When the pulp of a tooth is irreversibly inflamed or necrotic and the apex is open, conventional root canal treatment is difficult to perform and the outcome is uncertain. Traditionally, the apexification procedure has consisted of multiple and long-term applications of calcium hydroxide [Ca(OH)2] to create an apical barrier to aid the obturation. Recently, artificial apical barriers such as those made with mineral trioxide aggregate (MTA) have been used in teeth with necrotic pulps and open apices. More recently, procedures referred to as regenerative endodontics have received much attention as an option for these teeth. The purpose of this article is to provide a comprehensive literature review from May 1952–May 2011 regarding the management of teeth with necrotic pulps and open apices. This review covers the articles published in dental journals and book chapters regarding the definition, history, materials used, animal and human studies, mechanisms of action, prognosis, as well as advantages and disadvantages of apexification, apical plugs, and regenerative endodontics.