[Value of magnified panorama image for diagnosis of fractures of the central mandibular segment].

Abstract

The accuracy of sonographic imaging of displaced mandibular fractures has been investigated experimentally. Mandibles taken from fresh pig cadavers have been osteotomized and fracture displacement according to the three types of dislocation has been performed. The bony fragments were connected by threads to enable reproducible ranges of displacement. The investigations were performed with 7.5, 10 and 13 MHz linear arrays. Longitudinal and lateral displacements from 1 to 10 mm and axial displacements from 1 degree to 5 degrees were investigated. We could find, that B-mode-sonography is very sensitive to detect the direction of displacement in mandibular fractures, if at least 1 mm of displacement exists. The measurements of the amount of displacement show, that the difference of the sonographic measurements and the real existing displacement depends on the direction of the displacement and the chosen frequency of examination. It is independent from the amount of displacement. The mean error of all examination is less than 0.4 mm. The greatest difference between the real displacement and the measured one is found in axial displacement from 1 degree to 3 degrees. The results show, that B-mode sonography is a reliable method detecting displaced fractures of the mandible and the clinical application of the method can be recommended. The sonographic detection of nondisplaced fractures is a problem which needs further technical development.