This study aims to consolidate all epidemiologic data on severe periodontitis (SP) and generate internally consistent prevalence and incidence estimates for all countries, 20 age groups, and both sexes for 1990 and 2010. A systematic review of the literature identified 6,394 unique citations, of which 513 were reviewed in full. After further screening, 72 studies were included, involving 291,170 individuals aged 15 years or older in 37 countries. SP was the sixth-most prevalent condition globally. The global age-standardized prevalence of SP was static at 11.2% in 1990 and 10.5%-12.0% in 2010. The age-standardized incidence of SP in 2010 was 701 cases per 100,000 person-years, a nonsignificant increase from the 1990 incidence. Prevalence increased gradually with age, showing a steep increase between the third and fourth decades of life, driven by a peak in incidence around 38 years of age. There were considerable variations in prevalence and incidence between regions and countries. The study highlights the need for policymakers to be aware of the predictable increasing burden of SP due to the growing world population, increasing life expectancy, and a significant decrease in the prevalence of total tooth loss from 1990 to 2010. The findings underscore the enormous public health challenge posed by SP and are a microcosm of the epidemiologic transition to noncommunicable diseases in many countries. The study used a Bayesian metaregression tool, DisMod-MR, to model the data and account for variations in study populations and definitions. The results provide a comprehensive understanding of the global burden of SP and its implications for public health policy.This study aims to consolidate all epidemiologic data on severe periodontitis (SP) and generate internally consistent prevalence and incidence estimates for all countries, 20 age groups, and both sexes for 1990 and 2010. A systematic review of the literature identified 6,394 unique citations, of which 513 were reviewed in full. After further screening, 72 studies were included, involving 291,170 individuals aged 15 years or older in 37 countries. SP was the sixth-most prevalent condition globally. The global age-standardized prevalence of SP was static at 11.2% in 1990 and 10.5%-12.0% in 2010. The age-standardized incidence of SP in 2010 was 701 cases per 100,000 person-years, a nonsignificant increase from the 1990 incidence. Prevalence increased gradually with age, showing a steep increase between the third and fourth decades of life, driven by a peak in incidence around 38 years of age. There were considerable variations in prevalence and incidence between regions and countries. The study highlights the need for policymakers to be aware of the predictable increasing burden of SP due to the growing world population, increasing life expectancy, and a significant decrease in the prevalence of total tooth loss from 1990 to 2010. The findings underscore the enormous public health challenge posed by SP and are a microcosm of the epidemiologic transition to noncommunicable diseases in many countries. The study used a Bayesian metaregression tool, DisMod-MR, to model the data and account for variations in study populations and definitions. The results provide a comprehensive understanding of the global burden of SP and its implications for public health policy.