A thirty-five-year-old woman was referred to an endodontic specialist for retreatment of tooth 12. The tooth was symptomfree, but a radiograph revealed apical periodontitis and lateral periodontitis. The old root filling was of poor technical quality. Clinical and radiographic examination also revealed a type IV invagination in the tooth. A decision was made for endodontic retreatment and treatment of the invagination canal. Notice the enamel structures in invagination.