Teething is the process by which an infant's first teeth (the deciduous teeth, often called "baby teeth" or "milk teeth") sequentially appear by emerging through the gums. Teething may start as early as three months or as late as twelve months. The first teeth typically appear between six and nine months. It can take several years for all 20 teeth to complete the tooth eruption; they typically arrive in pairs. Though the process of teething is sometimes referred to as "cutting teeth", when teeth emerge through the gums they do not cut through the flesh. Instead, special chemicals are released within the body that cause some cells in the gums to die and separate, allowing the teeth to come through.