Leukemia, particularly acute leukemia, is characterized by leukemic cells losing their ability to differentiate and mature, remaining at various stages of cell development. This results in a significant reduction in mature, functional white blood cells. Consequently, patients with acute leukemia have extremely low immune function. Therefore, more than half of the patients initially present with fever as the primary symptom. Fever indicates infection, which can spread to multiple parts of the body, with oral inflammation, gingivitis, and pharyngitis being the most common. Thus, patients with acute leukemia who also have gingivitis may experience toothache.