title: A comparative study of metal artifacts from common metal orthodontic brackets in magnetic resonance imaging.
abstract: OBJECTIVE
  This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging.
  
  
  METHODS
  A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo T1 -weighted images, fast spin-echo T2 -weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images.
  
  
  RESULTS
  Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets.
  
  
  CONCLUSIONS
  With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.
authors.affiliation: Department of Maxillofacial Radiology, Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Dalili Kajan
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Jalil
authors.initials: J
authors.lastname: Khademi
authors.affiliation: Department of Radiology, Poursina Hospital, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Alizadeh
authors.affiliation: Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Yasamin
authors.initials: Y
authors.lastname: Babaei Hemmaty
authors.affiliation: Department of Biostatistics, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Atrkar Roushan
keywords: Artifacts; Magnetic Resonance Imaging; Orthodontic Brackets; Orthodontic Wires