Segmented Intraoral Scanning With a Palatal Marker for Complete-Arch Digital Implant Impressions: An In Vitro...

To compare four complete-arch implant impression workflows-segmented right/left IOS merged via a palatal marker (IOS-LEGO-Seg), continuous full-arch IOS with a palatal marker (IOS-LEGO-Full), continuous full-arch IOS without a palatal marker (IOS-Full), and a conventional open-tray PVS impression followed by cast fabrication and cast scanning (CI)-and to evaluate whether segmentation combined with a palatal marker improves agreement with a laboratory reference dataset in a maxillary edentulous model.

A maxillary edentulous dental cast with six implants was used to compare IOS-LEGO-Seg, IOS-LEGO-Full, IOS-Full, and CI. Intraoral scans were acquired, with 10 repetitions per condition. Datasets were superimposed onto a master reference scan using three alveolar-ridge markers; the palatal marker was excluded. The primary outcome was the concordance rate, defined as the proportion of intraoral scan body surface points within ±50 μm of the reference. A linear mixed-effects model was used to compare workflows (α = 0.05).

IOS-LEGO-Seg achieved the highest concordance, followed by IOS-LEGO-Full, IOS-Full, and CI (p < 0.001). The concordance rate was comparable between the IOS-LEGO-Full and IOS-Full groups, indicating that the addition of a palatal marker alone did not improve accuracy. Site-specific analysis revealed lower concordance at the distal molars (#16 and #26) in the non-segmented IOS workflows; however, this effect was mitigated by the segmented approach. The CI group did not show site-specific differences.

The segmented workflow with a palatal marker may represent an accessible strategy for improving the accuracy of maxillary complete-arch implant impressions.