There is no expiry date: amalgam usually outlasts composite, and your habits decide the rest.
NHS patient information notes amalgam fillings are more hard-wearing and usually outlast composite or glass ionomer fillings, and the ADA says material choice weighs durability against cavity size, location, and appearance. Big fillings, tooth grinding, high sugar exposure, and cleaning gaps shorten any filling's life. Replacement is event-driven, not scheduled: leaking or stained edges, cracks, chips, new decay around the filling, or pain and sensitivity that persist. Sensitivity after a new filling should settle within a few weeks; NHS guidance says contact the clinic if it has not resolved within 4 weeks.
What to do
Common questions
How long do fillings last?
Fillings are durable, not permanent. NHS patient information says amalgam metal fillings usually outlast composite white fillings, while the ADA notes dentists weigh how long a filling could last alongside the size and location of the cavity when choosing material. In practice, well-placed fillings often serve for a decade or more, and some last decades, but lifespan depends on things material cannot control: how big the filling is, whether you grind your teeth, your decay risk, and how well you clean around the edges. The failure modes are slow and visible: edges leaking or staining, the filling cracking or chipping, new decay forming around it, sensitivity that does not settle, or a piece breaking away. NHS guidance says some sensitivity after a new filling should resolve within a few weeks, and you should contact the clinic if it has not settled within 4 weeks, since that can signal a deeper problem. The practical answer: you do not replace fillings on a schedule; your dentist checks them at check-ups and replaces them when they fail or start leaking.