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Artifacts of Magnetic Resonance Imaging Caused by Ni-Cr Alloy and Co-Cr Alloy in Prosthodontics

Author: ZhouZhi
Tutor: JinGuangSheng
School: Zhejiang University
Course: Clinical Stomatology
Keywords: Magnetic resonance imaging Artifacts Porcelain fused to metal restorations Nickel-chromium alloy Cobalt-chromium alloy
CLC: R783
Type: Master's thesis
Year: 2011
Downloads: 41
Quote: 2
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Abstract


Magnetic resonance imaging (magnetic resonance imaging, MRI) has a high resolution of soft tissue, can be a multi-angle tomography and x-ray radiation, etc., is an important means to assess lesions of the head, neck and oral and maxillofacial Oral and maxillofacial metal material is widely used, such as silver amalgam fillings, orthodontic brackets and wire, titanium and repair metal alloy materials. Into the MRI the master magnetic field in the metal can interfere with the magnetic resonance signal, generated artifacts affect normal anatomical structures and lesions of the image display, which to some extent limit the MRI in oral and maxillofacial applications. The size and the kind of the metal material of metal artifacts, size, magnetic field strength, and the scan sequence. More commonly used in the clinical 1.5T field strength 3.0T high field strength MRI. Understand commonly used metal materials in the mouth produce artifacts in MRI scans severity and scope of dental metallic materials selection application of clinical examination and MRI have important guiding significance. Objective: To observe involved in the analysis of nickel-chromium alloy and cobalt-chromium alloy porcelain crown / bridge image 1.5T and 3.0T magnetic resonance imaging artifacts, compare metallic materials caused the largest area and observation of artifacts artifacts surrounding anatomical structures. Methods: Clinical uplink 1.5T or 3.0T brain MRI fast spin echo sequence (FSE / TSE) scan and wearing a nickel-chromium alloy or Cr alloy porcelain crown / bridge 70 patients, a total of metal artifacts 89 cases front teeth, and posterior group, observe the metal artifact involved range. Posterior teeth group are grouped according to the magnetic field strength, alloy types and number of teeth, measuring the maximum area of ??the artifacts and compare results using the SPSS 17.0 statistical software t test, P lt; 0.05 difference was statistically significant. Results: In the same field strength, the cobalt-chromium alloy artifacts area larger than the nickel-chromium alloy with the same number of teeth, and the difference was statistically significant (P lt; 0.05); with a strong, with the number of teeth the increase, the the same alloy porcelain restorations maximum artifact area corresponding increase in differences between groups were statistically significant (P lt; 0.05); compared with 1.5T MRI scan 3.0T MRI scan the same teeth and artifacts formed by the restoration of the same alloy materials increases, the differences among the groups was statistically significant (P lt; 0.05). Artifacts mainly involving the upper and lower alveolar bone and the soft tissues of the lip and cheek tongue, teeth number more artifacts affect the wider the range, only the larger of the individual artifacts involving the lateral border of the palatine bone and the floor of the mouth. All artifacts were not affected nose, orbital, butterfly ethmoid sinus, brain and cervical images. Conclusions: 1) nickel-chromium alloy, cobalt-chromium alloy can be formed in MRI obvious artifacts, cobalt-chromium alloy artifacts than the nickel-chromium alloy artifacts more obvious. Take into account the impact of the nickel-chromium alloy and cobalt-chromium alloy artifacts of oral and maxillofacial MRI dentistry selection of repair materials should try to avoid the use of both alloy material. 2) PFM crown and bridge length of the longer, the greater the resulting artifacts. The clinical base metal the Longbridge repair body and oral multiple base metal fixed prosthesis should be avoided. 3) Choose low-field MRI scanner, can reduce the size of the artifacts, but there is no significant difference of the artifacts of the major anatomical structures, so choose low field MRI machines can not completely avoid metal artifacts of Oral and Maxillofacial the impact of MRI. 4) commonly used base metals such as nickel-chromium alloy and cobalt-chromium alloy porcelain repair the body caused by metal artifacts ranging than its predecessor, with a certain distance of oral and maxillofacial lesion MRI restorations, metal artifacts may not be considered impact, without removal of the prosthesis.

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