Lingual mandibular osteonecrosis after dental impressions for orthodontic study models.

A 43-year-old man sought orthodontic treatment to close anterior diastemas. During the impression procedure for routine documentation, the orthodontic assistant exerted excessive pressure on the metallic tray; 2 days later, the patient reported the detachment of a small piece of mucosa overlying the mylohyoid crest and was referred to a maxillofacial surgeon with a diagnosis of lingual mandibular osteonecrosis. The etiology of bony osteonecrosis is discussed, together with the anatomic variations that can be present in the basal bone and that must be carefully checked before an impression is taken.