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VOLUME 3 NO. 2 , 2019

ONLINE FIRST

Randomized Controlled Clinical Trial of All-Ceramic Single-Tooth Implant Reconstructions Using Modified Zirconia Abutments: Results at 5 Years After Loading
Andrea Laass / Irena Sailer / Ju¨rg Hu¨sler / Christoph H. F. Hämmerle / Daniel S. Thoma

Randomized Controlled Clinical Trial of All-Ceramic Single-Tooth Implant Reconstructions Using Modified Zirconia Abutments: Results at 5 Years After Loading

The objective of this trialstudy was to assess whether submucosal veneering of internally connectedzirconia abutments influences clinical, radiographic, and technical outcomes ofsingle-tooth implant-borne reconstructions at 5 years after loading. A total of20 patients with 20 single-tooth implants in the anterior or premolar area ofthe maxilla or mandible were included. The implants were randomly restored withfixed single-tooth reconstructions using either pink-veneered customizedzirconia abutments (test group = 10) or nonveneered customized zirconiaabutments (control group = 10). All reconstructions were adhesively cementedwith all-ceramic crowns. Follow-up examinations were performed at baseline (7to 10 days after crown insertion) and at 1, 3, and 5 years after loading, atwhich points the following were assessed: periodontal parameters such asprobing depth (PD), bleeding on probing (BOP), and marginal bone levels, aswell as technical outcomes using the modified United States Public HealthService (USPHS) criteria. Statistical comparisons were based on theWilcoxon-Mann-Whitney test. Sixteen patients attended the 5-year follow-up. At5 years, the implant survival rate was 100% and the prosthetic survival ratewas 94.1% (one abutment fracture in the test group). Veneering of the submucosalpart of zirconia abutments resulted in significantly higher mean PD values: 3.6± 0.4 mm (test group) and 3.0 ± 0.5 mm (control group), P = .042. Marginal bonelevels at 5 years and changes up to 5 years were not significantly differentbetween groups (P > .05). One crown exhibited an abutment fracture and twocrowns a minor chipping (17.6% overall technical complication rate). Limited bya small sample size, veneering of the submucosal part of internally connectedzirconia abutments led to outcomes that were less favorable biologically (PD,BOP, and KM), but similar to nonveneered abutments radiographically andtechnically.