Revisiting the marginal gap in the digital dental age - Clinical relevance of finish line location in IOS-based...

Digital workflows have been increasingly being used in prosthodontics, but differences between conventional impressions and intraoral scans are still not fully understood. One important aspect is the finish line, as previous studies suggest that preparation margins captured with intraoral scanners (IOSs) are often located more coronally compared to those obtained from conventional impressions. While these vertical deviations can be quantified digitally, it remains unclear whether they are clinically detectable and which of the 2 finish lines represents the more accurate trueness. In this article, preparation margins from a digitized master cast and from an IOS dataset were compared using 3D analysis. Vertical deviations of up to 730 µm were measured, with the IOS-based margins lying more coronally in certain areas. To explore whether these differences are clinically relevant, 2 fixed dental prostheses were fabricated- one based on the conventional workflow and one based on the digital workflow. Both restorations were evaluated intraorally by 2 blinded clinicians. Both considered the FDPs to be clinically acceptable, although there were deviations in their evaluation.