The oral cavity is the intersection of medicine and dentistry and the window into the general health of a patient. Hundreds of diseases and medications impact the oral cavity, and pathologic conditions in the mouth have a greater systemic impact than many providers appreciate. It is unclear whether there is true causality or just an association between periodontal disease and certain other systemic conditions, including atherosclerotic vascular disease, pulmonary disease, diabetes, pregnancy-related complications, osteoporosis, and kidney disease. Diabetes has a true bidirectional relationship with periodontal disease, and there is strong evidence that treating one condition positively impacts the other. A shared trait of periodontal disease and these medical conditions is that they are chronic conditions that take a long time to develop and become clinically significant. Primary prevention-treating the patient prior to the onset of symptoms, myocardial infarction, stroke, diabetic complications, or significant periodontal disease-is the challenge. Complications associated with these conditions cause significant morbidity and mortality and are incredibly costly to the healthcare system. Unfortunately, a lack of access to primary medical or dental care prevents some patients from engaging the system until a negative event has occurred. Despite the absence of clear evidence of causality and the direct impact of treatments, the consequences of these chronic conditions for the population are well understood. Dentists, family physicians, and all primary care providers must increase their collaboration and communication to maximize the benefit to patients.