentist may need to remove more healthy tooth structure to place it than with some other materials (MouthHealthy).
Safety. The ADA says the best available scientific evidence shows amalgam is a safe and effective filling material and that existing amalgam fillings in good condition do not need to be removed. The FDA says the available evidence does not show that mercury exposure from amalgam leads to adverse health effects in the general population, but it recommends that certain higher-risk groups avoid amalgam when possible and appropriate. Those groups include pregnant women and women planning a pregnancy, nursing women, children (especially under six), people with pre-existing neurological disease or impaired kidney function, and people allergic to mercury or the other metals in amalgam (FDA). The FDA also generally does not recommend removing amalgam fillings that are in good condition unless there is a medical need, because removal itself can expose you to mercury vapor and damage healthy tooth structure.
Composite resin (tooth-colored fillings)
Composite is a tooth-colored resin material that is bonded to the tooth. MouthHealthy lists tooth-colored composites among the main alternatives to amalgam and notes that, these days, even many back-tooth fillings are done in composite because people prefer the natural look. Composite generally requires the tooth to be kept dry while it is bonded, which is one reason amalgam can still be a better choice in some hard-to-reach or wet areas, as the FDA notes.
Composite is also the material behind cosmetic dental bonding. If you are interested in using it to repair a chip or reshape a tooth rather than fill a cavity, see our dental bonding guide.
Glass ionomer
Glass ionomers are another tooth-colored option mentioned by MouthHealthy. Dentists often consider them for certain small fillings, fillings near the gumline, and some fillings in children. Ask your dentist how a glass ionomer filling would be expected to hold up on the specific tooth being treated.
Inlays and onlays: ceramic, zirconia or gold
When a cavity is too large for a simple filling but the tooth does not need a full crown, a dentist may suggest an inlay or onlay. These are made outside the mouth (in a lab or with in-office milling) and then cemented in place. MouthHealthy lists ceramic, zirconia and gold inlays and onlays as filling options. They usually take more than one step or a special in-office system, and they typically cost more than a direct filling. If a tooth is badly broken down, a crown may be the better repair; our dental crown guide compares crown types.
Side-by-side summary
- Amalgam: very durable, tolerates moisture during placement, quick, lowest cost; silver color; may need more tooth removed; FDA advises certain groups to avoid it when possible.
- Composite: tooth-colored, bonded to the tooth; needs a dry field; common for front and many back teeth.
- Glass ionomer: tooth-colored; often used in specific situations such as small or gumline fillings.
- Ceramic, zirconia or gold inlays/onlays: made outside the mouth for larger repairs; more involved and usually more costly.
How dentists choose a material
Your dentist will usually weigh:
- Location. Back teeth take heavy chewing forces; front teeth are more visible.
- Size and depth of the cavity. Large cavities may need a stronger material, an onlay or a crown.
- Moisture control. Cavities below the gumline or in hard-to-isolate areas can favor materials that tolerate moisture.
- Your decay risk. The FDA notes amalgam is useful in patients with a high risk of decay.
- Your health and preferences. Pregnancy, allergies, kidney or neurological conditions, and appearance all matter.
- Cost and coverage. Dental plans sometimes pay for a tooth-colored filling on a back tooth only up to what they would pay for amalgam. Check your plan before treatment.
Cost and insurance
We do not publish price figures for fillings, because fees vary widely by region, practice and the size of the filling. What the sources do say is that amalgam is the least expensive filling material (FDA) and that inlays and onlays involve more steps than a direct filling. The best way to know your own cost is to ask for a written estimate that lists each procedure. Our guide to reading a dental treatment plan explains what to look for, and understanding dental insurance covers how plans typically pay for basic restorative care.
Questions to ask your dentist
- Which materials are suitable for this specific tooth and cavity, and why do you recommend this one?
- How much healthy tooth will need to be removed with each option?
- Does my health history (pregnancy, allergies, kidney or neurological conditions) affect the choice?
- How will my insurance pay for each option, and what would I owe?
- What should I expect after the filling, such as temporary sensitivity?
After a filling
Some people notice short-term sensitivity to cold or pressure after a filling. If a filled tooth stays sensitive, feels high when you bite, or starts to ache, call your dentist; a bite adjustment or further evaluation may be needed. Our article on sensitive teeth explains other common causes of sensitivity.
Key takeaways
- You have a say in which filling material is used.
- Amalgam is durable and low cost; the FDA recommends certain higher-risk groups avoid it when possible, and generally advises against removing amalgam fillings that are in good condition.
- Tooth-colored composites and glass ionomers look natural but have their own placement requirements.
- Inlays, onlays and crowns are for larger repairs.
Frequently asked questions
Should I have my old silver fillings replaced?
Not just because they are amalgam. Both the ADA and the FDA say fillings in good condition generally do not need to be removed, and the FDA notes that removing sound fillings can expose you to mercury vapor and remove healthy tooth structure. Replace a filling if it is broken, leaking or decayed underneath, or if your dentist identifies a medical reason.
Is amalgam safe during pregnancy?
The FDA lists pregnant women and women planning a pregnancy among the groups who should avoid new amalgam fillings when possible and appropriate. Talk to your dentist about alternatives. Our guide to dental care during pregnancy covers other considerations.
Are tooth-colored fillings as strong as amalgam?
It depends on the material, the size of the filling and where it is. Amalgam is known for strength in large back-tooth fillings; modern composites are widely used in back teeth too. Your dentist can explain the expected trade-off for your tooth.
Why might my insurance not pay fully for a white filling?
Some plans pay for a tooth-colored filling on a back tooth only up to the amount they would pay for amalgam, leaving you to pay the difference. Check your plan’s terms before treatment.
What if I’m allergic to metals?
The FDA says people with an allergy or sensitivity to mercury or the other metals in amalgam should not get amalgam fillings. Tell your dentist so you can choose another material.
Sources
By the Dentist Review Editorial Team.
This article is for general information only and is not medical advice. Talk to a licensed dentist about your own situation. See our disclaimer.
Featured image: “Set of dental tools and instruments on a table in a clinic during a procedure” by Shixart1985, via Wikimedia Commons, licensed CC BY 2.0. Resized and compressed for the web.
Our guides are written and reviewed by the Dentist Review editorial team. We research each topic using public, authoritative sources such as the CDC, the National Institutes of Health (NIH/NIDCR), the American Dental Association (ADA) and CMS, and we update guides when guidance changes. Guides are for general information only and are not dental or medical advice; please read our disclaimer and learn more about us.