Old Silver Fillings: Replace Them or Leave Them Alone?

A silver filling placed in 1996 is not automatically a problem in 2026. Plenty of them are still sealed, still solid, and still doing exactly what they were put there to do. Age and color are not diagnoses.

What matters is whether the filling and the tooth around it are intact, and that is something you can partly judge yourself once you know what to look for.

Should you replace old silver fillings or leave them alone?

So the job is to watch the sound ones, fix the failing ones, and be clear about which is which. When one does need to go, the usual replacement is a bonded tooth-colored composite filling or, for a tooth that has lost too much structure, something stronger.

Are amalgam fillings safe? What the FDA and ADA actually say

Amalgam is roughly half elemental mercury by weight, bound into a hard alloy with silver, tin and copper. Once set, it gives off very small amounts of mercury vapor, and a little more when you chew hard or grind your teeth. Nobody disputes that part. The question is whether the amount matters.

The American Dental Association's position is that amalgam is a safe and effective filling material, and it points to systematic reviews that have not linked amalgam fillings to systemic disease in the general population. You can read the ADA's summary of the amalgam evidence for yourself.

The FDA agrees for most people, with a caveat it added in September 2020. It named groups who may be more susceptible to mercury vapor and recommended that, where possible and appropriate, these patients receive non-amalgam materials for new fillings:

• Women who are pregnant, planning a pregnancy, or nursing
• Children, especially those under six
• People with a pre-existing neurological condition such as multiple sclerosis, Alzheimer's or Parkinson's disease
• People with impaired kidney function
• Anyone with a known sensitivity or allergy to mercury or the other metals in amalgam

Read the second half of that guidance carefully, because it is the half that gets left out online. The FDA does not recommend that anyone, including people in those higher-risk groups, remove or replace existing amalgam fillings that are in good condition unless a health professional considers it medically necessary. A true allergy to amalgam is one such reason. It is uncommon, and it tends to show up as a persistent sore or lacy white patch on the cheek or tongue right where the tissue rests against the filling.

Why drilling out a sound filling exposes you to more mercury than leaving it

This is the part that surprises people. A set amalgam filling sitting quietly in a tooth gives off very little vapor. Cutting it out with a high-speed drill heats and pulverizes it, and that produces a short spike well above what the filling releases day to day. The FDA cites exactly this, a temporary increase in exposure, as one of its two reasons for advising against the removal of intact fillings.

The other reason is the tooth itself. No filling comes out cleanly. Removing one always takes a margin of healthy enamel and dentin with it, so the new filling is larger than the old one and the walls left standing are thinner. Do that to a tooth that had no problem and you have traded a stable restoration for a bigger one whose own clock has just started.

So if the goal is to lower your mercury exposure, the procedure works against it, at least in the short term. Wanting them out because you dislike the look is a legitimate choice, and yours to make. Know the trade: you gain appearance and you spend tooth structure.

Signs an old silver filling is failing

Some of these you can spot in a bathroom mirror with a good light. Others only show up in the chair.

• A visible crack or missing corner in the filling. Metal that has fractured no longer seals.
• A ditch or gap at the edge. If floss or the tip of your tongue catches where metal meets tooth, the margin has opened. Bacteria fit into gaps far smaller than anything you can feel.
• Floss that shreds, or food that packs into the same spot every meal when it never used to.
• A gray or bluish shadow in the enamel beside the filling. Sometimes this is only metal staining showing through thin enamel. Sometimes it is decay underneath. The two look alike from the outside, so it needs a proper look.
• A hairline crack in the tooth running away from the filling, or a cusp that has started to look glassy and hollow.
• Sharp pain when you bite down or let go, especially on something small and hard like a seed. That pattern often points to a crack. Our guide to what pain on biting usually means walks through the possibilities.
• New sensitivity to cold or sweets in a tooth that has been quiet for years.

One limitation to know about: metal is opaque on an X-ray. Decay sitting directly beneath or behind an amalgam can stay hidden on the image until it is fairly advanced. That is why a dentist checks these fillings by eye and by feel along the margins too, instead of trusting the film alone.

And if a chunk breaks off and you swallow it? A piece of set amalgam generally passes through the gut without being absorbed in any meaningful amount. The tooth is the concern. It now has an open hole and possibly a sharp edge, so have it looked at within a few days even if nothing hurts.

How amalgam fails differently from tooth-colored fillings

Amalgam is not glued in. It is packed into a cavity that was cut wider at the bottom than at the top, and it stays put mechanically, like a dovetail joint. Over the years it corrodes slightly at the edges, and oddly that helps: the corrosion products tend to plug the microscopic gap between metal and tooth. The filling itself rarely wears out. What gives way is the tooth around it.

