Problems ?I have had some problems with some previous dental work? ?I had a filling done a few months ago and everything was fine and then I started to get some sensitivity to hot/cold and now it?s a bit tender to bite on. I went back to the dentist and they tried me on a special toothpaste and that didn?t help. Why is this happening when the filling is only 4 months old? Should I go back to the same dentist for this or should I get a second opinion?