Virtual Intraoral Scanner for Error Analysis and Dynamically Weighted One-Point Bidirectional Path Search Based on Feature Extraction for Margin Lines

Abstract

Dental restorations are prostheses attached to prepared teeth to treat tooth damage and replace the function of tooth occlusion, thus their design accuracy and quality are crucial. However, some techniques in the digital workflow of dental restoration fabrication, such as scan data acquisition, mesh model generation, and margin line extraction, pose several challenges. This study is divided into three parts that present methods for overcoming these challenges in order to improve the digital workflow. First, a virtual intraoral scanner was developed to overcome the shortcomings of the conventional testing process for measuring scanner accuracy. This module provides functionality for the digital testing process that enables measurement of scanner accuracy in a virtual environment based on parameter values. Second, scan data is converted into a mesh model with topology information suitable for the CAD environment. Third, to address the issues with previous papers on margin line extraction, a bidirectional path search algorithm that requires only a single input point is proposed. In order to assess the proposed algorithm, margin lines taken from various types of prepared teeth are demonstrated and compared with those made using relevant previous methods and a commercial dental computer-aided design system. The comparison showed that the proposed algorithm can calculate accurate margin lines from a single input point. Moreover, under the same conditions, the proposed algorithm outperformed a commercial dental system for experimental crown and inlay/only models.