Hi.. Can understand your concern.. As per your complain it is seen that when you get a filling done using a metallic filling material which is Silver Amalgam which contain silver and mercury can lead to an odd taste in mouth. It is not seen always but can be experienced by a few patients. In case if you have got a tooth coloured filling the acid present in the liquid which is used to mix with the powder to make the filling that can be placed in the tooth can lead to sore taste in the mouth but does not lasts for a very long time. Altered taste can also occur in case of leaky filling in which the filling is not done properly leading to seepage of fluids and food debris inside the tooth causing food impaction , infection and bad taste. Other reason for foul taste in mouth can be due to dry mouth,intake of certain medicines,poor oral hygiene, oral infections etc.. I would suggest you to consult your dentist and get evaluated for the cause of your problem. If dental filling is the cause the dentist can replace the filling with the other material or if there is any infection treatment of the same can help.. If dental problem is not found consult a general physician and get evaluated.. Hope your query is solved.. Thanks and regards.. Dr.Honey Nandwani Arora.