Influence of Abutment Fabrication Method on 3D Fit at the Implant-Abutment Connection

To three-dimensionally evaluate the internal fit at the implant-abutment interface of abutments fabricated with different workflows using a combination of the silicone replica technique and microcomputed tomography (μCT).

Thirty abutments were fabricated to restore internal-connection implants and were divided into three groups according to fabrication method: (1) full digital (abutment machined using CAD/CAM system); (2) Ti-Base (prefabricated standard Ti-Base abutments); and (3) UCLA (UCLA-type abutments) (n = 10/group). Linear and volume measurements were performed to assess the internal misfit using a silicone replica of the implant-abutment interface misfit area, which was three-dimensionally reconstructed after μCT. The internal discrepancies in three different regions of interest (Gap_superior, Gap_marginal, and Gap_center) were assessed. Data were statistically evaluated using ANOVA and Tukey test (P < .05).

Ti-Base and UCLA abutments presented significantly lower misfit volume (0.49 mm³, 95% CI: ± 0.045 mm³ and 0.48 mm³, 95% CI: ± 0.045 mm³, respectively) and mean internal gap (25.20 μm, 95% CI: ± 3.14 μm and 27.97 μm, 95% CI: ± 3.14 μm, respectively) than the full digital group (0.70 mm³, 95% CI: ± 0.045 mm³; 34.90 μm, 95% CI: ± 3.14 μm) (P < .001), but did not differ from each other (P = .825). While Gap_center was significantly higher in the full digital group (P < .001), Gap_superior and Gap_marginal did not demonstrate significant differences among groups. All regions were statistically similar within groups, except for Gap_center in the full digital group, which exhibited higher mean values compared to the other regions (P = .000). The 3D measurements for quantification of internal discrepancy were strongly associated with the 2D measurements.

Ti-Base and UCLA abutments exhibited better internal fit at the implant-abutment interfaces compared to a fully digitalized workflow (CAD/CAM custom abutments).