Cause-related therapy is key in the management and resolution of the two most common oral diseases: dental caries and periodontal disease. This is the first phase of treatment for those diseases. The aim is to remove, reduce, or eliminate the main causes of the disease. When referring to caries and periodontal disease, the primary etiology is bacterial plaque so the cause-related therapy phase should include plaque control as a major component. This can be achieved by constantly and continuously educating patients about the pathophysiology of the diseases and by helping them develop proper daily plaque removal techniques. Furthermore, various professional therapeutic interventions are delivered as necessary to eliminate or suppress other etiologic or risk factors. In this case series, the principles of proper cause-related therapy are demonstrated through three cases that were successfully managed by nonsurgical periodontal therapy. Biologic and clinical rationales are also discussed. Keywords: dental plaque, gingivitis, nonsurgical periodontal therapy, oral hygiene, periodontitis