Marotti Juliana, Broeckmann Judith, Chuembou Pekam Fabrice, Praça Luciano, Radermacher Klaus, Wolfart Stefan
Centre for Implantology, Department of Prosthodontics and Biomaterials, Medical School RWTH Aachen University, Aachen, Germany.
Centre for Implantology, Department of Prosthodontics and Biomaterials, Medical School RWTH Aachen University, Aachen, Germany.
Ultrasound Med Biol. 2019 Feb;45(2):558-567. doi: 10.1016/j.ultrasmedbio.2018.09.027. Epub 2018 Nov 16.
Because of its ability to capture hard structures behind soft tissue, ultrasound-based micro-scanning may be a promising alternative for taking digital impressions of teeth, especially in the case of subgingival margin preparations. The aim of this study was to assess the accuracy of ultrasound impressions taken of subgingivally prepared teeth compared with digital optical impressions. Ten extracted human teeth (7 pre-molars, 3 molars) were prepared for crowns with chamfer finish line and then digitized using two different intra-oral scanners (Cara Trios, 3 Shape, Heraeus Kulzer, Hanau, Germany; and Lava COS; 3M ESPE, Seefeld, Germany) and one extra-oral scanner (Cares CS2, Straumann, Basel, Switzerland). Afterward, the preparation margin was covered with porcine gingiva (thickness ranged between 0.3 and 0.9 mm), and every sample was scanned with a high-frequency ultrasound scanner under experimental subgingival conditions. Optical scanning processes were performed without gingiva. The data sets were superimposed on each other for pairwise comparisons, and deviations between different scans were determined using a 3-D evaluation software (CloudCompare). Kruskal-Wallis and post hoc tests (Dunn-Bonferroni) were applied to detect significant differences at p ≤ 0.05. The ultrasound scanner was able to detect subgingival preparation margins. Mean deviations for all comparisons ranged from 12.34 to 46.38 µm. There were no statistically significant differences between superimpositions of intra-oral and extra-oral scans (Trios-Lava, Lava-CS2, Trios-CS2), whereas in comparisons between intra-/extra-oral scans and ultrasound scans, mean deviations were statistically significantly higher. There were no significant differences with respect to type of tooth (pre-molar and molar). However, gingiva thickness was significantly correlated with the quality of the ultrasound scan; thin layers had better image quality than thicker layers. Ultrasound was able to scan tooth preparation margins covered with gingiva, although with less accuracy than achieved by conventional optical scanners (non-covered margins). Gingiva thickness may play an important role in ultrasound scan accuracy.
由于基于超声的微扫描能够捕捉软组织后方的硬组织结构，它可能是获取牙齿数字印模的一种有前景的替代方法，特别是在龈下边缘制备的情况下。本研究的目的是评估龈下制备牙齿的超声印模与数字光学印模相比的准确性。选取10颗拔除的人类牙齿（7颗前磨牙，3颗磨牙），制备带有倒角终线的牙冠，然后使用两种不同的口内扫描仪（Cara Trios，3Shape，贺利氏古莎，德国哈瑙；以及Lava COS；3M ESPE，德国塞费尔德）和一种口外扫描仪（Cares CS2，士卓曼，瑞士巴塞尔）进行数字化处理。之后，用猪牙龈覆盖制备边缘（厚度在0.3至0.9毫米之间），并在实验性龈下条件下用高频超声扫描仪对每个样本进行扫描。光学扫描过程在没有牙龈的情况下进行。将数据集相互叠加进行成对比较，并使用三维评估软件（CloudCompare）确定不同扫描之间的偏差。应用Kruskal-Wallis检验和事后检验（Dunn-Bonferroni）来检测p≤0.05时的显著差异。超声扫描仪能够检测到龈下制备边缘。所有比较的平均偏差范围为12.34至46.38微米。口内和口外扫描的叠加之间（Trios-Lava、Lava-CS2、Trios-CS2）没有统计学上的显著差异，而在口内/口外扫描与超声扫描的比较中，平均偏差在统计学上显著更高。在牙齿类型（前磨牙和磨牙）方面没有显著差异。然而，牙龈厚度与超声扫描质量显著相关；较薄的层比较厚的层具有更好的图像质量。超声能够扫描覆盖有牙龈的牙齿制备边缘，尽管准确性不如传统光学扫描仪（未覆盖边缘）。牙龈厚度可能在超声扫描准确性中起重要作用。
