Hi.. Can understand your concern.. As per your complain burning sensation of gums and sensitivity can be either due to tooth problem or gum infection. As you have got fillings replaced, at times during removal of old fillings and cleaning the cavity to refill it again there can be opening up of the nerves and blood vessels present in the central portion of the tooth in a small chamber known as pulp chamber.. If the pulp is exposed and filling is done over it, it leads to inflammation of nerves leading to sensitivity to hot and cold and pain and burning sensation.. Other thing is that there can be infection in the gums leading to inflammation of the gums known as gingivitis and burning and sensitivity can be due to it.. Few other conditions which can cause burning sensation are burning moth syndrome,dry mouth ,side effect of some medicine etc.. I would suggest you to see an Oral Pathologist who can take detailed medical and dental history and do a clinical evaluation to rule out the exact cause of your problem and can either plan a treatment for you or refer you to an appropriate specialist.. Till the time you can apply numbing gels like Orabase or mucopain gel to the gums to relieve burning.. Other thing which can reduce sensitivity is desensitizing toothpastes.. Hope your query is solved.. Thanks and regards... Dr.Honey Nandwani Arora.