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CAD/CAM - international magazine of digital dentistry

I technique _ monolithic posterior tooth restorations thin,thebuccalcuspwallswereinanacceptablecon- dition. The main objective was to maintain the tooth by restoring it with a crown. Following the prepara- tion phase, impressions were taken of the upper and lower jaws and the occlusal relationship was estab- lished. Then, the clinician fabricated the provisional restoration chairside with the help of a customized tray. _Fabrication of long-term temporaries According to the treatment plan, the patient would have to wear long-term temporaries for a period of several months. In order to fabricate these restorations, a wax-up was created (Figs. 1 & 2). In this type of situation we prefer to use the manual wax-up technique, because we have found this method to be faster. Alternatively, the restorations could have been virtually designed. Irrespective of the method used, a lasting result can only be achieved if the technician has an in- depth knowledge of the principles of functional occlusion. The waxed up crowns were transformed into long-term temporaries with CAD/CAM equip- ment. First, the physical models and wax-ups were digitally scanned (Zenotec D500, Wieland Dental) and the STL file was imported into a cor- responding design software (Dental DesignerTM, 3Shape) (Fig. 3). Then, all the parameters were suitably adjusted and the construction data was transferred to the milling machine (Zenotec se- lect, Wieland Dental), where the restoration was cut from a PMMA-based disc (Telio CAD for Zenotec) (Figs. 4 & 5). The milled crowns were re-worked only mini- mally and then placed on the model. In order to impart the PMMA restorations with a natural- lookingappearance,theirsurfacetexturewasfin- ishedinsuchawaythatanaturalplayoflightwas achieved.Thecrownsweresubsequentlypolished with a special polishing medium and goat’s hair brushes (Fig.6a). Next, the clinician removed the chairside provisional restorations and cemented the long-term temporaries with a suitable luting composite (TelioR CS Link) (Fig. 6b). Fig. 5_The milled crowns before they were trimmed from the PMMA disc. Fig. 6a_The completed long-term temporaris made of PMMA on the model and… Fig. 6b_ … in the mouth. Fig. 7_Same digital data set: preparation for the fabrication of the zirconium oxide crowns (Zenostar Zr Translucent) with CAD/CAM equipment. 22 I CAD/CAM 2_2015 Fig. 5 Fig. 6a Fig. 6b Fig. 7

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