Do Fillings and Crowns Need Replacing on a Schedule?

Patients often ask a version of the same question: "My filling is ten years old — isn't it due to be replaced?" It is a reasonable assumption. We replace tires at a certain mileage and smoke detectors on a schedule, so it feels natural that a restoration would have a set lifespan too. Dentistry does not quite work that way.

The confusion is understandable, partly because we are used to being told when things wear out, and partly because manufacturers and dentists do talk about typical lifespans. But a typical lifespan is a loose guide, not a countdown. A restoration is a repair, and like any repair its working life depends on how it was made, where it sits, and how it is treated afterward — not on the date it went in.

There is no calendar date stamped on a filling or crown. A restoration is replaced when there is a clinical reason to replace it — not because a given number of years has passed. Some last a long time with no trouble; others need attention sooner. The deciding factor is condition, not age alone.

Why "lifespan" numbers are slippery

You will see average lifespans quoted for different materials, and they are not meaningless — but averages hide enormous variation. Two people can receive the same type of filling on the same day and have very different outcomes a decade later.

That is because a restoration's working life depends on a tangle of factors: the material used, the size and location of the restoration, how heavily you chew or grind, your diet, how well plaque is kept under control around it, and whether new decay develops at its edges. A small filling in a well-cared-for mouth faces very different stresses than a large one in someone who clenches at night.

So the useful question is not "how old is it?" but "how is it doing?" — and that is something a dentist assesses by looking and, where needed, with X-rays, rather than by counting birthdays.

What actually makes a restoration fail

Restorations do not last indefinitely because the mouth is a demanding environment: wet, warm, acidic at times, and subjected to heavy repeated forces. Over the years, a few things tend to be what brings a filling or crown to the end of its service.

Recurrent decay at the margins

The join between a restoration and the natural tooth — the margin — is a vulnerable zone. If plaque collects there and is not cleaned away, new decay can start underneath or around the edge. This recurrent decay is one of the more common reasons a restoration is replaced, and it is often why a filling that felt fine needs attention after a check-up and X-rays.

Wear, cracks, and chips

Fillings can wear down, chip, or develop cracks over time, especially under grinding or clenching forces. Crowns can chip or their underlying tooth can be affected. A worn or fractured restoration may no longer seal the tooth well, which opens the door to decay and sensitivity.

Leaking or failing seals

A good restoration seals the tooth against bacteria and fluid. As materials age or margins break down, that seal can fail, sometimes allowing leakage at the edges. This is not always visible or painful to the patient, which is one reason regular examinations matter even when nothing hurts.

Changes in the tooth around it

Sometimes the restoration itself is sound, but the tooth supporting it changes. A tooth that has had a large filling for years can develop a crack, or a crown's underlying tooth can be affected by decay below the gumline. In these cases the decision is not really about the restoration's age but about the health of the tooth it sits on. A dentist weighs the whole picture — restoration and tooth together — rather than one in isolation.

Signs worth paying attention to

You will not always know when a restoration needs attention — some problems are silent and show up only on examination. But certain signals are worth mentioning to your dentist rather than waiting out.

• New or lingering sensitivity to hot, cold, or sweet in a restored tooth.
• A rough edge, a visible crack, or a piece that has chipped away.
• Discomfort when biting down on a particular tooth.
• A filling that feels loose, or a crown that shifts.
• Staining, darkening, or a visible gap at the margin of a filling or crown.

None of these necessarily means replacement is certain — but they are reasons to have the tooth looked at rather than assume it will settle. Catching a problem at the margin early can sometimes mean a smaller repair rather than a larger one later.

The case for not replacing too eagerly

There is a flip side worth stating. Replacing a sound restoration "just because it is old" is not without cost to the tooth. Each time a filling is removed and redone, a little more tooth structure is usually lost, and the cavity preparation tends to get larger. Over a lifetime of needless replacements, that adds up.

For that reason, a restoration that is intact, well-sealed, and causing no problems is often best left alone and monitored. "If it is working, watch it" is a defensible approach. The judgement about whether a restoration is genuinely serviceable or quietly failing is exactly the kind of thing that benefits from a trained eye at routine visits, and from the broader scope of restorative dentistry when a repair or replacement is warranted.

A related point: not every failing restoration needs a like-for-like replacement. Depending on what has gone wrong, the options can range from a small repair to the margin, to a new filling, to a crown if the tooth has lost too much structure to hold a filling reliably. A larger failure in a tooth that has been restored several times may call for a more involved plan. Which path makes sense depends on how much healthy tooth remains and what the tooth is being asked to do.

Every tooth and every patient is different. Factors such as grinding, dry mouth, diet, and gum health all shift the odds, and a dentist's in-person assessment — not a rule of thumb about years — is the right basis for deciding whether a filling or crown should be left, repaired, or replaced. Outcomes vary from person to person.

Frequently asked questions

Do fillings expire?

Not in the sense of a fixed expiry date. A filling is replaced when there is a clinical reason — such as recurrent decay at its edges, a crack, wear, or a failing seal — rather than simply because a certain number of years has passed. A sound, well-sealed filling causing no problems is often best monitored rather than replaced.

How long do crowns last?

It varies widely. A crown's working life depends on the material, how heavily the tooth is used, grinding habits, oral hygiene around the margin, and whether decay develops at its edge. Some serve well for many years; others need attention sooner. A dentist assesses condition rather than relying on age alone.

Can an old filling be fine to leave alone?

Yes. If a restoration is intact, sealing the tooth, and not causing symptoms, many dentists will monitor it rather than replace it, since redoing a restoration usually removes a little more tooth structure each time. Regular examinations help catch any change before it becomes a larger problem.

Why would a filling that felt fine suddenly need replacing?

Because some problems are silent. Decay at the margin or a failing seal can develop without pain and may only show up on examination or X-rays. This is one of the reasons routine check-ups matter even when a tooth feels comfortable.

Sources & further reading

• Canadian Dental Association — Fillings — an overview of filling materials and what to expect.
• Canadian Dental Association — Dental Procedures — plain-language explanations of common restorative treatments.
• Government of Canada — Tooth decay — how decay develops, including around existing restorations.