A 12-year-old female patient presented with diffusely enlarged fibrous gingivae, enamel hypoplasia, an anterior open bite and impacted permanent maxillary canines. The patient's mother reported that the child had an unremarkable medical history and was currently not taking any medications. Radiographic examination showed features of amelogenesis imperfecta affecting all erupted teeth and the impacted permanent maxillary canines. The clinical differential diagnosis included hereditary gingival fibromatosis or diffuse peripheral odontogenic fibromas involving both the maxilla and mandible. Gin-givectomies from the anterior maxillary and mandibular regions were performed and submitted for histological assessment.