1 Graduate School of Engineering, Tohoku University, Sendai, Japan;
Dentomaxillofac Radiol. 2014;43(6):20140080. doi: 10.1259/dmfr.20140080. Epub 2014 May 2.
The three-dimensional shape information of teeth provides useful information. However, obtaining accurate three-dimensional shapes of teeth is difficult without extracting them physically. In this study, we aimed to develop a method for automatically extracting accurate three-dimensional shapes of teeth from dental CT images.
The proposed method includes pre-processing and region extraction. Pre-processing is a combination of image-processing techniques that enhances tooth regions. In the region-extraction process, the region-growing method is introduced for extracting a region of each tooth. Constraint conditions determined by considering the characteristics of the structure of teeth are introduced for accurate extraction. Finally, morphological image processing is applied for eliminating discontinuous points.
We carried out an experiment in which the three-dimensional shapes of teeth were reconstructed from dental CT images. Quantitative evaluation was performed by measuring the three-dimensional spatial accordance rates between the region obtained by the proposed method and the manually extracted region. The proposed method was significantly more accurate than an existing method at the 5% level.
The experimental results showed that the proposed method reconstructs the shapes of teeth with high precision. However, an unextracted region remained at the surface of the enamel. Solving this problem and improving the extraction accuracy are important topics for future work.
牙齿的三维形状信息提供了有用的信息。然而，如果不将其物理提取，就很难获得牙齿的准确三维形状。本研究旨在开发一种从牙科 CT 图像中自动提取牙齿准确三维形状的方法。
所提出的方法包括预处理和区域提取。预处理是图像处理技术的组合，可增强牙齿区域。在区域提取过程中，引入了用于提取每个牙齿区域的区域生长方法。为了实现准确提取，引入了考虑牙齿结构特征的约束条件。最后，应用形态图像处理消除不连续点。
我们从牙科 CT 图像中重建了牙齿的三维形状。通过测量所提出的方法获得的区域与手动提取的区域之间的三维空间符合率，进行了定量评估。在所提出的方法在 5%的水平上显著比现有方法更准确。
实验结果表明，所提出的方法可以高精度地重建牙齿的形状。然而，在牙釉质表面仍存在未提取的区域。解决这个问题并提高提取精度是未来工作的重要课题。
