White fillings or silver fillings: what is the difference?

White (composite) fillings are made from a tooth-coloured resin, while silver (amalgam) fillings are a mixture of metals that includes mercury. Composite blends in with a tooth and is often chosen for a front tooth, while amalgam is particularly hard-wearing and is sometimes chosen for a large filling in a back tooth. A dentist recommends the material best suited to a particular tooth.

In short

• White (composite) fillings are made from a resin matched to your tooth’s colour and are commonly used where the filling will show.
• Silver (amalgam) fillings are a mixture of metals, including mercury, and are particularly hard-wearing in a large cavity or a back tooth that does a lot of chewing work.
• Composite takes longer to place than amalgam, since the tooth must be kept clean and dry throughout the appointment.
• Major health bodies regard amalgam as safe, though some countries are moving away from it mainly for environmental reasons connected to its mercury content.
• Which material suits a particular tooth depends on its size, position and the forces it will need to withstand, which a dentist assesses on examination.

This article is part of the fillings information on this site for patients in Cape Town.

What is a white (composite) filling made from?

A composite filling is made from a resin mixed with fine particles of glass or silica, matched to the shade of your tooth. It bonds directly to the tooth, so less of the natural tooth sometimes needs to be removed to place it, and it can be used on a front or back tooth. Composite has good durability and resistance to fracture in a small or medium-sized filling, though research generally shows it does not last quite as long as amalgam, particularly on the biting surface of a back tooth. It also takes longer to place than amalgam, because the site must be kept clean and dry throughout, and it can be more likely to need replacing over time. For what generally drives the cost of a filling, see How much does a filling cost in Cape Town?

What is a silver (amalgam) filling made from?

Dental amalgam is a mixture of metals, including mercury, silver, tin and copper, that has been used to fill teeth for more than 150 years. Once set, it forms a hard, stable material that is particularly strong and hard-wearing, which is why it is often chosen for a large cavity or a back tooth carrying a lot of chewing force. It does not bond to the tooth in the way composite does, so slightly more of the tooth is sometimes shaped away to hold it in place, and its silver colour makes it more noticeable than a composite filling. Major health bodies regard amalgam as safe for adults and children, and the amount of mercury vapour released during ordinary use is well within recognised safety limits. Even so, some countries are moving away from it, mainly because of the mercury it contains once a filling is eventually removed from a tooth or from the environment, rather than because of any risk to a patient with the filling in place. The World Health Organization is coordinating an international effort to phase down the use of dental amalgam worldwide, with a phase-out target of 2034.

Which material is right for a particular tooth?

There is no single correct answer, since the right choice depends on where the tooth sits in the mouth, how large the cavity is, and how much chewing force the tooth will carry. A small filling on a front tooth is usually composite, for appearance. A large filling on a back molar may suit either material, and your dentist weighs up strength, appearance and how long the tooth needs to last. A tooth that is too damaged for either type of filling to hold may need a different kind of restoration instead. See How long does a dental crown last? for when a crown becomes the better option.

Is one material more likely to leave a tooth sensitive?

Either material can leave a tooth feeling sensitive to hot, cold or pressure for a while after it is placed, particularly if the cavity was deep. See Is it normal for a tooth to be sensitive after a filling? for how long this usually lasts and when to contact the practice. If a filling feels uneven, or the sensitivity has not settled after a few weeks, ask for an appointment rather than waiting for your next check-up.

How do I reach Dr Davies?

Dr Davies treats adults and children at BRS Dental, on Strand Street in the Cape Town city centre, and can advise on the material best suited to a particular tooth after an examination. To make an appointment, call her directly on her own mobile, which is shown on this page. This page gives general information and does not replace an examination.