Dental implants are used routinely throughout the world to replace missing teeth. With the broadening of treatment options and an increasing number of clinicians that provide implant therapy, it is important to ensure that the treatment methods used meet the highest clinical standards. The ITI Treatment Guide series is a compendium of evidence-based implant-therapy techniques in daily practice. Written by renowned clinicians and supported by contributions from expert practitioners, the ITI Treatment Guides provide a comprehensive overview of the various indicated treatment options. The management of different clinical situations is discussed with an emphasis on sound diagnostics, evidence-based treatment concepts, and predictable treatment outcomes with minimal risk to the patient. Volume 13 of the ITI Treatment Guide series provides clinicians with the latest evidence-based information on the prevention and management of peri-implant diseases. This information is based in part on the proceedings of the 6th ITI Consensus Conference held in Amsterdam in 2018, as well as on a review of the current literature. Seventeen clinical cases presented by experienced clinicians from all over the world illustrate the diagnosis and treatment of peri-implant diseases.