Quantitative measurements of the articular areas of mandibular condyles with temporomandibular joint disorders using magnetic resonance imaging.

OBJECTIVE: The authors sought to clarify the variation in the condylar anterior functional surface (AFS) of patients with temporomandibular joint (TMJ) disorders using quantitative measurements by magnetic resonance imaging (MRI). METHODS: MR images of 68 joints (2 males, 32 females) were used. The subjects were classified into three groups: with/without defects of cortical bone groups and a combination group without defects. The AFS was measured as the length between the protrusive point and the apex of the condyle on MRI (4-mm-thick slices), and the quad value of the length was defined as the area on the slice. The summed quad values of all slices were used as the AFS area. Differences in the areas among the three groups were compared by one-way analysis of variance (ANOVA). RESULTS: The non-defect group had significantly larger AFS areas than the defect group. CONCLUSIONS: Quantitative measurement on MR images clarified the changes in the condylar sagittal appearance.

Root canal filling materials spread pattern mimicking root fractures in dental CBCT images.

OBJECTIVE: To clarify the cause of artificial tooth-root fracture lines in cone beam computed tomography (CBCT) images caused by root canal filling materials and to enhance the diagnostic performance of CBCT. STUDY DESIGN: We analyzed the CBCT images of 18 extracted human teeth (9 upper central incisors and 9 lower premolars) that were filled with a size 50 gutta-percha cone and inserted into tooth sockets in a human skull. RESULTS: The CBCT images of the incisors displayed artificial lines in the oblique directions, notably the mesiobuccal, distolingual, distobuccal and mesiolingual directions, but only rarely in the cross-directions (buccal, lingual, mesial, and distal). In the premolars, the reverse was true, with lines mainly in the cross-directions, mesial and distal directions particularly. The lines were predominantly at the cervical slice. CONCLUSIONS: Artifacts resulting from root filling material appear along the long axis of the alveolar bones, and resemble root fractures.