What is a filling?

A filling is something that the dentist puts into a tooth to restore a cavity, or return a chipped tooth to its normal shape. The choice of filling material will depend upon many factors including the size of the cavity, the type of tooth and your bite. 


Why do I need a filling?

Tooth decay

This is the most common reason for needing a filling. If the decay has spread into the inner dentine of your tooth, or you have symptoms, such as sensitivity, the tooth will require restoring.

Decay generally occurs as a result of a sugary or acidic diet, not enough fluoride around the teeth and/or inadequate cleaning. 

Some of your back teeth have fissures and pits on the biting surface which makes them hard to clean and more prone to decay. If you have crowded teeth they become harder to clean as they are on top of one another which makes them more prone to decay. 

Tooth wear

Sometimes tooth wear will make a filling necessary, especially if you have symptoms. The filling has a protective role, to seal the exposed dentine, prevent decay and sensitivity.  


If you have chipped or broken a tooth, a filling can restore both its natural look and use. Discoloured areas on a teeth or exposed roots can be covered up to improve their appearance.

A previous filling has failed

Fillings can fail over time due to decay setting in around the filling, the tooth or filling breaking or excessive wear.

On front teeth if a previous filling has discoloured it may need to be changed for aesthetic reasons. 

Types of fillings

There are a few different types of fillings which are covered below. 

Amalgam fillings

Amalgam fillings are silver coloured, and are best known as silver metal fillings. They are made by combining a silver metal alloy powder with mercury. Amalgam is long lasting and hard wearing and it has been used in fillings for over a century. They are normally used for the back teeth and can last over ten years. 


Are there any risks from amalgam fillings?

Mercury in dental amalgam is not poisonous once it has been combined with the other materials in the silver alloy and its chemical nature change renders it harmless. Research into the safety of dental amalgam has been carried out for decades and no reputable controlled studies have found a connection between amalgam fillings and any medical problems.

Composite fillings

Composite or white fillings are tooth coloured and are made from quartz, silica and other ceramic particles. After the tooth is prepared, the filling is bonded onto the tooth and a light is shone onto the filling to set it.

Why should I consider white fillings?

White fillings bond to the surrounding tooth tissue, hence less tooth is removed leaving a stronger, well reinforced tooth

They also have the advantage of having a natural appearance where different shades of material are used to best mimic the colour of your own teeth.

Do they last as long as metal fillings? Are they as strong?

White fillings have always been considered less long lasting than silver amalgam fillings, however new materials are available with properties that are comparable to silver amalgam.


The life expectancy of any filling depends on where it is in your mouth and how heavy your bite is. Your dentist can advise you on the life expectancy of your fillings, and which material is most appropriate, as metal fillings are still used and in some cases will be superior.


Is it worth replacing my amalgam fillings with white ones?

It is usually best to change fillings only when your dentist decides that an old filling needs replacing.  Our advice is to replace old fillings with a restoration that strengthens the tooth. 

Glass Ionomers

A less well known filling is the glass ionomer. This filling is based on the reaction of a powder and liquid to create a solid material. They also release fluoride which can help prevent decay. However they are not very strong but are ideally suited for baby teeth fillings or dressings. 

Gold inlay

Gold is stable and inert and shares a similar wear resistance and expansion pattern to natural tooth. It results in less tooth damage over time. Cast gold restorations don’t just fill the tooth, they support the tooth from the crushing forces when chewing. An inlay is similar to a filling where it fills the inside of the tooth, but is made in the laboratory from a custom mould.


Porcelain inlay

At Dental Sense, we now utilise digital technology to design perfectly fitting porcelain inlays. Porcelain is hard wearing, long lasting and has the benefit of being tooth-colured. All inlays are made by a specialist technician thus the accuracy, shape, fit and longevity are better than a filling, particularly if the cavity is large.

What is the difference between the fillings?

At Dental Sense we offer different types of fillings and the options will be given to you based on the best outcome for your tooth. In most cases you will be given more than one option and you will be able to pick the one that you would prefer.

There are some restrictions on the types of materials clinicians can provide in certain teeth under the NHS. Your dentist will discuss the filling options with you. 

Last Updated December 2020

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