Objectives There are no in vivo studies comparing multiple intraoral scanners for the completely edentulous maxilla to PVS impressions. Investigations comparing intraoral scanners to polyvinyl siloxane impressions focus on comparing the overall scan and not individual anatomical regions. This study aims to evaluate two intraoral scanners and compare the results for different anatomical regions on the completely edentulous maxillary arch.

Materials and methods Nineteen patients were recruited with a completely edentulous maxilla. A custom tray was constructed, and a sectional border moulded polyvinyl siloxane impression was made then scanned. An intraoral scan of the edentulous maxilla with a Trios 4 (3Shape, B/V) and Medit i700 (Medit corporation) was then captured. The scans were analysed for negative and positive surface deviations along with root mean square for distinct anatomical regions compared to the polyvinyl siloxane impression. A two-way ANOVA followed by Tukey HSD post hoc tests for each scanner was conducted for all anatomical regions to determine differences between the regions.

Results There was no significant difference between the two intraoral scanners included in this study for all anatomical regions or for the overall scan (0.435, 0.38), palatal vault (0.18, 0.181), ridge (0.218, 0.209), and post dam (0.233, 0.229) anatomical regions. Significantly higher deviation (p<0.05) was observed for the peripheral regions (0.607, 0.557) for each intraoral scanners Trio 4 and Medit i700.

Conclusion Different intraoral scanners can capture all areas of a completely edentulous maxilla consistently, when compared to a polyvinyl siloxane impression, apart from the peripheries.

Clinical significance Care should be taken when scanning the peripheries. These regions are problematic to capture with an intraoral scanner. Border moulding should still be considered the optimal impression technique for the completely edentulous maxilla. The intraoral scanners investigated did not make a difference for the anatomical regions investigated.