C2F-3DToothSeg: Coarse-to-fine 3D tooth segmentation via intuitive single clicks

3D tooth segmentation is a challenging fundamental problem in computer-aided design (CAD) systems for orthodontic treatment planning. Existing methods of tooth segmentation cannot meet the require-ments for both efficiency and accuracy. This paper presents a coarse-to-fine 3D tooth segmentation algorithm, called C2F-3DToothSeg, to improve tooth segmentation. The algorithm consists of two steps: extraction of the coarse gum line and optimization of this line. A concavity-sensitive harmonic field is searched in a local region of entire dental meshes to produce a series of isolines. The best isoline is selected as the coarse gum line, which is then optimized by a heuristic feature line extraction scheme to yield an accurate gum line. Extensive visual and numerical experiments demonstrate that our C2F-3DToothSeg has better overall performance in accuracy and efficiency compared to other existing methods directly applicable in orthodontic CAD systems. A point on the tooth surface is loosely found to locate the center zone of each individual tooth via a simple intuitive single click of the operation. The experiments also show that our method is robust to different complex dental models; for example, it copes with bulge bubbles, decay and cavity issues, and dental accessories. (c) 2021 Elsevier Ltd. All rights reserved.