There are a number of different fillings including:
Mercury in dental amalgam is not poisonous once it is combined with the other materials in the amalgam filling. Its chemical nature changes so that it is harmless. Research into the safety of dental amalgam has been carried out for over 100 years. So far, no reputable controlled studies have found a connection between amalgam fillings and any medical problem.
Composite fillings are strong, but may not be as hard wearing as amalgam fillings. Composite fillings are tooth coloured and are made from powdered glass quartz, silica or other ceramic particles added to a resin base. After the tooth is prepared, the filling is bonded onto the area and a light shone onto it to set it. The dentist will choose a shade to match your existing teeth, although over time staining can happen.
White fillings have always been considered less long lasting than silver amalgam fillings. But there are now new materials available with properties comparable to silver amalgam, and these are proving to be very successful. The life expectancy of a white filling can depend greatly on where it is in your mouth and how heavily your teeth come together when you bite.