This book illustrates the precautions for dental treatment with patients with medical diseases and presents the correlation and relationship between oral symptoms and systemic diseases. It is organized into two parts; the first part is symptomatology presenting the description of some symptoms as general remarks. Then comes the part explaining the diseases, which describe the associations between each medical disease and the oral conditions. Chapters provide intraoral figures and in-depth information to help readers understand the symptoms, mechanisms, and responses, the comorbidities, and medications. As the number of patients with lifestyle-related diseases and metabolic syndrome is in increases, it is important to understand the perioperative oral care for patients with malignant diseases.