The dentigerous cyst is formed from the accumulation of fluid between reduced enamel epithelium and the crown of an unerupted tooth. It is the second most common type of odontogenic cyst with an occurrence of about 24% compared to all cysts of the jaws2 and is seen more frequently associated with mandibular third molars, maxillary canines and upper third molars3 and present themselves mainly as unilateral cysts, unilocular with asymptomatic episodes of acute pain occurring when there is secondary infection. In tomographic exams, these lesions are presented with well defined edges and unilocular associated with crowns of impacted teeth, including the cemento-enamel junction.3 This lesion is usually small however when larger leads to some cortical expansion and a decrease in thickness and can lead to bone fracture. Treatment selection is based on age, size, location, root development, tooth position and relationship with the adjacent teeth and vital structures. Treatment modalities are enucleation or marsupialization. Complementary diagnosis exams are important both for planning issues either for reasons of identification of potentially clinical and pathological situations adjacent to the reason for patient consultation. Our patient complained of pain at the level of pre-molars, because the prosthesis was traumatizing the inclusion zone. After request of panoramic radiography was found a suggestive radiological image of a dentigerous cyst, assymptomatic, but with considerable dimensions. Keywords: enucleation, dentigerous cyst, marsupialization