CAD/CAM - international magazine of digital dentistry

24 I I case report _ CAD/CAM restoration The lithium-disilicate crystals in the IPS e.max ma- terial, in particular, deflect, branch or blunt cracks, increasing the flexural and overall strength of the material to a range of 360 to 400 MPa.3 These high-strength characteristics, capacity for milling to full-contour and placement with adhesive bonding or conventional cementation renderIPSe.maxCADmonolithicrestorationsprac- tical for restoring in-office implant restorations.4 Additionally,astrongbondbetweentherestoration and underlying tooth substrates can be achieved.5 _Case presentation A 28-year-old patient presented with retained primary molars 55 and 65 (Figs. 1–3). These would be extracted and replaced with implant-support- ed crown restorations fabricated in-office using the E4D CAD/CAM system and a lithium-disilicate (IPS e.max CAD) material. The Value 1 Impulse blocks were selected because they are ideal for implant crowns, providing the ideal level of trans- lucency. Implants were placed and the patient was pro- vided with zirconium abutments (Astra OsseoSpeed, DENTSPLY). To fabricate the crown restorations, the abutments were scanned using the E4D intra- oral scanner (Fig. 4), and the zirconium abutment margins were marked (Fig. 5). TheE4DICEsoftwareenabledeasyviewingofthe zirconium margins in subgingival locations (Fig. 6). Fig. 8_The restoration’s material thickness was verified using the E4D Autogenesis software. The blue areas equalled 2 mm and the green 1.5 mm, which was ideal for the selected IPS e.max CAD lithium-disilicate material. Fig. 9_The E4D Autogenesis software resulted in appropriate anatomical contours. Fig. 10_The IPS e.max CAD Value 1 Impulse blocks were milled and fired in one cycle, producing highly aesthetic monolithic crown restorations. Fig. 11_Postoperative view of the milled restorations. Fig. 12_Postoperative facial view of the completed restorations. Fig. 13_Postoperative view of the final monolithic crowns on the abutments to replace the retained primary teeth 55 and 65. CAD/CAM 4_2013 Fig. 10 Fig. 8 Fig. 12 Fig. 13 Fig. 9 Fig. 11