Automated scanning of dental impressions

Presented in this paper is an automated scanning procedure of a dental impression that utilizes an SLS (Structured Light System). The proposed procedure identifies missing areas from the initial scanning data from default orientations and attempts to locate additional scanning orientations to fill the missing areas. The core part of the proposed procedure is an algorithm that computes additional scanning orientations using the information of the missing areas. The algorithm was designed carefully by considering three major technological requirements of the problem: dual visibility, reliability, and efficiency. To satisfy the dual visibility requirement, the proposed algorithm uses the concept of a visibility map as well as the diameter of a spherical polygon. Once dual visibility is satisfied, the proposed algorithm attempts to locate the optimal scanning orientation to maximize the reliability (accuracy) of the scanning data by finding the centroid of a convex spherical polygon. As the proposed procedure is based on well-known 2D geometric algorithms, it is very efficient. The applications of the proposed procedure include not only dental impressions but also other small objects that do not have CAD models. (C) 2009 Elsevier Ltd. All rights reserved.