Methods: Ten subjects were each given five serial whole-head MR scans. Before each MR scan a different set of custom acrylic EssixTM retainer-type trays was inserted over the subject's upper and lower teeth. Each pair of trays (upper and lower) held a set of twenty ideally positioned orthodontic brackets made of different materials (stainless steel, titanium, ceramic, plastic). A control MR scan was made using custom EssixTM trays and no orthodontic brackets. The resultant MR images were evaluated by a panel of three board certified neuroradiologists who assessed the degree of distortion present in predetermined regions of the head.
Results: Significant intracranial MRI distortion was present in all of the scans conducted with stainless steel brackets. No intracranial MRI distortion was detected in the control scans or in scans conducted with titanium, ceramic and plastic brackets.
Conclusions: Orthodontic patients at risk for needing medically necessary MR diagnostic scans should not receive fixed orthodontic appliances made of stainless steel. In fact, since it is impossible to predetermine which patients may require future MR scans, it may be advisable to universally use titanium, ceramic or plastic orthodontic brackets instead of stainless steel.