[A comparative study of two imaging techniques for the diagnosis of sagittal fracture of mandible condyle].

OBJECTIVE: To investigate the relationship between fractured fragment and joint disc displacement after sagittal fracture of mandibular condyle (SFMC). METHODS: based on CT examination, SFMC were classified into fissue, displacement and dislocation type. Based on oblique sagittal MRI examination, the displacement of joint disc was grouped into type A and type B. Abnormal superiorposterior attachment was classified into elongation and avulsion type. RESULTS: CT exmination were taken in 26 patients with 41 SFMC. There were 5 SFMC (12%) with fissue type, 18 SFMC (44%) with displacement type and 18 SFMC (44%) with dislocation type. Both CT and MRI examination were taken in 19 patients with 32 SFMC. There were 27 (84%) SFMC with disc displacement. Five SFMC with type fissue showed no signs of disc displacement. Among 15 SFMC with type displacement, there were 3 cases with type A disc displacement and 12 cases with type B disc displacement. All the dislocated SFMC (12 cases) were type B disc displacement. In term of superiorposterior attachment figures, 4 cases (4/5) of type fissue SFMC showed normal. 14 cases (14/15) of the displacement SFMC showed elongated and all cases with dislocated SFMC showed sign of avulsion. There were 20 cases (63%) showing superior joint effusion. There were 13 cases (13/15) with displaced SFMC and 6 cases with dislocated SFMC showing joint effusion. One case with fissue SFMC showed no sign of joint effusion. CONCLUSIONS: Joint effusion, disc displacement and abnormal superiorposterior attachment were related to the displacement of condyle which was involved with SFMC.