Cell death occurs in physiological conditions and as a result of injury or disease. Programmed cell death has an important role in the development and homeostasis of human tissue. Aberrant regulation of this process is thought to cause numerous diseases, including developmental disorders, neurodegenerative disease, and cancer. Apoptosis is the main type of programmed cell death and is well understood. However, recent intensive studies have revealed other types of programmed cell death. Here, we include an overview of three types of programmed cell death: apoptosis, necroptosis, and autophagic cell death. We also provide information on damage-associated molecular patterns (DAMPs), which have pro-inflammatory effects and are reportedly associated with cell death. Finally, we discuss the link between programmed cell death and periodontal disease and propose a hypothetical role for programmed cell death and DAMPs—which are released from cytoplasm of necrotic cells—in periodontal disease initiation. (J Oral Sci 54, 137-149, 2012)