Composite vs Amalgam Fillings: Why We Choose Tooth-Colored

Tooth-colored composite fillings have become the default restoration for most cavities in modern dental offices because they bond directly to enamel, preserve more healthy tooth structure, and blend in seamlessly with the surrounding tooth. Traditional silver amalgam is still considered safe by the American Dental Association and the FDA, but its mercury content, lack of bonding, and metallic appearance have shifted clinical practice toward composite for the great majority of restorations. At Carlmont Dental Care in Belmont, we place tooth-colored composite as our standard material and reserve amalgam removal for situations where it makes clinical sense.

What's actually in each material?

Dental amalgam is a metal alloy that has been used for more than 150 years. It's made by mixing roughly equal parts liquid elemental mercury with a powdered blend of silver, tin, and copper. Once placed and condensed into a prepared cavity, it hardens into a strong, wear-resistant filling — but it stays silver-gray for the life of the restoration.

Composite resin is a tooth-colored mixture of a plastic resin matrix and finely ground glass or ceramic particles. Instead of being packed into a mechanical undercut the way amalgam is, composite is bonded to the tooth with a dental adhesive and cured with a blue light in thin layers. The result is a restoration that's chemically attached to the tooth itself.

Why most dentists now choose composite

The shift toward composite isn't just about looks, though aesthetics matter to most patients. Several practical advantages drive the change:

• Less healthy tooth removed. Amalgam needs a mechanical "box" with undercuts to lock it in place, which often means cutting away sound enamel that doesn't have decay. Composite bonds, so the preparation can follow the shape of the cavity itself.
• Bonded strength. Because composite adheres to the tooth, it can help reinforce remaining tooth structure rather than simply filling a hole.
• No mercury. Composite contains no heavy metals. While research consistently finds amalgam safe for the general population, the FDA issued a 2020 safety communication recommending that pregnant women, nursing mothers, children under six, and people with certain neurological or kidney conditions avoid new amalgam fillings when an alternative is appropriate.
• Aesthetics. Composite is shade-matched to your existing tooth color, so a filling on a premolar or front tooth isn't visible when you smile or laugh.
• Repairability. If a composite chips or wears at the edge, it can often be touched up by bonding new material to the old. Amalgam typically has to be cut out and replaced.

Where amalgam still has an edge

It would be misleading to suggest amalgam has no advantages. On molars under heavy chewing load, well-placed amalgam restorations have historically shown excellent longevity, and the material is more forgiving of moisture during placement — useful in difficult-to-isolate areas. The ADA and major global health bodies continue to recognize amalgam as safe and effective, and we don't recommend removing intact, well-functioning amalgam fillings simply to swap materials. That kind of "prophylactic" replacement exposes you to more mercury vapor than leaving the filling alone.

That said, modern composite materials and bonding systems have closed much of the historical durability gap, especially when restorations are placed under a rubber dam in a dry, controlled field — which is the protocol Dr. Nancy Jiang, Dr. Amanda Lee, and Dr. Michael Chen follow for restorative work.

What's happening globally with amalgam

You may have heard that amalgam is being phased out. The Minamata Convention, an international treaty focused on reducing mercury use, agreed in late 2025 to phase out dental amalgam worldwide by 2034 except where clinically necessary, and the U.S. Indian Health Service announced it will discontinue amalgam use in 2027. Environmental concerns — mercury entering wastewater — are a major driver, which is why the EPA already requires dental offices to install amalgam separators. The direction of travel is clear, even if amalgam remains an option in the U.S. for now.

How we decide what's right for your tooth

Material choice is one part of a larger conversation. The size and location of the cavity, how much healthy enamel is left, your bite force, your aesthetic preferences, and your medical history all factor in. For very large cavities on back teeth, a bonded composite onlay or a crown sometimes outperforms a direct filling of either material. Our team will walk you through the options and provide a written estimate after your exam.

Common questions about composite vs amalgam fillings

Q: Should I have my old silver fillings removed?

Not unless there's a clinical reason — decay underneath, a cracked tooth, an open margin, or a broken filling. Replacing intact amalgam purely for cosmetic or mercury concerns isn't generally recommended, since drilling out the old filling temporarily increases mercury vapor exposure.

Q: How long do composite fillings last?

With good home care and regular cleanings, modern composite fillings commonly last roughly 7 to 10 years, and often longer on smaller restorations. Longevity depends heavily on cavity size, bite forces, grinding habits, and oral hygiene.

Q: Are composite fillings safe during pregnancy?

Composite is the preferred restorative material during pregnancy because it contains no mercury. If you're pregnant or planning to be, let us know so we can plan timing and materials accordingly.

Q: Will my insurance cover composite on a back tooth?

Most of the PPO plans we accept — Delta Dental PPO, Aetna, MetLife, Cigna, Guardian, and others — cover composite, though a few still downgrade benefits on molars to the amalgam fee schedule. We'll verify your specific plan before treatment.

Q: What if I can't pay for treatment all at once?

We offer in-house membership plans starting at $30 per month for patients without insurance, and 0% APR financing through CareCredit and Proceed Finance for larger treatment plans.

Talk with our Belmont team

If you have a tooth that's bothering you, an older filling you'd like evaluated, or you simply want a second opinion on a recommended restoration, our team is happy to help. Call Carlmont Dental Care at (650) 591-1984 or book online at carlmontdentalcare.com to schedule a consultation at our office on Carlmont Drive in Belmont. Mandarin- and Spanish-speaking team members are available if that makes the visit easier.