Dark-field microscopy is a method of examining a drop of live blood taken from a patient’s finger under a high-magnification microscope using a special light-refracting system, without any chemical staining. This analysis observes the movement, shape, and microscopic structures of blood cells (erythrocytes, leukocytes) within the plasma. If the patient has very intense, insidious chronic gum infections or hidden root cysts in their mouth, the erythrocytes are seen to stick together in a coin-like arrangement (Rouleau formation) in the dark field, indicating decreased tissue oxygenation and chronic inflammation. Furthermore, the immobile and lifeless appearance of leukocytes (immune cells) proves a compromised immune system. After cleaning the oral foci, follow-up examinations show that the blood cells have become free and revitalized, appearing live again.