Crown or filling after root canal for a tooth in a pretty good shape? (Photo)

There was a little gum recession on tooth 29, so my dentist did a small filling along the gum line, but the filling came off later, and she did the filling again. 8 months after that, a lump started growing near that tooth, my dentist told me I need a root canal, but she said the tooth’s death is not related to the filling, and I need a crown after root canal. Since the tooth has no other decays or cavities, 1. will a filling be good enough? 2. it died because of the gumline filling?