Retention of a maxillary primary canine: fifty years above and beyond the call of duty.

A case is reported of a retained maxillary primary canine that functioned effectively over fifty years. At the time of exfoliation the tooth was still of normal length and was lost not because of ankylosis and root resorption, but because of periodontal disease. Excellent histological preservation of the specimen at the time of exfoliation, together with a very complete clinical history, permitted the development of a detailed description of a tooth and its dying pulp while under function over a long period of time.