| The basic requirement for facial prostheses is to realize the emulate rehabilitation, including emulate shape, emulate color, emulate quality of the material and emulate function. The traditional facial prostheses were made up by hand-curved and wax-cast, so, its anatomical shape was limited by carve techniques from technicians. Moreover, it was time consuming process to turn off, which hinder the development of facial prostheses. CAD/CAM system utilized the process of modern computer self-controlling to replace that of the difficult hand-making for prostheses, improving the cosmetic effect and work efficiency. We developed and established the 3-D external nasal morphological databank to provided the foundation for CAD/CAM system of facial prostheses.The content was as follows:1. A plaster model of normal external nose was scanned five times by laser scanner in different inclined angles and the nasal surface configuration of point-cloud data was reconstructed in reverse engineering software respectively.2. 11 plaster models of normal external nose were chosen and scanned by 3-D laser scanner. After reconstruction in software, the point-cloud digital noses were measured according to anthropometry. The data of measurement were statistically test with the data measured to plaster model by hand.3. The external nasal surface CAD model was construct in the software. Atfirst the point-cloud data noses were pretreated including filtering the useless point, pruning the boundary of 3-D nasal digital models, wiping off the interfering points to show the clear brim for nostrils. Then the digital noses were partitioned to six areas by the nasal anatomical features: nasal bridge area, nasal tip and collumella area, left and right dorsal areas, left and right ala and nostril areas, the surface model of each areas were construct and connected to a group. With adding the background color, the surface CAD model of external nose was finished.4. 12 plaster models which belonged to 6 types noses were searched and scanned. The data documents were primarily saved as ASC format in Surface software. We measured the nasal length and width of those 12 noses and replace the original data with the standard data of Han nationality, so, We got 12 digital noses with the same size, then we saved the documents by each type with both ASC format and IGS format.5. The reborn of the special areas of digital nasal surface CAD models was realized in pro-engineering software. After that we mended the adjusted surface to its neighbor surface, smoothed the steps, switched the data to STL format. A CAD nasal model which left and right ala and nostril areas was adjusted was then passed on to CAM process.Results indicated that:1. The external nasal 3-D digital model was integrity when the blind areas lied in nostril areas which had the lest effect to the morphology of nose.2. Comparing the result achieved from hand-measuring to that from laser scan measuring software, the absolute error for all index was no more than lmm,the relative error was no more than 5%. It was proved to be reliable for the system of 3-D laser scanner to achieve the external nasal point-cloud data model and to measure and analysis the external morphology of the nose.3. After constructing the point-cloud digital nose to surface model bydividing the model according to the anatomical features, we achieved the clear nasal surface CAD model which could exhibit the complex anatomical morphology of nasal ala and collumella. The high quality CAD model was achieved with average 0.03mm error and could be visualized from any observing angles by rotating the 3-D nasal surface model.4. We got both point-cloud models and surface models of 6 type external digital noses with the same size and constructed Han nationality standard external nasal morphological databank.5. We realized the aesthetic adjustment process for each type nose and achieved the natural nasal appearance through the CAD software on the basis of personal computer. The feasibility of the adjusted CAD m...
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