Novel methods for quantifying soft tissue changes after orthognathic surgery

Laser scanners are becoming increasingly important as a tool for quantifying the outcome of facial surgery. However, few computer algorithms have been developed for this purpose. Researchers have either measured the differences in the positions of (manually located) landmarks, or have taken radial measurements of the distances between surfaces. Neither of these techniques provides satisfactory information about the shape changes between surfaces. In this paper, alternative methods are proposed and their performance is compared with that of the radial method. Tests on two patients show that the Correspondences by Sensitivity to Movement (CSM) and closest point algorithms provide the most realistic measurements of the differences between two surfaces. The CSM method was found to be useful for pinpointing areas where the shape has changed.