Staging and grading of periodontitis: framework and proposal of a new classification and case definition
Introduced the stage (severity) and grade (progression) framework used today.
Tonetti MS, Greenwell H, Kornman KS. (2018). Staging and grading of periodontitis: framework and proposal of a new classification and case definition. Journal of Periodontology, 89(Suppl 1), S159–S172.