Types of Dental Fillings: Which Material Suits Which Tooth?

Five things: how big the cavity is, where it sits, how hard the tooth is bitten on, whether it can be kept dry while the filling is placed, and cost. A back molar under heavy bite force and a small cavity beside the gum on a front tooth are different problems, and a material that suits one can fail in the other.

That is why a good answer to which is better is a question back: which tooth, and how big is the cavity.

Composite resin is built up in thin layers and set with a light. It bonds to the tooth, so less healthy tooth needs to be removed, and it can be matched to the colour of the tooth. It is the usual choice for visible teeth and is widely used on back teeth too.

It is technique sensitive. It has to be placed on a dry tooth, and a large composite in a heavily bitten back tooth can wear or chip over time. Composite also costs more than the simpler materials.

Glass ionomer cement (GIC) bonds to the tooth chemically and releases a little fluoride. It is tolerant of moisture, which makes it useful in small cavities near the gum line, on roots, in children's milk teeth, and as a temporary filling.

It is weaker and wears faster than composite, so it is generally not chosen for large fillings on the biting surfaces of adult back teeth.

Amalgam is a metal alloy that has been used for well over a century. It is strong and tolerant of moisture, but it is dark, it needs more tooth removed to hold it, and many people prefer not to have metal in their mouth. Major health regulators consider it safe for most people, and some guidance advises avoiding it in pregnancy, so ask your dentist if that applies.

A ceramic or composite inlay or onlay is made in the lab and bonded in, for a cavity too large for a direct filling but where a full crown would remove too much tooth. It costs more and takes two visits. When so much tooth is lost that even an inlay will not hold, a crown may be the sounder option.

There is no honest single number. A small filling in a well-cleaned mouth can last many years, while a large one in a heavily bitten tooth, or in someone with frequent sugar exposure or a dry mouth, may need replacing sooner. New decay at the filling edge is the commonest reason for failure, which is why stopping decay in the first place matters after the filling as much as before.

Replace a filling that has cracked, lifted, or has a gap or rough edge that catches food, or when an X-ray shows decay under it. For the visit itself, see tooth fillings, and for what decides the fee, the teeth filling cost page.