Development of a simulator for educational oral surgery using virtual reality

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In 1996 and 1997, basic problems were studied for construction of a simulator for orthognathic surgery The programs of sulerimposition of the (lata for frontal and lateral cephalograms, CT and dental casts were developed. Using the programs, the coordinate system delineated by the cephalograms could be applied to the data for CT and dental casts, and these three data could be observed in the same coordinate system. Subsequently, construction of simulator for orthognathic surgery, especially sagittal split ramus osteotomy, was tried in 1998, using AVS Medical viewer of graphics workstation.Region growing technique was used for extraction of the mandible. A voxel model was then made with the data for cancellous bone, so this model could be applied to complex simulation. A threshold value was defined as 200 Hounsfield units. Formerly, osteotomy could be simulated in two-dimensions. In this system, osteotomy could be simulated in the maneuver that, reflected actual surgical procedures, inc … More luding saw, bur and osteotome after development. of modules. Consequently, surgical procedures could be simulated in three-dimensional computer graphics. Three-dimensional computer graphics could contain the data for dental casts, and this made it possible to automate shift of lateral bone fragments after splitting with high precision. Furthermore, function of detecting interference between two bone fragments after splitting was developed, and this enabled to analyze bony interference that it was formerly difficult to predict, and this clarified that. bony interference caused various problems.In this system, it. took about. an hour to simulate the osteotomy, and we can apply this system to other surgical procedures after altering osteotomy lines. This system possessed high reality because of three-dimensional graphics with high resolution and use of data with high reliability, and this system possessed satisfactory function of educational simulator. Furthermore, this system would be useful for clinical application including diagnosis and investigation of treatment plan. Less