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Prosthetic devices can be fitted in various ways. Digital technologies have made their mark in implantology for quite a while, and they provide options for quality solutions. Classical indications for implant-prosthetic treatments include dentures for the toothless jaw. For this type of dentures, clinical studies document a high survival rate of about 85 to 90% (Attard et al. 2004a, Attard et al. 2004b) with observation periods of up to 20 years...

case report _ CAD/CAM I nation of the accuracy of the casting fit it makes sense to perform the so-called Scheffield test. For this test, a screw is mounted and fastened on the post on one side of the distal implant. When fastening the screw, the transfer jig must not lift off the other implants. Further, there must not be any gaps. If the screw can be fastened without making the transfer jig move the conclusion can be drawn that the impression has exactly copied the situation in the mouth. In case that the test has a negative result a transfer defect can be assumed. In such a case, the transfer jig should be separated, and all posts should be fastened with screws, so that a new impression casting can be taken. Once an exact impression has been secured and the tooth arrangement has been adjusted, the CAD/CAM manufacture of the supraconstruction can begin. First, the work model and the tooth arrangement are sent to a Compartis ISUS Planning Centre. There, the virtual construction of the attachment is made according to the specifications of the dentist(s) and dental technician(s). In the present case, a bar attachment construction made of titanium with distal attachments (Preci-Vertix, CEKA Germany) has been chosen. The tooth arrangement determines the space available for the supraconstruction and the alignment towards the chewing area. This information then constitutes the foundation for computer-assisted design of the supraconstruction, the CAD process. For this purpose, first, special scan posts are screwed into the implants, in order to determine the position of the implants with a first scan. Then a second scan is done with the wax arrangement, in order to determine the available space and the orientation of the supraconstruction. Then, the desired supraconstruction is designed with the help of special software. This constitutes the basis for the manufacture of the supraconstruction utilising the CNC process (Fig. 5). Dental technicians and care providers will then receive the construction suggestion of the Compartis ISUS Planning Centre by email with the request for release or for advice of possibly required changes. As soon as the release is obtained the manufacture of the attachment begins. The Compartis ISUS system ensures, particularly by applying modern cutting machines and special cutting strategies with all the materials, a perfect quality of the surfaces which dispense with the need for manual after-processing also as far as the retaining elements are concerned (Fig. 6). Then the dental laboratory can commence with the manufacture of the secondary construction. In the present case, first, a secondary structure was made by means of electroplating (Solaris, DeguDent), and the plastic matrix for the Preci-Vertix retaining elements was incorporated. After that, a cast tertiary structure was made of a cobalt-chromium alloy and bonded with the galvanoplastic structure. The supraconstruction was completed using the already existing tooth arrangement. Several in-vitro examinations prove the excellent accuracy of fit in these CAD/CAM manufactured constructions. In a comparison of five different techniques for the manufacture of implant supraconstructions, the CAD/CAM structures showed a median accuracy of fit of 25 µm, while cast structures had median gaps of 78 µm width (Torsello et al. 2008; Fig. 7). However, the advantage of the CAD/CAM technology is not only the highly precise manufacture of suprastructures made of pure titanium and Co-Cr alloys; there is also its applicability to a broad range of indications. Starting out from the scan data, the virtual construction allows for a wide range of variations in terms of various forms of supraconstructions, from the simple round bar to retaining element attachments or to a bridge frame for fixed constructions. With a CAD/CAM system, it is also possible to virtually incorporate active holding elements such as extracoronal retaining joints, bars and press buttons. In summary, it can be said that the CAD/CAM technology is also ideal for the processing of alternative materials on titanium and NEM basis. It provides these advantages: _High mechanical resilience thanks to homogeneous pore-free materials; _Tension-free fit thanks to precise CNC manufacturing technology; _Suitability for a large width of indications thanks to individual computer-assisted design. The integration of the virtual design supplements the trusted manufacturing technology based on cutting and hence opens up possibilities of new indications for using alternative materials in implant prosthodontics._ Editorial note: Bibliographical reference is immediately available for download at www.zwponline.info/fachgebiete/implantologie. _contact Dr med dent Sven Rinke, MSc, MSc Geleitstr. 68 63456 Hanau, Germany E-mail: rinke@ihr-laecheln.com implants implants 1 _ 2010 I 19