Ken Ueda

Stability of the mandible after sagittal ramus osteotomy for correction of prognathism

The change in the position of the mandible after sagittal ramus osteotomy was evaluated on lateral cephalograms and in dental casts in 44 patients with mandibular prognathism. The postoperative relapse of the mandible at four landmarks was less than 1 mm on cephalograms and 1.1 mm at the first molar on the side with the larger posterior movement. The tendency to relapse was greater in cases in which large posterior and/or lateral movements of the mandible occurred at surgery. The importance of proper postoperative care and avoidance of lateral shift of the mandible to minimize relapse is stressed.

Three-dimensional analysis of facial morphology before and after orthognathic surgery

A method for three-dimensional analysis of the facial hard- and soft-tissue morphologies is described. The soft-tissue analysis consisted of calculating three-dimensional values of reference points on the face by perspective transformation of their values in two pairs of photographs, taken simultaneously, from the right and left sides of the face. The shape of the mandible was analyzed three-dimensionally by the simultaneously taken frontal and lateral cephalograms. The hard- and soft-tissue changes were analyzed with the method in 28 patients in whom mandibular prognathism had been corrected by orthognathic surgery. The magnitude of the surgically-produced soft tissue volumetric changes in the anterior mandibular region was proportional to the posterior movement of the mandible. Asymmetry of the face also improved in response to correction of lateral deviation of the mandible and a close correlation between the directional indices of asymmetry of the hard and soft tissues was observed. Thus, the method was found to be quite useful for the analysis of facial morphology in jaw deformity.

Spontaneous regeneration of the condyle following hemimandibulectomy by disarticulation

Abstract A rare case of spontaneous regeneration of the mandibular condyle following hemimandibulectomy by disarticulation is described.

Recurrent melanotic neuroectodermal tumour of infancy. Case report and survey of 16 cases.

A case of melanotic neuroectodermal tumour of infancy (MNTI) with rapid recurrence is described, together with a survey of 16 reported recurrent cases. The recurrent lesion was successfully treated by wide excision of the maxilla. The recurrent tumour had two lesions of different natures, one consisting of a lobular mass indistinguishable from the primary tumour but located remote from the original site and the other showing diffuse infiltration of tumour cells deep in the medulla of the maxilla. A survey of the recurrent cases indicated that, although incomplete removal of the primary tumour, dissemination of tumour cells during surgery and a multicentric origin could be the causes of a recurrence, the presence of a silent lesion which may express an aggressive growth on stimulation may also explain the complex behaviour of the tumour.

Three-dimensional analysis for prediction and assessment of mandibular movement in orthognathic surgery in the ramus

A new method (Three-Dimensional (3-D) Analysis of Mandibular Movement) was developed to evaluate the movement of the mandible during surgery and in postoperative years, in three dimensions. The analysis was done with the aid of preoperative cephalograms and preoperative, predicted and postoperative dental models. The method consisted of measuring the amount and direction of the movements of defined points on the dental models and displaying the movement of other bony landmarks in the cephalometric tracings by coordinate transformation. All the calculations for the coordinate transformation were performed with the aid of a micro-computer. The results of an analysis with the method in two cases indicated that it is quite useful in determining the operative procedure as well as in evaluating the postoperative stability of the mandible, because in addition to the vertical and antero-posterior movement, it enables us to see the lateral movement of the mandible.

Three-dimensional prediction of mandibular movement in the treatment of prognathism

The three-dimensional movements of the mandible that might occur during surgical correction of mandibular prognathism were analyzed preoperatively in 40 patients. Direct measurements were made on the dental models used to predict postoperative occlusion, and the results were transferred to the cephalometric tracings using three-dimensional coordinate transformation. Menton, gonion, and two bony points on the posterior borders of the ascending rami were chosen on the frontal and lateral cephalograms for prediction of the antero-posterior, vertical, and lateral movements. In most cases a reasonable amount of movement without much lateral shift at the posterior border of the mandible was predicted to occur when the postoperative position of the mandible was established to provide a stable occlusion. However, there were five cases in which predicted lateral movement at one of the posterior borders exceeded 5 mm, and, in four of them, protrusion of the mandible was not accompanied by lateral deviation. It was concluded that careful preoperative planning and postoperative treatment are necessary in these cases because a large amount of lateral movement at the site of operation might lead to postoperative relapse following ramus osteotomy.

Treatment of “idiopathic midline destructive disease” by irradiation: A case report

An unusual case with an aggressive destructive granulomatous lesion of the maxilla is reported. Although the possibility of infection and neoplasm could be ruled out, a definite diagnosis could not be established even by repeated biopsies which showed the lesion to be a non-specific inflammatory process. Since Wegeners granulomatosis was most unlikely, the patient was treated by radiotherapy which caused rapid remission of the lesion with no sign of recurrence after 4 years. The clinical and histological findings as well as the responsiveness to the treatment were most indicative of idiopathic midline destructive disease. Effective management of lethal midline granuloma of unknown aetiology is discussed.

Xerox copy of the dental cast for analysis of the stability of mandibular osteotomy

Stability of the mandible was analysed with a Xerox copy of the dental cast in 35 cases of mandibular prognathism corrected by ramus osteotomies. The occlusal relationship in the Xerox copy was illustrated by superimposing two contact points on the upper and lower dental arches and the change in the position of the lower dental arch in relation to the upper dental arch was obtained by superimposing the latter on preoperative, predicted postoperative, and six months postoperative occlusions. The stability of the mandible was analysed by measuring the movement of five landmarks (two posterior, two molar and one incisor points) set around the lower dental arch to represent the movement of the mandible. The relapse was estimated by the movements of the landmarks from the predicted postoperative occlusion to the six months postoperative occlusion. The mean estimated anterior relapses at the posterior and molar points with the larger predicted movement and the incisor point were between 0.9 mm. and 2.0 mm. at six months postoperatively, whereas on the side with the smaller predicted movement, the points moved posteriorly by 0.6 mm. and 0.5 mm. Despite the fact that the amount of the predicted lateral movement was much smaller than that of the predicted posterior movement at operation, the posterior points were estimated to relapse laterally by 2.0 mm. and 1.7 mm.(ABSTRACT TRUNCATED AT 250 WORDS)