Leprogenic odontodysplasia: new evidence from the St. Jørgen’s medieval leprosarium cemetery (Odense, Denmark)

Leprogenic odontodysplasia (LO), also known as dens leprosus, consists of anomalous root development of the permanent upper incisors. This dental anomaly was first reported by Danielsen in 1968 among Danish juvenile skeletons from medieval leprosaria cemeteries. As yet, no clinical cases have been documented and the etiological and epidemiological significance of the condition are poorly understood. The aim of this study is to discuss a case of LO found amongst the skeletons from the St. Jørgen’s leprosarium cemetery (13th–16th/17th centuries), housed in the ADBOU (Anthropological Database of Odense University), Southern Denmark University. A juvenile individual presents a disarticulated maxillary right central incisor possessing a short root that shows a groove caused by marked constriction beginning approximately 1.5 mm above the neck. From this groove, the diameter decreases considerably until the apex. Atrophy of the anterior alveolar maxillary process, extending laterally from the central incisors to the canines, is also apparent. This individual exhibits additional rhinomaxillary lesions (e.g. absorption of the piriform margin including the anterior nasal spine) and foot changes (including phalangeal acro-osteolysis) compatible with a diagnosis of lepromatous leprosy. This case contributes to the debate about the significance of this rare condition, particularly in terms of its presence in Scandinavian skeletons from medieval leprosaria cemeteries. Possible interpretations are discussed, including the pathognomonic value of the specific lesion and whether it indicates early childhood onset of leprosy during the Middle Ages. The understanding of LO epidemiology and its relationship with leprosy will benefit from future clinical and skeletal studies.