| The nose positions in the center of the face, which plays a key role in constructing the beauty of human beings. Individuals afflicted with nasal defect suffer not only from the deficit or loss of physiological function, but also from severe adverse psychological consequence. The surgeon is limited by the availability of tissue, the compromise of the local vascular bed by radiation in tumor patients, and the physical condition of the patients. Therefore, prostheses are usually needed to restore normal facial appearance in most cases. In clinic, traditionally facial prosthesis has been made by handworked sculpted wax pattern, which is not advanced enough to meet the practical needs of emulation. Rencently, the reverse engineering and rapid prototyping techniques provide us a new method. This study applied these novel techniques in the field of facial defect restoration, focusing on the individualized 3-dimentional (3D) emulational design and the related research of rapid manufacture for nasal defect. The aim of this study is also to find a new way for the individualized 3-dimentional emulational design of nose and other single facial organ. The method can also be used in the maxillofacial surgery, plastic surgery, and many other areas.Acquisition of 3D image of facial soft tissure is the first step in the reverse engineering and the base of facial prostheses design. At first, this study discussed the accuracy of 3-Dimensional Sensing System and Rapid Prototyping machine for manufacturing facial prostheses of computer aided design and computer aided manufacturing (CAD/CAM). Then a new CAD method for the nasal prosthesis was set up as follows: Acquisition of 3D image of patient's facial soft tissue and measuring major facial landmarks were carried out. According to the results obtained above the most similar healthy 3D image of nose was chosen. These two images in the CAD software was merged and digital model of nasal prostheses was achieved. Then the wax model of nasal prostheses was manufactured in RP machine. The model was last transformed to the nasal silicon rub prostheses. This study applied the new method satisfyingly in clinic and manufactured nasal prostheses for a nasal defect patient for the first time to our knowledge. The method can provide foundation for 3D emulational design and RP manufacturing of nose and other single facial organ. From the present study, following conclusions could be drawn:1. The accuracy of Three Dimentional Sensing System is 0.03mm. But in the practice, accuracy decreased because of operation and so on. Through measuring of the ruler, the accuracy is 0.09mm. It satisfies the demands of 3-D digital data acquisition of facial soft tissue in clinic and indicating that this system is reliable and can be used in clinic to replace the manual measurement.2. The basic principle of AFS-360 laser rapid prototyping machine is Selective Laser Sintering (SLS). Manufacturing accuracy is 0.15mm through measuring the panes manufactured with wax powder and PSB powder. After infiltrating resin, the accuracy did not change significantly. It satisfies the demands of manufacturing facial prostheses in clinic.3. Compared the 3D reconstructing of facial soft tissue separately by 3-Dimentional Sensing System scanning and CT scanning, the former has many advantages: higher accuracy, less time consuming, lower cost. It can be used in establishing 3D digital database of healthy Chinese facial image. CT scanning can obtain image from all kinds of shapes. Therefore, we should choose the right type of scanning according to different demands.4. A 3D image of nasal defect patient's facial soft tissue was acquired. The major anatomy structures were measured three dimensionally. Then according to the results and patient's preference, the most similar healthy 3D image of nose was chosen. The selected nasal image was matched with the 3D facial image of patient and modified until the patient felt satisfied with the appearance. After merging these two images in the CAD software, the digital model of nasal prostheses was finished. Then wax model of nasal prostheses was manufactured in RP machine. This study applied the new method satisfyingly in clinic and manufactured nasal prostheses for a nasal defect patient for the first time to our knowledge. The communication between doctor and patient was improved and individualized 3-dimentional emulational design was realized by exhibiting the restoration effect to the patient and modifying the prostheses according to patient's preference in Geomagic software. The wax model manufactured by RP could be easily transformed into silicone rubber, which simplified the steps of clinic work. The method can provide a new method for 3D emulational design and RP manufacturing of nose and other single facial organ.5. Defect area resin cast model was manufactured for the first time using RP machine. The nasal silicon rubber prostheses were transformed by it. The margin fits well on the defect area in clinic try-in procedure. The work achieved satisfying results and primarily explored the feasibility of this novel technique in this field.
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