Accuracy of complete-arch digital implant impression with or without scanbody splinting: an in vitro study

Objectives: To assess accuracy of implant complete-arch digital impression with intraoral scanner (IOS) and implant scanbody splinting (ISS).Methods: An edentulous mandibular model with 4 analogues was fabricated. Four polyetheretherketone (PEEK) implant scanbodies (ISBs) were scanned, according to a randomized sequence, by investigated IOS with (ISS+) and without implant scanbody splinting (ISS-), resulting in 30 test and 30 control files. The model was digitized by industrial optical scanner and the related file superimposed to the test and control files by a best fit algorithm. Linear (Delta X, Delta Y and Delta Z-axis) and angular deviations (Delta ANGLE) were evaluated for each analogue. A global measure of linear absolute error (Delta ASS) was calculated considering the sum of absolute linear discrepancies. Influence of ISS and implant position on IOS accuracy was assessed using General Linear Model and possible interaction between ISS and implant position evaluated.Results: Implant position showed a significant main effect (p<0.0001) and interaction with ISS (p=0.0454) when Delta ASS was considered as response variable. Posterior implants resulted as less accurate. ISS was able to reduce Delta ASS for both distal analogues (4.7, p=0.0188). When Delta ANGLE was considered as a response variable, implant position and ISS showed significant main and interactive effects (p=0.0039, p<0.0001, p<0.0001). Analogue 3.6 was associated with highest angular discrepancy. This error was significantly reduced by ISS (p<0.0001).Conclusions: Complete-arch implant digital impression with scanbody splinting showed a significant improve-ment of the overall accuracy, particularly reducing linear and angular deviations at the most critical posterior implant positions.Clinical significance: : Intraoral scanner accuracy for implant complete-arch digital impression could be improved by a low cost, easy to assemble and use implant scanbodies splinting 3D printed modular chain.