CDEN0109

26 I I industry report _ CAD/CAM _Today, practising dentistry without digital technology and CAD/CAM procedures is unimagin- able. Intra- and extra-oral imaging, scanning of antagonists and impressions, on-screen 3-D de- signing, the use of innumerable tooth shapes from thetoothdatabase,thedesignofanatomicocclusal surfaces, functional articulation on virtual models, subtractive processing of high-performance ce- ramics—none of this would be possible without the use of computers. The groundwork for this quantum leap in dental technology was laid in 1985. Using a Fairchild video sensor (which at the time was only used for military purposes and for which special permission was re- quired for use in dentistry), for the first time it was possible for a preparation—made visible intra- orally with a triangulation camera—to be measured multidimensionally and transferred onto a screen. Then, with the help of a PC, imaging software, and a connected CNC grinding unit, the first inlay of silicate ceramic was produced at the University of Zurich. In those days, only a few could imagine the new technologies and revolutionary treatment possibil- ities awaiting dentistry thanks to this development. Since then, more than 28 million all-ceramic restorations have been produced worldwide using CAD/CAM technology, both chairside and in the dental laboratory. Computerised milling machines have made subtractive processing of glass- and oxide ceramics possible from which to fabricate aesthetic, high-quality restorations with a repro- ducible, consistent material quality at a reduced cost. Relatively recently, discussion was centred on accuracy of fit, cost-effectiveness, and user- friendliness. The quality of CAD/CAM restorations was viewed critically, and only a few leaders in the field investigated this technology with scientific rigour. Currently, the initially hesitant, and even sceptical, attitude towards computer-manufac- tureddentalprostheseshasbeenreplacedbyoneof approval, and this technology has become a stan- dard procedure. From a technical point of view, the development of 3-D image capture was propelled not only by more powerful microprocessors, but also by CCD image sensors with high-resolution photodiodes, aswellasopticalandtactilescannersthathelpread and upload preparations and models to the soft- ware. Laser scanners provide an impulse capacity for reproducing tooth surfaces at a rate of thou- sands of measured points per second. Upgraded CAD software with 3-D graphics applications re- ceives the digital signals and recreates the clinical surface needing restoration. Using‘occlusalsettling’withpreformedocclusal surfaces from the tooth databank, the software then virtually rebuilds the tooth surface. The cusps of the occlusal surface are ‘settled’ into their oc- clusal position. An articulation programme takes the occlusal characteristics of antagonists and the adjacent teeth’s occlusal surfaces and creates a contact-point pattern that fulfils the criteria of the individual function. An acquired, regional func- tional generated path registry detects sites that in- terferewiththeglidingspaceandreducesthemau- tomatically (Fig. 1). cosmeticdentistry 1_2009 CAD/CAM wasjustthebeginning Author_ Manfred Kern, Germany