An impression was made at implant level 2 weeks after the second stage of the surgery in order to fabricate a single crown. A definitive full-zirconia crown (yttria-stabilized zirconium oxide) with an angulated screw channel (NobelProcera FCZ Implant Crown, NobelBiocare AB) was manufactured in the determined colour at a centralized milling facility (NobelProcera Service Center, Mahwah, NJ, USA) and then stained and glazed at a dental laboratory to attain the final colour (Ceram Essence and Ceram Glaze Paste, Ivoclar Vivadent, Schaan, Liechtenstein). The adapter and crown were assembled and screw-retained onto the implant with a torque of 35Ncm. The screw access hole was sealed with a cotton pellet and light-curing composite material (Fig. 2). The design of the occlusal surface allowed functional loading of restoration and implant. Immediately after placing the restoration, thorough oral hygiene instructions were given to all the patients.

Clinical and radiographic evaluations were performed 1 month and 1 year after restoration placement. The following criteria were considered:

Implant survival. The survival rate of the implant was assessed 1 year after definitive restoration placement. An implant was defined as a failure when it was deemed necessary to remove the implant because of implant mobility as a consequence of loss of osseointegration;

The marginal bone level as measured on standardized intraoral radiographs;

Assessment of plaque accumulation with the modified Plaque Index [16];

Assessment of bleeding tendency with the modified Sulcus Index [16];

Assessment of peri-implant inflammation with the Gingival Index [17];

Presence of calculus

Probing pocket depth: measured to the nearest millimetre using a manual periodontal probe (Williams-Sulcus color-coded probe, Hu-Friedy, Chicago, IL, USA). The peri-implant sulcus was probed at four sites (at the mesial, distal, buccal and lingual/palatal side);

Restoration survival;

Complications related to the restoration;

Patients’ satisfaction. Patients were asked to complete a questionnaire 1 year after restoration placement;

Success rate: calculated from the criteria of success as proposed by Albrektsson and colleagues in 1986 [18].