Model-free digital-correction workflow for multi-implant restorations: A clinical proof-of-concept study

This clinical proof-of-concept study evaluates the feasibility and accuracy of a digital workflow for fabricating and correcting implant-supported restorations of multiple dental implants in an edentulous maxilla using intraoral scanning and reverse-scan bodies.

An intraoral scan (IOS) was performed using vertical scan bodies in one patient with four implants in the edentulous maxilla. Ten verification bars (VB) were fabricated and clinically assessed. Nonpassive VBs were sectioned and reconnected intraorally (splinted verification bars, SVBs) and then scanned using reverse-scan bodies and a laboratory scanner. New verification bars (NVB) were fabricated based on these data. The linear and angular deviations between the implants were analyzed across the IOS, VBs, SVBs, and NVBs. Statistical analysis included Welch's ANOVA and post hoc testing (α = 0.05).

None of the VBs achieved a clinically passive fit. IOS-VB comparisons showed mean linear deviations of 14-77 µm, with four measurements >100 µm. Mean deviations between VBs and SVBs ranged from 35 to 173 µm, with 20 measurements >100 µm. In contrast, SVB-NVB mean deviations ranged from 4 to 27 µm, with only one >100 µm. All NVBs demonstrated a clinically passive fit and no significant differences were observed between the SVBs and NVBs (P > 0.05).

Under the specific conditions of this proof-of-concept study, a combined digital-correction workflow using reverse-scan bodies and integrated titanium base abutments achieved clinically acceptable outcomes. However, multiple variables were modified simultaneously; therefore, the contribution of each step to the final passive fit could not be isolated.