One‐piece versus two‐piece zirconia abutment supported single implant crown in the esthetic region: 3‐Year results from a split‐mouth randomized controlled clinical trial

Abstract

ObjectivesTo compare the clinical, radiographic, and immunological outcomes between one‐piece versus two‐piece zirconia abutments supported single implant crowns in the esthetic region.Materials and MethodsThe study followed a split‐mouth, double‐blind, and randomized controlled clinical design for a duration of 3 years. Twenty‐two eligible patients with 44 implants were randomly assigned to two groups: Group 1 (one‐piece zirconia abutment with zirconia base, n = 22) and Group 2 (two‐piece zirconia abutment with titanium base, n = 22). The primary outcome was the technical complication rate. Additionally, survival rates, cytokines concentrations in peri‐implant crevicular fluid (PICF), peri‐implant conditions, marginal bone loss, and pink/white esthetics score (PES/WES) were assessed as secondary outcomes.ResultsTwelve of 22 patients attended the 1‐year follow‐up (due to the COVID pandemic), and 19 patients attended the 3‐year examination. Two abutments in Group 1 were fractured after 10 and 12 months in function. Additionally, one screw loosening occurred in Group 1 at 1‐year follow‐up. The 3‐year technical complication rate was significantly higher in Group 1 than that in Group 2 (15.79% vs. 0%, p < .001). The 3‐year implant survival rate was 100% in both groups. The concentration of IFN‐γ in PICF was significantly upregulated in Group 2 (p = .018). Furthermore, the IL‐6 concentration was positively correlated with BOP% (p = .020).ConclusionsTwo‐piece zirconia abutments exhibited superior technical performance compared to one‐piece designs during a 3‐year follow‐up in the anterior region. However, further long‐term research is necessary to verify the immunological stability of two‐piece zirconia abutments.