I had new filling of all my molars, both sides, 3 weeks ago. Since then I've been experiencing a lot of pain, sometimes around one specific molar, other times all along the mouth, with high sensitivity to temperature. When I went back to my dentist he said it was either because of loss of dental enamel due to the cleaning or that I may need a root canal. He made a composite around the molar that hurt me most, pain somewhat got better that day, but it always comes back.