The authors evaluate the possible use of osteodistraction techniques to restore the vertical dimension of the mandibular ramus after reduction during surgical treatment of TMJ ankylosis. They report the case of a fully grown female patient with monolateral right TMJ ankylosis following previous fracture injury who was treated at the Maxillofacial Surgery Unit of George Eastman Hospital in Rome. The patient underwent removal of the ankylotic block and the concomitant restoration of the vertical dimension of the mandibular ramus achieved using subperiosteal osteodistraction. Bichat's bubble flap was used as the interarticular interposition material. The distractor was activated one week after surgery with daily increments of 1 mm for a total of 7 days. Clinical and instrumental tests performed after the removal of the distractor and after a cycle of physiotherapy confirmed the good functional recovery of the joint and the restored vertical dimension of the mandibular ramus. The authors affirm that the method used represents a valid alternative for correcting loss of height after extensive resection of ankylotic joint processes in fully-grown patients.