Evaluation of the accuracy of digital workflow for implant-supported full-arch fixed dental prostheses using a novel micro-CT measurement technique.

Purpose: This study aims to evaluate the accuracy of fit of full-arch implant titanium frameworks fabricated from a fully digital workflow using a novel micro-CT measurement technique.

Materials and methods: A 3D-printed model with four implant analogs was fabricated. A baseline micro-CT was obtained after placing temporary cylinders on the model. Next, the printed model was scanned with an intraoral scanner (TRIOS 5), and the STL files were used to fabricate 10 titanium frameworks. Each framework was placed back on the model, and another micro-CT was taken under two conditions: single screw test (SST-CT) and final fit test (FFT-CT), and the measurements were compared to the baseline. Framework passivity was evaluated using a single-screw test (SST) and a screw-resistance test (SRT). The accuracy of the intraoral scans was assessed by superimposing the 10 scans with a laboratory scan STL to determine if the misfit was due to scanning or milling and designing errors.

Results: None of the frameworks was deemed acceptable using SST-CT, and only three had an acceptable fit using FFT-CT. SST and SRT non-passivity rates were 60% and 80%, respectively. Superimposition analysis revealed that only two intraoral scans used for framework fabrication fell within the acceptable deviation range of 150 microns, suggesting a high tendency for scanning errors and a possible milling or designing error in two samples.

Conclusion: The results show a significant level of misfit. This suggests that the full-digital workflow for full-mouth rehabilitation can present some limitations. Due to the rapid advancement in intraoral scanning, further studies are required to validate these findings.