Amalgam fillings typically last between 10 and 20 years, though many survive well beyond that range. One large review calculated a median survival time of 22.5 years for amalgam, while surveys from private dental practices report a more common range of 6 to 15 years depending on the size and location of the filling. The short answer: your silver filling will likely outlast a comparable composite (tooth-colored) filling, but how long it actually lasts depends on where it sits in your mouth, how large it is, and how you treat it.
What the Survival Numbers Look Like
Studies on amalgam longevity produce a wide spread because filling life depends heavily on context. Longitudinal research conducted at dental schools, where conditions are closely controlled, reports median survival times ranging from about 11 to over 40 years. Data from private practices, which better reflects real-world conditions, clusters between 7 and 22 years. A systematic review looking at fillings tracked for at least five years found median lifespans between 5 and 23 years, with amalgam’s annual failure rate sitting between 0.16% and 2.83%. That lower failure rate is notably better than composite resin, which ranges from about 1% to over 9% per year.
Compared head to head, amalgam restorations show median survival times exceeding 16 years, while composite fillings come in around 11 years. The gap narrows somewhat with modern composite materials, but amalgam still holds an edge for durability in the back teeth where chewing forces are highest.
Why Size and Location Matter
Not all amalgam fillings age the same way. A small, single-surface filling on the biting surface of a tooth faces far less stress than a large filling spanning three or four surfaces. Eight-year data from a large real-world database illustrates this clearly: single-surface amalgam fillings failed about 14% of the time over that period, while fillings covering four or five surfaces failed closer to 18.5%. The more tooth structure the filling replaces, the less natural tooth remains to support it, and the greater the risk of fracture.
Location plays a role too, though the differences are more modest. Lower jaw molars showed the highest eight-year failure rate at about 19%, while upper jaw premolars had the lowest at roughly 15.5%. Lower jaw teeth generally take slightly more punishment during chewing, which may explain the difference. If you have a large amalgam filling on a lower molar, it’s reasonable to expect a somewhat shorter lifespan than a small filling on an upper premolar.
How Amalgam Fillings Fail
Silver fillings don’t just dissolve or wear away evenly. The most common reason they need replacement is fracture of the surrounding tooth, not failure of the filling material itself. In one clinical study of 217 replaced amalgam restorations, nearly 30% were replaced because the outer wall of the tooth (the non-functional cusp) cracked. Another 21% failed because the inner cusp fractured. Recurrent decay, where new cavities form at the edges of the old filling, accounted for about 18% of replacements.
This pattern makes sense when you consider that amalgam doesn’t bond to tooth structure the way composite does. It’s held in place by the shape of the cavity. Over years of biting forces, the remaining tooth walls can weaken and eventually crack, especially when the filling is large. Bulk fracture of the amalgam itself can also happen, sometimes triggered by decay undermining the filling from below, but it’s less common than tooth fracture.
Signs Your Filling May Need Replacement
Amalgam fillings don’t come with an expiration date stamped on them, and many dentists will leave a well-functioning filling in place for decades. But certain changes suggest it’s time for an evaluation:
- Pain when chewing on that tooth, which can indicate a crack in the filling or the tooth beneath it.
- New sensitivity to hot or cold foods and drinks, especially if it’s getting worse over time.
- Dark staining or discoloration at the edges of the filling, which can signal a gap forming between the filling and the tooth.
- A persistent bad taste in your mouth near that tooth. Cracked or leaking fillings can trap bacteria and food debris.
- Visible cracks, chips, or rough edges on the filling surface, particularly gray lines running along the filling.
- A loose feeling when you press the filling with your tongue.
If a filling falls out entirely, the exposed tooth is vulnerable to rapid decay and infection, so that warrants prompt dental attention. A filling that’s simply old but shows no signs of breakdown doesn’t necessarily need to be replaced.
What Affects How Long Yours Will Last
Beyond size and location, several habits and health factors influence filling longevity. Teeth grinding (bruxism) is one of the biggest accelerators of failure. The repeated, excessive force can crack both the filling and the surrounding tooth years earlier than normal. If you grind at night, a night guard can meaningfully extend the life of your restorations.
Oral hygiene matters because recurrent decay is the second most common reason fillings fail. Bacteria that accumulate at the margins of a filling can create new cavities that undermine the restoration from the edges inward. Regular brushing, flossing, and dental cleanings help keep those margins intact. A diet high in sugar and acidic foods accelerates this process by feeding the bacteria that cause decay and softening enamel.
Systemic health conditions that reduce saliva flow or affect immune function can also speed up degradation. Dry mouth, whether from medications or medical conditions, removes one of your body’s primary defenses against the bacteria that cause secondary cavities around existing fillings.
Safety Considerations
Amalgam contains about 50% mercury by weight, which releases low levels of mercury vapor over time. For most adults, the FDA considers this exposure level safe. However, the FDA recommends that certain groups avoid new amalgam fillings if possible: pregnant women, nursing mothers, children under six, people with kidney problems, those with neurological conditions, and anyone with a known allergy to mercury or other amalgam components like silver, copper, tin, or zinc.
This recommendation applies to placing new amalgam fillings, not necessarily removing existing ones. Removing an intact amalgam filling actually creates a temporary spike in mercury exposure during the drilling process. For most people with functioning silver fillings, the consensus is that leaving them in place is safer than removing them solely over mercury concerns. If your filling does need replacement for other reasons, your dentist can discuss whether composite or another material makes sense for the new restoration.