Understanding and managing periodontal diseases: a notable past, a promising future.

Throughout the 20th century, an understanding of the role of causative bacteria and the susceptible host in the initiation and progression of periodontal disease(s) has emerged from the research efforts of scientists and clinicians worldwide. Over time, specific bacterial types, such as Porphyromonas gingivalis, were discovered and shown to be important in the cause of periodontal disease. At the same time, inflammatory mediators, such as prostaglandins and interleukins, and enzymes, such as matrix metalloproteinases, were discovered and found to be important participants in the destruction of periodontal tissues. Acquired and inherited environmental risk factors began to emerge that could explain, in part, the susceptibility of individuals to periodontal disease. The discovery of antibiotics, beginning with sulfanilamide, penicillin, and streptomycin, led to additional strategies for managing periodontal disease. With the discovery of the mechanism of action of aspirin, scientists began to develop new strategies for treating diseases that focused on controlling inflammation. Thus, host-modulating therapies emerged for the management of periodontal disease through the control of inflammation. At the end of the 20th century, an old concept in medicine and dentistry reappeared: that the infection and inflammation of periodontal disease in the mouth could reach distant sites via the bloodstream. Apparently oral disease could, in fact, contribute to systemic diseases, such as atherosclerosis, diabetes, and adverse outcomes in pregnancy. This concept of the oral health-general health connection is now supported by sound and rational evidence-based observations. Clearly, the 21st century has arrived with a new understanding of the nature of periodontal diseases based on a notable era of discovery. There is a promising future for preventing and treating this common and troubling condition that affects not just the mouth but also the whole body.