Introduction: The talon cusp is defined as a developmental anomaly in which an accessory cusp-like structure projects in the area of the cingulum or cementoenamel junction in the anterior teeth attached to the lingual surface of the crown, ranging in size, shape, length and degree of union with the surface. Case report: This study aimed to report a case of a patient who came to Clinic for Preventive Dentistry of Federal University of Pernambuco, Recife-PE, Brazil, complaining of pain in the upper left region. The clinical exam observed the presence of a supernumerary tooth with talon cusp type III in the canine region which had a carious lesion in the developmental groove at the mesial surface and caused a prolonged retention of permanent tooth. Conclusion: With this we want to emphasize that the Dental Surgeon be aware of the changes caused by dental morphological variations, seeking to conduct a proper treatment plan, meeting the functional and aesthetic needs of the patient.