Endodontic disease is a biofilm-mediated infection, and the rationale for endodontic treatment is the elimination of biofilm i.e. to eradicate the infection, prevent microorganisms from infecting or re-infecting the root and/or periradicular tissues. Understanding the virulence of these endodontic microbiota within biofilm is essential for the development of novel therapeutic procedures for intracanal disinfection. Accordingly, a review of endodontic biofilm types, antimicrobial resistance mechanisms, and current and future therapeutic procedures for endodontic biofilm is provided. The aim of this book is to provide a contemporary overview of endodontic microbiology and biofilm polymicrobiality, provide an understanding of the host response, and how together these impact upon clinical treatment. Ultimately, it is intended to provide insight into novel opportunities and strategies for the future diagnostics, treatment, and prevention of endodontic disease.