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32 I I industry report _ lithium disilicate the milling process, a second heat-treating process is performed in a porcelain furnace at approxima- tely 850 °C, at which temperature the metasilicate is dissolved and the lithium disilicate crystallises. This results in a fine-grain glass-ceramic with 70 % crystal volume incorporated into a glass matrix. With two crystal types and two microstructures during processing, the IPS e.max CAD material demonstrates distinctive properties during each phase. The intermediate lithium-metasilicate crys- tal structure promotes easily milling, without ex- cessive bur wear, while maintaining high toleran- ces and marginal integrity. In the blue stage, the glass-ceramiccontainsapproximately40%volume lithium-metasilicatecrystalsthatareapproximate- ly 0.5 µm. The final-stage microstructure of lithium disilicategivestherestorationitssuperiormechan- ical and aesthetic qualities. In this stage, the glass- ceramic contains approximately 70 % volume lithium-disilicate crystals that are approximately 1.5 µm (Figs. 12–15). Thelaboratoryprocess Once designed and milled, the IPS e.max ceramic restorationsarethenpreparedforfinalaestheticad- justments.Afterthemillingspruehasbeenremoved, the technician defines surface texture and occlusal anatomy using diamond and carbide burs, carefully avoiding any alteration to the perfected occlusal andinterproximalcontacts.Afterwards,restorations are rinsed to remove surface debris and dried. Then, the milled blue restorations are placed in a conven- tional ceramic furnace for the crystallisation pro- cess.Theserestorationsweredigitallydesignedwith an incisal cut-back design that will allow a minimal application of translucent ceramics to mimic the incisal effects found in nature. Contoured to final anatomic shape, the restorations are further aes- thetically improved by subtle colouring and glazing. Restorationplacement Next,5%hydrofluoricacid(IPSCeramicEtching Gel, Ivoclar Vivadent) was applied for 30 seconds onto the internal surfaces of the glazed restora- tions. Then they were rinsed and dried. This was fol- lowed by a silane coupling agent (Monobond-S, Ivoclar Vivadent), which was also placed for a minute onto the internal surfaces, and then air- dried. For the final cementation, Variolink Veneer (Ivoclar Vivadent) was used. After excess cement had been removed, final light-curing was done. The occlusal contacts were then reviewed and excur- sivepathwayfreedomwasconfirmed.Owingtothe correct capture and alignment of the bite-registra- tion information, few adjustments were required. _Conclusion IPS e.max is about restorative options. Dentists and technicians now have a material with which they can do anterior or posterior restorations. With four different opacities or translucencies available, a variety of creative aesthetic options can be ac- complished in a restoration. Dentists and their lab- oratory ceramists now have the opportunity to be more creative for their patients (Figs. 16–18)._ Editorial note: A complete list of references is available fromthepublisher. Figs. 16–18_Maxillary anterior section restored with CAD/CAM-designed and -milled e.max restorations, using a micro-layering technique for aesthetics. CAD/CAM 1_2012 Lee Culp ChiefTechnology Officer, Microdental Laboratory, Dublin,California Prof Edward A.McLaren Professor,Founder and Director,UCLA Post Graduate Esthetics; Director,UCLA Center for Esthetic Dentistry, LosAngeles,California CAD/CAM_about the authors Fig. 16 Fig. 17 Fig. 18