A two-year-old, male Amur tiger (Panthera tigris tigris) presented for vital pulp therapy of a complicated crown fracture of right mandibular canine (404). On complete oral exam a right mandibular swelling was revealed in the region of PM4 (408) with multiple erupted and partially erupted deformed and discolored tooth structures. Intraoral radiographs of the area revealed multiple embedded tooth structures of various sizes with no mandibular bone lysis or soft tissue changes. If untreated, these abnormal tooth structures were at risk for developing endodontic and periodontal disease. There was also risk of dentigerous cyst formation from the remnant enamel organ from the embedded tooth structures.1 Surgical extraction of the tooth structures with synthetic bone graft and histopathologic examination was recommended and performed. Histopathologic diagnosis was dysplastic odontogenesis. Regional odontodysplasia (RO) is a rare, non-hereditary human developmental disorder of unknown etiology affecting a localized area of the dentition.2-5 Clinically, the affected teeth are localized to one arch having abnormal morphology and discoloration with eruption of affected teeth often being delayed.2-5 Other conditions such as dentinal dysplasia, dentinal amelogenesis, and dentinogenesis imperfecta are similar to RO; however, these conditions affect the entire dentition.2-5 RO may also be misdiagnosed as malformed teeth or odontoma. Cases of RO do not have the radiolucent zone of soft tissue around the abnormal tooth structures, which is pathognomonic for an odontoma.6 Initially this case was thought to be a malformed tooth but, all clinical, radiographic, and histopathologic characteristics were consistent with diagnosis of regional odontodysplasia.2-5
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