Written by Dr James Tran, principal dentist at Lumi Dental.
A filling is a repair, not a permanent replacement for tooth structure, so a fair question before or after having one is how long it will last. The honest answer is that it depends on the material, where the tooth sits, and how you look after it, but useful average figures do exist. This guide walks through the typical lifespan of the two main filling materials, what shortens or extends that life, and the signs that tell you a filling is due for attention.
Key takeaways
- Tooth-coloured composite fillings commonly last around 7 to 10 years, and often longer for small, well-placed fillings.
- Silver amalgam fillings tend to last longer on average, frequently 10 to 15 years or more.
- The main reason composite fillings fail is new decay at the edges; for amalgam it is usually fracture of the tooth or filling.
- Grinding, poor oral hygiene, large fillings, and heavy biting forces all shorten a filling's life.
- Sensitivity, pain on biting, a rough edge, or a dark line can signal a filling that needs checking.
The one rule: a filling lasts as long as the seal holds
The single idea that explains filling longevity is the seal. A filling works by sealing the cleaned-out cavity so bacteria cannot get back in. As long as that seal between the filling and the tooth stays intact, the filling keeps doing its job. When the seal breaks down, whether through a crack, wear, or a tiny gap, bacteria seep underneath and new decay begins where you cannot brush it away. Almost everything that shortens a filling's life comes back to the seal failing, which is why regular check-ups that catch early breakdown are so valuable.
Typical lifespan by material
| Filling type | Typical lifespan | Main reason it fails |
|---|---|---|
| Composite (tooth-coloured resin) | Around 7 to 10 years, often longer if small | New decay at the margins |
| Amalgam (silver) | Around 10 to 15 years or more | Fracture of the tooth or filling |
| Glass ionomer | Shorter, often used for children or non-biting surfaces | Wear in high-force areas |
These are general averages from clinical research, not guarantees. Studies consistently show amalgam edging ahead on raw longevity, with some reporting median survival beyond 16 years for amalgam against roughly 11 years for composite. That said, modern composites have narrowed the gap considerably and are the material of choice for visible teeth because they match the tooth and preserve more structure. For background on the different repair options, see our guide to dental filling costs.
What shortens a filling's life
- Grinding and clenching. Repeated heavy force fatigues fillings and can crack them or the tooth around them.
- Large fillings. The more of the tooth a filling replaces, the less natural structure supports it, and the sooner it may need upgrading to an onlay or crown.
- Poor oral hygiene. Plaque at the margins invites new decay, the leading cause of composite failure.
- Habits like chewing ice or hard lollies, which stress the filling.
- Position. Fillings on back teeth that take the brunt of chewing wear faster than those on front teeth.
Signs a filling needs replacing
Fillings often give warning before they fail completely. Book a check if you notice:
- New sensitivity to hot, cold, or sweet on a filled tooth
- A sharp pain when biting down, which can suggest a crack or a gap
- A rough, chipped, or catching edge you can feel with your tongue
- A dark line or shadow around the filling, or a visible gap
- Food consistently trapping around the tooth
- A filling that feels loose or has partly come away
Catching these early usually means a straightforward replacement rather than a larger restoration. Ongoing sensitivity can have other causes too, as covered in our article on sensitive teeth.
What happens when a filling fails
If the seal has failed but the tooth is otherwise sound, a like-for-like replacement filling is usually enough. If decay has spread or the remaining tooth is weak, your dentist may recommend a larger restoration such as an inlay, onlay, or crown to protect what is left. Where decay has reached the nerve, root canal treatment may be needed before the tooth is rebuilt. This is why replacing a failing filling promptly, rather than waiting for pain, tends to keep treatment smaller and simpler.
How to get the most from your fillings
- Brush and floss well to keep the margins free of plaque and prevent new decay.
- Wear a night guard if you grind, to spread the load off your fillings and teeth.
- Avoid chewing ice and very hard foods, which crack fillings and enamel alike.
- Keep regular check-ups, so worn seals are caught before decay sets in underneath.
- Prevent new cavities with good habits, covered in our guide to preventing tooth decay.
Frequently asked questions
Do fillings need to be replaced eventually?
Most do, since no filling lasts forever. The seal between filling and tooth gradually breaks down over years, so fillings are monitored at check-ups and replaced when they wear, crack, or leak. Small, well-cared-for fillings can last a long time before that point.
Are white fillings as durable as silver ones?
On average, amalgam fillings last a little longer, but modern composites have closed much of the gap and perform very well in small to medium restorations. Composite is preferred for visible teeth because it matches the tooth and preserves more structure. Your dentist can advise which suits a particular tooth.
Does a filling hurt when it is failing?
Not always. Some failing fillings cause sensitivity or pain on biting, while others cause no symptoms until decay is advanced. This is why regular check-ups matter, as a dentist can spot a breaking-down filling before it becomes painful.
Can I make my fillings last longer?
Yes. Good brushing and flossing, a night guard if you grind, avoiding ice and very hard foods, and regular check-ups all extend the life of a filling by protecting the seal and preventing new decay at the edges.
The takeaway
Dental fillings are durable repairs, not permanent ones. Composite typically lasts around 7 to 10 years and amalgam often longer, but the real determinant is whether the seal holds, which depends heavily on your habits and check-up routine. Watch for the warning signs and act early, and a small replacement usually beats a large repair. To have your fillings checked, the team at Lumi Dental in Melrose Park is happy to help. See our general dental care or current offers on the deals page. This article is general information and not a substitute for personal dental advice.
