Accuracy of complete-arch, all-on-4 implant scans under simulated intraoral variables

The aim of the present study was to investigate the accuracy of complete-arch digital scans for all-on-4 implant treatment under simulated intraoral variables.

A maxillary model designed to receive four implants in the regions of first molars and canines was used. Intraoral digital scans were completed in a simulation device by simulating two different clinical scenarios (normal intraoral variables [NIV] and limited intraoral variables [LIV]). Digital scans were obtained using five different IOSs: Trios 3, Primescan, iTero 2, Medit i500, and Aadva IOS. Ten scans of each IOS were made and exported as STL files. Assessment of precision and trueness was conducted with a 3D software analysis program. A total of 100 STL files were used for trueness evaluation. Each STL file was individually aligned with the reference scan using the best fit algorithm tool, and 3D differences were calculated using the root mean square (RMS) value.

Regarding trueness, repeated-measure analyses of variance and Bonferroni comparison tests revealed significant differences between the subgroups based on different IOSs, intraoral variables, and implant locations (P 0.001). The Aadva IOS presented significantly higher mean RMS values than Trios 3, Primescan, iTero 2, and Medit i500 (P 0.001). Implant locations 26 and 16 significantly affected the RMS values in all IOS groups (P 0.001), and implant locations 13 and 23 presented no significant difference (P > 0.05). Regarding precision, significant differences were found among different IOSs, intraoral variables, and implant locations (P 0.001). The lowest mean RMS values were obtained in the Trios 3 group with the implant locations of 13 and 23 under NIV. The shortest scanning time was recorded in the Primescan group under NIV, followed by Trios 3, Aadva IOS, iTero 2, and Medit i500. The scanning time was extended under LIV for all IOSs tested.

Accuracy and scanning time of complete-arch all-on-4 implant scans were affected by intraoral variables. Simulating intraoral variables while testing IOSs might help to better validate their clinical use.