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.
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