Accuracy of a patient 3-dimensional virtual representation obtained from the superimposition of facial and intraoral scans guided by extraoral and intraoral scan body systems

Abstract

Statement of problemA patient 3-dimensional virtual representation aims to facilitate the integration of facial references into treatment planning or prosthesis design procedures, but the accuracy of the virtual patient representation remains unclear. PurposeThe purpose of the present observational clinical study was to determine and compare the accuracy (trueness and precision) of a virtual patient obtained from the superimposition procedures of facial and intraoral digital scans guided by 2 scan body systems. Material and methodsTen participants were recruited. An intraoral digital scan was completed (TRIOS 4). Four fiduciary markers were placed in the glabella (Gb), left (IOL) and right infraorbital canal (IOR), and tip of the nose (TN). Two digitizing procedures were completed: cone beam computed tomography (CBCT) (i-CAT FLX V-Series) and facial scans (Face Camera Pro Bellus) with 2 different scan body systems: AFT (ScanBodyFace) and Sat 3D (Sat 3D). For the AFT system, a reference facial scan was obtained, followed by a facial scan with the participant in the same position as when capturing the CBCT scan. For the Sat 3D system, a reference facial scan was recorded, followed by a facial scan with the patient in the same position as when capturing the CBCT scan. The patient 3-dimensional representation for each scan body system was obtained by using a computer program (Matera 2.4). A total of 14 interlandmark distances were measured in the CBCT scan and both 3-dimensional patient representations. The discrepancies between the CBCT scan (considered the standard) and each 3-dimensional representation of each patient were used to analyze the data. The Kolmogorov-Smirnov test revealed that trueness and precision values were not normally distributed (P<.05). A log10 transformation was performed with 1-way repeated-measures MANOVA (α=.05). ResultsThe accuracy of the virtual 3-dimensional patient representations obtained by using AFT and Sat 3D systems showed a trueness ranging from 0.50 to 1.64 mm and a precision ranging from 0.04 to 0.14 mm. The Wilks lambda detected an overall significant difference in the accuracy values between the AFT and Sat 3D systems (F=3628.041, df=14, P<.001). A significant difference was found in 12 of the 14 interlandmark measurements (P<.05). The AFT system presented significantly higher discrepancy values in Gb-IOL, TN-IOR, IOL-IOR, and TN-6 (P<.05) than in the Sat 3D system. The Sat 3D system had a significantly higher discrepancy in Gb-TN, TN-IOL, IOL-3, IOL-6, TN-8, TN-9, TN-11, IOR-11, and IOR-14 (P<.05) than in the AFT system. The Wilcoxon signed-rank test did not detect any significant difference in the precision values between the AFT and Sat 3D systems (Z=-0.838, P=.402). ConclusionsThe accuracy of the patient 3-dimensional virtual representations obtained using AFT and Sat 3D systems showed trueness values ranging from 0.50 to 1.64 mm and precision values ranging from 0.04 to 0.14 mm. The AFT system obtained higher trueness than the Sat 3D system, but both systems showed similar precision values.