Retreatment: Here is an interesting case of root canal retreatment from a failed initial attempt at initial endodontic treatment. This particular case was filled with a carrier-based filling material, which has no solvent. This, along with the presence of a metal post cemented in the tooth, makes it inherently more difficult to treat. If you look closely at the photo of the post-treatment access, there is a 3rd canal (not separate) within one of the roots. Another cool case!