Clinical accuracy and responsiveness of 3D software for measuring facial dimensions at altered vertical dimensions

To evaluate the accuracy of two 3D measurement software programs in measuring facial dimensions obtained from a stationary facial scanner, using clinical measurements as a reference, and assess the responsiveness to incremental vertical dimension (VD) alterations.

Soft tissue landmarks were marked on the faces of 20 healthy participants for both clinical and digital measurements. Vertical distances were measured starting at a baseline VD of 0 mm (maximum intercuspation), increasing in 2-mm increments up to 6 mm using resin blocks placed between the central incisors. Horizontal distances were measured only at baseline (0 mm). Clinical measurements were performed by two examiners using a digital vernier caliper. Digital measurements were performed using two 3D software programs: MeshLab (direct point-to-point connection) and Obi (discrete landmark selection method). Agreement between clinical and digital measurements was evaluated using repeated-measures ANOVA, generalized estimating equations, Bland-Altman analysis, and Passing-Bablok regression.

Digital measurements yielded slightly greater distances compared to clinical measurements, with MeshLab consistently showing larger discrepancies than Obi. Nevertheless, measurements from both software programs remained within clinically acceptable limits. Higher beta-coefficient values were observed for vertical distances than for horizontal distances, particularly when measuring longer distances between points. Both digital methods effectively detected incremental changes in vertical distances, comparable to clinical measurements.

Stationary facial scanners combined with 3D measurement software provided clinically acceptable accuracy for linear facial measurements. The discrete landmark selection method showed slightly better precision compared to the direct point-to-point connection method, particularly for longer distances between facial landmarks.

Facial scans and associated measurement software provide reliable facial measurements for prosthetic rehabilitation, such as vertical dimension evaluation, within digital workflows. Subtle accuracy differences between software highlight the importance of careful selection and optimization to minimize errors impacting treatment outcomes and enhance clinical efficiency.