Polyclinic of Prosthodontics and Biomaterials, Greifswald University, Greifswald, Germany.
PLoS One. 2012;7(2):e31766. doi: 10.1371/journal.pone.0031766. Epub 2012 Feb 22.
Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images.
Test samples of 44 materials (Metal and Non-Metal) commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software.
In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact.
Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images.
牙体修复物（如牙冠、牙填充物和正畸器具）引起的伪影是头颈部磁共振成像（MRI）和计算机断层扫描（CT）的常见问题。本体外研究的目的是确定和评估不同牙科修复材料在 CT 和 MRI 图像中产生的伪影。
制作了 44 种（金属和非金属）常用牙科修复材料的测试样本，并将参考样本嵌入明胶模具中。对样本进行 1.5T MRI 成像和 CT 扫描，并在二维平面上进行评估。使用数字图像分析软件测量伪影的大小和变形。
在 MRI 中，44 种材料中有 13 种产生伪影，而在 CT 中，44 种材料中有 41 种显示伪影。根据伪影的大小对 MRI 和 CT 图像中产生的伪影进行分类。
基于金属的修复材料对 CT 有强烈影响，而对 MRI 图像的伪影较少。复合材料中发现的稀土元素（如三氟化镱）会在 MRI 和 CT 中产生伪影。认识到这些发现将有助于牙科材料制造商和开发者生产出在 MRI 和 CT 图像中产生较少伪影的材料。
