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ePaper created 2015-03-06, 14:42:46 | version 1.33.01
I overview _ implant prosthetics Figs. 4 & 5_Fitting accuracy below 50 μm is possible for CAD/CAM full-arch reconstructions providing passive fit with minimal stress. bone in the upper jaw is clinically often over- estimated.6 According to the characteristics of an atrophy of the alveolar ridge, the prosthetic- oriented planning will control the implant posi- tioning and type of reconstruction of the opera- tion virtually in advance. _CAD/CAM technologies in implant prosthetics Closelyconnectedtocomputer-assistedimplant planning is the CAD/CAM technology (Computer- Aided Designing/Computer-Assisted Manufactur- ing), which has significantly changed the dental medicine in the course of the past twenty years.7 The more parallel dental implants can be planned and clinically placed, the easier and more stable the design (Fig. 2) of CAD/CAM frameworks/FDPs (FixedDentalProstheses)andbarsmadeoftitanium or zirconia can be kept. These materials are also characterised by improved technical and biological features. Consequently, technical and biological complications are to be expected less often.8, 9 Depending on the connection type of implant systems, also full-ceramic reconstructions can be screwed together directly on the implant’s level (Fig. 3). The fitting accuracy of implant-borne CAD/ CAM-titanium and -zirconia reconstructions are significantly higher than the conventionally produced bridges with cast alloys.10 By now, most of the major manufacturers offer their own CAD/CAM systems and have centralised produc- tion facilities for manufacture of frameworks and bridges at their disposal. Thus, a fitting accuracy below 50 μm (Fig. 4 & 5) seems routinely possible for full-arch reconstructions with the required care and know-how of the production process.11-13 The CAD/CAM production is specific for metals like titanium and ceramics, as for example zirco- nia. For milling with CNC-machines, especially suitedmillingcuttersareused.Afterthemillingof zirconia in the overdimensioned green-/white- body, the final crystallisation (sintering and HIP) of the work piece is made. Despite of automated and mechanical processes, the CAM step requires the experience of specialised engineers who are able to oversee the processes and step in if problems occur. Thecurrentdevelopmenteffortsandadvance- ments take place in the area of software possi- bilities and the connection of individual digital subareas. Thereby, a universal data format (STL) enables the forwarding of data by intra- or extra- oral scanners via CAD- and CAM software. How- ever, it probably might take some time until the various providers will open their systems com- pletely and thus enable users to freely choose between the digital work steps._ Editorial note: A list of references is available from the publisher. 34 I CAD/CAM 1_2015 Fig. 4 Fig. 5 PD Dr med.dent.Joannis Katsoulis,MAS Department of Reconstructive Dentistry and Gerodontology School of Dental Medicine University of Bern Freiburgstrasse 7 3010 Bern Switzerland joannis.katsoulis@zmk.unibe.ch CAD/CAM_contact CAD0115_32-34_Katsoulis 02.03.15 12:51 Seite 3 CAD0115_32-34_Katsoulis 02.03.1512:51 Seite 3