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38 I I industry report _ SensAble Technologies _For more than a hundred years, dental labora- torieshavedesigneddentalrestorationsthesameway byusingalost-waxprocessinaccordancewithwhich the design is first modelled by hand in wax, then reviewed, refined, invested and finally burned out in the process of creating a mould that will be used for casting.Twenty-fiveyearsago,earlydentalCAD/CAM solutions, such as Sirona’s CEREC system, applied technology proven in automotive and aerospace design to the design of zirconia substructures (or copings) for crowns, allowingpartofthepro- cess to go digital. How- ever, while copings are simple, thimble shapes and relatively straight- forward to design digi- tally, other types of commonly prescribed removable restorations, such as partial dentures, are not, owing to their highlyirregularandintri- cate shapes. In addition, dental laboratory technicians are skilled artisans— havinghonedtheirmanualdexterity,artisticstyleand design techniques over many years—not tech savvy engineers.Thesefactorsmakeitextremelydifficultfor them to use traditional dental CAD/CAM systems to createcomplex,organic-shapeddentalrestorations. Creating dental restorations is partly science and partly an art. Each individual’s mouth and tooth shape is uniquely his/her own, meaning that a dental restoration is an individualised work of art, sculpted fromscratchinbite-sizedform.Computerscangreat- ly speed the design process and add precision, for examplebyeliminatingstepssuchastheneedforare- fractory model, applying digital wax thicknesses con- sistently and automatically, and assuring fast design iterationsoraremake,ifneeded.Furthermore,having digitalclaspdesignsandmeshpatternsatyourfinger- tipsalsohelpsacceleratethedesignprocess. Until recently, dental CAD/CAM systems were either surface or solid modellers, utilising the same parametric technology and the accompanying rigid, hierarchical workflow as CAD/CAM systems that are used for industrial design. These traditional dental CAD/CAM systems also require that the laboratory’s restoration designer use a 2-D computer mouse to manipulate the design, which prevents the designer from leveraging the dexterity and artisanship they have spent years perfecting. While the laboratory technician may be able to see the restoration on screen, with a mouse they cannot feel the contours of the teeth and tissues, or the thickness or smooth- nessofarestoration’ssurface—pivotalfeedbackthat allows them to design accurately and efficiently. In 2008, SensAble introduced what some dental authorities have called a revolutionary 3-D touch- enabled solution for dental restoration design. The company’s SensAble Dental Lab System remains the only proven digital solution to support the design andproductionprocessforremovablepartialframe- works and has since been expanded to handle full contour crown and bridge work and, with additional software, veneers. The system is based on voxel technology (think of voxels as 3-D pixels), which provides unparalleled speed and design flexibility. This 3-D modelling ap- proachmeansthatlaboratorytechnicianscanhandle even the most challenging cases and can literally de- sign any type of restoration they can imagine. If they canwaxit,theycandesignitontheSensAblesystem. Thisabilitytouseonesystemtocreatemultipletypes of restorations allows dental laboratories to leverage their investment across more lines of business, an important option in challenging economic times. WiththeSensAblesystem,dentallaboratorytech- nicians use a haptic device, which the company calls a3DVirtualTouchstylus,insteadofamouse,allowing themtoliterallyfeeltheevolvingrestorationthatthey aredesigningonscreenastheycarveandsmoothdig- italwax.Theresult,accordingtonumerousEuropean dentallaboratories,isbusinesschanging.Whenden- tal restoration designers are suddenly offered a way to design digitally in which they can still use their sense of touch in the design process, they can tran- sition more easily to working in the digital domain CAD/CAM 2_2010 Haptic input improves digital dental restoration design Author_ Bob Steingart, USA Fig. 1 Fig. 1_Full upper digital partial.