To perform advanced periodontal therapy to save a natural tooth or to extract it and place an implant-which is best? Several considerations need to be made to make the proper decision. Endodontic conditions, proper reconstruction of a devitalized tooth, and the possibility of correct prosthetic treatment are all factors to be considered. From a strictly periodontal point of view, in the presence of a stable, vital, intact, periodontally involved, single-rooted tooth, a few fundamental criteria need to be considered to make the proper decision. These criteria will be discussed through analysis of therapy outcomes over a period of at least 10 years.