When you go for a dental exam, your dentist checks your fillings and may suggest that you replace any loose or broken ones. Your dentist also looks for signs of decay, such as brown or black spots and may want to use X-rays to take a closer look at problem spots.
If you have a cavity, your dentist may keep an eye on it (if it's small) or fill it right away. If a large cavity is not filled, it can get bigger and cause pain. The tooth may even have to be removed and replaced with a false (or artificial) tooth.
Overview - If you have a cavity and it needs a filling, there are different kinds of fillings to do the job.
Metal Fillings - Dental amalgam is the most common type of filling used in Canada today but other metal fillings may be appropriate depending on your oral health needs.
Tooth-coloured Fillings - Composite fillings and fillings made out of glass ionomer materials are the same colour as your natural teeth.
Source: Canadian Dental Association