Fabricating nasal prostheses using four-dimensional facial expression models.

Purpose Patients with facial prostheses face challenges such as maintenance of the prosthesis in place, especially around the margins, because of movement of surrounding facial skin. Conventional facial prostheses are fabricated on stationary models based on two points: neutral expression and smiling expression. We developed four-dimensional (4D) facial expression models which shape facial expressions that change over several points in time using a morphing technique. We fabricated facial prostheses using 4D models and evaluated their accuracy and fit compared with prostheses generated with the two-expression technique.Methods Seven patients with nasal defects or nasal deformities participated in this study. Facial expression morphing prostheses were fabricated based on the 4D scanned data of each patient, using five points between neutral expression (0%) and smiling (100%). Five nasal prostheses, one for each point, were evaluated in each patient objectively and subjectively for accuracy and fit.Results On subjective evaluation, the nasal prostheses fabricated using the 4D facial expression models had better marginal sealing over the range from the neutral expression to smiling, and showed better attachment during facial movement on objective evaluation.Conclusions Facial prostheses fabricated using 4D facial expression models provided better marginal sealing than those fabricated using conventional two-point modeling.