CAD/CAM - international magazine of digital dentistry

08 I I CE article _ daily digital dentistry Glassceramic In the glass ceramic category, with E4D Dentist you have the two most popular ceramics in the history of dentistry right at your fingertips, IPS Empress CAD and IPS e.max CAD in block form. These blocks can be used together or separately depending on the clinical situation to create ex- tremely aesthetic restorations. Here an example is shown milling both IPS Empress (#7–#10) and e.max CAD (#6 and #11) (Figs. 4-6). Leucite-reinforcedceramics IPSEmpressusheredintheaestheticrevolution, andI’vehadnearly15yearsofclinicalutilizationof the IPS Empress material, first via the press tech- nique and now through milling of the IPS Empress CAD blocks. IPS Empress CAD blocks are available in two translucencies (LT and HT), as well as the extremely useful IPS Empress CAD Multiblock. The IPS Empress CAD Multiblock has a blend of translucency and colour intensity graduating through the block from the cervical position to the occlusal/incisal. The coordinated software of the E4D Dentist System (DentaLogic) provides a simple way to po- sition your restoration first virtually then actually within the block in order to customize the shade and translucency of your restoration even before you begin any customization. The clinical docu- mentation, verification and confidence of using IPS Empress have been established via long-term data.4 Lithiumdisilicateceramic IPS e.max is a high-strength ceramic with a flexural strength of 360–400 MPa that defines a new level of strength for metal-free restorations. While veneering ceramics (for metal, zirconia or ceramic substructures), it exhibits strengths in the 100–120 MPa range, IPS e.max CAD provides a monolithic full-contour material that was pre- dicted to resist fractures and chipping greater than other layered processes (veneered metals, ceramics or zirconia). In a comparative study of durabilityandfractureresistancebetweenlayered, lab-fabricated zirconia restorations and mono- lithicIPSe.maxrestorations,theIPSe.maxrestora- tions provided reduced fracture and more durable results.5 IPS e.max CAD blocks have the unique charac- teristic of being distributed in a partially crystal- ized stage (blue to violet coloured). This means that after milling, the IPS e.max CAD blocks need Figs. 4–6_IPS e.max CAD and IPS Empress CAD provide strength and beauty for challenging esthetic cases. CAD/CAM 1_2013 It’s all about the preparation It should be noted that the proper and successful utili- zation of any of the metal-free types of materials (resin, resin ceramic, glass ceramic) require following approved preparation guidelines.These are simply providing proper clearancefortheparticularmaterial—typically1.5–2mm occlusally(2mmforimplantrestorations)and1mmaxially; heavy chamfer or shoulder; rounded internal angles and butt joint margins—which need to be visible! All digital capture systems today can only capture what they see and if you clinically can’t see the margins, don’t try and capture them digitally; first gain visualization through proper soft-tissue management. With all these materials,the preparation is of the upmost importance! Concern has been raised by those without firsthand ex- perience about the aesthetic limitations of mono-block restorations or the limited longevity of surface-character- ized (glazed) metal-free restorations. It should be noted that it is often the dental bur that removes the glazed surface and not natural wear; one need only walk on 2,000-year-old tiles in Europe to realize the natural fusion of the glazed material into the base ceramic. Proper design, record (bite) taking and attention to detail in the use of various software packages along with the replication of the virtual design in ceramic after choosing the correct shade and translucency, quickly relieve any hesitation about aesthetics and reinforce the benefits of doing and more and more chairside restorative treatment. Fig. 4 Fig. 5 Fig. 6 Table I