CORRELATION BETWEEN MAGNETIC-RESONANCE-IMAGING DISTURBANCES AND THE MAGNETIC-SUSCEPTIBILITY OF DENTAL MATERIALS

Objectives. The purpose of this study was to correlate the size and th e orientation of image disturbances observed on specific samples of de ntal materials with their magnetic susceptibility. The measurement of the magnetic susceptibility was performed in the 10(-5) or 10(-6) rang e using MRI to establish a classification of dental materials. Methods . Cylindrical dental alloy samples incorporating gold, silver, and pal ladium were placed in a Pyrex beaker filled with distilled water. Imag es were performed at 0.13 Tesla using two-dimensional Fourier transfor mation and projection reconstruction at 360 degrees imaging methods. T he magnetic susceptibilities were obtained by measuring distances betw een spots having the highest intensity on the image. Results. Avery di scriminating classification may be established on MRI criteria. This m ethod permits one to determine the dia- or para-magnetic character of the dental materials tested. Only palladium-based alloys have been det ected to be paramagnetic with kappa > 0. One of the silver-based alloy s did not induce detectable distortion because its susceptibility was very close to that of distilled water. Based on this MRI data, the use of this material may be recommended for applications that may be subj ected to MRI evaluation. Significance. With the increasing use of MRI as a diagnostic tool, it is useful to establish a classification of pr osthetic biomaterials compatible with MRI.