[Preliminary application study of digital technology for constructing three-dimensional facial symmetry reference...

Objective: To explore the impact of digital technology in constructing a three-dimensional (3D) symmetry reference plane (SRP) for esthetic restoration of anterior teeth and to evaluate its clinical applicability. Methods: A cross-sectional study was conducted from February to May 2024, involving 20 patients [11 males and 9 females, aged (36.8±11.4) years] who underwent anterior esthetic restorations at the Department of Stomatology, People's Hospital of Ningxia Hui Autonomous Region. Symmetrical reference planes of patients' 3D facial models were constructed using three different algorithms: weighted Procrustes analysis (WPA), Procrustes analysis (PA) based on the ontology-mirror correlation method, and iterative closest point (ICP). The SRP defined by an associate chief physician served as the control (true-value group). The angular errors between each algorithm group and the true-value group were compared. The optimal algorithm was selected and combined with a three-dimensional digital smile design (DSD) to create virtual patients, followed by designing anterior restorations. The visual analogue scale (VAS) was used by patients to score the aesthetic restoration results of the conventional design (control group) and the algorithm-based design (algorithm group). Results: The angular errors of the WPA, PA, and ICP groups were 1.43°±0.66°, 1.82°±0.88°, and 4.74°±2.03° respectively, with statistically significant differences among the groups (F=41.10, P<0.001). Pairwise comparisons showed that the WPA group had significantly smaller angular errors compared to the PA and ICP groups (P<0.05). The VAS scores for aesthetic restoration were significantly higher in the algorithm group (8.09±0.74) compared to the control group (6.30±1.38) (t=-5.49, P<0.001). Conclusions: The SRP constructed using the WPA algorithm demonstrated minimal angular error when compared to the expert-defined SRP and is considered the optimal choice in clinical practice, yielding high patient satisfaction.