Systematic reviews have reported on the associations between changes in the stomatognathic system and chronic systemic diseases. The research findings available to date highlight the close relationship between dental, oral, and maxillofacial diseases and chronic general diseases. Knowledge of these disease correlations is highly relevant for a patient-centered, interdisciplinary therapeutic strategy. The most common shared risk factors—smoking, age, sex, body mass index (BMI), and overweight—can drive the simultaneous progression of dental and chronic systemic diseases. There are studies on chronic systemic diseases that demonstrate that these conditions increase the risk of developing diseases of the masticatory system, but a reverse development is equally possible. This article outlines the relationships between dental, oral, and maxillofacial diseases and chronic systemic diseases (using diabetes mellitus, coronary heart disease, and periodontitis as examples). It aims to foster an understanding of the causal interactions. Only specialized knowledge based on sufficient clinical expertise contributes to higher quality care for patients with dental complaints and chronic systemic diseases. This requires, in the treatment of correlated diseases, a culture of communication with information exchange and support in diagnostic and therapeutic decision-making between the specialized disciplines of medicine and dentistry.