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ePaper created 2017-03-17, 11:21:45 | version 1.38.0
| case report digital workflow Immediate implant placement and loading— a digital chairside worklow Author: Dr Wiebe Derksen, Netherlands In the last years, new technologies have been intro- duced to implant dentistry. For example, cone beam computed tomography (CBCT) and computer-as- sisted implant surgery systems are used to deter- mine the best position for an implant. By superim- position with computer-aided design data of the planned prosthetic restoration, a result-oriented plan can be developed. It is finally implemented by use of a drill guide. Accuracy of guided surgery In order to measure the accuracy of this workflow, numerous studies have been conducted. Most of them focus on a workflow that involves the produc- tion of a conventional working model based on an impression and its digitisation with a laboratory scanner. The accuracy measurements are usually carried out by comparison of the initial CBCT scan, including the planned implant position with a CBCT scan that shows the actual implant position. A systematic review of the literature1 reveals that the highest accuracy is obtained with the use of tooth-supported drill guides and a fully guided ap- proach with implant insertion through the guide. Integration of intraoral scanners Fig. 1 Fig. 1: X-ray showing internal resorption of the maxillary right lateral incisor. Fig. 2: Clinical picture of the initial situation. Figs. 3 & 4: Extracted tooth fragment (Fig. 3) bonded to the adjacent teeth as a temporary restoration (Fig. 4). With the idea that it might be possible to optimise the process by use of an intraoral scanner, a new pro- cedure was developed at the Academic Center for Dentistry Amsterdam. In this workflow, the initial im- pression is taken with the 3M True Definition Scanner. The device offers the benefit of capturing the soft tissue without difficulties due to the use of scan pow- der. The generated STL file is superimposed with the CBCT scan, the implant position planned, and the im- plant placed. Then, the intraoral scanner comes into play again: a scanbody is placed and the situation scanned to compare the planned and the final implant position, and to produce the prosthetic restoration. In this way, a second CBCT scan can be avoided. Clinical trial A clinical trial was conducted to evaluate the accu- racy of this procedure: 148 implants were placed in a total of 70 patients using a fully guided protocol based on an intraoral and a CBCT scan. According to preliminary results, the implants were placed with higher accuracy in this study than in earlier investi- gations reviewed. The accuracy of the prosthetic procedure was assessed as well. For this purpose, the patients were split into two groups. In one group, a scanbody was placed and an impression was taken with the 3M True Definition Scanner. In the other group, a polyether impression was taken. Based on the impressions, monolithic crowns and bridges were produced. Without information about the previous process, the dental practitioner received Fig. 2 Fig. 3 Fig. 4 16 CAD/CAM 1 2017