Accuracy of face scan-based virtual facebow records: A comparison between two registration methods.

Abstract

Purpose: Accurate maxillary positioning is critical in digital prosthodontics, particularly when transferring the spatial relationship of the maxilla to a virtual articulator. This study aimed to compare the accuracy of the two most common registration methods, three-dimensional (3D) match and UV (landmark-based point-pair registration) match, for virtual facebow transfer and to investigate whether the type of facial scanner used influences the accuracy of these registration techniques.

Materials and methods: A cone beam computed tomography (CBCT) scan of a manikin was used as the reference. The maxillary arch was scanned with three anatomical landmarks and aligned to the CBCT. A computer-aided design and computer-aided manufacturing (CAD-CAM)-printed facebow fork was affixed to the arch, followed by facial scans using the EinScan HX and iPad (10 scans each). For each scan, two registration methods (3D match and UV match) were performed, generating 40 virtual alignments. Superimpositions were completed in Exocad, and accuracy was evaluated by comparing each registration to the CBCT reference using a Python script to measure linear and angular deviations. Trueness and precision were analyzed using a linear mixed model.

Results: 3D match generally outperformed UV in both trueness and precision. The industrial scanner combined with 3D match yielded the highest accuracy, with linear trueness of 0.98 ± 0.67 mm and precision of 1.31 ± 0.79 mm (p < 0.001). With the iPad, 3D registration demonstrated significantly superior angular accuracy (p < 0.050).

Conclusion: 3D registration provides higher accuracy than UV match, and 3D registration, in combination with an industrial-grade scanner, offers higher accuracy in virtual facebow transfer than using iPad.