Parameters to Improve the Accuracy of Intraoral Scanners for Fabricating Tooth-Supported Restorations.

Objectives: To review the factors that impact the accuracy of intraoral scanners (IOSs) when fabricating tooth-supported restorations.

Overview: Factors can have a different impact on IOS accuracy depending on the scanning purpose. If the goal is to fabricate tooth-supported restorations, it is essential to review the following operator-related factors: IOS technology and system, scan extension and starting quadrant, scanning pattern, scanning distance, and rescanning methods. Additionally, it is critical to interpret the following patient-related factors differently: edentulous spaces, presence of existing restorations on adjacent teeth, and characteristics of the tooth preparation (build-up material, geometry, total occlusal convergence [TOC], finish line location, and surface finishing), and interdental spaces (between tooth preparations or between preparation and the adjacent tooth).

Conclusions: For crown or short-span fixed dental prostheses, a reduced scan extension is recommended. For complete-arch scans, it is advisable to start the scan in the same quadrant as the preparation. If the IOS permits locking the scan, rescanning may be indicated. Restorations on tooth preparations and adjacent teeth reduce accuracy. The simpler the geometry and the larger the TOC, the higher the IOS accuracy. Intracrevicular finish lines result in lower accuracy than equigingival or supragingival positions. Air-particle procedures showed better accuracy than coarse and fine grit and immediate dentin sealing. The greater the space between a preparation and the adjacent tooth, the better the accuracy.

Clinical implications: Dental professionals must understand and handle the factors that impact the scanning accuracy of intraoral scanners differently depending on the purpose of the scan.