Influence of implant scanbody material, position and operator on the accuracy of digital impression for complete-arch: A randomized in vitro trial

Purpose: To evaluate the influence of implant scanbody (ISB) material, position and operator on the accuracy of a confocal microscopy intraoral scanning (IOS) for complete-arch implant impression. Methods: An edentulous maxillary model with 6 internal hexagonal connection analogues was scanned with an extraoral optical scanner to achieve a reference file. Three ISBs made of different materials (polyetheretherketone (Pk), titanium (T) and Pk with a titanium base (Pkt)) were scanned with IOS by 3 operators. The resulting 45 test files were aligned to the reference file with a best fit algorithm. Linear (Delta X, Delta Y and Delta Z-axis) and angular deviations (Delta ANGLE) were assessed. Absolute values of the linear discrepancies were summed up to obtain a global measure of linear absolute error (Delta ASS). Influence of ISB material, position and operator was statistically assessed using the mixed general linear model. Results: At multivariate analysis, when Delta ASS was considered as response variable, it was identified a significant influence of material (p <0.0001) and position (p= 0.0009) while no significant operator effect was detected. When Delta ANGLE was considered as response variable, material and position significantly influenced the expected Delta ANGLE (p =0.0232 and p <0.0001) and no operator effect was identified. Conclusions: The investigated IOS for complete-arch digital impression was influenced by the ISB material with peek reporting the best results on both linear and angular measurements followed by titanium, peek-titanium resulting as the less accurate. Implant angulation affected significantly the linear deviations while implant position the angular deviations. Operator did not show any significant effect on the IOS accuracy. (C) 2019 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.