Edentulism is the clinical word for being wholly or partially toothless, or having one or more missing teeth. The loss of all teeth is called full edentulism, while the loss of only some teeth is called partial edentulism. While edentulism can be a genetic defect and takes place naturally in some species such as sloths and anteaters, this is rare and most cases of edentulism in humans is the consequences of tooth loss. A person who has one or more missing teeth is said to be edentulous or edentate. The causes of edentulism in humans are most often cavities, poor oral hygiene, gum disease, bone loss, and other periodontal issues. Teeth play an important role in appearance and health: they give the face a fuller appearance while also enabling the proper enunciation of words and syllables. Untreated edentulism can cause the chin to protrude and the cheeks to appear sunken into the face.