Accuracy (trueness and precision) of two handheld scanners and a smartphone for three-dimensional facial scanning: An in vivo study.

PURPOSE: The aim of this in vivo study was to evaluate and compare the accuracy (trueness and precision) of three portable facial scanning methods: a professional handheld structured-light scanner (P-HS), a low-cost handheld structured-light scanner (LC-HS), and a smartphone with a depth-sensing camera (SP). MATERIALS AND METHODS: Twelve adult volunteers were recruited. Seventeen facial soft-tissue landmarks were marked with adhesive fiducials, and 12 inter-landmark distances were measured. Ten repeated facial scans were acquired from each participant with each method, plus reference scans from an industrial reference scanner. The relative error (RE) was calculated, and trueness and precision were expressed as the mean (Mean-RE) and standard deviation (SD-RE) of REs per participant, distance, and method. The methods were compared using linear mixed-effects models, with pairwise comparisons adjusted by the Holm method (α = 0.05). RESULTS: Statistically significant differences were found in the trueness and precision. The P-HS was the most accurate. The P-HS and SP showed comparable precision, about twice that of the LC-HS, which was the least precise and tended to overestimate. Despite a near-zero net trueness, the SP produced the largest deviations at individual distances. Differences between the trueness and precision of P-HS and SP were not statistically significant. CONCLUSIONS: The facial scanning method significantly affected accuracy. The P-HS best suits high-fidelity workflows; the LC-HS remained within clinically acceptable limits in other studies for less demanding tasks; and the SP was least accurate where point-to-point fidelity is required. Method selection should follow the accuracy each workflow requires.