If you’ve had dental work done over the years, there’s a good chance you have at least one amalgam — or “silver” — filling somewhere in your mouth. They’ve been used for generations, and most have done their job quietly for decades. So it’s understandable that a lot of patients at Whitehorse Dental feel uneasy when they read something online suggesting those old fillings might be “leaking” or that the mercury in them could be making them unwell.
It’s one of the more common worries I hear across the chair in Blackburn, and it deserves a straight, honest answer — not scare tactics. Here’s what “leaking amalgam” actually means, what the genuine risks are, and how I decide with a patient whether a filling is fine to leave alone or worth replacing.
What amalgam fillings actually are
Amalgam is a blend of metals — mostly silver, tin and copper, bound together with mercury. That combination sets into a hard, hard-wearing material that copes well with the heavy forces at the back of the mouth, which is why it was the go-to filling for cavities for so long, and why it’s still perfectly serviceable in a lot of mouths today.
The mercury is the part that makes people nervous, so let’s deal with it directly. In a set amalgam filling, the mercury is chemically bound within the alloy — it isn’t sitting loose in your tooth. Major health authorities, including Australia’s Therapeutic Goods Administration and dental bodies internationally, regard set amalgam as a safe filling material for the general population. The main groups where a more cautious approach is sometimes recommended are children, and people who are pregnant or have specific medical sensitivities — which is a conversation worth having individually, not a reason for blanket panic.
So what does a “leaking” filling really mean?
This is where the wording online can be misleading. A “leaking” amalgam filling usually has nothing to do with mercury escaping into your body. It means the seal between the filling and the tooth has broken down, leaving a microscopic gap.
That gap matters — not because of the metal, but because it lets saliva, food and bacteria seep underneath the filling, where your toothbrush can’t reach. That’s what leads to the genuine problem: new decay forming underneath an old filling, hidden from view, slowly weakening the tooth from the inside.
So the real risk of a leaking amalgam isn’t poisoning. It’s a cavity you can’t see, developing under a filling that still looks fine on the surface.
Signs your filling might be failing
A failing filling often gives you a few quiet clues before anything dramatic happens:
- Sensitivity to hot, cold or sweet in one particular tooth that comes and goes
- A dark line or shadow appearing around the edge of the filling
- A rough or chipped edge you can feel with your tongue
- Food consistently catching in the same spot
- A dull ache when biting on that tooth
None of these are an emergency on their own, but they’re all worth having checked rather than hoping they settle.
What causes them to break down
Amalgam is durable, but nothing in the mouth lasts forever. Fillings tend to fail for a few predictable reasons:
- Age and wear. A filling placed twenty or thirty years ago has been chewed on hundreds of thousands of times.
- Grinding and clenching. The same overnight forces that crack teeth also fatigue old fillings.
- Temperature changes. Metal expands and contracts slightly with hot and cold food and drink, and over years that flexing can open up tiny gaps at the margins.
- Decay at the edges. Once a small gap forms, decay accelerates the breakdown.
What to do if you think yours is leaking
The honest answer is: have it looked at, but don’t rush to rip out every silver filling you own.
When a patient comes in worried about an old amalgam, I assess it properly — a visual exam, checking the margins, and usually a check-up and clean with X-rays, because decay underneath a filling is often only visible on an X-ray, not to the naked eye. That tells us whether the filling is genuinely failing or simply old but sound.
From there it comes down to the evidence in front of us:
- If the filling is intact and sealed, replacing it purely out of mercury worry usually isn’t recommended — removing a sound filling means drilling away more of your natural tooth for no real benefit.
- If it’s leaking or there’s decay underneath, then it does need attention, and that’s a genuine reason to replace it.
Replacing a failed amalgam
When a filling does need replacing, most patients today choose a tooth-coloured (composite) filling. These bond directly to the tooth, match your natural colour, and let us conserve more of the healthy tooth structure. For a small-to-moderate cavity that’s usually the straightforward option.
If decay has spread further and there isn’t much sound tooth left to work with, a filling may no longer be enough to hold the tooth together long-term — in those cases we’d talk through a crown instead, and I’ll always explain why and what each option involves before we decide together. And if an old filling has failed suddenly and you’re in pain, that’s when emergency dental care is the right call rather than waiting.
The proactive approach
Most failing fillings I see in Blackburn aren’t caught because something went badly wrong — they’re caught early, at a routine visit, before the tooth underneath was affected. That’s really the whole point of regular check-ups: an old amalgam can be monitored over time, and we only act when the evidence says it’s needed.
So if you’ve been quietly worrying about the silver fillings in your mouth, the best thing you can do isn’t to panic about mercury — it’s to have them reviewed so you actually know where they stand.
If you’ve noticed sensitivity, a dark edge, or you’d simply like your older fillings checked over, you’re welcome to book online or call us on (03) 8838 8820. We’re at 129A Canterbury Road, Blackburn — a short walk from Blackburn Station and easy to reach from across the Whitehorse area.