Many of the dental implants, devices, materials, and objects evaluated for ferromagnetic qualities exhibited measurable deflection forces (e.g., brace bands, brace wires, etc.) but only the ones with magnetically-activated components appear to present potential problems for patients during MR procedures (also, see Magnetically-Activated Implants and Devices). The issues that exist for magnetically-activated dental implants include possible demagnetization of the magnetic components and the substantial artifacts that the magnetic parts produce on MR imaging.
In general, most dental implants, devices, and materials made from ferromagnetic materials (with the exception of dental implants that incorporate magnetically-activated components) tend to be held in place with sufficient counter-forces to prevent them from causing problems related to movement or dislodgment in association with MR systems operating 3-Tesla or less. In addition, for the dental devices that have undergone evaluation, MRI-related heating does not appear to pose problems.
Wezel, et al. (2014) conducted an investigation to determine MRI issues for common dental retainer wires at 7-Tesla in terms of potential RF heating and magnetic susceptibility effects (i.e. artifacts). Electromagnetic simulations and experimental results were compared for dental retainer wires placed in tissue-mimicking phantoms. Simulations were then performed for a human model with dental wire in place. Additionally, image quality was evaluated for different scanning protocols and wires. The findings indicated that the simulations and experimental data in phantoms agreed well, with the length of the wire correlating to maximum heating in phantoms being approximately 47-mm. Even in that case, no substantial heating occurred when scanning within the specific absorption rate (SAR) guidelines for the head at 7-Tesla. Artifacts from the most ferromagnetic dental wire were not significant for any brain region. Wezel, et al. (2014) concluded that dental retainer wires appeared to be acceptable for patients undergoing MRI at 7-Tesla. Notably, these findings are specific to the wire types, configurations, and the particular MRI conditions that were used in this study.
Ayyildiz S, et al. Radiofrequency heating and magnetic field interactions of fixed partial dentures during 3-Tesla magnetic resonance imaging. Oral Surg Oral Med Oral Pathol Oral Radiol 2013;116:640-7.
Blankenstein FH, et al. Signal loss in magnetic resonance imaging caused by intraoral anchored dental magnetic materials. Rofo 2006;178:787-93.
Gegauff A, Laurell KA, Thavendrarajah A, et al. A potential MRI hazard: Forces on dental magnet keepers. J Oral Rehabil 1990;17:403-410.
Gorgulu S, et al. Effect of orthodontic brackets and different wires on radiofrequency heating and magnetic field interactions during 3-T MRI. Dentomaxillofac Radiol 2014;43:20130356.
Hasegawa M, et al. Radiofrequency heating of metallic dental devices during 3.0 T MRI. Dentomaxillofac Radiol 2013;42:20120234.
Hasegawa M, et al. 3-T MRI safety assessments of magnetic dental attachments and castable magnetic alloys. Dentomaxillofac Radiol 2015;44:20150011.
Hubalkova H, et al. Dental alloys and magnetic resonance imaging. Int Dent J 2006;56:135-41.
Ideta T, et al. Investigation of radio frequency heating of dental implants made of titanium in 1.5 Tesla and 3.0 Tesla magnetic resonance procedure: Measurement of the temperature by using tissue-equivalent phantom. Nihon Hoshasen Gijutsu Gakkai Zasshi 2013;69:521-8.
Klinke T, et al. Artifacts in magnetic resonance imaging and computed tomography caused by dental materials. PLoS One 2012;7:e31766.
Lissac MI, Metrop D, Brugigrad, et al. Dental materials and magnetic resonance imaging. Invest Radiol 1991;26:40-45.
Miyata K, et al. Radiofrequency heating and magnetically induced displacement of dental magnetic attachments during 3.0 T MRI. Dentomaxillofac Radiol 2012;41:668-74.
New PFJ, et al. Potential hazards and artifacts of ferromagnetic and nonferromagnetic surgical and dental materials and devices in nuclear magnetic resonance imaging. Radiology 1983;147:139-148.
Omatsu M, et al. Magnetic displacement force and torque on dental keepers in the static magnetic field of an MR scanner. J Magn Reson Imaging 2014;40:1481-6.
Oriso K, et al. Impact of the static and radiofrequency magnetic fields produced by a 7T MR imager on metallic dental materials. Magn Reson Med Sci 2015 Epub ahead of print.
Shellock FG. Ex vivo assessment of deflection forces and artifacts associated with high-field strength MRI of “mini-magnet” dental prostheses. Magnetic Resonance Imaging 1989;7 (Suppl 1):38.
Shellock FG, Crues JV, Editors. MRI Bioeffects, Safety, and Patient Management. Biomedical Research Publishing Group, Los Angeles, CA, 2014.
Shellock FG, Crues JV. High-field strength MR imaging and metallic biomedical implants: An ex vivo evaluation of deflection forces. Am J Roentgenol 1988;151:389-392.
Tymofiyeva O, et al. Influence of dental materials on dental MRI. Dentomaxillofac Radiol 2013;42:2012.
Wezel J, et al. Assessing the MR compatibility of dental retainer wires at 7 Tesla. Magn Reson Med 2014;72:1191-8.
Zho SY, et al. Artifact reduction from metallic dental materials in T1-weighted spin-echo imaging at 3.0 tesla. J Magn Reson Imaging 2013;37:471-8.