Purpose: To compare caries experience and periodontal status between two US populations that lived a century apart. Materials and Methods: The University of Pittsburgh, School of Dental Medicine possesses a collection of skulls that was organised in the first half of the 20th century. Those individuals are likely to have lived in the northeast United States during the late 19th century and the early 20th century. The present study measured caries and periodontal disease morbidity in the collection of skulls and compared the data with current prevalence rates of these diseases in the United States (from the third National Health and Nutrition Examination Survey 1988-94). Results: Periodontal health appears to have improved since this population resided, over 150 years ago. On the other hand, Americans between the ages of 16 and 39 appear to have the same prevalence of caries as a group of individuals that lived 150 years ago. Conclusions: The periodontal health of Americans has probably improved in the last 100 years. The individuals identified that were free of caries and periodontal disease among the group that lived during the 19th century may have some protective factor against these diseases. Schlagwörter: dental caries, epidemiology, periodontitis