Crowns fabricated out of monolithic all-ceramic materials appear to be a clinically good alternative to conventionally produced all-ceramic restorations with a core material and layered veneering ceramic in teeth (Bindl & Mörmann 2007). Monolithic crowns may be also suitable for implant-borne reconstructions. Digital technologies can be used to design (computer-aided design – CAD) and fabricate (computer-aided manufacturing – CAM) such reconstructions. By using CAD/CAM procedures, the fabrication time and thus the associated production costs for the reconstructions can be kept low. CAD/CAM systems can be found in both dental laboratories (lab-side) and dental offices (chair-side). Three steps can be defined in the workflow of CAD/CAM reconstructions: 1. Taking a digital impression by means of an intraoral scanner, 2. Digitally designing the reconstruction (CAD) and 3. Machining the digitally designed reconstruction out of a pre-fabricated ingot (CAM) (Beuer et al. 2008; Fasbinder 2013). The most common digital impression systems are the True Definition Scanner (3M, St. Paul, Minnesota, USA), the iTero (Align Technology, Inc. San Jose, California, USA) systems and the TRIOS (3 Shape, Copenhagen, Denmark) (Fasbinder 2013). These systems are devices that were used exclusively for impression-taking in the dental office. The digital data files are then transmitted to the dental laboratory or for centralized production (Beuer et al. 2008). The Cerec Omnicam, Cerec Bluecam (Sirona, Bensheim, Germany) and the E4D Dentist system (Planmeca, Helsinki, Finland) are currently the only CAD/CAM systems available that allow the dentist to perform all three steps of the CAD/CAM process to be integrated in the dental office (Fasbinder 2013).

As the biting forces in the posterior region are high, the use of high-strength monolithic materials may be advantageous when it comes to restoring implants in the premolar and molar area. Especially as it is known that the threshold value for tactile perception in implants is more than 8-fold higher compared with teeth (Hämmerle et al. 1995). For this purpose, materials such as lithium disilicate glass-ceramic and yttrium oxide partially stabilized zirconia (Y-TZP) are available to produce full-contour reconstructions. Y-TZP shows good mechanical properties with a flexural strength of 900 MPa (Strub et al. 2010). However, choosing the strongest available full-ceramic material brings the disadvantage of compromised esthetic outcomes due to the high opacity of Y-TZP. In recent years, improvements have been made to make Y-TZP more translucent (Fehmer et al. 2014). Nevertheless, in esthetically high demanding indications, Y-TZP may not be the material of choice. In contrast, lithium disilicate shows better optical properties and can still reach a flexural strength of 350 MPa (Strub et al. 2010).

Monolithic crowns can be manufactured out of Y-TZP or lithium-disilicate blanks. The milled restorations can then be adhesively luted on prefabricated titanium-implant abutments or titanium resin bases, which are provided by different manufacturers for the chair-side or the lab-side fabricated implant reconstructions.

This case presentation displays the workflow and the production steps of two different monolithic implant reconstructions using a chair-side and lab-side system for the digital impression and the CAD/CAM procedures. The aim of this case report was to compare the two different workflows and their potential benefits and limitations as well as the material properties of two different reconstruction types.