The influence of the superimposition procedure and type of intraoral impression on the superimposition accuracy of CBCT scans with dental impressions in implant planning: an in-vitro study.

Purpose: The aim of this study was to investigate the superimposition of CBCT data with virtual models of the oral situation directly generated using an IOS and with indirectly generated plaster models.

Methods: Two different radiopaque jaw models were first scanned using a CBCT unit. Secondly, ten scans using an IOS and ten alginate impressions were made. The alginate impressions were cast with plaster and the plaster models were digitized using a laboratory scanner. Virtual Reference models generated with an industrial scanner were superimposed with the data sets of the virtual models using both a best-fit procedure on the palate and on the teeth. Deviations in two toothless areas were statistically evaluated.

Results: The superimposition of the directly generated models with the CBCT-based datasets showed lower deviations. Lower deviations were also calculated for the best-fit based on the teeth. The lowest deviations were found for model 1 with direct modeling and superimposition over the teeth with 0.008 mm (indirect: 0.210 mm; P = 0.001) and for model 2 with 0.010 mm (indirect 0.106 mm; P = 0.002).

Conclusions: Virtual models of the oral situation generated directly using an IOS are better suited for superimposing with CBCT-based datasets than indirectly generated ones. The best-fit on the teeth is superior to that on the palate.