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ePaper created 2017-12-06, 11:14:19 | version 1.38.0
| industry case, the SDI has been placed vertically to achieve the required stability (Fig. 5). The CT marker, containing the fiducial marker used for the registration of the CT scan to the patient, was attached to the V-type arm on the fix-plate at one end. At the other end, the assembly was placed over the SDI’s square head and secured to it using a setscrew which was embedded in the aluminium bracket, with this creating a complete “NaviStent” (Fig. 6). The scan prosthesis was then modified to accom- modate the aluminium bracket before it was placed over the maxillary edentulous ridge (Figs. 7 & 8). For accuracy purpose, it is imperative that the scan pros- thesis is stable, while at the same time it should not interfere with the NaviStent. Fig. 11: Prosthetic implant planning using the Navident software. Fig. 12: Real-time feedback is provided by Navident using a Jaw Tag and Drill Tag during surgery. Fig. 13: The alveolar crest was levelled by a rongeur. CT scan Figs. 14–16: Implants are placed exactly as planned. The following CBCT imaging protocol for Navident dynamic navigation was applied during CT imaging. Before the scanning procedures, both the modified scanning prosthesis and the NaviStent had been placed into the patient’s upper jaw (Figs. 9 & 10). A CT marker was then connected to the NaviStent. A scout view had been acquired prior to the actual scan to verify the presence of the CT marker in the CT scan. In order to allow for accurate registration, at least three corners of the fiducial marker must be present in the scan. In order to maintain a high level of accuracy during navigation, it is mandatory that the slice thickness must not exceed a maximum of 0.4 mm. In this case, the slice thickness had been set to 0.3 mm. Afterwards, the scan was exported in DICOM format, then imported into Navident. Osteotomy planning When the CT scan is imported into Navident, a pro- prietary algorithm detects the fiducial’s image in the scan, then registers it with a mathematical model of the fiducial that is stored in the computer memory. This enables Navident to map the Jaw Tag, which is Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 11 Fig. 12 40 implants 3 2017