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the Australian Dental Association
Written by the Australian Dental Association, Nov 05, 2021
Fact Checked

Fillings are used to replace natural tooth structure when it becomes fractured, broken or damaged by tooth decay. When and if you require a filling, your dentist has access to a range of filling materials to fix your teeth and restore their shape and function.

Filling material options

When a filling is required there are a variety of materials that can be used to fix the tooth. Each material used to fix teeth has its own unique properties and advantages. Factors that can influence the choice of filling material include the position of the tooth within the mouth, the way the teeth bite together and the size of the filling required. Your dentist will give you advice on what is best for your situation.

Amalgam

Dental amalgam is a silver-coloured filling material. It is made of mercury, silver, copper, zinc and tin. It has been used as a filling material to fix teeth for over 150 years and has one of the longest life-expectancies of dental filling materials. Over time, it has also been the subject of extensive research.

Amalgam was commonly used by dentists in the 1990’s. These days it is used less commonly with some dental practices no longer using it at all.  Amalgam is strong and long-lasting, however more tooth structure needs to be cut away to fix the tooth with an amalgam filling. This is because the amalgam is held in place by the shape of the cavity that is cut into the tooth. Amalgam does not stick to the tooth surface like white filling materials, such as composite resin.

This filling material is silver in colour and can appear darker over time. Some people claim that mercury in dental amalgam can cause negative health consequences, however research has shown that the mercury in amalgam fillings is poorly taken up by the body. Small amounts of mercury from amalgam do get into the blood but are removed by the kidneys and passed out of the body in urine. The only two proven side-effects of amalgam:

  • Lichen planus, involving small sores on the gum or inside of the cheek.
  • An allergic reaction affecting the soft tissues near the filling. Signs of an allergic reaction can include swelling, redness, and itching, but these are rare.

The use of amalgam in dental clinics has reduced over time, however this is not due to concerns directly related to human health but concerns about the environment. Mercury from dental clinics can make its way into the environment. To combat this, dentists have created policies and installed equipment for the safe disposal of amalgam waste to limit the amount released into the environment.

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A dental amalgam filling in a molar tooth. Getty Images.

Should I remove my amalgam fillings?

Dental amalgam is considered a safe and effective filling material. It is not necessary to remove and replace amalgam fillings in your teeth for no specific reason. There is no evidence that the replacement of healthy amalgam fillings using a different filling material, without a specific reason will produce a better health outcome for patients.
If you choose to have your amalgam fillings removed, make sure you understand the consquences of this decision. Each time a filling is removed from a tooth, more tooth strucuture is cut away. As well, there is no guarantee that the new filling or the material will be better than amalgam filling already in place. All dentists are trained in the removal and replacement of amalgam fillings. There are no 'specifialist' qualifications required. 

Although dental amalgam is no longer commonly used, your dentist may still recommend it as the filling material of choice for certain situations.

Composite resin

Composite resin is the tooth-coloured or white filling material that is used to fix broken or decayed teeth. Unlike dental amalgam, composite resin fillings are adhered to the surface of the tooth. This is called bonding. Because composite resin is bonded to the tooth’s surface, less tooth structure needs to be removed for the filling to be placed. This means more natural tooth structure can be kept.

A filling colour that matches the tooth being fixed can be chosen so that it blends with the colour of the tooth. When the colour is well matched, these fillings can be undetectable to the eye. It can be used for fillings in both the front and back teeth.

Before and after a composite resin filling in a molar tooth. Getty Images.

Left Cavity cut into the tooth after removing tooth decay. 
Right Cavity filled with a tooth-coloured composite resin filling.
This filling was completed using a rubber dam to isolate the tooth from the rest of the mouth.

Glass-ionomer cement

Glass-ionomer cement (GIC) is also a white or tooth-coloured filling material however it is not as strong as composite resin. Fluoride is an ingredient in this filling material. It is often used for fissure sealants and temporary (interim) fillings.

Gold and porcelain

Fillings can also be made of gold and porcelain. These fillings are created outside of the mouth and then cemented into the tooth’s cavity. These are called inlays. A gold inlay will be very durable over the long-term, while a porcelain inlay is both strong and able to be matched to the colour of your tooth. Both gold and porcelain inlays take time to prepare and manufacture and will usually require at least two appointments to complete.

Gold inlay used to fix a molar tooth. Getty Images.

Fissure sealants

Fissures are the grooves that are naturally present on the top, biting surface of the back teeth. These grooves can be very thin and deep which can cause food and bacteria to become stuck. When this occurs over and over, it can increase the risk of tooth decay developing within the grooves.

A fissure sealant is a thin coating placed over the grooves of the teeth. It is done as a protective mechanism to prevent food and bacteria sticking in the grooves which decreases the risk of tooth decay occurring. They are most commonly placed in the grooves of the back adult molar teeth in children and teenagers. Sometimes other teeth may also require fissure sealant treatment. It will appear white or clear in colour and using the teeth will cause the fissure sealant to wear down over time.

Fissure sealant in a back molar teeth. Getty Images.


Fissure sealants are not required in all children. Your dentist will advise if this treatment is recommended in your childrens teeth.

Temporary fillings

Your dentist may call a filling they are placing in your tooth as temporary. In certain situations, a temporary filling may be placed in a tooth because, for example, the filling material will need to be removed again at your next dental appointment. Example situations where this may be done can include:

  • when multiple treatments of the same tooth are required for a few appointments in a row,
  • there is insufficient time to complete a treatment in one dental visit,
  • during emergency dental treatment, or
  • when sealing a tooth cavity between root canal treatment appointments.

After a filling

Following a dental appointment where a filling has been completed, it is not uncommon for the treated tooth to be sensitive. The tooth may be sensitive when placing pressure on the tooth or to hot and/or cold temperatures for a few days. This is called post-operative sensitivity. Any post-operative sensitivity should decrease over the days following the initial treatment. If the sensitivity continues or becomes worse, turning into pain, you should return to your dentist for them to investigate further.

How long will my filling last?

Fillings will not last forever. Over time fillings can become worn, chipped, or cracked, or discoloured. Over time, pressure applied to teeth can cause the joint between the tooth and the filling to open. This can allow food particles and decay-causing bacteria to gather in this space and this may cause tooth decay. How long a filling lasts can also depend on how well you care for it, this means twice daily toothbrushing and cleaning between the teeth daily.
Fillings can discolour or no longer match the colour of your natural tooth over time. This may be a concern for some people when it affects the front teeth. A dentist can replace the filling to improve the appearance.

Summary

Small surface cavities can be filled in less than 30 minutes with little to no discomfort. Deeper cavities that are near a tooth's pulp may be more painful and take longer to fill. There are several options for the type of filling used and the type of anesthetic you might need. Talk to your dentist about the best choices for you. Seeing your dentist for regular check-ups can allow them to monitor your fillings. They can detect and treat any issues before they become more serious. If you're due for a check-up but do not have a regular dentist use the ADA's Find-A-Dentist search tool to find a ADA member dentist near you.