This document discusses the influence of systemic conditions on the periodontium. It begins by introducing periodontitis as a chronic bacterial infection and how host responses can vary between individuals. Systemic disorders can impair the host's immune defenses, creating opportunities for more severe periodontal disease. Several specific systemic factors are then examined in more detail, including hormonal changes, diabetes mellitus, and female sex hormones. The effects of these conditions on the periodontium are explored through their impact on factors like subgingival microbiota, polymorphonuclear leukocyte function, collagen metabolism, and wound healing. Treatment considerations for periodontal disease in systemic disease patients are also briefly addressed.