In 2009, the book SAC Classification in Implant Dentistry was published, and the SAC Classification scheme has received widespread acceptance in the dental profession. The SAC Classification provides an evidence-based, objective framework for the assessment of the potential difficulty, complexity, and risk of an implant-related treatment for a given clinical situation and serves as a guide for clinicians in both patient selection and treatment planning. From the book’s initial release, clinical techniques, materials, and technology have continued to evolve and, in early 2017, the ITI recognized that there was a need to review the SAC Classification. The fully revised second edition of the SAC Classification in Implant Dentistry has been updated to ensure consistency with contemporary implant practice. Illustrated by new clinical case reports, this edition gives an even more detailed and comprehensive overview of the risks in implant dentistry and the practical application of the SAC Classification.