Search

Objective. To observe changes in the pharyngeal airway and the hyoid bone position after mandibular setback osteotomy in 30 patients with mandibular prognathism by means of 3-dimensional computed tomography (3DCT). Study design. Preoperative and postoperative computed tomography (CT) examinations were performed on 17 patients treated by sagittal split ramus osteotomy with rigid osteosynthesis and on 13 patients treated by intraoral vertical ramus osteotomy without osteosynthesis. The amount of mandibular setback was measured by the preoperative to postoperative difference of the mandibular position in axial CT images. The sizes of the preoperative and postoperative pharyngeal airway were evaluated from semitransparent and crosscut 3DCT images. Postoperative displacement of the hyoid bone was evaluated by a technique to superimpose a postoperative hard tissue 3DCT image on the preoperative image. The helical scan technique was used in the CT examination. The volume rendering technique was used to create 3DCT images. Results. The mean mandibular setback was 7.8 ± 2.1 mm with a range of 5 to 11 mm. Three months after surgery, the lateral and frontal widths of the pharyngeal airway had decreased significantly in comparison with the preoperative width. The mean reduction rates of the lateral and frontal width were 23.6% and 11.4%, respectively. The diminished airway did not recover by either 6 months or 1 year after surgery in most cases. Downward and posterior displacement of the hyoid bone was seen postoperatively. There were positive correlations between the amount of mandibular setback and reduction of the lateral width of the pharyngeal airway (r = 0.54) and the amount of hyoid bone displacement (r = 0.42). There were no significant differences between the two surgical techniques. Conclusion. Three-dimensional computed tomography was a practical imaging technique to evaluate the morphologic airway changes. The pharyngeal airway may have irreversible narrowing after mandibular setback surgery. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:278-87)

Solitary bone cyst is a radiolucent lesion classified as a pseudocyst with a variety of reported shapes including round, oval, and irregular. In the long bones, a truncated cone shape has been described, and the fallen trabecula sign is seen in association with pathologic fracture. The purpose of this study was to classify and document the various shapes, to describe the width versus height dimensions of jaw SBCs, to determine the identifying signs of trauma, and to evaluate other reported radiographic features. Radiographs of 44 SBCs in 43 patients were studied. Sixty-four percent demonstrated the cone shape, and four subtypes of this shape were identified. Other shapes included oval (16%), irregular (16%), and round (4%). Radiographic signs of trauma were observed in 28% of the cases. No evidence of the "fallen trabecula sign" was found in this series.

In the present study, new MRI techniques were used to evaluated the pathologic condition of a mucosal cyst in the maxillary sinus. The contrast enhancement technique using Gd-DTPA clearly revealed the cystic nature of the lesion. The diagnostic information about the relationship between the mucosal cyst and periodontal disease, and the precise location of the cyst in relation to the walls of the maxillary sinus were obtained by panoramic MR image and alternate positioning of the patient.

Six cases of solitary (simple) bone cyst with typical clinical, radiographical, and histological findings were examined by bone scintigraphy. Bone scintigraphy using99mTc-HMDP was performed prior to operation. No uptake of99mTc-HMDP in these solitary bone cysts was demonstrated.

The authors present examples of the significantly improved diagnostic imaging for cystic lesions in the jaw bone, floor of the mouth and maxillary sinus with Gadolinium-DTPA (Gd-DTPA) enhanced MRI. Twelve cases of cystic lesions, which were 6 cases of intra-osseous odontogenic cysts and cystic tumors, 2 cases of epidermoid cysts in the floor of the mouth and 4 cases of cystic polyp of the maxillary sinus. Improved MR images provided useful information delineating the thickness of circumscribed soft tissue wall (cystic wall), the location of the intra-cystic substance and the configuration of the tumor masses.

The effects of 1) X-irradiation and 2) hyperthermia at a temperature of 43 degrees C individually and in combination have been investigated using cultured 8-day mouse embryos. B6C3F1 embryos were exposed to 0.3-2.0 Gy of X-rays, 5-20 min of heating, or 5 min of heating and irradiation at 0.3, 0.6, and 0.9 Gy. Irradiation alone at 0.3 Gy showed no apparent effect on embryonic development, but irradiation at 0.6-2.0 Gy caused a dose-dependent increase in malformed embryos. Heating alone for 5 min produced no malformed embryos, while heating for 10-20 min caused malformations as a function of heating time. Combined treatments produced higher frequencies (22.2-100%) of malformations than those of the sum of the separate treatments (0-41.7%). Malformations observed were primarily microphthalmia, microcephaly, and open neural tubes. The results indicate that in cultured mouse embryos irradiation combined with a "nonteratogenic dose" of hyperthermia directly exerts an additive effect on formation of the malformed embryos. In addition, a single occurrence of left-sided tail was produced by hyperthermia alone, while four occurrences were produced in combination with radiation.