Eruption failure Unerupted dentition Unerupted tooth HP:0000706 A tooth which does not erupt within the teeth eruption timeline and after the loss of eruption potential. Failure of eruption of tooth SNOMEDCT_US:109542004 Pseudoanodontia UMLS:C1290587 Usually a tooth erupts at a stage of half or two-thirds of root formation. There are established norms for the timing of eruption and tooth stages in both deciduous and permanent teeth. It may be difficult to discern Delayed eruption from failure of eruption: failure indicates it will never erupt, delayed indicates it may still erupt. Eruption failure may be caused by an isolated obstacle (supernumerary teeth), ankylosis of impacted teeth, or disturbances of biological eruption pathway. Partial or complete non-eruption of not initially ankylosed teeth due to a disturbed eruption mechanism result in a severe form of posterior open bite that usually worsens from anterior to posterior. Eruption failure is usually asymmetrical, affects more posterior teeth and both dentition may be involved. The diagnosis eruption failure requires clinical and radiographic examinations. Pseudo-anodontia Abnormality of dental eruption