Summary : When decay has eaten away at the tooth a hole remains. The dentist needs to fill this hole produced by the decay, a 'filling' is thus placed.

Today there are basically two types of filling, 'silver' fillings and 'white' fillings. There has been much bad publicity regarding silver fillings as they contain mercury, a toxic substance.

There is much controversy regarding dental amalgam as it contains mercury, a potentially toxic substance. Despite this fact it has many clinical advantages.

What you should know.

Removing an old amalgam generates a lot of free mercury as the drill cuts the silver fillling into a powder. Ironically many patients request replacement of silver fillings because they are worried about the toxicity of the mercury in their old fillings. Some dentists, who specialist in treating patients with such concerns use breathing apparatus both for themselves and staff and the patient while removing old amalgams.

The corrosion is also an advantage as any small gaps between the tooth and filling are taken up by the products of corrosion. This prevents the entry of bacteria or sugar underneath the filling.

Metal fillings conduct very easily, for this reason dentists place an insulating layer under the amalgam.

When the tooth has decay only in the top surface then a small filling can be placed.
When the decay is greater one of the end walls of the tooth may be broken down. The dentist will need to place a metal band around the tooth to form this wall when they place the fillings. This acts like a cake tin.
When a tooth has a lot of decay the dentist will need to place a new wall at the back and front parts of the tooth. When teeth have big fillings they are more likely to break , usually it is the thin walls of enamel that break off.
These materials are used in the front of the mouth or for smaller fillings on the molar teeth. They are available in many shades which allows the dentist to match to the tooth which is being filled. This may be a disadvantage in back teeth as it is difficult to see what is part of the tooth or part of the filling material later should the filling need to be removed.

These fillings may cause teeth to be sensitive afterwards as they shrink when during setting. This causes the walls of the tooth to be pulled in and held in tension. The join to one wall may break leaving a microscopic gap which bacteria may invade. Later this may cause more decay if the diet is not controlled.

These are the other type of white fillings. They are not as nice looking as composite as they have large bits of glass in them which produces a rough texture. The main advantage of these materials is that they release fluoride which helps prevent decay. This makes them popular for fillings in childrens teeth.

These materials tend to be used for small back fillings, fillings in childrens baby teeth and fillings on root surfaces.

Patients often attend the dentist at short notice or without appointments. If a patient has lost a filling or in pain, a temporary filling material allows the dentist to rapidly place a restoration which will protect the tooth from hot drinks, cold air and bacterial invasion.

Some temporary dressings contain 'oil of cloves' which is an obtundant effect. This means that it desensitizes the nerve so that it is less sensitive.

It is a misconception that a temporary filling will last only a short time. One material called 'Poly F' can last well over a year and is stronger than many of the white filling materials.

The disadvantage of these materials is that they don't look much like enamel, having a appearance similiar to that of polyfilla.