A variety of materials are commonly used in oral treatment. These materials have promoted the development of dentistry. At the same time, the materials in the patient’s mouth have also become an important factor in the head imaging examination. This problem has long caused domestic and foreign experts, scholars and The attention of the majority of patients. Two recent studies on the impact of oral materials on magnetic resonance imaging (MRI) published in the journal Dentomaxillofac Radiol, the journal of the International Society of Oral and Maxillofacial Radiology, can help dentists better understand the effects of oral materials The impact of MRI examination.

Different dental materials have different effects on MRI

A US-Germany joint study shows that the resin sealant AHPlus, glass ionomer cement, gutta-percha, zirconium dioxide, and certain composite materials cause low image distortion during MRI examination, and can even remain on the target tooth during MRI examination. . The paper was published in the journal "Oral and Maxillofacial Radiology" [Dentomaxil lofac Radiol, 2013, 42(6): 20120271].

The researchers studied a series of standard dental materials under the 1.5 T intensity MRI system. The geometric distortion method is used to evaluate the magnetic susceptibility of these dental materials under the spin echo sequence and gradient echo sequence, respectively. Through retrospective analysis of images of patients with different dental materials in the mouth, the measurement results of this in vitro test were calibrated.

As a result, the test material showed a certain degree of distortion. Resin sealant, glass ionomer cement, gutta-percha, zirconium dioxide, and composite materials provided by a test manufacturer are classified as fully compatible materials, which cause less distortion. Such materials can even be used for MRI inspections. Keep on the target tooth. The composite material provided by another manufacturer under test caused relatively strong geometric distortion and was therefore classified as compatibility degree I. Materials that are also classified in this category include amalgam, gold alloy, gold-ceramic crown, titanium alloy, and nickel-titanium orthodontic wire. Materials with a magnetic susceptibility greater than 200ppm (the magnetic susceptibility of water) are classified as incompatible materials, including stainless steel orthodontic devices and cobalt-chromium alloys. The researchers suggest that such materials should not be present in the patient's oral cavity during any MRI examination. Inside.