ABSTRACT
World Workshop on the Classification of Periodontal and Peri-implant Diseases and Conditions was held in Chicago on November 9 to 11, 2017. More than one hundred experts from all over the world attended the conference and updated the 1999 classification of periodontal diseases and conditions, and developed a similar scheme for peri-implant diseases and conditions. The case definitions and diagnostic criteria were also established to aid clinicians in the use of the new classification. Nineteen review papers and four consensus reports covering relevant areas in periodontology and implant dentistry were simultaneously published in special issue of Journal of Periodontology and Journal of Clinical Periodontology in June 2018. This paper summarizes the new classification of periodontal and peri-implant diseases and conditions, and briefly introduce the changes made to the 1999 classification.