Check out the Materials used to fill holes in the Teeth

Holes created by tooth decay or fracture are usually filled/restored to stop pain and the progression of the decay. Filling the tooth also helps restore the tooth back to function and aesthetics.
There are basically 2 types of filling materials; temporary and permanent.

1. Temporary filling materials: as the name implies are materials placed temporarily on the tooth with the intention of replacing it with a permanent one at a later date. They are not as strong as permanent materials and are easier to remove.
2. Permanent filling materials: are placed permanently and can stay as long as 10-15 years or more without needing replacement. 

Amalgam filling:

Permanent Filling materials your Dentist will often use include

• Amalgam: a silver coloured material. It is strong and inexpensive. It is mainly used for filling the back teeth(areas not readily visible when you talk or laugh).
• Composite: is a white material that matches the colour of the tooth. A light is usually shone on it during the filling process. This is to make it hard enough to withstand forces of chewing. They often absorb stains(such as coffee and tobacco) with time. They can be used for both front and back teeth. 
• GIC(Glass Ionomer Cement): is also a white filling that blends with the colour of the tooth. It can be used for both adults and children. It is the preferred filling material in children because it has the ability to release fluoride which prevents tooth decay. It also forms a good bond to the tooth(sticks to the tooth). 

White filling

White fillings are generally preferred to silver fillings because they blend with the tooth colour and are not easily noticed.

The choice of filling material is largely determined by your dentist who knows what material will work best for you depending on the size of the hole and the area affected.