Influence of patient head position and facial scanner viewing angle on the accuracy of the true horizontal plane located using an app-based facial scanner.

Authors

Marta Revilla-León, Edgar García-Zea, Juan Carlos Gallardo-Bastidas, Abdul B Barmak, John C Kois

Published in

The Journal of prosthetic dentistry. Oct 07, 2026. Epub Oct 07, 2026.

Abstract

App-based facial scanners capable of automatically generating reference planes, including the true horizontal plane (THP), have been developed to integrate virtual patient representations and transfer them to the virtual articulator. However, the influence of the patient head position and the facial scanner viewing angle on the accuracy of the THP located using an app-based facial scanner remains unknown.
The purpose of this in vivo study was to evaluate the influence of the patient's head position and facial scanner viewing angle on the accuracy of the THP located using an app-based facial scanner (FS) integrated into a smartphone.
A total of 5 landmarks were placed on the face of a volunteer. Three scans (reference scans) were acquired with an app-based FS (Qlone) integrated into a smartphone (iPhone Pro 17) and an extraoral scan body (Kois Scan Body) capable of registering the THP relative to the natural head position (NHP). Two groups were defined depending on the volunteer's head position: without (NoNHP group) and with (NHP group) the self-balance and mirror technique to obtain NHP. Two subgroups were created based on the facial scanner viewing angle: at the level (Level subgroup) of or above the interpupillary line (Above subgroup) (n=15). Each reference and experimental scan with the THP generated by the FS was exported. The reference scans were mounted into the virtual articulator (Panadent PCH) by using the THP contained in the extraoral scan body (DentalCAD). Linear measurements were obtained from the landmarks to the auxiliary plane parallel to the articulator's reference table. Each experimental scan was registered to the reference scan using the landmarks as common points without altering the orientation of the corresponding THP. The THP was then oriented parallel to the sagittal plane of the upper arm of the articulator. Lastly, the same linear measurements were calculated. The average of the linear measurements obtained from the 3 reference scans was used as the reference to calculate distortions for each experimental scan. Two-way ANOVA and Tukey tests were used to analyze trueness. The Levene test was used to analyze precision (α=.05).
Posterior right plane discrepancies were found between the groups (P<.001) and subgroups (P<.001) with a significant group×subgroup interaction (P=.008). Overall anterior plane discrepancies were revealed between the groups (P<.001) and subgroups (P<.001). Overall posterior left plane discrepancies were found between the groups (P<.001) and subgroups (P<.001), with a significant group×subgroup interaction (P<.001). The NHP group obtained significantly better overall posterior right and anterior and posterior left THP trueness than the NoNHP group. The Same subgroup demonstrated significantly better overall posterior right and anterior and posterior left THP trueness than the Above subgroup. The NoNHP group had better overall posterior right THP precision than the NHP group. The Above subgroup demonstrated better overall posterior right and left THP precision than the Level subgroup.
The patient head position and facial scanner viewing angle influenced the accuracy of the THP located using the app-based FS tested.

PMID:
42844099
Bibliographic data and abstract were imported from PubMed on 08 Oct 2026.

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