[Evaluation of measurement accuracy of three facial scanners based on different scanning principles].

To evaluate and compare the measurement accuracy of three facial scanners, based on different scanning principles: line laser, structured light and stereophotography.Three-dimensional (3D) digital face models of the same plaster head model were obtained by three facial scanners separately. The measurement values of the length of 10 feature lines and the angle of 5 feature angles were measured on these 3D models in the software respectively. The standard values of these characteristics were measured by a coordinate measure machine (CMM) with high accuracy. Statistical and surveying analyses were made between the measurement values and standard values. Facial morphology theory measurement accuracy of these three facial scanners was obtained finally.There was no statistical significant difference between the measurement values from the three facial scanners and the standard value from CMM. The 3dMD and Faro scanners were better in length measurements and the length measurement accuracy was about 0.2 mm. The Faro scanner was also better in angle measurements and the angle measurement accuracy was about 0.5°.The three facial scanners all have good reliability in facial measurements, and their actual measurement accuracy for patients needs further research.