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ePaper created 2015-09-09, 12:07:54 | version 1.38.0
review _ implant abutment I colour change. Zirconium dioxide did not induce visible colour changes in 2 and 3mm thick mucosa.6 With the background of the available clinical evidence and systematic reviews, no differences were found between zirconium dioxide and metal abutments in clinical performance based upon aesthetic, technical, or biological outcomes.7–10 In vitro studies have shown statistically signifi- cant greater wear of zirconium dioxide than of titanium abutments inside the titanium im- plant.11 However, the clinical relevance remains unclear. In our clinic, we have been using Straumann CARES CAD/CAM fabricated zirconium dioxide abutmentssince2009onadailybasisinaesthetic cases with bone level implants, and have had no issues with abutment fractures so far. The correct CAD/CAM design of a zirconium dioxide abut- ment and the quality and precision of the con- necting part into the implant play a crucial role in long-term success. Focusing on the outcome of histological studies, an in vivo study shows that there were no visible differences in soft tissue health in peri-implant mucosa adjacent to zirco- nium dioxide and titanium abutment surfaces.12 Another study found that soft tissue around zir- conium dioxide heals faster than when in contact with titanium.13 A systematic review14 evaluating the existing literature on zirconium dioxide abutments con- cludesbasedonevidencefromanimalandhuman histological studies that zirconium dioxide is as suitable a material for dental implant abutments as titanium. Regarding plaque accumulation, zirconium dioxide appears to have a lower ten- dency for surface-bound bacterial plaque in early stages, which is advantageous. _Conclusion and clinical recommendation Abutment selection in aesthetic sites Implant abutments are located in a transition zone where they are in contact with the implant and the surrounding peri-implant tissues. There- fore, the choice of abutment is of major impor- tance, especially in a sensitive region like the aesthetic zone. For single-unit reconstructions, zirconium dioxide abutments are indicated, which can be either standard or customised depending on the prosthetic position of the implant. For multi-unit reconstructions, zirconium dioxide abutments are recommended for cement-retained bridges, I 15CAD/CAM 3_2015 Fig. 12Fig. 11 Fig. 14 Fig. 13