The mucosa exogenous pigmentation may occur in consequence of dental materials contact, such as amalgam pigmentation. Aim: This paper reports a rare case of oral pigmentation due to extrusion of N-Rickert root canal sealer from a pre-existing fistula associated with a lateral canal in a 47-year-old female patient. Subjects and Methods: The clinical presentation was a well-defined grayish macule of about 3 mm located in the attached gingiva close to the maxillary left central incisor. Analysis Used and Results: Upon identification of endodontic treatment and a mesial lateral canal, a CT scan was requested. According to the endodontist that performed the prior treatment the tooth was filled with Rickert Pulp Canal SealerTM (Sybron Endo) and there was a material extrusion through a fistula associated with the infected lateral canal at the time. Conclusion: The knowledge of exogenous pigmentations caused by dental materials is necessary to proper diagnosis.