Composite is bonded to the tooth. That lets the dentist remove less structure and helps tie the remaining walls together. Its weak point is the bond line. When that seal breaks down, decay can restart along the edge.

Replace, watch or crown? A decision table

Why big old fillings so often end in a crown

Patients are often startled when a tooth that "only had a filling" comes back with a crown recommendation. The reason is arithmetic that started decades ago.

Because amalgam needs that undercut shape, the original preparation removed more tooth than a modern bonded filling would. A large one leaves the cusps standing as thin walls on either side of a block of metal that does nothing to hold them together. Every bite pushes those walls outward by a hair. After twenty or thirty years of that, cracks at the base of a cusp are common, and the classic ending is a cusp shearing off on something unremarkable, like a bread crust. Night-time grinding multiplies the load.

Then there is the replacement cycle. Each time a filling is redone, the cavity gets a little wider and deeper. A tooth on its third filling may be more filling than tooth. At that point another filling, silver or white, is being asked to hold together walls that cannot hold themselves, and it won't. A crown that covers the whole tooth, or an onlay that caps the weak cusps, binds what is left so it stops flexing.

The usual tipping points are a filling that spans most of the width between the cusp tips, a cusp worn thin at its base, or any crack running from the filling toward the outside of the tooth. We go through those criteria in detail in how dentists decide between a crown and a filling, and the middle-ground options in our piece on crowns versus onlays for cracked teeth.

Waiting has a cost here. A cusp that breaks above the gumline usually means a crown. One that breaks below the gumline, or a crack that reaches the nerve, can mean a root canal first, or a tooth that cannot be saved at all. If you grind, a night guard is a sensible precaution for heavily filled molars.

What replacing a silver filling involves

A straightforward swap is commonly a single visit of roughly 30 to 60 minutes per tooth. In general terms, it goes like this:

1. Numbing. Local anesthetic, the same as for any filling.
2. Isolation and suction. The tooth is isolated, and strong suction and plenty of water spray are kept right beside it so particles and vapor are carried away instead of swallowed or inhaled.
3. Sectioning the old filling. Cutting the amalgam into a few chunks and lifting them out creates less heat and less vapor than grinding the whole thing to dust.
4. Finding out what is underneath. This is the moment of truth. Decay or a crack under the metal cannot be fully judged until the filling is out, so a planned filling occasionally becomes an onlay or a crown partway through. You should be warned of that possibility before the visit starts.
5. Rebuilding. Composite is bonded in layers, hardened with a curing light, shaped and polished. Your bite is checked before you leave.

Afterward, some cold sensitivity for a few days up to a couple of weeks is normal. A tooth that feels "tall" when you chew needs a quick bite adjustment, so call instead of waiting it out. Sensitivity that grows instead of fading needs a recheck.

Will insurance pay to replace a silver filling?

Broadly, dental plans pay for need, not preference.

• Documented failure is usually a covered reason. Decay, a fractured filling or a broken tooth is typically handled like any other filling claim.
• Elective replacement often is not. Swapping an intact filling for appearance is commonly classed as cosmetic and left to you.
• Back-tooth downgrades. Some PPO plans pay for a composite on a molar at the lower amalgam rate, called an alternate benefit, and you cover the difference.
• Replacement time limits. Many plans will not pay to redo a filling on the same tooth surface within a set window, often a year or two, regardless of who placed the first one.
• Crowns sit in a different category. A tooth that needs a crown usually falls under major services, with a lower coverage percentage and sometimes a waiting period.

Every plan words this differently, and Denti-Cal and Medi-Cal have their own criteria. Our front desk works with most PPO and HMO plans as well as Denti-Cal and Medi-Cal, and can look at your benefits before you commit to anything.

Questions to ask before anyone drills

• What exactly is wrong with this filling: a crack, an open margin, decay? Can you show me?
• If it is intact, what happens if we simply watch it?
• How much tooth will be left once the old filling is out, and is a filling still the right repair?
• Will this be submitted to my plan as necessary or as elective?

A recommendation to replace every silver filling in your mouth at once, without a specific defect identified in each tooth, deserves a second opinion.

Not sure which of yours are fine?

If your fillings are older than your current phone number and you would like to know which are sound and which are on borrowed time, Dr. Sameer Aljanedi can check each one and show you the findings before recommending anything. Request an exam at our Downey office or call (562) 928-5559. Se habla español.