Walk into most modern dental offices today and the fillings you will receive are composite, the tooth-colored resin material. Amalgam, the silver-mercury alloy that defined cavity treatment for over 150 years, is still in clinical use globally but has largely been phased out of new placements in U.S. cosmetic and general practice. This guide explains what each material actually is, the honest pros and cons, where the mercury concern stands today, and what to do if you have old amalgam fillings.
What each material actually is
Composite
A tooth-colored resin made from a plastic matrix mixed with glass or ceramic filler particles. It is placed in layers, each cured (hardened) with a blue LED light, and bonded directly to the prepared tooth. Composite has been in widespread clinical use since the 1970s, with modern formulations dramatically improved over the early generations.
Amalgam
A metal alloy made by combining a powdered mix of silver, tin, and copper with elemental mercury. Once mixed, the result hardens into a durable, silver-colored filling. Amalgam has been used in dentistry for more than 150 years. It is still legally available in the United States and is still used in some specific clinical situations, but its share of new fillings has declined significantly as composite has matured.
Pros and cons, honestly
Composite
Strengths
- Matches the natural color of teeth; nearly invisible in everyday view
- Bonds chemically to tooth structure, allowing more conservative preparation (less healthy tooth removed)
- No mercury content
- Can repair small chips, close minor gaps, and reshape teeth in addition to filling cavities
- Can be repaired or added to in place, often without removing the original filling
Trade-offs
- Historically less durable than amalgam in very large fillings on back teeth, though modern composite formulations have closed much of this gap
- More technique-sensitive to place well, requires good isolation and a dry working field
- Slightly higher cost than amalgam per filling
- May develop staining at the edges over many years, though this is usually a cosmetic issue rather than a structural one
Amalgam
Strengths
- Exceptional long-term durability under heavy chewing forces, often 15 to 20 years or more
- Lower cost per filling than composite
- Less technique-sensitive to place well; tolerates a less- than-perfectly-dry working field
- Long clinical track record going back over a century
Trade-offs
- Obviously silver in color; visible in the mouth
- Does not bond to tooth structure, so the cavity preparation must be cut to a retentive shape, removing some healthy tooth
- Contains elemental mercury (about 50% by weight), bound into a stable alloy
- Can expand and contract with temperature, occasionally contributing to tooth cracking in very large amalgam restorations over time
- Many U.S. patients and dentists prefer the aesthetics of composite for any visible tooth surface
What about the mercury in amalgam?
This is the question that drives most of the modern interest in composite. The honest, evidence-based answer:
The American Dental Association (ADA), the U.S. Food and Drug Administration (FDA), the World Health Organization (WHO), and the U.S. Centers for Disease Control and Prevention (CDC) all currently consider dental amalgam safe for most patients. The mercury in amalgam is chemically bound into a stable alloy and releases at very low rates during chewing and grinding, well below thresholds shown to cause harm in healthy adults.
That said, the FDA issued a recommendation in 2020 advising against amalgam for certain higher-risk groups, including pregnant women and women planning pregnancy, nursing women, children under six, patients with neurological disease or kidney disease, and patients with known mercury sensitivity. For these populations, composite (or other mercury-free alternatives) is the recommended option.
For everyone else, the FDA position is that there is not sufficient evidence to recommend removing existing amalgam fillings purely because of the mercury content. The act of removing amalgam itself releases more mercury vapor than leaving the filling in place undisturbed.
Should I replace my old amalgam fillings?
Our recommendation is consistent with the major dental and public-health authorities: do not replace existing amalgam fillings purely because they are amalgam, unless you are in one of the FDA-identified higher-risk groups above.
There are good clinical reasons to replace an old amalgam, and we recommend replacement when any of these are present:
- The filling has decay underneath it (visible on x-ray or clinical exam)
- The filling is leaking (food packing in, staining at the margins, sensitivity that did not exist before)
- The filling is fractured, chipped, or has a piece missing
- The tooth around the filling is cracked or weakened to the point that a crown is the safer long-term restoration
- The filling is in a highly visible location and you would prefer the aesthetic of composite
At your routine exam we look at every existing restoration and tell you which ones are stable and which ones are showing signs of needing replacement. We do not recommend wholesale replacement of stable amalgam fillings, and we are happy to explain our reasoning at your visit.
What we do at Dental Salon
For new fillings, we use composite. It matches the tooth, bonds directly to tooth structure, and lets us be more conservative with the cavity preparation, all of which align with the evidence-based standard of care in modern U.S. dentistry. For very large fillings on back teeth in heavy grinders, we sometimes recommend an onlay or crown rather than a very large composite, because both materials have limits in those situations and a more comprehensive restoration is the safer long-term answer.
For existing amalgam fillings, we examine and monitor them at every visit. We recommend replacement only when there is a real clinical reason (decay, leakage, fracture, cracked tooth) or when the patient is in one of the FDA's higher-risk groups and is choosing replacement for that reason. We do not recommend amalgam replacement as a profit-driven cosmetic upgrade.
At Dental Salon, both our Lincoln Park and Schaumburg offices place composite fillings and assess existing amalgams as part of routine preventive care. We follow ADA and FDA guidance; if you have specific concerns about existing fillings, we are happy to discuss your situation at a regular exam, no separate consultation needed.
Frequently asked questions
Do you place amalgam fillings?
No. For new fillings we use composite. Composite is the modern standard of care for the vast majority of cavity treatment in the United States, and it lets us be more conservative with the tooth structure we keep.
Is it dangerous to have amalgam fillings in my mouth?
For most patients, no. The ADA, FDA, WHO, and CDC all currently consider dental amalgam safe for the general population. The FDA recommends against amalgam for certain higher-risk groups (pregnant or nursing women, children under six, patients with kidney or neurological disease, patients with mercury sensitivity), and for these patients we recommend composite or other mercury-free alternatives.
Should I have my old amalgam fillings removed?
Not purely because they are amalgam, unless you are in one of the FDA's higher-risk groups above. We recommend replacement when there is a real clinical reason: decay underneath, a leaking margin, fracture, or a cracked tooth that needs a more comprehensive restoration. The act of removing a stable amalgam itself releases more mercury vapor than leaving it undisturbed, so wholesale replacement of stable fillings is not something we recommend.
How long do composite fillings last?
Most composite fillings last 7 to 15 years, depending on the size of the filling, the patient's bite, grinding habits, and oral hygiene. Smaller composite fillings often last considerably longer; very large composites in heavy chewing areas may need replacement or upgrading to a crown sooner.
Does insurance cover composite fillings?
Most dental plans cover composite fillings on front teeth at the same rate as amalgam. Coverage on back teeth varies: some plans cover composite at the amalgam rate (you pay the difference); others cover composite at full rate; some HMO plans only cover amalgam on molars. We verify benefits before treatment. See our insurance and financing page.
Are composite fillings FSA or HSA eligible?
Yes. Both composite and amalgam fillings are eligible expenses under FSA and HSA accounts. Bring your account card to the appointment.
Disclaimer
This article summarizes current evidence-based positions from the ADA, FDA, WHO, and CDC as of publication. Decisions about existing fillings depend on a clinical exam and your specific health history. Talk with your dentist before deciding whether to replace existing restorations.