The accuracy of reverse scan body technique for capturing full-arch digital implant impressions: An in vitro study

This study assessed the accuracy of full-arch implant prostheses milled using a reverse scan body (RSB) impression technique compared to those generated from a digitized master cast using a desktop scanner.

A mandibular All-on-4 master cast was created and digitized using a reference desktop scanner. For each RSB scan (Group 1), an interim milled polymethylmethacrylate (PMMA) prosthesis was picked up from the cast, RSBs were hand-tightened, and captured using an intraoral scanner (IOS). For Group 2, abutment-level scan bodies were hand-tightened into the multiunit abutments (MUAs) of the master cast and scanned using a desktop scanner. The deviation between each resultant scan from each group was digitally compared to the MUAs position of the digitized master cast. The digital deviation and clinical passivity (modified one screw and screw resistance tests) between the milled zirconia prosthesis from each group were compared to the master cast.

The deviation of the RSB-IOS impression (median = 0.07 mm) was statistically significant (p = 0.015) when compared to the desktop scan impression (median = 0.05 mm). For the milled zirconia prostheses, a similar statistically significant difference was observed with corresponding deviation values of 0.15 ± 0.02 and 0.11 ± 0.01 mm for the RSB and the desktop scanner groups, respectively. The passivity of the zirconia prostheses on the master cast showed variability when judged by three outcome assessors.

The RSB technique was inferior to the desktop scan in terms of digital impression and definitive prostheses accuracy. However, the RSB technique produced zirconia prostheses within the clinically acceptable deviation value of 0.15 mm.