3-D UTE MRI of Ceramic Orthodontic Appliances on the Dentition

Introduction: Three-dimensional (3D) imaging is currently a hot topic in orthodontics and dentistry. There are many articles in the literature on the use of 3D CBCT and its applications to diagnosis, treatment planning and patient education. The use of non-ionizing magnetic resonance imaging (MRI) has not been considered as an imaging modality for routine orthodontic diagnosis due in part to its poor performance in imaging dental hard tissue. This investigation focused on the use of non-ionizing MRI and its clinical application to orthodontics. Traditional MRI is capable of imaging the soft tissue components including TMJ pathology, muscles and attachments, however, until the recent introduction of ultra-short-echo time (UTE) MRI, hard tissues with very short T2/T2* relaxation times were difficult to accurately image. Objectives: The purpose of this study was to determine if UTE MRI technology could be used to image teeth in orthodontics. The objectives of this study were to determine the accuracy and resolution of UTE MRI on dental morphology and its application to the field of orthodontics with respect to appliance affect on morphology. Methods: High resolution 3 Tesla UTE MRI was preformed on sixty extracted human premolar teeth with fixed ceramic orthodontic appliances. ‘Real' measurements of the tooth morphology and orthodontic appliance morphology were made with calipers and compared with ‘non-real' MRI images. Three ceramic bracket types including 3M Clarity, American Radiance, and Ormco Ice were studied. Results: Visual evaluation of the images revealed that enamel, dentin, pulp and ceramic orthodontic appliances could be delineated at a high level with the use of UTE MRI. Real vs. Non-real measurements show dimensional accuracy with the use of UTE MRI with a power > 0.05. Conclusions: Ceramic orthodontic appliances, without metal components, seemingly cause no dental image distortions and are readily visible on the UTE MRI scans.