Quantitative Assessment Protocol for Facial Soft Tissue Volumetric Changes with Stereophotogrammetry

The assessment of the impact of dental and orthodontic treatment, as well as of orthognathic surgery on facial soft tissue, is critically important, because these types of treatment can significantly impact facial esthetics and, therefore, patient satisfaction. Accurate evaluation of the facial soft tissue response is essential for the achievement of optimum treatment results. Three-dimensional (3D) stereophotogrammetry is a reliable, radiation-free, non-invasive tool that can be used for quantitative assessments of the soft tissue surface, offering a highly accurate representation of the facial structures. The aim of this protocol is to demonstrate a methodology that can be used for the quantitative assessment of facial soft tissue changes with the use of stereophotogrammetry. For the video demonstration, we used a 3D image analysis software. The proposed protocol includes the steps of image preparation, spatial registration to a 3D axis, selection and superimposition of the areas of interest, and calculation of the volume of the area included between the two soft tissue surface images that are involved in the assessment. This protocol has been tested for its validity and reproducibility and can have variable applications for clinical as well as research purposes.