Shorts

1. Anodontia: This is the complete absence of teeth. It is a rare condition where an individual fails to develop any teeth.
2. Oligodontia: This term is used when an individual has fewer teeth than the typical dental formula, which is six incisors, two canines, two premolars, and six molars in the permanent dentition (excluding the third molars or wisdom teeth). The term "hypodontia" is often used synonymously with oligodontia, but hypodontia can also refer to a broader range of conditions characterized by the congenital absence of one or more teeth, whereas oligodontia is more specifically the absence of six or more teeth.
3. Microdontia: This condition involves teeth that are smaller than normal. It can affect either the primary or permanent dentition and may involve one tooth or multiple teeth.
4. Dens in dente: This is a rare developmental anomaly where a tooth forms within the dental crown of another tooth, typically in the form of a small tooth-like structure. It is not a condition of tooth number but rather an abnormality of tooth structure.