Department of Oral and Maxillofacial Radiology, Yonsei University College of Dentistry, Seoul, Korea.
Department of Advanced General Dentistry, Yonsei University College of Dentistry, Seoul, Korea.
Central Dental Laboratory, Dental Hospital of Yonsei University, Seoul, Korea.
目的本研究旨在评估由锥束计算机断层扫描（CBCT）转换数据的数字模型制成的3D打印临时牙冠的边缘和内部间隙。材料与方法从患者的单冠修复体中取出16个聚乙烯基硅氧烷印模，并使用CBCT进行扫描。使用定制开发的软件将扫描数据转换为肯定的标准三角剖分语言（STL）文件。用口内光学扫描仪（IOS）扫描人造石模型，以将表面精度与CBCT获得的STL数据进行比较。使用数字光处理3D打印机，将转换后的STL文件用于制造带有光敏聚合物的中间冠。复制方法用于分析准确性。用数字显微镜测量每个临时牙冠的复制样品的边缘和内部间隙。进行了Friedman检验和Mann-Whitney U检验（Wilcoxon符号秩检验），以95％的置信度比较边缘间隙和内部间隙的测量值。结果CBCT和IOS的均方根值在41.00至126.60μm之间，平均值为60.12μm。边际间隙，内部间隙和总间隙的平均值分别为132.96（±139.23）μm，137.86（±103.09）μm和135.68（±120.30）μm。中颌和颊舌面之间的边缘或内部间隙没有统计学上的显着差异，但是边缘区域（132.96μm）和咬合区域（255.88μm）具有显着的平均差异。结论基于CBCT STL数据制作的临时牙冠的边缘间隙在临床成功的可接受范围内。通过不断发展的高分辨率CBCT和数字模型转换技术，CBCT可能成为获取用于临时牙冠制造的数字模型的替代方法。
OBJECTIVES
This study aimed to evaluate the marginal and internal gaps in 3D-printed interim crowns made from digital models of cone-beam computed tomography (CBCT) conversion data.
MATERIALS AND METHODS
Sixteen polyvinylsiloxane impressions were taken from patients for single crown restorations and were scanned using CBCT. The scanning data were converted to positive Standard Triangulation Language (STL) files using custom-developed software. The fabricated stone models were scanned with an intraoral optical scanner (IOS) to compare the surface accuracy with the STL data obtained by CBCT. The converted STL files were utilized to fabricate interim crowns with a photopolymer using a digital light-processing 3D printer. The replica method was used to analyze the accuracy. The marginal and internal gaps in the replica specimen of each interim crown were measured with a digital microscope. The Friedman test and Mann-Whitney U test (Wilcoxon-signed rank test) were conducted to compare the measurements of the marginal and internal gaps with a 95% level of confidence.
RESULTS
The root-mean-square values of the CBCT and IOS ranged from 41.00 to 126.60 μm, and the mean was 60.12 μm. The mean values of the marginal, internal, and total gaps were 132.96 (±139.23) μm, 137.86 (±103.09) μm, and 135.68 (±120.30) μm, respectively. There were no statistically significant differences in the marginal or internal gaps between the mesiodistal and buccolingual surfaces, but the marginal area (132.96 μm) and occlusal area (255.88 μm) had significant mean differences.
CONCLUSION
The marginal gap of the fabricated interim crowns based on CBCT STL data was within the acceptable range of clinical success. Through ongoing developments of high-resolution CBCT and the digital model conversion technique, CBCT might be an alternative method to acquire digital models for interim crown fabrication.
