A filling replaces part of a tooth that has been damaged, usually by decay. Many fillings are placed to replace old fillings that have either broken or where further decay has occurred under the filling. Often, we have to remove old fillings because of pain in the tooth.

Basically there are two types of filling: ‘silver’ amalgam fillings and ‘white’ composite fillings.

‘Silver’ Amalgam fillings: Pros and cons

Silver amalgam fillings are very hard so they resist wear very well and can often last for decades. However, because the material does not ‘stick’ to the tooth, it has to be packed into a cavity which has been shaped in order to keep the filling in. In most cases this works fine, but parts of a tooth restored with amalgam can be weak and this can result in the tooth breaking.

There are two other major drawbacks of amalgam fillings. Firstly, as the picture shows, they don’t look very nice. Notice that not only is the filling unsightly, but it causes the surrounding tooth to appear grey. The other issue with amalgam is that it contains mercury. On it’s own, mercury is a toxic metal, but when incorporated with other metals such as silver, copper, and tin, as with dental amalgam, it sets hard and no longer has its harmful effects, so it’s still widely used all over the world. However, some scientists believe that there is potential for amalgam to be harmful in some people. If you have any concerns about this, you should ask your dentist. Amalgam fillings can be replaced with white, composite fillings.

‘White’ Composite fillings: pros and cons

Unlike amalgam, composite filling materials do not contain mercury, so if you have concerns about the safety of mercury fillings, composite fillings may be better for you.

The main advantage is obvious: appearance. It is possible to restore a tooth with a high quality composite material so that it looks like a natural tooth. The materials come in a choice of many subtly different shades so that a perfect match with your own tooth can be achieved. Unlike amalgam, composite filling materials form a strong bond with the tooth so in many cases less tooth preparation is needed. This potentially makes the tooth less likely to break. Although composite won’t resist wear as well as amalgam, modern high quality materials that are specifically designed for use on chewing surfaces of back teeth are extremely durable and can still last for many years.

Drawbacks? Well, firstly, composite fillings are more expensive than amalgam fillings and they take longer to place. Secondly, particularly for big fillings, the tooth can become sensitive to heat and cold afterwards. This is rarely a problem however and can be prevented by careful placement of the material in several stages. more information about composite. Some teeth may not be suitable for restoration with composite. It is important for the success of composite fillings that a dry field is achieved and this is not always possible with a deep filling that goes beneath the gumline. Composite won’t stick to teeth properly if there are contaminents such as saliva or blood around.

How much do they cost?

It depends on the size of the filling to be done and the number of tooth surfaces involved. Generally speaking, amalgam fillings cost between £40 and £93, and composite fillings between £48 and £150.

Are there any alternatives to fillings?

Yes, see our section on inlays and crowns.

More info: Composite materials are set using an intense blue light. The material is specially engineered to react to the specific wavelength of blue light. This so called ‘command set’ means that dentists can accurately control the placement of each part of the filling and you don’t have to wait before you can chew on it. Sensitivity after placement of composite filling has been reported, but seems to be prevented if the filling is placed in small increments. This is because composite materials shrink very slightly when they are set. If the shrinkage is too great, as it would be if the filling was placed in one piece, it puts tension on the tooth which can lead to the sensitivity. Your dentist will take care to place the composite filling in several small increments to eliminate this problem. The degree of shrinkage in modern composite materials that are specifically designed for use in back teeth is very low – about 0.5%.