Applications of rapid prototyping technology in maxillofacial prosthetics

Purpose: The purpose of this study was to compare the accuracy, required time, and potential advantages of rapid prototyping technology with traditional methods in the manufacture of wax patterns for two facial prostheses. Materials and Methods: Two clinical situations were investigated: the production of an auricular prosthesis and the duplication of an existing maxillary prosthesis, using a conventional and a rapid prototyping method for each. Conventional wax patterns were created from impressions taken of a patient's remaining ear and an oral prosthesis. For the rapid prototyping method, a cast of the ear and the original maxillary prosthesis were scanned, and rapid prototyping was used to construct the wax patterns. For the auricular prosthesis, both patterns were refined clinically and then flasked and processed in silicone using routine procedures. Twenty-six independent observers evaluated these patterns by comparing them to the cast of the patient's remaining ear. For the duplication procedure, both wax patterns were scanned and compared to scans of the original prosthesis by generating color error maps to highlight volumetric changes. Results: There was a significant difference in opinions for the two auricular prostheses with regard to shape and esthetic appeal, where the hand-carved prosthesis was found to be of poorer quality. The color error maps showed higher errors with the conventional duplication process compared with the rapid prototyping method. Conclusion: The main advantage of rapid prototyping is the ability to produce physical models using digital methods instead of traditional impression techniques. The disadvantage of equipment costs could be overcome by establishing a centralized service.