Dental Tribune United Kingdom Edition

ble today). A decision to make an all- zirconia abutment with an an- gle of inclination above 15° is quite risky. Hence, the solution we adopted was to modify the crown while not changing the shape of the abutment. Such an approach requires the at- tending dentist to play a major role in the process so that the preparation and transfer of the emergence profile of the abut- ment and prosthetic crown cor- respond perfectly to the natural tooth. Using composite mate- rial, the doctor shapes the tem- porary restoration to retain the place for the final crown for a period of several weeks so that it later can serve as a model for the definitive crown. It is important to remember that as the gingiva is being shaped the patient must at all times be pro- vided with a temporary restora- tion, guaranteeing support for the soft tissue. Therefore, the doctor trans- ferred the emergence profile with the help of a doubling of the crown with the abutment. After the crown had been removed, pattern resin was applied in its place. Simultaneously, a stand- ard zirconia abutment was modified in the dental labora- tory into the desired shape us- ing a water-cooled high-speed bur and then scanned. An im- age of the scan was modified by superimposing a second scan over the projected emergence profile of the crown. Both parts were joined together in the CAD programme and the struc- ture thereby created was cut from the Provi Disc composite material (Robocam), which is often used for temporary res- torations. At this stage, the best approach is to try in the cut-out substructure and if necessary improve its size and shape. Only if the fit is perfect will a substructure be cut out from zirconium dioxide. The choice of material is something that should be con- sidered very carefully. Observ- ing the rule of ‘what, where and when?’ the choice will depend on the position of the abutment, its colour characteristics and the quantity of light diffusion needed. The last factor has a great impact on the natural ap- pearance of the prosthetic res- toration. For this very reason, I try above all to use all-ceramic materials, especially in the an- terior section. The material used in the present case study was zirconi- um dioxide (Robocam), which is processed in a machine sup- plied by the same company called Robomill 5. The machine mills all available soft materi- als and the water cover makes it possible to cut IPS e.max ce- ramics (Ivoclar Vivadent). Following a consultation with an attending dentist, it was agreed that owing to the large superstructure of the mu- cosal section on the vestibular side the restoration would have to be screw retained. Such a solution ensures that the pa- tient’s oral hygiene can be ex- amined frequently in that area. The abutment and crown were joined together in the laborato- ry in order to avoid any possible complications owing to excess cement left after the restoration had been placed in the patient’s mouth. The part serving as the emergence profile of the crown from the gingiva was not cov- ered with veneering porcelain. It was only polished to a shine without covering it with glaz- ing. The surface of the zirco- nia prepared in such a way has a greater chance of adhering tightly to the patient’s gingiva. The present case study con- firms that modern prosthetics could not exist without modern solutions such as CAD/CAM. Summary What other innovations will surprise us in the not-too- distant future? Will traditional layering and firing of ceramics be replaced by other methods? This remains an open question, but perhaps the profession of the dental technician will soon be limited to working only and exclusively with computers. Acknowledgements I would like to thank my wife, Dorota Michalik, for her artistic veneering of the prosthetic res- toration presented, as well as Dr Kristian Owczarczak, for his great contribution as a dentist, and with whom I carried out the clinical case study. DT All the prosthetic restora- tions were made using the CAD/ CAM Robocam, and the materi- als used were Robocam zirconi- um dioxide, IPS e.max (Ivoclar Vivadent) and Vision veneering ceramics. ‘What other innovations will surprise us in the not-too-distant future? Will traditional layering and firing of ceramics be replaced by other methods?’ Fig. 12d Prepared abutment Figs. 13a, b & c Finished zirconium dioxide substructure on the cast. Buccal view (b). Palatal view (c) Fig. 14 Fitting of abutment and coping Fig. 15 Diffusion of light in Robocam Fig. 16 Abutment and coping prior to fir- ing and bonding Fig 13a Fig 13b Fig 13c Fig. 17 Palatal view of veneered crown bonded to the abutment Fig. 18 Visible emergence area, free of ceramic Figs. 19a, b & c Finished crown in situ Fig 19a Fig 19b Fig 19c Fig. 20 Palatal view of screw-retained crown Fig. 21 Crown in full smile Figs. 22a & b Pre- and post-op situation Fig 22a Fig 22b Fig 12d November 19-25, 201214 Implant Tribune United Kingdom Edition page 13DTß About the author Robert Michalik graduated from the Faculty for Dental Technicians in Warsaw Medical School in 1987. After two years of work in the Medi- cal University’s dental laboratory, he opened his own dental labora- tory, Inter-Dent, which he is still running. In 2003, he was the first in Poland to start working with dental CAD/CAM systems. In 2007, he be- gan development of the first Polish CAD/CAM system in collaboration with Delcam and 3Shape. Also in 2007, he submitted an application to patent a method of creating tel- escopic crowns with intermediate crowns. He is the author of several articles for the trade press. Laboratorium Inter-Dent Ul. Pustułeczki 23 02-811 Warsaw Poland www.inter-dent.pl info@inter-dent.pl