Best of Both Modalities: Fusing CBCT and Intraoral Scan Data Into a Single Tooth Image

Cone-Beam CT (CBCT) and Intraoral Scan (IOS) are dental imaging techniques widely used for surgical planning and simulation. However, the spatial resolution of crowns is low in CBCT, and roots are not visible in IOS. We propose to take the best of both modalities: a seamless fusion of the crown from IOS and the root from CBCT into a single image in a watertight mesh, unlike prior works that compromise the resolution or simply overlay two images. The main challenges are aligning two images (registration) and fusing them (stitching) despite a large gap in the spatial resolution between two modalities. For effective registration, we propose centroid matching followed by coarse- and fine-registration based on the point-to-plane ICP method. Next, stitching of registered images is done to create a watertight mesh, for which we recursively interpolate the boundary points to seamlessly fill the gap between the registered images. Experiments show that the proposed method incurs low registration error, and the fused images are of high quality and accuracy according to the evaluation by experts.