Comparison Of 5 Common Dental Materials MRI Artifacts And The Research Method To Reduce The Artifacts

Objective:Compare dentistry commonly used three kinds of metal and two kinds of ceramic materials’differences in different sequences and the methods to reduce the artifact research.Methods:Observe the five kinds of materials whether there will be a shift or a mass ejection in the MR machine. three kinds of metal and two kinds of ceramic material made into the same shape and size of the incisor crowns, put it into a plastic tank filled with saline and scan through 3.0T,1.5T and0.35T MR machine, then get T1WI, T2WI images. Compare the differences of various materials in different artifacts field magnetic resonance scans. Put the artifact’s heaviest cobalt-chromium alloy into the 1.5t MR machine. We scan it with varieties of parameters and sequences and then contrast the images。Result:1. Zirconia crown has no significant artifacts crown when it was scanning in three kinds of field strength MR machine. Casting ceramics, precious metal alloys, nickel-chromium alloys, cobalt-chromium porcelain alloy in various field strength MR machines were found artifacts caused by them were 0.12 (cm2)±0.02,0.47 (cm2) ±0.15,4.50 (cm2) ±0.72,5.22 (cm2)±0.72, artifacts area in ascending order were cast ceramic<precious metal alloys<nickel-chromium alloys<cobalt-chromium porcelain alloy, this 4 kinds of materials in the T2W1 average area in artifacts is greater than the T1WI average area in artifacts, the difference has no statistical significance (P> 0.05). The average area of casting ceramic artifacts produced in different field strength MR machine, with increasing field strength increases, the difference artifacts area has no statistical significance (P> 0.05), precious metal alloys, nickel-chromium porcelain alloys, cobalt-chromium porcelain alloy artifacts produced in different field strength MR machine, with the field strength increases, in T1WI and T2WI artifacts area have increased, artifacts area was statistically significant difference (P<0.05). In a different field strength MR machine, the above four kinds of materials produced in the area T2WI artifacts were less than or equal to produce artifacts area in T1WI, artifacts area was no significant difference (P> 0.05).2. The Cobalt chromium alloy in different sequences’ artifact size is as followin: DWI>SWI>PROPELLER>FS-FSE-T2WI>FLAIR-FSE-T2WI>STIR-FSE-T2WI> FSE-T2WI>The shorter TE FSE-T2WI series>short chain of echo FSE-T2WI series >Larger bandwidth FSE-T2WI series>Small voxel FSE-T2WI series. Contrast to FSE T2WI sequences, DWI, SWI, PROPELLER-FSE-T2WI, FS-FSE-T2WI, artifact areas are greater than the FSE-T2WI sequences’ artifacts area, artifacts area difference was statistically significant (P< 0.05). FLAIR-FSE-T2WI, STIR-FSE-T2WI artifact areas are greater than the FSE-T2WI sequences’ artifacts area, artifacts area difference hasno statistically significant (P>0.05).The Artifacts area of short TE FSE T2WI sequence and short chain of echo FSE-T2WI sequence are smaller than that of FSE T2WI sequence, difference artifacts area has no statistical significance (P>0.05). The Artifacts area of large bandwidth FSE T2WI sequence and small voxel FSE-T2WI is less than that of FSE T2WI sequence, artifacts area difference was statistically significant (P<0.05). Short TE, short chain of echo, large bandwidth and small voxel can reduce artifacts. Large bandwidth and small voxel are more effective.Conclusion:zirconia ceramic and casting ceramics these two common oral ceramic material almost no artifacts or artifacts not obvious. Three common dental metallic materials: Alldental Alfa Ceramic90 precious metal alloys, CW-PA-type nickel-chromium alloy dental porcelain and new formulations Wirobond C cobalt-chromium ceramic alloy tends to cause MRI artifacts, and with the high increase of the main magnet field, artifacts area increases. precious metal alloys, nickel-chromium alloys, cobalt-chromium porcelain alloy will produce different degree of artifacts in MRI scans, obvious impact on the surrounding tissue, to reduce the artifacts can be considered:(1) In the low field MRI examination. (2) Selecting the appropriate parameters and sequence. (3) Using special scan series.