Influence of implant scanbody wear on the accuracy of digital impression for complete-arch: a randomized in vitro trial

The aim of this study was to evaluate the influence of implant scanbody (ISB) wear on the accuracy of digital impression for complete-arch. A polymethylmethacrylate (PMMA) edentulous mandibular model with four internal hexagonal interlocking conical connections was scanned with an extraoral optical scanner to achieve a reference file. Four cylindrical polyetheretherketone (PEEK) ISBs were scanned 30 times with IOS, and the test files were aligned to the reference file with a best-fit algorithm. For each analog linear (Delta X, Delta Y and Delta Z-axis) and angular deviations (Delta ANGLE) were assessed. Euclidean distance (Delta EUC) was calculated from the linear deviation, reporting a mean of 82 mu m (SD 61) ranging from 8 to 347 mu m. Delta ANGLE error mean was 0.33 degrees (SD 0.20), ranging from 0.02 to 0.92 degrees. From a multivariate analysis, when Delta EUC was considered as a response variable, a significant influence of ISB wear by scan number in interaction to position for implant 3.6 was identified (p < 0.0001); when Delta ANGLE was considered as a response variable, a significant effect of position 3.6 was recorded ((p < 0.0001). The obtained results showed that the ISB wear negatively influenced the accuracy of IOS, suggesting that ISB base wear could be detrimental for the seating of ISBs on angulated implants.