Fourth molars: a clinical study.

Supernumerary teeth may be found in both the primary and permanent dentition, although they are more common in the permanent dentition. Presence of a fourth molar is rare, and such a tooth is almost invariably impacted. Dental practitioners should be aware of the possibility of encountering this rare supernumerary, its diagnosis and treatment. The authors of this article conducted a survey of patients in Montreal, looking specifically at the prevalence, aetiology, diagnosis, pathology and treatment of fourth molars. Their findings are reported here, and compared with data from the literature over the past 15 years.