Size of Tooth Crowns and Position of Teeth Concerning the Extension of Facial Plexiform Neurofibroma in Patients with Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant inherited tumour syndrome. NF1 is also a disorder of bone in terms of altered bone metabolism and bone dysplasia. Facial plexiform neurofibroma (PNF) is frequently associated with osseous alterations and may cause severe disfigurement. These PNFs regularly affect the oral cavity and teeth. PNF pose many problems in reconstructive and oral surgery. This study was undertaken to describe oral findings related to PNFs and to investigate the size and position of teeth in these tumours. Forty-eight patients with NF1 were investigated. Tumour type was histologically proven in all patients with PNF following aesthetic/functional orofacial surgery. Twenty-four patients were affected with a PNF and 24 had disseminated cutaneous neurofibroma (DCNF). In the PNF group, the side of the PNF was registered; PNF was unilateral in all cases. DCNF patients were 15 females and 9 males (mean age: 23.92±10.48 years, minimum: 6, maximum 45 years). Patients with PNF were 17 males and 7 females (mean age: 23.92±13.76 years, minimum 6, maximum 61 years). The right side was affected in 16 and the left in 8 PNF patients. All patients were orally investigated and dental casts were obtained. Distances of the alveolar processes and of the teeth were measured in transverse and sagittal planes. In order to evaluate the possible impact of the tumour localisation inside the trigeminal nerve, the topography of the affected facial areas was assigned to the trigeminal nerve branches. Radiographs were taken to asses the formation of dental roots, to reveal retained teeth and to estimate dysplastic areas of the jaws. The size of tooth crowns did not differ from published standards on tooth parameters of Caucasian individuals. The dental arches were symmetrically arranged in all patients of the DCNF group. However, the position of teeth showed some relevant differences in the PNF group. We observed spacing between teeth, probably due to interdental invasion of plexiform neurofibroma or interference of tumour tissue with the mesial drift of teeth. Maxilla and mandible showed characteristic alterations in the PNF group that were confined to the side and extension of a PNF. Oral inspection should be carried out in all patients with NF1. Unilateral alterations of the position of teeth and asymmetries of the jaws should alert the investigator to search for an ipsilateral PNF of the second or third trigeminal branch. The size and dimensions of too