Few studies have looked at the percentage of the time<unk><unk>  are present or the rate of<unk><unk>  eruption. The lack of up to five<unk>  (excluding third molars, i.e.<unk><unk>  is termed hypodontia. Missing third molars occur in 9-30% of studied populations. One large scale study on a group of young adults in New Zealand showed 95.6% had at least 1<unk>  tooth with an eruption rate of 15% in the maxilla and 20% in the mandible. Another study on 5000 army recruits found 10,767<unk> . The frequency of<unk>  lower third molars was found to be 72% in a Swedish study, and the frequency of retained<unk>  that are free of disease and symptoms is estimated to be between 11.6% to 29%, a percentage which drops with age. The incidence of<unk>  tooth removal was estimated to be 4 per 1000 person years in England and Wales prior to the 2000 NICE guidelines.
Impacted wisdom teeth
Toothache
Chattering teeth
Temporomandibular joint dysfunction
Melanocytic oral lesion
Facial trauma
Perforated eardrum
Enamel hypoplasia