Mercury is a deadly toxic element. It is well known that Mercury is highly toxic - causing renal failure, muscle tremor, memory loss and even life-threatening. Now, the content of mercury in dental fillings used by dentists to fill teeth often reaches 50%. 
Plastic fillers are much more expensive than mercury fillers and are easy to damage
 every responsible dentist should remove mercury containing fillings from the mouth of all filling patients, Instead, use a filler made of plastic.