The development of new high strength ceramic abutments can enhance the overall aesthetic outcome of an implant-supported prosthesis. This study was to compare the clinical application of alumina and zirconia ceramic implant abutments in the anterior region. Twenty-three consecutive patients requiring single-tooth implants in the anterior region were randomized to receive either an alumina ceramic abutment (CeraAdapt) or a zirconia ceramic abutment. All-ceramic (IPS-Empress 2) crowns were then fabricated and cemented over the abutments with composite cement. Peri-implant mucosal health and bone levels were evaluated by the gingival index and radiographs at 2-week and 1-year follow-up. Aesthetic outcomes as well as technical problems with the restorations were evaluated during the observation period from 12 to 48 months after functional loading. A total of 17 alumina ceramic abutments and 18 zirconia ceramic abutments were evaluated. No patients dropped out during the study period. Eighteen out of the 23 patients maintained good function throughout the study. The median observation period was 21 months. Ceramic crown loosening was found in two restorations at 1-week and 2-years respectively after insertion. One ceramic crown fractured at 1 week after insertion. At 1-year follow-up, mean marginal bone loss around implants was 1.2 +/- 0.5 mm and the peri-implant mucosa in relation to abutment or crown was healthy with a mean gingival score of 0.6 +/- 0.2. All patients were satisfied with the final aesthetic outcome. However, two alumina abutments fractured after two years of loading. In conclusion, both ceramic abutments have shown a favourable biological response and aesthetic outcome; however, zirconia abutments with their superior mechanical properties might be better for supporting single-tooth implant restorations in the aesthetic zone.