To evaluate the accuracy of superimposition of customized abutment library data onto scanned abutment data according to the extent of the scanning area.

A patient model was fabricated by a 3D printer (Probo, DIO Implant), and a customized abutment was fabricated using a four-axis milling machine (ARUM 4X-100, Doowon). The customized abutment library data were generated using a laboratory scanner (E3, 3Shape) for superimposition after intraoral scanning. A cone-shaped structure was embedded into the library data at the center of the connection part. The customized abutment was placed on the model, and the model was scanned using a laboratory scanner to produce reference data. Three different test group datasets were generated using intraoral scanner and computer-aided design software: (1) fully scanned customized abutment; (2) insufficiently scanned proximal surface; and (3) insufficiently scanned margin, assuming challenging intraoral conditions. The library data were superimposed onto each test group; thereafter, the distance and angle between the reference and test group data were analyzed by using the embedded cone. Statistical analysis was performed using one-way analysis of variance followed by post hoc Tukey test for multiple comparisons.

There were no statistically significant differences between the mean distance and angle of the test group data (with three different scanning areas) and the reference data.

The superimposition technique can be used clinically, not only when the scan is complete, but also when the proximal surface and margin of the customized abutment have been scanned incompletely.