How long does a composite filling last?

Several years. The lifespan depends on the size of the cavity, where it is — a molar takes the force of chewing — and on brushing around the bonded edge.

The resin is chosen to match the tooth shade. On a front tooth the layers are built up to reproduce the translucency of the edge, which takes a little longer in the chair.

It is done under local anaesthetic when the decay is deep, without one when it is superficial. Sensitivity to cold for a few days afterwards is common.

Composite Fillings

A molar isolated under a rubber dam before treatment

Repairing decay invisibly

A bonded resin, matched to the tooth.

Composite is a tooth-coloured resin, applied in layers and hardened in place. Unlike grey amalgam, it bonds to enamel rather than being held by its shape, which means less healthy tooth has to be removed around the decay.

It is the ordinary treatment for a moderate cavity today, and it is done in one appointment.

A molar isolated under a rubber dam after treatment

The point where a filling is no longer enough

How much tooth is left decides.

A filling replaces what decay destroyed; it does not strengthen what is left. When the cavity becomes wide, when a wall of the tooth is undermined, or when the decay has reached the nerve, composite no longer holds mechanically and a crown is needed — or root treatment first.

That is why decay caught early costs one appointment and decay left alone costs a course of treatment. The difference is almost never visible in the pain, which arrives late.

Learn more about dental crowns

A damaged tooth before a composite restoration

Replacing old amalgam fillings

An aesthetic or mechanical reason, not an urgent one.

An old amalgam can be replaced with composite: it is more discreet, and a bonded filling supports the walls of the tooth better. That is worth doing when the filling is leaking, when the tooth has cracked around it, or when it shows when you smile.

An intact, sealed amalgam, on the other hand, does not need changing. Removing one without a reason removes healthy tooth with it.

Composite Fillings — Frequently Asked Questions

How long does a composite filling last?: Several years. The lifespan depends on the size of the cavity, where it is — a molar takes the force of chewing — and on brushing around the bonded edge.
Is it visible?: The resin is chosen to match the tooth shade. On a front tooth the layers are built up to reproduce the translucency of the edge, which takes a little longer in the chair.
Does it hurt?: It is done under local anaesthetic when the decay is deep, without one when it is superficial. Sensitivity to cold for a few days afterwards is common.