The purpose of this study was to evaluate the accuracy of intraoral scanners by comparing the trueness and precision of two types of intraoral scanner and one type of extraoral scanner in measuring the distance between pairs of ball abutments in a model with multiple implants.
Four implants were placed on a lower jaw model for dental implant training. After ball abutments were attached to the implants on the reference model, the three-dimensional (3D) shape of the model was measured using a 3D coordinate-measuring machine. Subsequently, the 3D shape data of the model were obtained using two types of intraoral scanner (3M True Definition Scanner [TDS] and 3Shape Trios3 [TR3]) and one type of extraoral scanner (KaVo ARCTICA Auto Scan [KA]). Using the obtained 3D shape data, the trueness and precision in measuring the distance between pairs of the four ball abutments were compared among the scanners using 3D analysis software.
The intraoral scanner group had a greater error in the trueness and precision of the measurement site between the ball abutments than the extraoral scanner. The error in measurements with the intraoral scanners tended to increase with the distance between the ball abutments. Regardless of the distance, the extraoral scanner offered stable trueness and precision.
It is difficult to apply the current optical impression method using an intraoral scanner to a large number of missing teeth from the viewpoint of trueness and precision. The present findings suggest that intraoral scanners could be used for patients with a few missing teeth.
