School of Dentistry, Chonnam National University, Gwangju, Korea.
Am J Orthod Dentofacial Orthop. 2011 Oct;140(4):585-91. doi: 10.1016/j.ajodo.2011.04.018.
A precision 3-dimensional (3D) head model can be fabricated by integrating a digital dental model into a maxillofacial 3D image. The integration requires accurate registration of 2 image modalities. The aims of this study were to determine the registration errors for implementation of laser-scanned dental images into cone-beam computed tomography (CBCT) scan data and to examine the influence of the registration area on the accuracy of registration.
The CBCT scans were obtained from 30 adults, and the maxillofacial 3D images were reconstructed. Maxillary and mandibular dental casts were taken from the same subjects and scanned with a 3D laser scanner. The laser-scanned maxillary and mandibular dentition images were incorporated into the CBCT images of each arch in 3 ways according to the registration area: only the buccal surfaces, only the lingual surfaces, and both the buccal and lingual surfaces. Surface-based registration was performed by using an iterative closest point algorithm, and its errors were evaluated by measuring the 3D Euclidean distances between the surface points on the 2 images.
The registration errors ranged from 0.27 to 0.33 mm. The mandibular arch did not show significant differences in registration errors according to the selected area for the registration. The maxillary arch, however, showed significant differences according to the registration area. When the lingual surfaces only were used for registration, the errors were greater than for the other 2 methods. The errors were least when both the buccal and lingual surfaces were used for registration.
The results of this study indicate that accuracy in the integration of laser-scanned dental images into the maxillofacial CBCT images increases when a broad area is used for registration.
通过将数字牙科模型整合到颌面 3D 图像中，可以制作精确的 3 维（3D）头部模型。整合需要两种图像模式的精确配准。本研究的目的是确定将激光扫描的牙科图像集成到锥形束 CT（CBCT）扫描数据中的配准误差，并研究配准区域对配准精度的影响。
从 30 名成年人中获取 CBCT 扫描，并重建颌面 3D 图像。从同一受试者中取出上颌和下颌牙列模型并使用 3D 激光扫描仪进行扫描。根据注册区域，将激光扫描的上颌和下颌牙列图像以 3 种方式合并到每个弓的 CBCT 图像中：仅颊面，仅舌面，以及颊面和舌面。通过使用迭代最近点算法进行基于曲面的配准，并通过测量 2 个图像上的曲面点之间的 3D 欧几里得距离来评估其误差。
配准误差范围为 0.27 至 0.33 毫米。下颌弓的配准误差根据所选注册区域没有显著差异。然而，上颌弓的配准误差根据注册区域而有显著差异。当仅使用舌面进行注册时，误差大于其他 2 种方法。当同时使用颊面和舌面进行注册时，误差最小。
本研究结果表明，当使用较宽的区域进行注册时，将激光扫描的牙科图像集成到颌面 CBCT 图像中的准确性会提高。
