Both non-erupted teeth and supernumerary teeth are caused by the condition Gardner syndrome.
Gardner syndrome can be identified based on oral findings, including multiple impacted and supernumerary teeth, multiple jaw osteomas that give a "cotton-wool" appearance to the jaws, as well as multiple odontomas, congenital hypertrophy of the retinal pigment epithelium (CHRPE), in addition to multiple adenomatous polyps of the colon. An impacted tooth is one that fails to erupt into the dental arch within the expected developmental window. 
