A 3-DIMENSIONAL COMPUTERIZED MESH DIAGRAM ANALYSIS AND ITS APPLICATION IN SOFT-TISSUE FACIAL MORPHOMETRY

A modified computerized mesh diagram analysis that allows rapid and in dependent quantifications of soft tissue facial size and shape in the three-dimensional space is presented. Normal references are provided, and the application of the method is also exemplified by the analysis of two maxillofacial surgical patients. The Three-Dimensional Facial M orphometry method has been used for the collection of the x, y, z coor dinates of 22 soft tissue landmarks in 50 men and 50 women (all health y young white adults). The method detects the three-dimensional coordi nates of retroreflective, wireless markers positioned on selected faci al landmarks with two charge-coupled device cameras, working in the in frared field. The midpoint between the right and left tragus landmarks served as the origin of the coordinate axes, and the landmark coordin ates were rotated, setting the intercantheal line horizontal on both t he frontal and the horizontal planes, and the Camper's plane inclined at -7.5 degrees on the sagittal plane. A standardized mesh of equidist ant horizontal (dimension: half the upper face width), vertical (half the vertical projection of upper face height), and anteroposterior (ha lf the horizontal projection of upper face depth) lines was consequent ly constructed. The lattice was replicated on the entire face and comp rised 84 parallelepipeds. Both male and female reference meshes had a harmonious and symmetric appearance, with gender differences in facial size but not in facial shape. The standard normal reference was super imposed on the patient's tracing, and the global (size plus shape) dif ference was then evaluated by the calculation of the relevant displace ment vectors for each soft tissue landmark. A global difference factor was calculated as the sum of the modules of all the displacement vect ors. Consequently, a size normalization was performed, and the shape d ifference (size-standardized) was then evaluated by the calculation of new relevant displacement vectors for each landmark, as well as a sha pe-global difference vectors.