Best-Fit Alignment in the Digital Dental Workflow

Abstract

In recent years, together with the development of specific software for inspection and analysis of 3D images, reverse engineering has been integrated in different kind of workflows. Among other applications, this kind of software is used to assess the accuracy of different scanners such as intraoral scanners. These scanners are used to obtain digital replicas of the dental arches and then diagnose, plan and design the customized treatment for each patient. In dentistry, these replicas are known as digital impressions. However, the accuracy of digital impressions is often called into question and there have been many research studies that measure precisely this accuracy. In these research works, reverse engineering has been widely used by using standard mesh aligning tools and measuring average deviations of aligned meshes. These measured deviations often have no correlation with the deviations that can influence the success or failure of a restoration in the mouth. A specific clinical case, such as the placement of a framework on multiple implants, requires an accurate digital impression in which the distances between implants and the angulation of the scanbodies do not exceed a certain error. This error cannot be inferred by measuring the deviation between two meshes that have been aligned using software automatic alignment tools. In this study, a procedure for measuring the accuracy of digital impressions acquired with intraoral scanners has been proposed.