Odontomas are benign tumors of odontogenic origin characterized by their slow growth. They consist of enamel, dentine, cementum and pulpal tissue and constitute 22% of all odontogenic tumors. Two types of odontoma are recognized: compound and complex. The first is approximately twice as common as complex odontomas. The purpose of this study is to value the prevalence of this kind of tumors in the ambulatory-surgical gambit and their clinical symptoms. We want to emphasize the exceptional spontaneous eruption of this tumors and we report a case of erupted complex odontoma. We made the revision of the cases of diagnosed odontomas between 1983 and 2001 in the Clínica Ntra. Sra. del Remei, in the Centro Médico Teknon and the Master de Cirugía e Implantología Bucal of the Odontologic Clínic (Barcelona University). We analyzed their prevalence, distribution in gender, age of the patients, anatomic location, adjacent structures affectation, symptoms, histologic classification and treatment. 52.4% of the cases were diagnosed in females. 37.7% of the tumors were complex odontomas and 62.3% were diagnosed as compound odontomas. 55.7% of all cases were in the maxilla and 44.3% in the mandible. The anterior portion of maxilla was the most common location (54% of cases). Only a case (1.6%) was erupted, in the molars area of the maxilla.