This paper outlines criteria which allow the clinician to identify endodontically treated teeth that can be restored with a high level of predictability. The intent of the article is not to preclude the restoration of teeth that do not meet these criteria; it is to provide a science-based approach for identifying those teeth with a high probability of long-term success upon restoration. For an endodontically treated tooth not requiring a post, the requirements are for biologic width + ferrule length, (i.e. 4.5 mm of supra-bony solid tooth--dentin a minimum of 1 mm thick after preparation). A tooth requiring a post needs, in addition, enough root length to allow a 4 mm apical seal and a post length--apical to the crown margin, equal to the length of the crown. It is essential to assess the functional loads to which the restored tooth would be subjected. Teeth that are endodontically treated, or are likely to be in future, should be avoided as abutments supporting precision attachment RPDs, distal extension RPDs or cantilever FPDs.