Department of Oral and Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Department of Oral Biomaterials Development Engineering, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
J Prosthodont Res. 2019 Apr;63(2):239-244. doi: 10.1016/j.jpor.2018.12.006. Epub 2019 Jan 15.
Computed tomography (CT) imaging for three-dimensional (3D) printed models may improve the quality of surgical preoperative plans. Although metal objects can cause artifacts in CT images, integration of CT and digital dental arch imaging may solve this problem. The present study aimed to evaluate effects of the number of metal restorations and mandibular position during CT imaging on accuracy of reproduced models.
Stereolithography datasets from three sets of dental models having different numbers of metal restorations were obtained using a laboratory digitizing device (control) and CT equipment (nonintegrated data). CT scanning was performed under two conditions: intercuspal position (closed) and separated using paraffin wax (open). Nonintegrated data after metal artifact removal were separated into maxillary and mandibular dentition groups. The occlusal part of the control dentition and nonintegrated data were superimposed and integrated (integrated data). The root mean square (RMS) between the control and stereolithography data was calculated and analyzed with three-way analysis of variance and t-test with Bonferroni correction.
Increasing numbers of metal restorations resulted in increase in metal artifacts and RMS values. Moreover, the RMS of the closed dataset was significantly greater than that of the open dataset because of the creation of artificial occlusal surfaces. The RMSs of the integrated datasets were significantly smaller than those of the nonintegrated datasets, except for the open model without metal restorations.
Accuracies of reproduced maxillary and mandibular models decreased with increasing numbers of metal restorations and in the closed mandibular position during CT scanning.
计算机断层扫描（CT）成像可提高三维（3D）打印模型的手术术前计划质量。尽管金属物体可导致 CT 图像伪影，但 CT 和数字牙弓成像的整合可能会解决此问题。本研究旨在评估 CT 成像时金属修复体数量和下颌位置对复制模型准确性的影响。
使用实验室数字化设备（对照）和 CT 设备（非整合数据）获得三组具有不同数量金属修复体的牙模的立体光刻数据集。CT 扫描在两种条件下进行：牙尖交错位（闭合）和使用石蜡分开（打开）。经金属伪影去除后的非整合数据分为上颌和下颌牙列组。对照牙列的咬合部分和非整合数据被叠加和整合（整合数据）。计算对照和立体光刻数据之间的均方根（RMS），并使用三因素方差分析和 t 检验（Bonferroni 校正）进行分析。
金属修复体数量的增加导致金属伪影和 RMS 值增加。此外，由于人为的咬合面的产生，闭合数据集的 RMS 值明显大于开放数据集的 RMS 值。除了没有金属修复体的开放模型外，整合数据集的 RMS 值明显小于非整合数据集的 RMS 值。
随着 CT 扫描时金属修复体数量的增加和下颌闭合位置的增加，复制的上颌和下颌模型的准确性降低。
