i want to sue my dentist

Has anyone pressed charges on a dentist before? I had a root canal done 2 years ago which is painful now, at the time after having it done & doing the x ray, the dentist realized that the file had broken off in one of the roots that he had just filled in. He said it should not cause an issue and decided to do nothig about it. Here i am now 2 years later and its causing me issue- I may even need an implant because of his own mistake! I need some information please help!