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ePaper created 2017-03-17, 11:21:45 | version 1.38.0
digital dentures industry report | Fig. 4 Fig. 5a Fig. 5b Fig. 4: The UTS CAD device used to determine the occlusal plane. Figs. 5a & b: Base for the next design steps: anatomical impression of the jaws and digitised preliminary registration. the primary impression had been taken, the areas where excessive compression was present were slightly reduced with the help of a micromotor handpiece. Next, the secondary impression was taken with a low-viscosity silicone (Virtual Light Body Regular Set, Ivoclar Vivadent; Fig. 3). In order to determine the preliminary maxilloman- dibular relation and occlusal plane, two reference points, one on the chin and one on the nose, were marked and the distance between the two points was measured. The vertical dimension of occlusion was determined by subtracting approximately 2 to 3 mm from the soft interocclusal rest position, which corresponds to the freeway space. A Centric Tray (Ivoclar Vivadent) was used to record the maxillomandibular relation. Consisting of an acrylic arch with a retention rail, this device was loaded with impression material (Virtual Putty Regular Set). We asked the patient to slowly close the jaws to the preliminary vertical height. After the impression material had set completely, a UTS CAD device (Wieland Dental) was attached to the handle to establish the occlusal plane. This registration device measures the angle of the occlusal plane in relation to Camper’s plane (CP) and the bipupillary plane (BP). Once measured, the angles were transferred to the CAD software to reproduce the virtual position of the occlusal plane for the design of the 3-D bite plate (Digital Denture Professional add-on software module, Wieland Dental) and the denture. The Centric Tray was attached to the adapter of the UTS CAD and then the lateral braces of the bow were aligned to CP (Fig. 4). Next, the front part of the basic bow was aligned to the BP and the BP screw was fastened to secure the registration joint. The angle values of the patient were recorded on the order form, and then the form, impression and Centric Tray record were forwarded to the laboratory. In the laboratory, the impressions and the Centric Tray record (preliminary bite registration) were scanned using the Digital Denture Professional add-on—based on the Denture Digital Design software (3Shape)—and the ScanIt Impression (3Shape) add-on. CP and BP angle modifications can be implemented with the latter add-on. The programme brings the two scans together and produces two virtual models of the edentulous jaws, which are aligned according to the clinical situation (Figs. 5a & b). The dental technician created a 3-D bite plate for the functional impression and the needlepoint tracing record. The models were aligned to each other on the basis of the preliminary impression. Next, the dimension of the bite rims had to be estab- lished (Fig. 6). The 3-D bite plate design allows for insertion of both the bite rim supports for functional impression-taking and the registration plates of the Gnathometer CAD device (Wieland Dental) for needlepoint tracing. The CAD datasets of the 3-D bite plates were sent to a Zenotec select ion milling unit (Wieland Dental) for machining (Fig. 7). Fig. 6 Fig. 7 Fig. 6: Design of the 3-D bite plate taking the needlepoint tracing appliance (Gnathometer CAD) into account. Fig. 7: CAD/CAM-milled 3-D bite plates ready to be connected to the needlepoint tracing appliance. CAD/CAM 1 2017 25