Recent epidemiologic surveys and studies have provided important information on the prevalence, extent, and severity of periodontal diseases in the United States. Over 50% of adults had gingivitis on an average of 3 to 4 teeth. Subgingival calculus was present in 67% of the population. Adult periodontitis, measured by the presence of periodontal pockets > or = 4 mm, was found in about 30% of the population on an average of 3 to 4 teeth. Severe pockets > or = 6 mm were found in less than 5% of the population. Attachment loss > or = 3 mm was found in 40% of the population. Gingival recession accounted for a significant amount of attachment loss. The prevalence of early-onset periodontitis ranged from less than 1% in 14- to 17-year-olds to 3.6% in young adults aged 18 to 34. Extensive and severe periodontitis was much more prevalent in minorities, people with less than a high school education, and those who had seen a dentist infrequently and had subgingival calculus. Smoking and diabetes have been identified as risk factors, especially diabetics with poor metabolic control, a long duration of the disease, and extensive subgingival calculus. Under managed care, there has been an expansion of soft tissue management programs in the offices of general dentists and referral guidelines which limit referral of patients with moderate periodontitis. Quality-assurance mechanisms will be essential for the diagnosis and treatment of persons with periodontitis.