Akitoshi Kawamata

Three-dimensional computed tomographic evaluation of morphologic airway changes after mandibular setback osteotomy for prognathism.

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.

Three-dimensional computed tomography evaluation of postsurgical condylar displacement after mandibular osteotomy

OBJECTIVE The purpose of this study was to examine both condylar displacement of the temporomandibular joint after sagittal split ramus osteotomy with rigid osteosynthesis and intraoral vertical ramus osteotomy without osteosynthesis in patients with mandibular prognathism by means of three-dimensional computed tomography. STUDY DESIGN In this pilot study, five patients treated with sagittal split ramus osteotomy and 5 patients treated with intraoral vertical ramus osteotomy were evaluated. A technique to superimpose a postoperative three-dimensional computed tomography image on its corresponding preoperative image was designed. Postoperative condylar displacement, rotation, and tilting were measured in three-dimensional computed tomography images. RESULTS Within 3 to 6 months after surgery, changes in the inclination of the condylar axes were distinctly seen, although changes in the position of the condyles within the joints were minimal. In particular, outward rotation of the condylar long axes after intraoral vertical ramus osteotomy was a frequent finding. CONCLUSIONS The three-dimensional computed tomography superimposition technique was a practical method of evaluating postsurgical condylar displacement after mandibular osteotomy.

Colour Doppler sonographic analysis of blood-flow velocity in the human facial artery and changes in masseter muscle thickness during low-level static contraction

Muscle oedema, which can be seen as a thickness increment by ultrasonography, is important in provoking pain and fatigue during low-level contraction. Although oedema is related to the balance of inflow and outflow of blood, there are no data on the correlation between muscle thickness change and blood-flow. Blood-flow velocities in the facial artery and the muscle thickness changes were measured by colour Doppler ultrasonography in 30 healthy volunteers during 20 min contraction with 10% of maximum force. Thickness and velocity changes both reached a peak in the initial phase of contraction. The initial change of thickness did not correlate with the velocity in the facial artery, while those immediately after exercise showed a high correlation. The velocity changes in the facial artery might depend on both the general response to contraction and local metabolic or mechanical factors in the contracted masseters.

Gd-DTPA enhanced MRI for the oral and maxillofacial cystic lesion

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.

Bone scintigraphy in solitary (Simple) bone cyst of jaw

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. On the other hand, 2 cases of florid osseous dysplasia (Melrose et al. 1976) associated with bone cavities resembling solitary bone cyst showed remarkable uptake of99mTc-HMDP.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.On the other hand, 2 cases of florid osseous dysplasia (Melrose et al. 1976) associated with bone cavities resembling solitary bone cyst showed remarkable uptake of99mTc-HMDP.

Diagnosis of mucosal cyst in the maxillary sinus using advanced MR imaging techniques: Report of a case

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.

Effects of the combined treatment of cadmium chloride and X-rays on 8-day mouse embryos in vitro

SummaryThe combined action of cadmium and X-rays was examined on 8-day mouse embryos using a whole embryo culture system. B6C3F1 mouse embryos were explanted onto the headfold stage and cultured for 40 hrs. To examine the dose-effect relationships of the single treatments, the embryos were exposed to 1.2−2.2 μM cadmium or to 0.82−2.64 Gy of X-rays at 1 hr. after the explantation. In combined treatments, 1.58 μM of cadmium was applied at 1 hr. and X-rays of 0.82 or 1.24 Gy was applied at 1.5 hr. The end-points measured were the yolk sac diameter, crown-rump and head lengths, somite number, protein contents of yolk sac and embryo, and formation of the neural tube defect.Cadmium-induced neural tube defect increased as a function of dose in a highly curvilinear manner. The remaining end-points affected by the single treatments were also indicative to be curvilinear. The combined action of cadmium and X-rays was found to exert an additive effect on the inhibition of embryonic growth and a synergistic effect on the teratogenicity. The form of the dose-effect curves of the single agents was suggested to be responsible for teratogenic synergism. Other possibilities of interaction remain to be resolved.