DENTAL BUR FRAGMENTS CAUSING METAL ARTIFACTS ON MR-IMAGES

PURPOSE: Our purpose was to define the role of dental bur fragments in producing metal artifacts on MR images. METHODS: Dental prosthetic re constructions were made for two dogs. The two lower second premolars w ere prepared for full-cast crowns by using a diamond bur, The crown ma rgin was placed subgingivally on the right side (1 mm below the free g ingival margin) and at the same level as the free gingival margin on t he left side. After 1 week, full-cast crowns were cemented in place, M R imaging was performed 7 days later, RESULTS: Metal artifacts appeare d in both second premolar regions of the mandible on MR images, with t he right side, in which the crown margin was positioned subgingivally, displaying a larger signal distortion than the left side. After remov al of the crown, the artifact remained on the right. On histopathologi c examination, bur fragments were detected in the gingiva, more on the right than on the left, X-ray fluorescent element analysis showed iro n in the gingival tissue containing bur fragments. CONCLUSION: Distort ion of MR images was considered to be attributable in part to the dama ge of the gingiva and in part to the presence of dental bur fragments.