Background 
In spite of lacking evidence for advantages of substitutes over titanium, it seems that there is a basic movement of patients and dentists toward the use of metal free solutions also in implant dentistry. This tendency is strongly supported by of a growing cohort of patients with concerns over titanium sensitivity, allergies or intolerances irrespective of only weak evidence for clinical relevance as well as clinical concerns regarding aesthetic outcomes in the anterior region.

Aim/Hypothesis 
The aim of this study was to evaluate the outcomes of all-ceramic crowns on two-piece zirconia implants in a prospective randomized controlled study after up to 80 months

Materials and Methods 
21 patients with a total of 28 implants (14 zirconia and 14 titanium) were reviewed up to 80 months following restoration. Bleeding on probing (BOP), plaque index (PI), pink aesthetic score (PES), mean radiographic marginal bone resorption, and implant survival was determined.

Results 
After a mean observation time of 80.9 months (SD ± 5.5) the following data were assessed: Mean marginal bone level of        -1.38mm at zirconia (SD ± 0.81) and -1.17mm at titanium implants (SD ± 0.73). BOP of 16.43% (SD ± 6.16) at zirconia and 12.60% (SD ± 7.66) at titanium implants. PI of 11.07% (SD ± 8.11) at zirconia and 15.20 % (SD ± 15.58) at titanium implants. PES of 11.38 (SD ± 0.92) at zirconia and 11.56 (SD ± 1.01) at titanium implants respectively. Two zirconia implants and 1 titanium were lost within the evaluated period after implant surgery resulting in a survival rate of 85.7% for zirconia and 93.3% for titanium implants.

Conclusions and Clinical Implications 
In the present pilot trial no significant differences between adhesively luted zirconia abutments and all-ceramic restorations on two-piece zirconia implants could be observed after up to 80 months compared to a titanium control group. The small study population needs to be taken in consideration when interpreting the results.

All-ceramic restoration of zirconia two-piece implants ñ a randomized controlled clinical pilot trial - results of up to 80 months