Evaluation of Angle Changes in Reverse Margin Abutments on Excess Cement: A Comparison With Standard Implant Abutment Margins

Abstract

Dental implants are widely used for treating edentulism, but peri-implant diseases pose a challenge to their success. Excess cement in the gingival sulcus is a significant risk factor for these conditions. Reverse margin abutments have been suggested to minimize excess cement and related risks. This study aims to evaluate the effect of different reverse angles in abutments on reducing excess cement in the gingival sulcus. In this in vitro study, 3 abutments were designed using Solidworks Premium 2023 software: 1 with a chamfer margin and 2 with reverse margins at 30 degrees and 45 degrees angles. Each group consisted of 10 samples (n = 10). The abutments were fabricated using Ti-6Al-4V alloy via 3D printing. Crowns for the maxillary first molar were designed using computer-aided design/computer-aided manufacturing technology and made from zirconia. Thirty fixtures from the Straumann bone-level implant system (GH = 2, diameter 4.5 mm) were mounted in acrylic blocks, and the abutments were positioned on the fixtures. Temp-Bond temporary cement was applied under a pressure of 4 kg. After the cement had set, photographs were taken and analyzed using Adobe Photoshop 2024. The cement extension beyond the margin was quantified in both millimeters and pixels. Data were analyzed using Kruskal-Wallis and Mann-Whitney tests (alpha = .05). The abutment with a chamfer margin directed the cement toward the apical region, whereas the abutments with reverse margins pushed the cement outside the tissue. The reverse margin abutment with a 30 degrees angle showed a significantly lower excess cement than the chamfer margin abutment (P = .013). Similarly, the reverse margin abutment with a 45 degrees angle had significantly less excess cement than the chamfer margin abutment (P < .001). There was no statistically significant difference between the reverse margin abutments at 30 degrees and 45 degrees angles (P > .05). Using reverse margin abutments instead of chamfer margin abutments significantly reduced the remaining excess cement in the gingival sulcus. However, altering the angle of the reverse margin from 30 degrees to 45 degrees does not significantly impact the overall amount of residual cement.